Strong isolation by distance and evidence of population microstructure reflect ongoing Plasmodium falciparum transmission in Zanzibar

The Zanzibar archipelago of Tanzania has become a low-transmission area for Plasmodium falciparum. Despite being considered an area of pre-elimination for years, achieving elimination has been difficult, likely due to a combination of imported infections from mainland Tanzania, and continued local transmission. To shed light on these sources of transmission, we applied highly multiplexed genotyping utilizing molecular inversion probes to characterize the genetic relatedness of 282 P. falciparum isolates collected across Zanzibar and in Bagamoyo District on the coastal mainland from 2016-2018. Overall, parasite populations on the coastal mainland and Zanzibar archipelago remain highly related. However, parasite isolates from Zanzibar exhibit population microstructure due to rapid decay of parasite relatedness over very short distances. This, along with highly related pairs within shehias, suggests ongoing low level local transmission. We also identified highly related parasites across shehias that reflect human mobility on the main island of Unguja and identified a cluster of highly related parasites, suggestive of an outbreak, in the Micheweni district on Pemba island. Parasites in asymptomatic infections demonstrated higher complexity of infection than those in symptomatic infections, but have similar core genomes. Our data support importation as a main source of genetic diversity and contribution to the parasite population on Zanzibar, but they also show local outbreak clusters where targeted interventions are essential to block local transmission. These results highlight the need for preventive measures against imported malaria and enhanced control measures in areas that remain receptive for malaria reemergence due to susceptible hosts and competent vectors.

A call for change: addressing the implementation strategy using pre exposure Prophylaxis for combating the escalating HIV crisis in Zanzibar's key populations

The Integrated Bio-Behavioural Surveillance Survey of 2022-2023 among key populations report from Zanzibar has been released. The prevalence of HIV is estimated to be 21.1%, 11.4%, and 9.3% among Female Sex Workers, Men who have Sex with Men, and People Who Injected Drugs, respectively. This has prompted a closer examination of the factors contributing to this trend, with a particular focus on the low coverage of Pre-Exposure Prophylaxis in these key populations. The current prevalence reported in December 2023 signals a critical turning point that necessitates a reevaluation of the barriers and facilitators of Pre Exposure Prophylaxis intervention to combat the epidemic. It is imperative to acknowledge the severity of the situation and take decisive action to prevent further spread of the virus in the Isles.

Perception of residents on the impacts of beach tourism: The case of Nungwi village in Zanzibar, Tanzania

This study aimed to assess the perception of residents on the impacts of beach tourism in Nungwi village, one of the most lively beach tourist spots in Zanzibar, Tanzania. Data collection was carried out between June and August 2021 from 174 residents using a structured questionnaire. Descriptive statistics, T-tests and One-way ANOVA were employed. The revealed positively perceived impacts include the increase in entrepreneurial opportunities, employment, and access to basic social services. The study also identified the increase in income inequalities as well as cost of living to be the key aspects perceived negatively by the residents. The findings suggest occupation is a key differentiating factor in the association of tourism development to residents' pride in local culture, with corporate employees and entrepreneurs more likely to view positive contribution of tourism to residents' pride in local culture than farmers and fishermen. Furthermore, the study confirmed the heterogeneity of residents' perceptions regarding tourism impacts which were caused by five key variables, namely: length of residence in the area, occupation type, sex, age, and level of income. The study findings help to increase the baseline knowledge available to tourism stakeholders and insights that may be considered when developing and implementing tourism-related policies and plans. The study contributes to the residents' perception literature in a rural developing country context.

The hidden effects of COVID-19 on HIV services in Zanzibar: country report

The COVID-19 pandemic has had a major effect on HIV-related healthcare services. Zanzibar has experienced several interruptions of HIV services in the areas of testing and counselling, prevention of mother-to-child transmission of HIV, key population, care and treatment services as well due to the hospital operating at a reduced capacity and the strict visit restrictions with health care allocations to COVID 19 pandemic. The community HIV initiatives, such as index testing and ARVs medicine refills, were used to mitigate the consequences of the epidemic and can be applied in future emergencies. This report tries to reveal COVID-19's unnoticed consequences on HIV services in Zanzibar.

The Journey of Zanzibar's Digitally Enabled Community Health Program to National Scale: Implementation Report

BACKGROUND

While high-quality primary health care services can meet 80%-90% of health needs over a person's lifetime, this potential is severely hindered in many low-resource countries by a constrained health care system. There is a growing consensus that effectively designed, resourced, and managed community health worker programs are a critical component of a well-functioning primary health system, and digital technology is recognized as an important enabler of health systems transformation.

OBJECTIVE

In this implementation report, we describe the design and rollout of Zanzibar's national, digitally enabled community health program-Jamii ni Afya.

METHODS

Since 2010, D-tree International has partnered with the Ministry of Health Zanzibar to pilot and generate evidence for a digitally enabled community health program, which was formally adopted and scaled nationally by the government in 2018. Community health workers use a mobile app that guides service delivery and data collection for home-based health services, resulting in comprehensive service delivery, access to real-time data, efficient management of resources, and continuous quality improvement.

RESULTS

The Zanzibar government has documented increases in the delivery of health facilities among pregnant women and reductions in stunting among children younger than 5 years since the community health program has scaled. Key success factors included starting with the health challenge and local context rather than the technology, usage of data for decision-making, and extensive collaboration with local and global partners and funders. Lessons learned include the significant time it takes to scale and institutionalize a digital health systems innovation due to the time to generate evidence, change opinions, and build capacity.

CONCLUSIONS

Jamii ni Afya represents one of the world's first examples of a nationally scaled digitally enabled community health program. This implementation report outlines key successes and lessons learned, which may have applicability to other governments and partners working to sustainably strengthen primary health systems.

Risk of imported malaria infections in Zanzibar: a cross-sectional study

BACKGROUND

Zanzibar has made substantial progress in malaria control with vector control, improved diagnosis, and artemisinin-based combination therapy. Parasite prevalence in the population has remained around 1% but imported infections from mainland Tanzania contribute to sustained local transmission. Understanding travel patterns between mainland Tanzania and Zanzibar, and the risk of malaria infection, may help to control malaria importation to Zanzibar.

METHODS

A rolling cross-sectional survey linked to routine reactive case detection of malaria was carried out in Zanzibar between May 2017 and October 2018. Households of patients diagnosed with malaria at health facilities were surveyed and household members were tested for malaria using rapid diagnostic tests and a sub-sample by quantitative PCR (qPCR). Interviews elicited a detailed travel history of all household members who had travelled within the past two months, including trips within and outside of Zanzibar. We estimated the association of malaria infection with travel destinations in pre-defined malaria endemicity categories, trip duration, and other co-variates using logistic regression.

RESULTS

Of 17,891 survey participants, 1177 (7%) reported a recent trip, of which 769 (65%) visited mainland Tanzania. Among travellers to mainland Tanzania with travel destination details and a qPCR result available, 241/378 (64%) reported traveling to districts with a 'high' malaria endemicity and for 12% the highest endemicity category was 'moderate'. Travelers to the mainland were more likely to be infected with malaria parasites (29%, 108/378) than those traveling within Zanzibar (8%, 16/206) or to other countries (6%, 2/17). Among travellers to mainland Tanzania, those visiting highly endemic districts had a higher odds of being qPCR-positive than those who travelled only to districts where malaria-endemicity was classified as low or very low (adjusted odd ratio = 7.0, 95% confidence interval: 1.9-25.5). Among travellers to the mainland, 110/378 (29%) never or only sometimes used a mosquito net during their travel.

CONCLUSIONS

Strategies to reduce malaria importation to Zanzibar may benefit from identifying population groups traveling to highly endemic areas in mainland Tanzania. Targeted interventions to prevent and clear infections in these groups may be more feasible than attempting to screen and treat all travellers upon arrival in Zanzibar.

Malaria elimination in Zanzibar: where next?

In 2018, Zanzibar developed a national malaria strategic plan IV (2018-2023) to guide elimination of malaria by 2023. We assessed progress in the implementation of malaria activities as part of the end-term review of the strategic plan. The review was done between August and October 2022 following the WHO guideline to assess progress made towards malaria elimination, effectiveness of the health systems in delivering malaria case management; and malaria financing. A desk review examined available malaria data, annual work plans and implementation reports for evidence of implemented malaria activities. This was complemented by field visits to selected health facilities and communities by external experts, and interviews with health management teams and inhabitants to authenticate desk review findings. A steady increase in the annual parasite incidence (API) was observed in Zanzibar, from 2.7 (2017) to 3.6 (2021) cases per 1,000 population with marked heterogeneity between areas. However, about 68% of the detected malaria cases were imported into Zanzibar. Malaria case follow-up and investigation increased from <70% in 2017 to 94% and 96% respectively, in 2021. The review noted a 3.7-fold increase of the health allocation in the country's budget, from 31.7 million USD (2017/18) to 117.3 million USD (2022/23) but malaria allocation remained low (<1%). The varying transmission levels in the islands suggest a need for strategic re-orientation of the elimination attempts from a national-wide to a sub-national agenda. We recommend increasing malaria allocation from the health budget to ensure sustainability of malaria elimination interventions.

Clinical features of upper gastrointestinal endoscopy in 3146 patients: a 9-year retrospective cohort study in Zanzibar Archipelago, Tanzania

Background/objectives

To investigate the demographic features, primary endoscopic findings, and the status of Helicobacter Pylori (H. pylori) infection of the enrolled subjects who underwent upper gastrointestinal endoscopy (UGIE) in the Zanzibar Archipelago, Tanzania.

Methods

Between December 2013 and October 2021, a total of 3146 eligible participants were finally recruited in present retrospective cohort. Demographic information and endoscopic findings of each participant was retrieved. H. pylori infection was confirmed by rapid-urease test of gastric antral and body biopsies at endoscopy.

Results

Among the recruited subjects, 1691 (53.76%) are females, remaining 1455 (46.24%) are males. The median age of this retrospective cohort was 40 years ranging from 8 to 97 years. The common identified endoscopic findings included gastro-duodenitis, normal endoscopic finding, peptic ulcer disease (PUD), esophagitis, esophagogastric varices, esophageal and gastric cancer, respectively. After adjustment for sex and age, a significant risk of gastric and/or duodenal ulcer (OR, 2.51; 95% CI, 1.82-3.48, P<0.001) and gastric cancer (OR, 3.49; 95% CI, 1.27-9.58, P=0.015) in H. pylori positive group was observed. Stratified analysis indicated a significant relationship between duodenal ulcer with younger age (adjusted OR, 0.98; 95% CI, 0.97-0.99, p = 0.002), and the presence of H. pylori (OR, 2.01; 95% CI, 1.12-3.91, p= 0.021).

Conclusions

The present study revealed that gastro-duodenitis, PUD, and normal finding are the most common endoscopic diagnoses in Zanzibar. The presence of H. pylori is significantly associated with duodenal ulcer and gastric cancer.

Stakeholder perspectives on a door-to-door intervention to increase community engagement for malaria elimination in Zanzibar

BACKGROUND

Malaria remains a major public health problem in sub-Saharan Africa. The 2021 World Health Organization (WHO) World Malaria Report indicates a slowing in the decline of malaria incidence since 2015. Malaria prevalence in Zanzibar has been maintained at less than 1% since 2010, however from 2018 to 2021, the annual number of reported malaria cases has gradually increased from 4106 to 9290. Community engagement has been emphasized by the WHO for reducing malaria transmission. To better understand the potential for a door-to-door approach for malaria, a three-month pilot programme was carried out. This qualitative study aimed at understanding stakeholder experiences with the pilot programme and considerations for its implementation.

METHODS

Through multistage sampling, four shehias (wards-the lowest administrative structure) with comparatively high (> 1.9 per 1000) and four with low (< 1 per 1000) incidence of local malaria cases were selected and involved in a door-to-door pilot intervention. The qualitative study was conducted after the pilot intervention and employed focus group discussions and in-depth interviews. All field notes were written on paper and audiotaped using digital audio-recorders. Summaries were developed by integrating field notes with reviews of recordings; themes were developed based on the topics identified a priori. Responses for each theme were summarized using an iterative process.

RESULTS

Most community members reported high levels of acceptance of door-to-door interventions. Some factors that might affect implementation of door-to-door include, low risk perception of the disease, local beliefs and practice, lack of initiative from the programme level to involve communities, and political instability during the election period. All Community Health Volunteers (CHVs) recommended this approach for community engagement, however, ensuring adequate resources was identified as a key factor for ensuring its sustainability.

CONCLUSION

The door-to-door intervention was perceived as helpful for promoting community engagement. There are several factors to consider including ensuring that CHVs are provided with adequate education, regular supervision, and have access to essential resources. Community leaders should be fully involved in choosing CHVs that are acceptable to the community. To ensure sustainability, the government should allocate sufficient resources and improve coordination systems.

Socio-demographic trends in malaria knowledge and implications for behaviour change interventions in Zanzibar

BACKGROUND

Zanzibar is among the few places within East Africa that have documented a significant reduction of malaria morbidity and mortality. Despite tremendous gains over the past decade, malaria transmission still persists in Zanzibar. This study aimed at understanding levels of malaria knowledge to provide recommendations that can be used to reinforce and scale up targeted malaria social and behaviour change interventions.

METHODS

A descriptive cross-sectional survey was conducted through an administered questionnaire to 431 households selected randomly. The interviewees were the heads of household or representative adults above 18 years. This study investigated the levels of knowledge about the causes, symptoms, and prevention of malaria in areas with high (> 1.9 per 1000) and low (< 1 per 1000) incidence of local malaria cases. The Principal Component Analysis (PCA) was used to compute the composite variable of each category. Descriptive statistics were calculated to understand variables of interest between low and high transmission areas. Multinomial logistic regression model was used to compare knowledge on malaria based on key variables.

RESULTS

A total of 431 heads of households were interviewed. Respondent age, education level, and wealth status were significantly associated with variations in level of malaria knowledge. Old age was found to be significantly associated with low knowledge of malaria (P < 0.001). The majority of study participants who had secondary and higher education levels had good knowledge of malaria (P < 0.006). Participants characterized as middle-income had good knowledge compared to those characterized as low-income (P < 0.001).

CONCLUSION

The study identified existing gaps in malaria knowledge in low and high transmission areas. Low levels of malaria knowledge were documented among elderly and populations with lower education and income levels. There is a need to extend mobilization, advocacy, and expand channels of communication to reach all community members. The reported gaps in knowledge are important to consider when designing strategies to engage communities in malaria elimination in Zanzibar. Tailored social and behavioural change interventions aiming to increase malaria knowledge could enhance the uptake of malaria prevention services in the community.

Estimating population ITN access at council level in Tanzania

BACKGROUND

Since 2013, the National Malaria Control Programme in mainland Tanzania and the Zanzibar Malaria Elimination Programme have implemented mass insecticide-treated net (ITN) distribution campaigns, routine ITN distribution to pregnant women and infants, and continuous distribution through primary schools (mainland) and community leaders (Zanzibar) to further malaria control efforts. Mass campaigns are triggered when ITN access falls below 40%. In this context, there is a need to monitor ITN access annually to assess whether it is below threshold and inform quantification of ITNs for the following year. Annual estimates of access are needed at the council level to inform programmatic decision-making.

METHODS

An age-structured stock and flow model was used to predict annual net crops from council-level distribution data in Tanzania from 2012 to 2020 parameterized with a Tanzania-specific net median lifespan of 2.15 years. Annual nets-per-capita (NPC) was calculated by dividing each annual net crop by mid-year council projected population. A previously fit nonparametric conditional quantile function for the proportion of the population with access to an ITN (ITN access) as a function of NPC was used to predict ITN access at the council level based on the predicted NPC value. These estimates were compared to regional-level ITN access from large household surveys.

RESULTS

For regions with the same ITN strategy for all councils, predicted council-level ITN access was consistent with regional-level survey data for 79% of councils. Regions where ITN strategy varied by council had regional estimates of ITN access that diverged from the council-specific estimates. Predicted ITN access reached 60% only when "nets issued as a percentage of the council population" (NPP) exceeded 15%, and approached 80% ITN access when NPP was at or above 20%.

CONCLUSION

Modelling ITN access with country-specific net decay rates, council-level population, and ITN distribution data is a promising approach to monitor ITN coverage sub-regionally and between household surveys in Tanzania and beyond.

Awareness Status of Schistosomiasis among School-Aged Students in Two Schools on Pemba Island, Zanzibar: A Cross-Sectional Study

Schistosomiasis elimination has been set as a target in the Neglected Tropical Disease Roadmap of 2021 to 2030. The present study assessed the level of understanding, awareness and behaviors of schistosomiasis among students in Zanzibar and explored the influencing factors as the basis for reliable suggestions for the follow-up policy on schistosomiasis prevention and control. A Knowledge, Attitude and Practices (KAP) survey on students’ perceptions of schistosomiasis was conducted on students from grades 4−9 at two selected schools on Pemba, Zanzibar, from May through September in 2021. A total of 217 valid participants responded to the questionnaires. T-test and chi-squared tests were used to examine the association between the dependent and explanatory variables. Multiple linear regressions were used to analyze the influencing factors of KAP. The findings indicated a lack of knowledge about schistosomiasis among the participants. Although respondents were aware of the risks of infection, they continued to engage in high-risk activities. Age, family size and presence of hematuria were found as contributing factors. Elder students performed better on knowledge (p = 0.02) and attitude (p < 0.01) scores, and students with a smaller family received higher attitude scores (p = 0.04). Practice was significantly correlated with gender (p < 0.01) and hematuria (p < 0.01). Several kinds of health education should be adopted to raise students’ basic knowledge of schistosomiasis. It is also critical to make the community aware regarding schistosomiasis. Future efforts for the prevention and control of schistosomiasis should employ an integrated strategy combining communities with schools to encourage behavioral change.

Knowledge and skills of pre-eclampsia management among healthcare providers working in antenatal clinics in Zanzibar

BACKGROUND

Pre-eclampsia and eclampsia are the leading causes of perinatal morbidity and mortality worldwide. Early detection and treatment of preeclampsia is lifesaving; however, evidence suggests that the majority of women in low and middle income-countries are not routinely screened for high blood pressure during antenatal care, that those with severe and mild pre-eclampsia are not monitored for blood pressure and proteinuria as needed, and the magnesium sulphate is not administered as needed. The purpose of this study was therefore to assess knowledge and skills in pre-eclampsia and eclampsia management and their associated factors among healthcare providers working in antenatal clinics in Zanzibar.

METHODS

This was a cross-sectional analytical study conducted in all levels of healthcare facilities in Zanzibar. The study involved 176 healthcare providers (nurses and doctors) who were randomly selected. A self-administered questionnaire was used to collect data and descriptive and inferential statistics were used in the analysis whereby logistic regression models were employed. The Chi-square coefficient, odds ratio, and 95% confidence intervals were reported, and the level of significance was set at p < 0.05.

RESULTS

The mean age of healthcare providers was 35.94 (SD ± 7.83) years. The proportion of healthcare providers with adequate knowledge was 49.0%, and 47% had adequate skills. Knowledge level was predicted by working in higher healthcare facility levels (AOR: 3.28, 95% CI: 1.29-8.29), and having attended on-the-job training on pre-eclampsia (AOR: 7.8, 95% CI: 2.74 - 22.75). Skills were predicted by having attended on-job training (AOR: 8.6, 95% CI: 2.45 - 30.16), having working experience of five years or above in antenatal care units (AOR: 27.89, 95% CI: 5.28 - 148.89) and being a medical doctor or assistant medical doctor (AOR: 18.9, 95% CI: 2.1-166).

CONCLUSION

Approximately half of Zanzibar's ANC healthcare workers demonstrated inadequate knowledge and skills in preeclampsia care, indicating a critical need for targeted interventions to reduce maternal morbidity and mortality. Knowledge is predicted by attending on-the-job training and working in higher healthcare facility level, while skills is predicted by attending on job training, more years of working experience in antenatal care units and being a medical doctor or assistant medical doctor The study recommends the healthcare facility institutions to provide on-the-job training to for the healthcare providers working in lower healthcare facility levels.

The Indispensability of Snail Control for Accelerating Schistosomiasis Elimination: Evidence from Zanzibar

Schistosomiasis is a serious and neglected global tropical disease, affecting upwards of 230 million people, with more than 95% of infections concentrated in Africa. For many years, the main schistosomiasis control strategy in Africa focused on mass drug administration (MDA). The aim of this study was to compare the difference between MDA alone and alongside another intervention, namely snail control, by exploring effective measures for eliminating schistosomiasis. Retrospective data of human prevalence on Schistosoma haematobium and major control measures were collected from the China-Zanzibar-WHO Cooperation Project for Schistosomiasis Elimination (CZW) and the Zanzibar Elimination of Schistosomiasis Transmission (ZEST) project since 2012. The optimal order polynomial regression fitting model and joinpoint regression model (JRM) were used to analyze trends in schistosomiasis prevalence and the consistency of change points with strengthening of the control measures. In Unguja Island, the main control measure was MDA, and prevalence decreased to a nadir in 2019, and then rebounded. The R2 value of the optimal fitting model was 0.6641. There was a single JRM changepoint in 2019, the annual percent change (APC) was −19.3% (p < 0.05) from 2012 to 2019, and the APC was 59.7% (p > 0.05) from 2019 to 2021. In Pemba Island, the main control measures until 2016 was MDA, while integrated measures of MDA and snail control were implemented from 2017, the prevalence continuously decreased, and the R2 value was 0.8673. There was also a single JRM changepoint in 2017, the APC was −22.2% (p < 0.05) from 2012 to 2017, and was maintained at −8.6% (p > 0.05) from 2017 to 2021. Our data indicate that, while it is challenging to eliminate schistosomiasis by MDA alone, integrated measures, including both MDA and snail control, can prevent reinfection and help to eliminate the diseases in Africa.

Rebounding Malaria and the failures of eradication in Zanzibar: The World Health Organization campaign and the after effects, 1957-1985

This article presents a case study of the WHO's malaria elimination attempt in Zanzibar and the decades after the program's conclusion in 1968. Drawing on archival, ethnographic, and interview data, we find that Zanzibar experienced a rebound malaria epidemic in the 1970s-1980s when prevalence rates surged higher than they were prior to the WHO's intervention. We show that scientists were aware of the risks of rebound before it happened and recognized the rebound epidemic as it was happening. We argue that many of the challenges facing Zanzibar in the 1960s remain dilemmas today, and many of the ethical questions about rebound malaria remain unaddressed.

Identifying Programmatic Factors that Increase Likelihood of Health Facility Delivery: Results from a Community Health Worker Program in Zanzibar

INTRODUCTION

Community health worker (CHW) interventions have been utilized to address barriers that prevent pregnant women from delivering in health facilities in low- and middle-income countries (LMICs). The objective of this research was to assess the programmatic factors that increase the likelihood of health facility delivery within a large digital health-supported CHW program in Zanzibar, Tanzania.

METHODS

This study included 36,693 women who were enrolled in the Safer Deliveries program with a live birth between January 1, 2017 and July 31, 2019. We assessed whether long-term enrollment, recency of CHW pregnancy visit prior to delivery, and number of routine home pregnancy visits were associated with an increased likelihood of health facility delivery compared to home delivery. We used Chi-squared tests to assess bivariate relationships and performed logistic regression analyses to assess the association between each programmatic variable and health facility delivery, adjusting for relevant confounders.

RESULTS

We found that long-term enrollment was significantly associated with increased likelihood of health facility delivery, with the strongest relationship among women with a previous home delivery (OR = 1.4, 95%CI [1.0,1.7]). Among first-time mothers, two or more pregnancy visits by a CHW was positively associated with health facility delivery (OR = 1.8, 95%CI [1.2, 2.7]). Recent pregnancy visit by a CHW was positively associated with health facility delivery, but was not significant at the α = 0.05 level.

DISCUSSION

In this program, we found evidence that at least two routine home pregnancy visits, longer length of enrollment in the program, and recency of home visit to the delivery date were strategies to increase health facility delivery rates among enrolled mothers. Maternal and child health programs should undertake similar evaluations to improve program delivery.

A cluster of cutaneous larva migrans in travellers returning from Zanzibar

Beaches of East Africa are the place to relax, but when contaminated with animal faeces, they are a likely source of health problems, such as cutaneous larva migrans. Cases of CLM were diagnosed in Polish travellers returned from holidays in Zanzibar.

GPS-based fine-scale mapping surveys for schistosomiasis assessment: a practical introduction and documentation of field implementation

BACKGROUND

Fine-scale mapping of schistosomiasis to guide micro-targeting of interventions will gain importance in elimination settings, where the heterogeneity of transmission is often pronounced. Novel mobile applications offer new opportunities for disease mapping. We provide a practical introduction and documentation of the strengths and shortcomings of GPS-based household identification and participant recruitment using tablet-based applications for fine-scale schistosomiasis mapping at sub-district level in a remote area in Pemba, Tanzania.

METHODS

A community-based household survey for urogenital schistosomiasis assessment was conducted from November 2020 until February 2021 in 20 small administrative areas in Pemba. For the survey, 1400 housing structures were prospectively and randomly selected from shapefile data. To identify pre-selected structures and collect survey-related data, field enumerators searched for the houses' geolocation using the mobile applications Open Data Kit (ODK) and MAPS.ME. The number of inhabited and uninhabited structures, the median distance between the pre-selected and recorded locations, and the dropout rates due to non-participation or non-submission of urine samples of sufficient volume for schistosomiasis testing was assessed.

RESULTS

Among the 1400 randomly selected housing structures, 1396 (99.7%) were identified by the enumerators. The median distance between the pre-selected and recorded structures was 5.4 m. A total of 1098 (78.7%) were residential houses. Among them, 99 (9.0%) were dropped due to continuous absence of residents and 40 (3.6%) households refused to participate. In 797 (83.1%) among the 959 participating households, all eligible household members or all but one provided a urine sample of sufficient volume.

CONCLUSIONS

The fine-scale mapping approach using a combination of ODK and an offline navigation application installed on tablet computers allows a very precise identification of housing structures. Dropouts due to non-residential housing structures, absence, non-participation and lack of urine need to be considered in survey designs. Our findings can guide the planning and implementation of future household-based mapping or longitudinal surveys and thus support micro-targeting and follow-up of interventions for schistosomiasis control and elimination in remote areas. Trial registration ISRCTN, ISCRCTN91431493. Registered 11 February 2020, https://www.isrctn.com/ISRCTN91431493.

A descriptive qualitative case study of the experiences, perceptions and attitudes of pregnant women on Unguja island, Zanzibar, towards antischistosomal treatment

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Women were enthusiastic about keeping healthy during pregnancy.

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Women strongly valued high quality antenatal care and were encouraged to attend clinics by their families and community members.

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Women demonstrated poor retention of knowledge about schistosomiasis from school.

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The majority of women interviewed had missed mass drug administration rounds of praziquantel due to pregnancy or concerns about side effects.

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Women were unanimously agreeable to taking praziquantel during pregnancy if advised to do so by a healthcare professional.

Many countries exclude pregnant and lactating women from mass drug administration (MDA) programmes with praziquantel against schistosomiasis due to historic safety concerns over drug use during gestation and breast feeding. More than 10 years of empirical evidence from the field and a growing body of dedicated research has prompted the World Health Organisation and schistosomiasis control initiatives to advocate the inclusion of this vulnerable group into MDA. This qualitative descriptive case study explored, over a five-week period, the subjective experiences, perceptions, opinions, and attitudes of pregnant women attending government supported clinics on Unguja island, United Republic of Tanzania, towards praziquantel use during pregnancy in MDA programmes. The aim of the study was to identify and determine how to overcome potential barriers to effective use of MDA medications during pregnancy. Additionally, it was to determine trusted communication channels for future messaging and discover behavioural and community opportunities to increase participation of pregnant women in future MDA efforts. A 60 min, semi-structured qualitative interview was undertaken with 25 pregnant women recruited from 4 health centres on Unguja along with testing for Schistosoma haematobium infection. Using a modified-grounded theory approach, narrative data were transcribed, coded and analysed using a thematic analysis of the emergent themes. Women reported that they rely on traditional home remedies to stay healthy during pregnancy. Influenced by their mothers, husbands and neighbours, women predominately made medication choices during pregnancy and breastfeeding based on what they heard at home. Most women had been excluded from government MDA programmes in the past due to pregnancy. Women valued healthcare services for antenatal education and pregnancy advice. Women reported they would trust and follow direction from healthcare providers about taking praziquantel during pregnancy. Antenatal clinics offer an excellent opportunity to educate and expand praziquantel treatment to this cohort. Efforts should be augmented with training for providers and behavioural education for the community as a whole and family members of pregnant women.

Assessment of multidrug-resistant tuberculosis patient's skin drug reaction in Zanzibar: A certain causal relationship with Clofazimine

Drug-resistant tuberculosis (DR-TB) is a serious public health of concern. We present the management of multidrug-resistant (MDR)-TB with skin reaction in Zanzibar in a patient who had prior exposure to anti-TB drugs. The reaction developed 4 months later, following MDR-TB treatment, stopped when the drug was withdrawn, and reappeared when reintroduced. Close monitoring is important in managing DR-TB cases, and an active DR-TB safety, monitoring, and management is required to detect, monitor, and manage adverse events timely.

Risk factors associated with malaria infection identified through reactive case detection in Zanzibar, 2012-2019

BACKGROUND

Over the past two decades, Zanzibar substantially reduced malaria burden. As malaria decreases, sustainable improvements in control interventions may increasingly depend on accurate knowledge of malaria risk factors to further target interventions. This study aimed to investigate the risk factors associated with malaria infection in Zanzibar.

METHODS

Surveillance data from Zanzibar's Malaria Case Notification system from August 2012 and December 2019 were analyzed. This system collects data on malaria cases passively detected and reported by all health facilities (index cases), and household-based reactive case detection (RCD) activities linked to those primary cases. All members of households of the index cases were screened for malaria using a malaria rapid diagnostic test (RDT). Individuals with a positive RDT were treated with artemisinin-based combination therapy. Univariate and multivariate logistic regression analyses were done to investigate the association between RDT positivity among the household members and explanatory factors with adjustment for seasonality and clustering at Shehia level.

RESULTS

A total of 30,647 cases were reported of whom household RCD was completed for 21,443 (63%) index case households and 85,318 household members tested for malaria. The findings show that younger age (p-value for trend [Ptrend] < 0.001), history of fever in the last 2 weeks (odds ratio [OR] = 35.7; 95% CI 32.3-39.5), travel outside Zanzibar in the last 30 days (OR = 2.5; 95% CI 2.3-2.8) and living in Unguja (OR = 1.2; 95% CI 1.0-1.5) were independently associated with increased odds of RDT positivity. In contrast, male gender (OR=0.8; 95% CI 0.7-0.9), sleeping under an LLIN the previous night (OR = 0.9; 95% CI 0.7-0.9), having higher household net access (Ptrend < 0.001), and living in a household that received IRS in the last 12 months (OR = 0.8; 95% CI 0.7-0.9) were independently associated with reduced odds of RDT positivity. A significant effect modification of combining IRS and LLIN was also noted (OR = 0.7; 95% CI 0.6-0.8).

CONCLUSIONS

The findings suggest that vector control remains an important malaria prevention intervention: they underscore the need to maintain universal access to LLINs, the persistent promotion of LLIN use, and application of IRS. Additionally, enhanced behavioural change and preventive strategies targeting children aged 5-14 years and travellers are needed.

Risk factors for occurrence and abundance of Aedes aegypti and Aedes bromeliae at hotel compounds in Zanzibar

Background

A field survey was performed to investigate local environmental factors promoting occurrence and abundance of Aedes aegypti and Ae. bromeliae mosquitoes at hotel compounds in the south-east coastal region of Zanzibar Island.

Methods

The potential risk factors were determined using generalized linear mixed models. Aedes (Stegomyia) spp. indices such as container index (CI) and pupae per container (PPC) index were also estimated.

Results

Aedes aegypti and Ae. bromeliae were the most abundant vector species, accounting for 70.8% of all Aedes mosquitoes collected. The highest CI was observed for plastic containers irrespective of the season, whereas the highest PPC was observed for coconut shells and aluminium containers in the rainy and dry seasons, respectively. The risk of Aedes mosquito occurrence and abundance were significantly associated with presence of plastic containers, coconut shells, used tyres and steel containers. These were discarded in shaded places, in the open and gardens, or found in plant nurseries.

Conclusion

This study shows that Aedes species of global health significance occur at hotel compounds on this part of Zanzibar Island. The occurrence and abundance are sustained by the presence of abundant and poorly managed solid wastes and containers used for gardening tasks. This highlights an urgent need for the adoption of area-wide environmentally sustainable Aedes mosquito management interventions that also integrate solid waste management and ornamental plant production practices for reducing the risk of arboviral disease epidemics.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05005-9.

Novel tools and strategies for breaking schistosomiasis transmission: study protocol for an intervention study

Background

Global elimination of schistosomiasis as a public health problem is set as target in the new World Health Organization’s Neglected Tropical Diseases Roadmap for 2030. Due to a long history of interventions, the Zanzibar islands of Tanzania have reached this goal since 2017. However, challenges occur on the last mile towards interruption of transmission. Our study will investigate new tools and strategies for breaking schistosomiasis transmission.

Methods

The study is designed as an intervention study, documented through repeated cross-sectional surveys (2020–2024). The primary endpoint will be the sensitivity of a surveillance-response approach to detect and react to outbreaks of urogenital schistosomiasis over three years of implementation. The surveys and multi-disciplinary interventions will be implemented in 20 communities in the north of Pemba island. In low-prevalence areas, surveillance-response will consist of active, passive and reactive case detection, treatment of positive individuals, and focal snail control. In hotspot areas, mass drug administration, snail control and behaviour change interventions will be implemented. Parasitological cross-sectional surveys in 20 communities and their main primary schools will serve to adapt the intervention approach annually and to monitor the performance of the surveillance-response approach and impact of interventions. Schistosoma haematobium infections will be diagnosed using reagent strips and urine filtration microscopy, and by exploring novel point-of-care diagnostic tests.

Discussion

Our study will shed light on the field applicability and performance of novel adaptive intervention strategies, and standard and new diagnostic tools for schistosomiasis elimination. The evidence and experiences generated by micro-mapping of S. haematobium infections at community level, micro-targeting of new adaptive intervention approaches, and application of novel diagnostic tools can guide future strategic plans for schistosomiasis elimination in Zanzibar and inform other countries aiming for interruption of transmission.

Trial registration ISRCTN, ISCRCTN91431493. Registered 11 February 2020, https://www.isrctn.com/ISRCTN91431493

Emerging epidemics: is the Zanzibar healthcare system ready to detect and respond to mosquito-borne viral diseases?

Background

Effective control of emerging mosquito-borne viral diseases such as dengue, chikungunya, and Zika requires, amongst other things, a functional healthcare system, ready and capable of timely detection and prompt response to incipient epidemics. We assessed the readiness of Zanzibar health facilities and districts for early detection and management of mosquito-borne viral disease outbreaks.

Methods

A cross-sectional study involving all 10 District Health Management Teams and 45 randomly selected public and private health facilities in Zanzibar was conducted using a mixed-methods approach including observations, document review, and structured interviews with health facility in-charges and District Health Management Team members.

Results

The readiness of the Zanzibar healthcare system for timely detection, management, and control of dengue and other mosquito-borne viral disease outbreaks was critically low. The majority of health facilities and districts lacked the necessary requirements including standard guidelines, trained staff, real-time data capture, analysis and reporting systems, as well as laboratory diagnostic capacity. In addition, health education programmes for creating public awareness and Aedes mosquito surveillance and control activities were non-existent.

Conclusions

The Zanzibar healthcare system has limited readiness for management, and control of mosquito-borne viral diseases. In light of impending epidemics, the critical shortage of skilled human resource, lack of guidelines, lack of effective disease and vector surveillance and control measures as well as lack of laboratory capacity at all levels of health facilities require urgent attention across the Zanzibar archipelago.

Evaluation of a urogenital schistosomiasis behavioural intervention among students from rural schools in Unguja and Pemba islands, Zanzibar

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Children self-reported changes in urogenital schistosomiasis risk taking behaviours.

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Children self-reported an increase in swallowing anthelmintic drugs during MDA.

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Rebranding the concept of “worm” to “blood fluke” created a critical perceived health threat.

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The Health Belief Model was a viable foundation for the behavioural intervention.

Urogenital schistosomiasis is a common experience among children in Zanzibar. There is a paucity of behavioural science-based, health education and behaviour change (HEBC) interventions for school-aged children, those at greatest risk for urogenital schistosomiasis. We assessed the influence of a HEBC intervention, guided by the Health Belief model, among rural schoolchildren on Pemba and Unguja islands in Zanzibar, Tanzania. From 2012 to 2016, a cluster-randomized trial to assess three different interventions against urogenital schistosomiasis was conducted in 90 schools and shehias across Zanzibar. The HEBC intervention was implemented in 15 schools per island. In 2017, at the trial conclusion, we administered written questionnaires to schoolchildren from 4 HEBC intervention schools and 4 not HEBC exposed schools on each island, respectively. Responses were compared between students that were exposed or not exposed to the HEBC intervention using a Fisher's exact test. A total of 1451 students, 708 from intervention and 743 from non-intervention schools completed the questionnaire. Noting some between island differences, students who had received the HEBC interventions reported significant improvements in knowledge about Schistosoma haematobium transmission and personal risk, strategies for schistosomiasis prevention, and self-reported changes in risk behaviours: stopped washing laundry/dishes 49.4% (350/708) versus 5.8% (43/743), stopped bathing in streams/ponds 49.4% (350/708) versus 4.2% (31/743), and stopped playing in streams/ponds 40.8% (289/708) versus 10.8% (80/743). HEBC exposed children also reported a significant increase in swallowing tablets during mass drug administration (MDA) campaigns (when they had not before) 30.2% (214/708) versus 4.6% (34/743). The school based HEBC interventions were associated with desirable positive behaviour change among students. Data suggest that scaling up HEBC interventions to all schools in high-risk areas, augmented with bi-annual MDA, can help to reduce prevalence of urogenital schistosomiasis in Zanzibar, strengthening the possibility for future disease elimination.

Flatfoot in Africa, the cirripede Chthamalus in the west Indian Ocean

Barnacles of the genus Chthamalus are commonly encountered rocky intertidal shores. The phylogeography of the different species in the Western Indian Ocean is unclear. Using morphological characteristics as well as the molecular markers mitochondrial cytochrome oxygenase subunit I (COI) and the nuclear sodium-potassium ATPase (NaKA), we identified four clades representing four species in the Western Indian Ocean and its adjacent seas. Among these species, a newly identified species, Chthamalus barilani, which was found in Madagascar, Zanzibar and Tanzania. Chthamalus from the coasts of Tanzania and Zanzibar is identified morphologically as C. malayensis, and clusters with C. malayensis from the Western Pacific and the Indo Malayan regions. C. malayensis is regarded as a group of four genetically differentiated clades representing four cryptic species. The newly identified African clade is genetically different from these clades and the pairwise distances between them justify the conclusion that it is an additional cryptic species of C. malayensis. This type of genetic analyses offers an advantage over morphological characterization and allowed us to reveal that another species, C. barnesi, which is known from the Red Sea, is also distributed in the Arabian Sea and the Persian Gulf. We could also confirm the presence of the South African species C. dentatus in the Mozambique channel. This represents the Northeastern limit of C. dentatus, which is usually distributed along the coast of southern Africa up to the Islands of Cape Verde in West Africa. Altogether, based on a combination of morphology and genetics, we distinct between four clusters of Chthamalus, and designate their distribution in the West Indian Ocean. These distinctions do not agree with the traditional four groups reported previously based merely on morphological data. Furthermore, these findings underline the importance of a combining morphological and genetics tools for constructing barnacle taxonomy.

Quantifying plastics waste accumulations on coastal tourism sites in Zanzibar, Tanzania

Plastic pollution is becoming a growing concern on coastal tourism sites. Unquantified amounts of plastic materials are discharged into coastal waters with detrimental effects on local marine environments. With the expansion of the tourism industry, waste increasingly originates from tourism activities and ends up into the ocean due to poor management of solid waste post-consumption. This study explores the sources, abundance, and type of litter in Zanzibar, Tanzania by surveying four coastal tourism sites. The analysis illustrates the contributions to plastic pollution of four sectors of Zanzibar's economy (residential households, building and construction, tourism, and commercial sector). Findings suggest that plastic accounted for almost half (48.5%) of the waste inflow to the environment, and single-use packaging was the dominant litter item on all sampled sites.

COVID-19 and unpaid leave: Impacts of psychological contract breach on organizational distrust and turnover intention: Mediating role of emotional exhaustion

This study examines the influence of COVID-19 on unpaid leave, the direct impacts of psychological contract breach on organizational distrust and turnover intention, and their indirect impact through emotional exhaustion. The study used partial least squares to analyze the data set of 238 questionnaires from hospitality establishments. Results indicate a significant direct positive impact of psychological contract breach on organizational distrust and favorable indirect effects through emotional exhaustion. However, psychological contract breach had no direct effects on turnover intention. The study has equally found the positive effect of organizational distrust on turnover intention. The research provides both theoretical and practical implications and suggests areas for further studies.

Increased Sensitivity of Plasmodium falciparum to Artesunate/Amodiaquine Despite 14 Years as First-Line Malaria Treatment, Zanzibar

Artemisinin-based combination therapies (ACTs) are first-line treatments for uncomplicated Plasmodium falciparum malaria. ACT resistance is spreading in Asia but not yet in Africa. Reduced effects of ACT partner drugs have been reported but with little information regarding widely used artesunate/amodiaquine (ASAQ). We studied its efficacy in Zanzibar after 14 years as first-line treatment directly by an in vivo, single-armed trial and indirectly by prevalences of different genotypes in the P. falciparum chloroquine-resistance transporter, multidrug-resistance 1, and Kelch 13 propeller domain genes. In vivo efficacy was higher during 2017 (100%; 95% CI 97.4%-100%) than during 2002-2005 (94.7%; 95% CI 91.9%-96.7%) (p = 0.003). Molecular findings showed no artemisinin resistance-associated genotypes and major increases in genotypes associated with high sensitivity/efficacy for amodiaquine than before ASAQ was introduced. Thus, the efficacy of ASAQ is maintained and appears to be increased after long-term use in contrast to what is observed for other ACTs used in Africa.

Assessment of the core and support functions of the integrated disease surveillance and response system in Zanzibar, Tanzania

Background

Disease surveillance is a cornerstone of outbreak detection and control. Evaluation of a disease surveillance system is important to ensure its performance over time. The aim of this study was to assess the performance of the core and support functions of the Zanzibar integrated disease surveillance and response (IDSR) system to determine its capacity for early detection of and response to infectious disease outbreaks.

Methods

This cross-sectional descriptive study involved 10 districts of Zanzibar and 45 public and private health facilities. A mixed-methods approach was used to collect data. This included document review, observations and interviews with surveillance personnel using a modified World Health Organization generic questionnaire for assessing national disease surveillance systems.

Results

The performance of the IDSR system in Zanzibar was suboptimal particularly with respect to early detection of epidemics. Weak laboratory capacity at all levels greatly hampered detection and confirmation of cases and outbreaks. None of the health facilities or laboratories could confirm all priority infectious diseases outlined in the Zanzibar IDSR guidelines. Data reporting was weakest at facility level, while data analysis was inadequate at all levels (facility, district and national). The performance of epidemic preparedness and response was generally unsatisfactory despite availability of rapid response teams and budget lines for epidemics in each district. The support functions (supervision, training, laboratory, communication and coordination, human resources, logistic support) were inadequate particularly at the facility level.

Conclusions

The IDSR system in Zanzibar is weak and inadequate for early detection and response to infectious disease epidemics. The performance of both core and support functions are hampered by several factors including inadequate human and material resources as well as lack of motivation for IDSR implementation within the healthcare delivery system. In the face of emerging epidemics, strengthening of the IDSR system, including allocation of adequate resources, should be a priority in order to safeguard human health and economic stability across the archipelago of Zanzibar.

Analysis of an obstetrics point-of-care ultrasound training program for healthcare practitioners in Zanzibar, Tanzania

Background

A point-of-care ultrasound education program in obstetrics was developed to train antenatal healthcare practitioners in rural Zanzibar. The study group consisted of 13 practitioners with different training backgrounds: physicians, clinical officers, and nurse/midwives. Trainees received an intensive 2-week antenatal ultrasound course consisting of lectures and hands-on practice followed by 6 months of direct supervision of hands-on scanning and bedside education in their clinical practice environments. Trainees were given a pre-course written exam, a final exam at course completion, and practical exams at 19 and 27 weeks. Trainees were expected to complete written documentation and record ultrasound images of at least 75 proctored ultrasounds. The objective of this study was prospectively to analyze the success of a longitudinal point-of-care ultrasound training program for antepartum obstetrical care providers in Zanzibar.

Results

During the 6-month course, trainees completed 1338 ultrasound exams (average 99 exams per trainee with a range of 42–128 and median of 109). Written exam scores improved from a mean of 33.7% (95% CI 28.6–38.8%) at pre-course assessment to 77.5% (95% CI 71–84%) at course completion (P < 0.0001). Practical exam mean scores improved from 71.2% at course midpoint (95% CI 62.3–80.1%) to 84.7% at course completion (95% Cl 78.5–90.8%) (P < 0.0005). Eight of the 13 trainees completed all training requirements including 75 proctored ultrasound exams.

Conclusion

Trainees improved significantly on all measures after the training program. 62% of the participants completed all requirements. This relatively low completion rate reflects the challenges of establishing ultrasound capacity in this type of setting. Further study is needed to determine trainees’ long-term retention of ultrasound skills and the impact of the program on clinical practice and health outcomes.

Evaluation of Diagnostic Imaging Capacity and the Role for Point-of-Care Ultrasound (POCUS) within the Zanzibar Health System

Background: The Zanzibar Ministry of Health identified access to ultrasound (US) as a system priority due to limited diagnostic imaging capacity and consequent impact on patient care and requested a needs assessment in this regard. As a result, the objective of this study was to assess diagnostic imaging capacity focusing on ultrasound in Zanzibar, including health care providers’ (HCPs) current training, use, and barriers to implementation.  Methods: A previously published ultrasound needs assessment survey was modified and administered on-site at the eight public hospitals in Zanzibar among a convenience sample of HCPs. Demographics, perceived US needs, current training and practice, and availability of specialty support were assessed. HCPs also completed focused personal interviews (FPIs) to explore experience with training, interests, and barriers to ultrasound. On-site diagnostic imaging modalities were assessed.  Results: There were nine ultrasound machines present at six of the eight public hospitals assessed. All had x-ray, but only one had a CT scanner and a radiologist. There was no MRI capacity at the hospitals assessed at the time of the study. Survey data among 40 participants revealed that prior experience with POCUS was limited with only 10% reporting any prior ultrasound training or experience.  The majority of those surveyed (72%), indicated a ‘high’ interest in learning ultrasound.  Of those reporting interest in POCUS applications, obstetrics was the most often cited (70%). Lack of ultrasound machines (40%) and educators (28%) were identified as the greatest barriers. Conclusion: HCPs in Zanzibar have limited access to diagnostic imaging, including ultrasound, and expressed a high level of interest in learning point-of-care ultrasound. A shortage of machines and educators are the main barriers to widespread use. Obstetrics is the application for which ultrasound is currently most used and is the application HCPs are most interested in learning. Equipment and educational support for a POCUS program could improve care by increasing access to diagnostic imaging.

Mental Health and Quality of Life of Women One Year after Maternal Near-Miss in Low and Middle-Income Countries: The Case of Zanzibar, Tanzania

Women who experienced a maternal near-miss are at risk of mental health complications and lower quality of life, but long-term consequences are largely unknown. The aim of this study is to assess whether mental health symptoms and quality of life change over time and to examine associations with risk factors among post-partum women. In this cohort study, women with maternal near-miss were matched to women without or with mild complications at Mnazi Mmoja Hospital in Zanzibar. Depressive and post-traumatic stress disorder symptoms, and quality of life were measured at three, six, and twelve-months follow-up. A linear mixed-effects model was used for data analysis. Postpartum women in Zanzibar reported low levels of depressive and post-traumatic stress disorder symptoms. While depressive symptoms and quality of life trajectories were similar among women with and without maternal near-miss, differences for trajectories of post-traumatic stress disorder symptoms and physical quality of life were found. Social support, perinatal loss, and intercurrent illness were strongly associated with both depressive symptoms and quality of life in this group of Islamic women. These findings suggest that social support, embedded in the cultural context, should be considered in helping women cope with mental health issues in the aftermath of severe maternal complications.

Hypertension and diabetes in Zanzibar - prevalence and access to care

BACKGROUND

Cardiovascular diseases are among the most common causes of hospital admissions and deaths in Zanzibar. This study assessed prevalence of, and antecedent factors and care access for the two common cardiovascular risk factors, hypertension and diabetes, to support health system improvements.

METHODS

Data was from a population based nationally representative survey. Prevalence of hypertension was defined as systolic blood pressure ≥ 140 mmHg, diastolic blood pressure ≥ 90 mmHg or a self-reported diagnosis of hypertension; diabetes was defined as a fasting blood glucose ≥6.1 mmol/L or a self-reported diagnosis of diabetes. Care-cascades for hypertension and diabetes were created with four stages: being tested, diagnosed, treated, and achieving control. Multivariable logistic regression models were constructed to evaluate individual-level factors - including symptoms of mental illness - associated with having hypertension or diabetes, and with progressing through the hypertension care cascade. Whether people at overt increased risk of hypertension or diabetes (defined as > 50 years old, BMI > 30 kg/m2, or currently smoking) were more likely to be tested was assessed using chi squared.

RESULTS

Prevalence of hypertension was 33.5% (CI 30.6-36.5). Older age (OR 7.7, CI 4.93-12.02), some education (OR 0.6, CI 0.44-0.89), obesity (OR 3.1, CI 2.12-4.44), and raised fasting blood glucose (OR 2.4, CI 2.38) were significantly independently associated with hypertension. Only 10.9% (CI 8.6-13.8) of the entire hypertensive population achieved blood pressure control, associated factors were being female (OR 4.8, CI 2.33-9.88), formally employed (OR 3.0, CI 1.26-7.17), and overweight (OR 2.5, CI 1.29-4.76). The prevalence of diabetes was 4.4% (CI 3.4-5.5), and associated with old age (OR 14.1, CI 6.05-32.65) and almost significantly with obesity (OR 2.1, CI 1.00-4.37). Only 11.9% (CI 6.6-20.6) of the diabetic population had achieved control. Individuals at overt increased risk were more likely to have been tested for hypertension (chi2 19.4) or diabetes (chi2 33.2) compared to the rest of the population. Symptoms of mental illness were not associated with prevalence of disease or progress through the cascade.

CONCLUSION

High prevalence of hypertension and suboptimal management along the care cascades indicates a large unmet need for hypertension and diabetes care in Zanzibar.

Performance of a real-time PCR approach for diagnosing Schistosoma haematobium infections of different intensity in urine samples from Zanzibar

Background

Efforts to control and eliminate schistosomiasis have accelerated over the past decade. As parasite burden, associated morbidity and egg excretion decrease, diagnosis with standard parasitological methods becomes harder. We assessed the robustness and performance of a real-time PCR (qPCR) approach in comparison with urine filtration microscopy and reagent strip testing for the diagnosis of Schistosoma haematobium infections of different intensities.

Methods

The robustness of DNA isolation and qPCR was validated in eight laboratories from Europe and Africa. Subsequently, 792 urine samples collected during cross-sectional surveys of the Zanzibar Elimination of Schistosomiasis Transmission (ZEST) project in 2012–2017 were examined with qPCR in 2018. Diagnostic sensitivity of the qPCR was calculated at different infection intensity categories, using urine filtration microscopy as reference test. Spearman’s rank correlation between Ct-values and S. haematobium egg counts was assessed and Ct-value percentiles for infection intensity categories determined.

Results

S. haematobium Dra1 DNA-positive samples were identified correctly in all eight laboratories. Examination of urine samples from Zanzibar revealed Dra1 DNA in 26.8% (212/792) by qPCR, S. haematobium eggs in 13.3% (105/792) by urine filtration, and microhaematuria in 13.8% (109/792) by reagent strips. Sensitivity of the qPCR increased with augmenting egg counts: 80.6% (29/36) for counts between 1 and 4 eggs, 83.3% (15/18) for counts between 5 and 9 eggs, 100% (23/23) for counts between 10 and 49 eggs, and 96.4% (27/28) for counts of 50+ eggs. There was a significant negative correlation between Ct-values and egg counts (Spearman’s rho = − 0.49, P < 0.001). Seventy-five percent of the Ct-values were ≥ 33 in the egg-negative category, < 31 in the light intensity category, and < 24 in the heavy intensity category.

Conclusions

While the sensitivity of the qPCR was ~ 80% for very light intensity infections (egg counts < 10), in general, the Dra1 based qPCR assay detected twice as many S. haematobium infections compared with classical parasitological tests. The qPCR is hence a sensitive, urine-based approach for S. haematobium diagnosis that can be used for impact assessment of schistosomiasis elimination programmes, individual diagnosis, and in improved format also for verification and certification of elimination.

Trial registration

ISRCTN, ISRCTN48837681. Registered 05 September 2012 - Retrospectively registered.

Prevalence and risk factors associated with severe pre-eclampsia among postpartum women in Zanzibar: a cross-sectional study

Background

Severe pre-eclampsia is more dominant in low and middle-income countries. In Sub-Saharan Africa, severe pre-eclampsia remains a major public health problem contributing to high rates of maternal mortality. Few studies have investigated the relationship between severe pre-eclampsia and associated factors in East Africa. The aim of this study was to determine the prevalence and risk factors associated with severe pre-eclampsia among postpartum women in Zanzibar.

Methods

A hospital based analytical cross-sectional study design was used. Purposive sampling was utilized for the selection of hospitals. Proportionate sampling was used for selection of representatives from each hospital and participants were selected using systematic random sampling. Postpartum mothers were included in the study. The study was conducted by an interviewer who administered a questionnaire with close ended questions and chart review for data gathering. SPSS version 23 was used for data analysis and descriptive and multiple logistic regression was performed for control of confounders.

Results

This study included a total of 400 participants with a 100% response rate. Participants ranged from 17 to 45 years of age with mean age (SD) of 28.78 (±6.296). The prevalence of severe pre-eclampsia among postpartum women was 26.3% (n = 105). After adjusting for the possible confounders, factors associated with severe pre-eclampsia were; maternal age group of 15–20 years (AOR 3.839; 95% C. I 1.037–14.210), pregnancy from new partner/husband (AOR 7.561; 95% C. I 3.883–14.724), family history of high blood pressure (AOR 6.446; C. I 3.217–12.917), diabetes prior to conception (AOR 55.827; 95% C. I 5.061–615.868), having high blood pressure in a previous pregnancy (AOR 19.382; 95% C. I 4.617–81.364), paternal age above 45 (AOR 2.401; 95% C. I 1.044–5.519) and multifetal gestation (AOR 7.62; 95% CI 2.01–28.84).

Conclusion

The prevalence of severe pre-eclampsia among postpartum women in Zanzibar is high. Common risk factors in this setting include maternal age of 15–20 years, pregnancy with a new partner, family history of high blood pressure, pre-existing diabetes prior to conception, a history of high blood pressure in previous pregnancy paternal age greater than 45 and multifetal gestation.

Patterns of human exposure to malaria vectors in Zanzibar and implications for malaria elimination efforts

Background

Zanzibar provides a good case study for malaria elimination. The islands have experienced a dramatic reduction in malaria burden since the introduction of effective vector control interventions and case management. Malaria prevalence has now been maintained below 1% for the past decade and the islands can feasibly aim for elimination.

Methods

To better understand factors that may contribute to remaining low-level malaria transmission in Zanzibar, layered human behavioural and entomological research was conducted between December 2016 and December 2017 in 135 randomly selected households across six administrative wards. The study included: (1) household surveys, (2) structured household observations of nighttime activity and sleeping patterns, and (3) paired indoor and outdoor mosquito collections. Entomological and human behavioural data were integrated to provide weighted estimates of exposure to vector bites, accounting for proportions of people indoors or outdoors, and protected by insecticide-treated nets (ITNs) each hour of the night.

Results

Overall, 92% of female Anopheles mosquitoes were caught in the rainy season compared to 8% in the dry season and 72% were caught outdoors compared to 28% indoors. For individual ITN users, ITNs prevented an estimated two-thirds (66%) of exposure to vector bites and nearly three quarters (73%) of residual exposure was estimated to occur outdoors. Based on observed levels of ITN use in the study sites, the population-wide mean personal protection provided by ITNs was 42%.

Discussion/conclusions

This study identified gaps in malaria prevention in Zanzibar with results directly applicable for improving ongoing programme activities. While overall biting risk was low, the most notable finding was that current levels of ITN use are estimated to prevent less than half of exposure to malaria vector bites. Variation in ITN use across sites and seasons suggests that additional gains could be made through targeted social and behaviour change interventions. However, even for ITN users, gaps in protection remain, with a majority of exposure to vector bites occurring outdoors before going to sleep. Supplemental interventions targeting outdoor exposure to malaria vectors, and groups that may be at increased risk of exposure to malaria vectors, should be explored.

Monitoring the durability of the long-lasting insecticidal nets Olyset® and PermaNet® 2.0 in similar use environments in Zanzibar

BACKGROUND

Malaria transmission in Zanzibar has dramatically reduced in recent years but vector control interventions such as long-lasting insecticidal nets (LLIN) must continue to reach malaria elimination. To achieve this, the Zanzibar Malaria Elimination Programme needs actionable evidence of the durability of the LLIN brands distributed. This study compared physical and insecticidal durability of two LLIN brands: Olyset® and PermaNet© 2.0 in two similar districts on the islands of Unguja and Pemba.

METHODS

This was a prospective cohort study of representative samples of households from two districts, recruited at baseline 4 months after the mass campaign. All campaign nets in these households were labelled and followed up over a period of 33 months. Primary outcome was the "proportion of nets surviving in serviceable condition" based on attrition and integrity measures and the median survival in years. The outcome for insecticidal durability was determined by bio-assay from sub-samples of campaign nets.

RESULTS

A total of 834 campaign nets (121% of target) from 299 households were included in the study. Definite outcomes could be determined for 86% of the cohort nets in Unguja (PermaNet® 2.0) and 89% in Pemba (Olyset®). After 33 months, physical survival in serviceable condition was 55% in Unguja and 51% in Pemba. Estimated median survival was lower in Pemba at all time points with 2.3-2.7 years compared to 3.1-3.3 yeas in Unguja. Multivariable Cox proportionate hazard models confirmed the difference between brands (p < 0.0001) and identified household net-care attitude (p = 0.007) and folding of hanging nets during the day (p < 0.0001) as significant determinants, in addition to exclusive use of nets by adults (p = 0.03) and use only over a finished bedframe (p = 0.01). Optimal insecticidal effectiveness was 80% or higher for both brands at all time points when both cone bio-assays and tunnel tests were applied.

CONCLUSIONS

After 3 years of follow-up, Olyset® LLIN showed significantly lower physical survival compared to PermaNet® 2.0 LLIN even after adjusting for other variables of net-use environment and net handling. This suggests that the differences were driven by the textile characteristics of the LLIN brands.

Effectiveness of Mass Drug Administration on Neglected Tropical Diseases in Schoolchildren in Zanzibar, Tanzania

Soil-transmitted helminths and Schistosoma haematobium affect more than 3 billion people globally and mainly occur in sub-Saharan Africa. The present study assessed the overall infection status of a 1716-student cohort of school-children in Zanzibar and applied mass drug administration (MDA) to the cohort from 2007 to 2009. Schools in Pemba, Zanzibar, had a much higher prevalence of soil-transmitted helminth infections than those in Unguja, and the Chaani, Ghana, and Machui schools of Unguja exhibited high S. haematobium infection rates. The MDA program only partially controlled parasite infections, owing to high rates of re-infection. The infection rate of S. haematobium across all 10 schools, for example, was only reduced by 1.8%, and even this change not significant, even though the S. haematobiuminfection rates of the Chaani and Mzambarauni schools were significantly reduced from 64.4 and 23.4%, respectively, at the first screening, to 7.3 and 2.3% at the last screening. The overall infection rate of Ascaris lumbricoides was reduced from 36.0% at the first screening to 22.6% at the last screening. However, the infection rates for both Trichuris trichiuraand hookworm were generally unaffected by MDA. In the future, parasite control programs should involve strategically designed MDA schedules and holistic intervention (e.g., sanitation improvement, hygiene behavior changes, and control of intermediated hosts).

Women's knowledge of and attitudes toward cervical cancer and cervical cancer screening in Zanzibar, Tanzania: a cross-sectional study

Background

Cervical cancer is the most common cancer and the leading cause of cancer death among women in Tanzania. Knowledge of and willingness to receive a cervical cancer screening are important determinants of prevention. This study aimed to describe women’s awareness of cervical cancer and to explore the attitudes toward, acceptability of and barriers to cervical cancer screening (CCS) in Zanzibar.

Methods

A cross-sectional study was conducted from March to June 2018 involving 1483 women from 10 districts in Zanzibar who responded to questionnaires concerning their general demo-graphic characteristics, screening willingness and awareness of cervical cancer. Chi-square tests, analysis of variance (ANOVA) and stepwise multiple regression were conducted using STATA 15.1 software.

Results

The average total knowledge score (TKS) was 7.84 ± 5.32 on a 23-point scale. Educational level and family income were positively correlated with the TKS. Previous schistosomiasis history and family genetic disease history were strong predictors of screening willingness. Women were less likely to be screened freely if they had 7 or more deliveries and were unaware of any previous family tumor history. Age and educational level were negatively associated non-free screening willingness, while family income was positively associated; being divorced/widowed or single and being unaware of any previous family tumor history were predictors of screening reluctance, while previous disease history was a strong predictor of non-free screening willingness. Fear of screening and inconvenience were the primary concerns among the Zanzibari interviewees. Compared to the 20–49 age group, more women in the less than 20 and 50 or more age groups thought cervical cancer screening was not necessary. The highest rate of cognitive accuracy in regard to cervical cancer warning signs and risk factors was only 37.76%.

Conclusions

The findings revealed that knowledge of cervical cancer was poor. Educational level, family income and awareness of previous disease history were significant influencing factors of screening uptake. Specific awareness programs to increase knowledge of cervical cancer and screening willingness should be designed and implemented in the public without delay, especially for younger and elderly women.

Establishing views of traditional healers and biomedical practitioners on collaboration in mental health care in Zanzibar: a qualitative pilot study

BACKGROUND

This qualitative pilot study aimed to establish views of traditional and biomedical practitioners towards collaboration between the two sectors on the treatment of people with mental illness in Zanzibar, Tanzania.

METHODS

Six traditional healers (known as "waganga" in Swahili) and six nurses working in government secondary mental health services were invited to participate in a series of focus group discussions (FGDs). Two sets of FGDs took place approximately seven weeks apart. In each set, FGDs were conducted with traditional healers only, nurses only, and finally nurses and traditional healers together. FGDs were conducted in Swahili, audio-recorded and then translated to English by an independent translator and coded thematically using NVivo software.

RESULTS

All participants expressed that they were in favour of collaboration between traditional and biomedical practitioners on mental healthcare. Opinions varied regarding what form this collaboration should take. For many nurses and healers, there was acknowledgement of the role of the other group in providing treatment for people with mental illness, with support for the idea of bi-directional referrals between the two sectors. For some nurses, the value of collaboration would be purely in the education of traditional healers in the recognition of mental illness, with subsequent referral to biomedical services. For some traditional healers, the idea of collaboration seemed to appeal in part because of a perceived opportunity to learn additional skills from biomedical practitioners. Both categories of participant expressed a belief that patients possessed by a jinn (a spirit) or those that had been bewitched needed treatment by traditional healers. On the other hand, those with what participants considered to be "mental illness" needed treatment at the hospital clinic. However, some nurses felt that that traditional healers might be able to provide helpful treatment for mental illness, as well as those suspected to be affected by jinn or witchcraft. There was agreement on the need to establish clear referral pathways between the two service providers. The creation of an office for traditional healers at the hospital was an area where there was disagreement among participants.

CONCLUSIONS

We conclude that there is a positive view of collaboration among traditional healers and nurses who participated, and a willingness to work towards actual collaboration. The results suggest that views vary as to what form this collaboration should take, with opinions differing between nurses, as well as between traditional healers. Additional work is needed in order to further explore the nature of potential collaboration and extend the research to the wider population of traditional and biomedical practitioners in Zanzibar, to include primary health care workers.

Adequacy of macro and micronutrients in infants and young children's diets in Zanzibar, Tanzania

Background

A study was conducted in Zanzibar using ProPAN software to assess nutrient adequacy of foods given to infants and children aged 6–23 months old in Zanzibar.

Methodology

The 24-hr dietary recall method embedded in ProPAN software was used to determine the adequacy of energy, protein, iron, calcium, zinc and vitamin A in foods consumed by children. Sample of 200 mothers/caretakers with children aged 6–23 months were interviewed.

Results

Most frequent foods given to infants and children were tea, bread, white rice and fish. Key nutrients such as iron, zinc and vitamin A were below the recommended levels except for vitamin C from the diets consumed by children aged 11–23 months. Energy and protein were considered to be adequate as more than 90% of the children received enough of these nutrients. Mean age of introduction of complementary foods was four months.

Conclusion

Children diets were limited in fruits and vegetables that caused micronutrients of nutritional importance such as iron, zinc and vitamin A to be supplied below recommended level. Equally, fat intake was below recommended level. Nutrition education on appropriate complementary foods should be given to caregivers. Promotion of consumption of diversified diets and locally available nutrient dense foods should be emphasized so as to achieve adequate intake of nutrients to infants and young children.

[Current status of international discourse of China aid project of schistosomiasis control in Zanzibar]

Since the Eighteenth National Congress of the Communist Party of China, China has constantly innovated and developed its diplomatic concept, and proposed the important idea of the Community of Shared Future for Mankind (CSFM), which contributes a discourse system with Chinese characteristics to the world. It is indicated that discourse builds its subject and governs the subject's discourse practices, and the discourse subject strengthens and reiterates discourse rules in discourse practices. China aid project of schistosomiasis control in Zanzibar is a discourse subject of the CSFM discourse system. This paper analyzes the discourse status, discourse practices and the reiteration of discourse rules of China aid project of schistosomiasis control in Zanzibar.

Power quality and modern energy for all

This research provides a detailed mapping of voltage quality in a sub-Saharan African (SSA) community and connects power systems data to household surveys and interviews for a comprehensive understanding of life under an unreliable grid. Reliability within the context of “modern energy for all” in SSA has traditionally focused on power outages rather than voltage quality and on businesses rather than households. Our research expands on energy access scholarship and reliability concerns in SSA by offering an illustrative case study of access in Unguja, Tanzania. As electricity access expands in financially constrained communities, creating capacity-constrained connections, our Unguja study offers a crucial look at what that access means for SSA communities.

“Modern energy for all,” an internationally supported initiative to connect populations to electricity services, is expected to help reduce poverty-induced vulnerabilities. It has become a primary strategy for meeting sustainable development goals, especially in sub-Saharan Africa. However, when electricity is supplied by a capacity-constrained grid to a resource-constrained population, the service quality can vary both spatially and temporally. This research explores the quality of electricity services based on a case study of Unguja, Tanzania. Using 1) open-ended interviews, 2) detailed electricity-systems monitoring, and 3) household surveys, we show how voltage quality varies significantly, even within highly localized settings. Fluctuations result in dim lights at best and power outages and broken appliances at worst, denying many Unguja residents the expected benefits of access to modern energy. By combining an extensive understanding of the physical system together with interviews and surveys, this work presents a unique mapping of voltage quality in a system that is financially and physically constrained and highlights the consequences of poor-quality service for poor users.

Use of Routine Health Information System Data to Evaluate Impact of Malaria Control Interventions in Zanzibar, Tanzania from 2000 to 2015

BACKGROUND

Impact evaluations allow countries to assess public health gains achieved through malaria investments. This study uses routine health management information system (HMIS) data from Zanzibar to describe changes in confirmed malaria incidence and impact of case management and vector control interventions during 2000-2015.

METHODS

HMIS data from 129 (82%) public outpatient facilities were analyzed using interrupted time series models to estimate the impact of artemisinin-based combination therapy (ACT), indoor residual spray, and long-lasting insecticidal nets. Evaluation periods were defined as pre-intervention (January 2000 to August 2003), ACT-only (September 2003 to December 2005) and ACT plus vector control (2006-2015).

FINDINGS

After accounting for climate, seasonality, diagnostic testing rates, and outpatient attendance, average monthly incidence of confirmed malaria showed no trend over the pre-intervention period 2000-2003 (incidence rate ratio (IRR) 0.998, 95% CI 0.995-1.000). During the ACT-only period (2003-2005), the average monthly malaria incidence rate declined compared to the pre-intervention period, showing an overall declining trend during the ACT-only period (IRR 0.984, 95% CI 0.978-0.990). There was no intercept change at the start of the ACT-only period (IRR 1.081, 95% CI 0.968-1.208), but a drop in intercept was identified at the start of the ACT plus vector control period (IRR 0.683, 95% CI 0.597-0.780). During the ACT plus vector control period (2006-2015), the rate of decline in average monthly malaria incidence slowed compared to the ACT-only period, but the incidence rate continued to show an overall slight declining trend during 2006-2015 (IRR 0.993, 95% CI 0.992-0.994).

INTERPRETATION

This study presents a rigorous approach to the use of HMIS data in evaluating the impact of malaria control interventions. Evidence is presented for a rapid decline in malaria incidence during the period of ACT roll out compared to pre-intervention, with a rapid drop in malaria incidence following introduction of vector control and a slower declining incidence trend thereafter.

[A path analysis on China's participation in global health governance: a case study of China Aid of Schistosomiasis Control in Zanzibar]

Recently, China's participation in global health governance has been paid increasing global attention. This paper analyzed the current status and needs of African schistosomiasis control, the participation of China and international organizations in African schistosomiasis control and the progress of China Aid of Schistosomiasis Control in Zanzibar, with China Aid of Schistosomiasis Control in Zanzibar as an example. It is suggested that China may improve the capability of participation in global public health governance and international reputation through strengthening intergovernmental and international collaborations, providing successful disease control experiences and products and improving capability and team building.

Exploring Food Access and Sociodemographic Correlates of Food Consumption and Food Insecurity in Zanzibari Households

Rapid growth of the Zanzibari population and urbanization are expected to impact food insecurity and malnutrition in Zanzibar. This study explored the relationship between food access (FA) and sociodemographic correlates with food consumption score and food insecurity experience scale. Based on cross-sectional data of 196 randomly selected households, we first investigated the association between sociodemographic correlates and Food Consumption Score (FCS) and Food Insecurity Experience Scale using multilevel Poisson regression. Secondly, the role of FA in these associations was investigated by interaction with the respective correlates. About 65% of households had poor food consumption, and 32% were severely food-insecure. Poor FA was more prevalent in households with poor food consumption (71%). Polygamous households and larger households had a higher chance for severe food insecurity. In the interaction with FA, only larger households with poor FA showed a higher chance for severe food insecurity. In households having no vehicle, good FA increased the chance of having acceptable FCS compared to poor FA. By contrast, urban households with good FA had a twofold chance of acceptable FCS compared to rural household with poor FA. Poor FA, poor food consumption and food insecurity are challenging; hence, facilitating households’ FA may improve the population’s nutrition situation.

Awareness of Danger Signs during Pregnancy and Post-Delivery Period among Women of Reproductive Age in Unguja Island, Zanzibar: A Qualitative Study

Zanzibar is part of the United Republic of Tanzania with high levels of maternal mortality due to obstetric complications. Women's awareness on obstetric danger signs and early seeking of medical care is the first intervention in reduction of maternal deaths. This study explored awareness of danger signs among women of reproductive age in Unguja Island, Zanzibar. A community-based qualitative study using focus group discussions among women of reproductive age was conducted to explore awareness of danger signs between March and April 2016. Data was analyzed using thematic analysis. The study found that women were aware of danger signs during pregnancy but not during the post-delivery period. The mentioned danger signs during pregnancy included vaginal bleeding, fits, swelling of the legs and leaking of vagina fluid. Some women still believed that danger signs during pregnancy and post-delivery period were due to witchcraft leading to consultations with traditional healers and hence delays in seeking skilled medical care. In this context of misconceptions and cultural beliefs there should be investment in health education on danger signs to the community in general with involvement of traditional birth attendants and traditional healers who might play a role in advising and referring women with danger signs to the health facilities for care.

Historical perspectives on contemporary human-environment dynamics in southeast Africa

The human communities and ecosystems of island and coastal southeast Africa face significant and linked ecological threats. Socioecological conditions of concern to communities, governments, nongovernmental organizations, and researchers include declining agricultural productivity, deforestation, introductions of non-native flora and fauna, coastal erosion and sedimentation, damage to marine environments, illegal fishing, overfishing, waste pollution, salinization of freshwater supplies, and rising energy demands, among others. Human-environment challenges are connected to longer, often ignored, histories of social and ecological dynamics in the region. We argue that these challenges are more effectively understood and addressed within a longer-term historical ecology framework. We reviewed cases from Madagascar, coastal Kenya, and the Zanzibar Archipelago of fisheries, deforestation, and management of human waste to encourage increased engagement among historical ecologists, conservation scientists, and policy makers. These case studies demonstrate that by widening the types and time depths of data sets we used to investigate and address current socioecological challenges, our interpretations of their causes and strategies for their mitigation varied significantly.

Urogenital schistosomiasis elimination in Zanzibar: accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infections

Background

Urine filtration and microhaematuria reagent strips are basic standard diagnostic methods to detect urogenital schistosomiasis. We assessed their accuracy for the diagnosis of light intensity infections with Schistosoma haematobium as they occur in individuals living in Zanzibar, an area targeted for interruption of transmission.

Methods

Urine samples were collected from children and adults in surveys conducted annually in Zanzibar from 2013 through 2016 and examined with the urine filtration method to count S. haematobium eggs and with the reagent strip test (Hemastix) to detect microhaematuria as a proxy for infection. Ten percent of the urine filtration slides were read twice. Sensitivity was calculated for reagent strips, stratified by egg counts reflecting light intensity sub-groups, and kappa statistics for the agreement of urine filtration readings.

Results

Among the 39,207 and 18,155 urine samples examined from children and adults, respectively, 5.4% and 2.7% were S. haematobium egg-positive. A third (34.7%) and almost half (46.7%) of the egg-positive samples from children and adults, respectively, had ultra-low counts defined as 1–5 eggs per 10 ml urine. Sensitivity of the reagent strips increased significantly for each unit log10 egg count per 10 ml urine in children (odds ratio, OR: 4.7; 95% confidence interval, CI: 4.0–5.7; P < 0.0001) and adults (OR: 2.6; 95% CI: 1.9–3.7, P < 0.0001). Sensitivity for diagnosing ultra-light intensity infections was very low in children (50.1%; 95% CI: 46.5–53.8%) and adults (58.7%; 95% CI: 51.9–65.2%). Among the 4477 and 1566 urine filtration slides read twice from children and adults, most were correctly identified as negative or positive (kappa = 0.84 for children and kappa = 0.81 for adults). However, 294 and 75 slides had discrepant results and were positive in only one of the two readings. The majority of these discrepant slides (76.9% of children and 84.0% of adults) had counts of 1–5 eggs per 10 ml urine.

Conclusions

We found that many individuals infected with S. haematobium in Zanzibar excrete > 5 eggs per 10 ml urine. These ultra-light infections impose a major challenge for accurate diagnosis. Next-generation diagnostic tools to be used in settings where interruption of transmission is the goal should reliably detect infections with ≤ 5 eggs per 10 ml urine.

Trial Registration

ISRCTN, ISRCTN48837681. Registered 05 September 2012 - Retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3136-6) contains supplementary material, which is available to authorized users.