Awareness and knowledge of female genital schistosomiasis in a population with high endemicity: a cross-sectional study in Madagascar

Introduction

Female genital schistosomiasis (FGS) is a neglected disease with long-term physical and psychosocial consequences, affecting approximately 50 million women worldwide and generally representing an unmet medical need on a global scale. FGS is the chronic manifestation of a persistent infection with Schistosoma haematobium. FGS services are not routinely offered in endemic settings with a small percentage of women at risk receiving adequate care. Madagascar has over 60% prevalence of FGS and no guidelines for the management of the disease. This study aimed to determine FGS knowledge among women and health care workers (HCWs) in a highly endemic area of Madagascar.

Methods

A convenience sampling strategy was used for this cross-sectional study. Descriptive statistics including proportions and 95% confidence intervals (CI) were calculated, reporting socio-demographic characteristics of the population. Knowledge sources were evaluated descriptively. Binary Poisson regression with robust standard errors was performed; crude (CPR) and adjusted prevalence ratio (APR) with 95% CIs were calculated.

Results

A total of 783 participants were included in the study. Among women, 11.3% (n = 78) were aware of FGS while among the HCWs 53.8% (n = 50) were aware of FGS. The highest level of knowledge was observed among women in an urban setting [24%, (n = 31)] and among those with a university education/vocational training [23% (n = 13)]. A lower APR of FGS knowledge was observed in peri-urban [APR 0.25 (95% CI: 0.15; 0.45)] and rural [APR 0.37 (95% CI 0.22; 0.63)] settings in comparison to the urban setting. Most HCWs reported other HCWs [40% (n = 20)] while women mainly reported their family [32% (n = 25)] as being their main source of information in the 6 months prior to the survey.

Discussion and conclusions

Our study shows limited awareness and knowledge of FGS among population groups in the highly endemic Boeny region of Madagascar. With this study we contribute to identifying an important health gap in Madagascar, which relates to a disease that can silently affect millions of women worldwide. In alignment with the targets of the NTD roadmap, addressing schistosomiasis requires a paradigm shift for its control and management including a greater focus on chronic forms of the disease.

Prevalence and risk distribution of schistosomiasis among adults in Madagascar: a cross-sectional study

BACKGROUND

The goal to eliminate the parasitic disease of poverty schistosomiasis as a public health problem is aligned with the 2030 United Nations agenda for sustainable development goals, including universal health coverage (UHC). Current control strategies focus on school-aged children, systematically neglecting adults. We aimed at providing evidence for the need of shifting the paradigm of schistosomiasis control programs from targeted to generalized approaches as key element for both the elimination of schistosomiasis as a public health problem and the promotion of UHC.

METHODS

In a cross-sectional study performed between March 2020 and January 2021 at three primary health care centers in Andina, Tsiroanomandidy and Ankazomborona in Madagascar, we determined prevalence and risk factors for schistosomiasis by a semi-quantitative PCR assay from specimens collected from 1482 adult participants. Univariable and multivariable logistic regression were performed to evaluate odd ratios.

RESULTS

The highest prevalence of S. mansoni, S. haematobium and co-infection of both species was 59.5%, 61.3% and 3.3%, in Andina and Ankazomborona respectively. Higher prevalence was observed among males (52.4%) and main contributors to the family income (68.1%). Not working as a farmer and higher age were found to be protective factors for infection.

CONCLUSIONS

Our findings provide evidence that adults are a high-risk group for schistosomiasis. Our data suggests that, for ensuring basic health as a human right, current public health strategies for schistosomiasis prevention and control need to be re-addressed towards more context specific, holistic and integrated approaches.

Schistosomiasis control in adults: a call for action towards the goal of universal health coverage

Background

Schistosomiasis is a high-burden parasitic disease and endemic in tropical climates, such as Madagascar. Recently it is emerging in Europe. Chronic infections lead to disabilities including loss in work productivity. Current control strategies focus on school-aged children, thereby systematically excluding adults. The goal to eliminate the disease as a public health problem is aligned with the Sustainable Development Goals agenda, including Universal Health Coverage (UHC). We aim at assessing the distribution of schistosomiasis among adults in Madagascar, in order to promote more targeted public health initiatives against the disease.

Methods

In a cross-sectional study, 1477 blood samples were collected at three primary health-care centers in Madagascar from 03.21 to 01.22. A semi quantitative PCR assay was used to assess the presence of Schistosoma. Positivity rates with 95% Confidence Intervals (CI) were reported by gender and age groups.

Results

Our study population had a balanced gender distribution with 54.2% [CI: 51.7;56.8] of females and a median age of 37 years (IQR: 24-48). Preliminary results show an overall Schistosome positivity rate of 59.5% [CI: 57.0;62.0]. Positivity was higher in males 62.4% [CI: 58.7;66.1], than in females 57.1% [CI: 53.5;60.5]. Highest positivity was seen in the 18-34 year age group with 66.2% [CI: 62.7;69.6]. Lowest positivity of 46.2% [CI: 39.2;53.2] was observed in adults aged over 55 years.

Conclusions

Our preliminary results provide evidence of high positivity rates of schistosomiasis among adults in a highly endemic country. Differently from many studies, males seem more affected than females. The youngest age group, representing the more active workforce of a population, shows a higher positivity rate. Our data suggests that, in the logic of UHC and health as a human right, public health strategies for schistosomiasis need to be re-addressed towards a universal coverage of affected individuals.

Key messages

Awareness of Female Genital Schistosomiasis: A cross-sectional survey in rural Madagascar

Background

Infections with S. haematobium are endemic in tropical regions and emerging in some European countries. Prolonged chronic infection with S. haematobium can cause Female Genital Schistosomiasis (FGS), which can lead to serious gynecological conditions, including infertility. However, awareness of FGS is limited, as are adequate guidelines and public health strategies to manage the disease. The aim of this study is to determine the levels and quality of FGS awareness among women and healthcare workers (HCW) in the Boeny region of Madagascar, where the disease is endemic.

Methods

Data collection involved a cross-sectional survey of adult women (n = 694) and HCWs (n = 93) on topics, such as respondents’ sociodemographic background characteristics, FGS awareness, and risk perceptions. Results were analyzed using descriptive statistics including proportions and 95% confidence intervals.

Results

Of the 694 women included in the study, 11.2% (CI [9.0-13.8%]) had heard of FGS. Among these, 34.6% (CI [24.1-46.2%]) were unaware of the gynecological symptoms signature for FGS, and 41% (CI [30.0-52.7%]) were unaware of the urological symptoms of the disease. Out of the 93 HCW surveyed, 53.2% (CI [42.6-63.6%]) had heard of FGS. Among these, 42.0% (CI [28.1-56.8%]) were unaware of the gynecological symptoms, and 52.0% (CI [37.4-66.3%]) were unaware of the urological symptoms.

Conclusions

Preliminary results show overall low levels of FGS awareness among the study population. While more women reported to have never heard of FGS than HCW, the proportion of HCWs who did not know the gynecological and urological symptoms of FGS was higher. Given the occurrence of FGS in Europe and the chronic character of the disease it would be crucial to conduct similar investigations in Europe. Such findings can contribute to the design of targeted local and global FGS awareness campaigns to improve the health of women affected by this disease worldwide.

Key messages

• Awareness of FGS among the study population in Madagascar, an endemic country, is low.

• Lack of awareness can delay the identification of the disease and increase individual and community burden.

Exposure of pre-school aged children to schistosomiasis: a call for public health strategies

Background

Schistosomiasis is a disease of poverty, prevalent in tropical regions and emerging in Europe. Mass drug administration (MDA) is a common strategy to fight the disease. Pre-school aged children (PSAC) are conventionally considered not to be at high risk of infection and thus usually excluded from MDA. However, chronic infections at young ages can result in serious health consequences. Our study aims to better understand the schistosomiasis transmission routes in PSAC and risk perceptions among caretakers in the endemic context of Madagascar.

Methods

This is a cross-sectional sub-study embedded in the clinical trial freeBILy. Using a mixed methods approach, 86 women and their two-year-old children in four communities of the Amoron’ I Mania and Itasy regions of Madagascar in April 2022 were interviewed using structured questionnaires, focus group discussions and in-depth-interviews. Additionally, structured observational data were collected on the behaviours of 20 PSAC around waterbodies in the communities where notes and anonymised photos were taken.

Results

Preliminary analysis shows that knowledge of schistosomiasis, its transmission routes and effects is limited. Risky behaviours of children were reported during the observations. They joined their mothers during daily activities and spent between 3-60 mins in rivers, lakes and rice fields. The exposure time to potentially contaminated waters was sufficient to represent a risk for infection.

Conclusions

Even though our preliminary results show that PSAC are at risk of schistosomiasis infection, they are currently excluded from systematic public health interventions. The lack of risk awareness among caretakers in endemic countries calls for actions to establish tailored programs on health literacy and education. Treatment should be considered for PSAC as well as the implementation of awareness campaigns, both locally and globally given the re-occurrence of schistosomiasis in countries outside the tropics.

Key messages

• Pre-school aged children are exposed to the risk of early infection with schistosomiasis.

• Public health programs against schistosomiasis should address pre-school aged children in endemic countries and in health promotion strategies globally.

Madagascar's EPI vaccine programs: A systematic review uncovering the role of a child's sex and other barriers to vaccination

Background

Immunizations are one of the most effective tools a community can use to increase overall health and decrease the burden of vaccine-preventable diseases. Nevertheless, socioeconomic status, geographical location, education, and a child's sex have been identified as contributing to inequities in vaccine uptake in low- and middle-income countries (LMICs). Madagascar follows the World Health Organization's Extended Programme on Immunization (EPI) schedule, yet vaccine distribution remains highly inequitable throughout the country. This systematic review sought to understand the differences in EPI vaccine uptake between boys and girls in Madagascar.

Methods

A systematic literature search was conducted in August 2021 through MEDLINE, the Cochrane Library, Global Index Medicus, and Google Scholar to identify articles reporting sex-disaggregated vaccination rates in Malagasy children. Gray literature was also searched for relevant data. All peer-reviewed articles reporting sex-disaggregated data on childhood immunizations in Madagascar were eligible for inclusion. Risk of bias was assessed using a tool designed for use in systematic reviews. Data extraction was conducted with a pre-defined data extraction tool. Sex-disaggregated data were synthesized to understand the impact of a child's sex on vaccination status.

Findings

The systematic search identified 585 articles of which a total of three studies were included in the final data synthesis. One additional publication was included from the gray literature search. Data from included articles were heterogeneous and, overall, indicated similar vaccination rates in boys and girls. Three of the four articles reported slightly higher vaccination rates in girls than in boys. A meta-analysis was not conducted due to the heterogeneity of included data. Six additional barriers to immunization were identified: socioeconomic status, mother's education, geographic location, supply chain issues, father's education, number of children in the household, and media access.

Interpretation

The systematic review revealed the scarcity of available sex-stratified immunization data for Malagasy children. The evidence available was limited and heterogeneous, preventing researchers from conclusively confirming or denying differences in vaccine uptake based on sex. The low vaccination rates and additional barriers identified here indicate a need for increased focus on addressing the specific obstacles to vaccination in Madagascar. A more comprehensive assessment of sex-disaggregated vaccination status of Malagasy children and its relationship with such additional obstacles is recommended. Further investigation of potential differences in vaccination status will allow for the effective implementation of strategies to expand vaccine coverage in Madagascar equitably.

Funding and registration

AH, BT, FM, GN, and RR are supported by a grant from the Bill and Melinda Gates Foundation (grant number: OPP1205877). The review protocol is registered in the Prospective Register of Systematic Reviews (PROSPERO ID: CRD42021265000).

High seroprevalence of SARS-CoV-2 in Burkina-Faso, Ghana and Madagascar in 2021: a population-based study

BACKGROUND

The current COVID-19 pandemic affects the entire world population and has serious health, economic and social consequences. Assessing the prevalence of COVID-19 through population-based serological surveys is essential to monitor the progression of the epidemic, especially in African countries where the extent of SARS-CoV-2 spread remains unclear.

METHODS

A two-stage cluster population-based SARS-CoV-2 seroprevalence survey was conducted in Bobo-Dioulasso and in Ouagadougou, Burkina Faso, Fianarantsoa, Madagascar and Kumasi, Ghana between February and June 2021. IgG seropositivity was determined in 2,163 households with a specificity improved SARS-CoV-2 Enzyme-linked Immunosorbent Assay. Population seroprevalence was evaluated using a Bayesian logistic regression model that accounted for test performance and age, sex and neighbourhood of the participants.

RESULTS

Seroprevalence adjusted for test performance and population characteristics were 55.7% [95% Credible Interval (CrI) 49·0; 62·8] in Bobo-Dioulasso, 37·4% [95% CrI 31·3; 43·5] in Ouagadougou, 41·5% [95% CrI 36·5; 47·2] in Fianarantsoa, and 41·2% [95% CrI 34·5; 49·0] in Kumasi. Within the study population, less than 6% of participants performed a test for acute SARS-CoV-2 infection since the onset of the pandemic.

CONCLUSIONS

High exposure to SARS-CoV-2 was found in the surveyed regions albeit below the herd immunity threshold and with a low rate of previous testing for acute infections. Despite the high seroprevalence in our study population, the duration of protection from naturally acquired immunity remains unclear and new virus variants continue to emerge. This highlights the importance of vaccine deployment and continued preventive measures to protect the population at risk.

Clustering of Cryptosporidium species infections among sheep and cattle but not children in remote highland communities of Madagascar

Background

The aim of this study was to identify local transmission patterns of Cryptosporidium spp. infections among livestock and humans in four extremely rural and remote highland communities in Madagascar.

Methods

In this cross-sectional study, households were randomly sampled throughout a 1-year study period, with one feces sample collected from each child (≤ 5 years old), sheep and cattle. Cryptosporidium spp. were identified using a nested PCR assay targeting the 18S ribosomal RNA gene. All samples positive for Cryptosporidium hominis were further subtyped by sequencing the 60-kDa glycoprotein gene (gp60). Spatial clustering methods were applied to analyze potential transmission patterns.

Results

In total, 252 households participated in the study, and samples from 197 children, 862 cattle and 334 sheep were collected and included in the study. Of the samples collected, 11 (5.6%) from children, 30 (3.5%) from cattle and 42 (12.6%) from sheep tested positive for Cryptosporidium spp. Very little overlap in the species distribution between human and animal infections was found. Global (overall) and local (spatially defined) clustering was observed for Cryptosporidium spp. infections in sheep and for Cryptosporidium xiaoi/bovis infections among sheep and cattle.

Discussion

The results of this analysis do not support the occurrence of defined disease outbreaks, rather they point to a continuous series of transmission events that are spatially aggregated. Despite the close coexistence between humans, sheep and cattle in the study area, mutual transmission was not observed. Hence, the study underlines the importance of sustained sanitation and hygiene measures to prevent cryptosporidiosis transmission among infants, since asymptomatic children serve as an infection reservoir. Similarly, the study highlights the importance of improving hygiene to reduce the transmission of Cryptosporidium spp. in livestock, an infection with serious consequences, especially in newborn calves.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05434-0.

Seroprevalence of SARS-CoV-2 in urban settings in three sub-Saharan African countries (SeroCoV): a study protocol for a household-based cross-sectional prevalence study using two-stage cluster sampling

INTRODUCTION

The current COVID-19 pandemic has impacted the entire world with increasing morbidity and mortality and has resulted in serious economic and social consequences. Assessing the burden of COVID-19 is essential for developing efficient pandemic preparedness and response strategies and for determining the impact of implemented control measures. Population-based seroprevalence surveys are critical to estimate infection rates, monitor the progression of the epidemic and to allow for the identification of persons exposed to the infection who may either have been asymptomatic or were never tested. This is especially important for countries where effective testing and tracking systems could not be established and where non-severe cases or under-reported deaths might have blurred the true burden of COVID-19. Most seroprevalence surveys performed in sub-Saharan Africa have targeted specific high risk or more easily accessible populations such as healthcare workers or blood donors, and household-based estimates are rarely available. Here, we present the study protocol for a SARS-CoV-2 seroprevalence estimation in the general population of Burkina Faso, Ghana and Madagascar in 2021.

METHODS AND ANALYSIS

The SeroCoV study is a household-based cross-sectional prevalence investigation in persons aged 10 years and older living in urban areas in six cities using a two-stage geographical cluster sampling method stratified by age and sex. The presence of anti-SARS-CoV-2 IgG antibodies will be determined using a sensitive and specific SARS-CoV-2 IgG ELISA. In addition, questionnaires will cover sociodemographic information, episodes of diseases and history of testing and treatment for COVID-like symptoms, travel history and safety measures. We will estimate the seroprevalence of SARS-CoV-2, taking into account test performance and adjusting for the age and sex of the respective populations.

ETHICS AND DISSEMINATION

Ethical approval was received for all participating countries. Results will be disseminated through reports and presentations at the country level as well as peer-reviewed publications and international scientific conferences presentations.

Transmission of Cryptosporidium Species Among Human and Animal Local Contact Networks in Sub-Saharan Africa: A Multicountry Study

BACKGROUND

Cryptosporidiosis has been identified as one of the major causes of diarrhea and diarrhea-associated deaths in young children in sub-Saharan Africa. This study traces back Cryptosporidium-positive children to their human and animal contacts to identify transmission networks.

METHODS

Stool samples were collected from children < 5 years of age with diarrhea in Gabon, Ghana, Madagascar, and Tanzania. Cryptosporidium-positive and -negative initial cases (ICs) were followed to the community, where stool samples from households, neighbors, and animal contacts were obtained. Samples were screened for Cryptosporidium species by immunochromatographic tests and by sequencing the 18S ribosomal RNA gene and further subtyped at the 60 kDa glycoprotein gene (gp60). Transmission clusters were identified and risk ratios (RRs) calculated.

RESULTS

Among 1363 pediatric ICs, 184 (13%) were diagnosed with Cryptosporidium species. One hundred eight contact networks were sampled from Cryptosporidium-positive and 68 from negative ICs. Identical gp60 subtypes were detected among 2 or more contacts in 39 (36%) of the networks from positive ICs and in 1 contact (1%) from negative ICs. In comparison to Cryptosporidium-negative ICs, positive ICs had an increased risk of having Cryptosporidium-positive household members (RR, 3.6 [95% confidence interval {CI}, 1.7-7.5]) or positive neighboring children (RR, 2.9 [95% CI, 1.6-5.1]), but no increased risk of having positive animals (RR, 1.2 [95% CI, .8-1.9]) in their contact network.

CONCLUSIONS

Cryptosporidiosis in rural sub-Saharan Africa is characterized by infection clusters among human contacts, to which zoonotic transmission appears to contribute only marginally.

Limited specificity of commercially available SARS-CoV-2 IgG ELISAs in serum samples of African origin

OBJECTIVES

Specific serological tests are mandatory for reliable SARS-CoV-2 diagnostics and seroprevalence studies. Here, we assess the specificities of four commercially available SARS-CoV-2 IgG ELISAs in serum/plasma panels originating from Africa, South America, and Europe.

METHODS

882 serum/plasma samples collected from symptom-free donors before the COVID-19 pandemic in three African countries (Ghana, Madagascar, Nigeria), Colombia, and Germany were analysed with three nucleocapsid-based ELISAs (Euroimmun Anti-SARS-CoV-2-NCP IgG, EDI™ Novel Coronavirus COVID-19 IgG, Mikrogen recomWell SARS-CoV-2 IgG), one spike/S1-based ELISA (Euroimmun Anti-SARS-CoV-2 IgG), and in-house common cold CoV ELISAs.

RESULTS

High specificity was confirmed for all SARS-CoV-2 IgG ELISAs for Madagascan (93.4-99.4%), Colombian (97.8-100.0%), and German (95.9-100.0%) samples. In contrast, specificity was much lower for the Ghanaian and Nigerian serum panels (Ghana: NCP-based assays 77.7-89.7%, spike/S1-based assay 94.3%; Nigeria: NCP-based assays 39.3-82.7%, spike/S1-based assay 90.7%). 15 of 600 African sera were concordantly classified as positive in both the NCP-based and the spike/S1-based Euroimmun ELISA, but did not inhibit spike/ACE2 binding in a surrogate virus neutralisation test. IgG antibodies elicited by previous infections with common cold CoVs were found in all sample panels, including those from Madagascar, Colombia, and Germany and thus do not inevitably hamper assay specificity. Nevertheless, high levels of IgG antibodies interacting with OC43 NCP were found in all 15 SARS-CoV-2 NCP/spike/S1 ELISA positive sera.

CONCLUSIONS

Depending on the chosen antigen and assay protocol, SARS-CoV-2 IgG ELISA specificity may be significantly reduced in certain populations probably due to interference of immune responses to endemic pathogens like other viruses or parasites.

Performance of a rapid diagnostic test for the detection of Cryptosporidium spp. in African children admitted to hospital with diarrhea

BACKGROUND

Cryptosporidium is a protozoan parasite that causes mild to severe diarrhoeal disease in humans. To date, several commercial companies have developed rapid immunoassays for the detection of Cryptosporidium infection. However, the challenge is to identify an accurate, simple and rapid diagnostic tool for the estimation of cryptosporidiosis burden. This study aims at evaluating the accuracy of CerTest Crypto, a commercialized rapid diagnostic test (RDT) for the detection of Cryptosporidium antigens in the stool of children presenting with diarrhoea.

METHODS

A cross-sectional study was conducted in four study sites in Sub-Saharan Africa (Gabon, Ghana, Madagascar, and Tanzania), from May 2017 to April 2018. Stool samples were collected from children under 5 years with diarrhoea or a history of diarrhoea within the last 24 hours. All specimens were processed and analyzed using CerTest Crypto RDT against a composite diagnostic panel involving two polymerase chain reaction (PCR) tests (qPCR and RFLP-PCR,) as the gold standard.

RESULTS

A total of 596 stool samples were collected. Evaluation of the RDT yielded a very low overall sensitivity of 49.6% (confidence interval (CI) 40.1-59.0), a specificity of 92.5% (CI 89.8-94.7), positive predictive value of 61.3% (CI 50.6-71.2), and negative predictive value of 88.5% (85.3-91.1) when compared to the composite reference standard of qPCR and RFLP-PCR for the detection of Cryptosporidium species. Moreover, the performance of this test varied across different sites.

CONCLUSION

The weak performance of the studied RDT suggests the need to carefully evaluate available commercial RDTs before their use as standard tools in clinical trials and community survey of Cryptosporidium infections in pediatric cohorts.

Seroprevalence of Leptospira spp. Infection in Cattle from Central and Northern Madagascar

Leptospirosis is a zoonotic disease of global importance, especially in tropical countries. The current Leptospira spp. seroprevalence in cattle from central and northern Madagascar is unknown. Thus, the aim of this study was to determine the seroprevalence resulting from infections with pathogenic Leptospira spp. in zebu cattle from these areas. Serum samples from 194 animals were tested by microscopic agglutination test (MAT) using a panel of 12 serovars as antigens. Samples with a titer of ≥1:100 were considered positive. The overall seroprevalence was 59.3% (95% CI; 52.0–66.2%) with titers ranging from 1:100 to 1:1600. Among the seropositive animals, the most frequent antibody reactions were against serovar L. Tarassovi (serogroup L. Tarassovi) with 40.2% (33.3–47.5%), followed by L. Hardjo (L. Sejroe) with 13.9% (9.5–19.8%), L. Grippotyphosa (L. Grippotyphosa) with 9.8% (6.2–15.1%), L. Pomona (L. Pomona) with 7.7% (4.5–12.7%) and L. Autumnalis (L. Autumnalis) with 5.2% (2.6–9.5%). Less than 5% of the samples reacted positively against the remaining serovars. These results indicate a very high exposure of Malagasy cattle to Leptospira spp. which, consequently, poses a definite risk for people working with cattle acquiring this zoonotic infection.

Melioidosis in Africa: Time to Uncover the True Disease Load

Melioidosis is an often fatal infectious disease with a protean clinical spectrum, caused by the environmental bacterial pathogen Burkholderia pseudomallei. Although the disease has been reported from some African countries in the past, the present epidemiology of melioidosis in Africa is almost entirely unknown. Therefore, the common view that melioidosis is rare in Africa is not evidence-based. A recent study concludes that large parts of Africa are environmentally suitable for B. pseudomallei. Twenty-four African countries and three countries in the Middle East were predicted to be endemic, but no cases of melioidosis have been reported yet. In this study, we summarize the present fragmentary knowledge on human and animal melioidosis and environmental B. pseudomallei in Africa and the Middle East. We propose that systematic serological studies in man and animals together with environmental investigations on potential B. pseudomallei habitats are needed to identify risk areas for melioidosis. This information can subsequently be used to target raising clinical awareness and the implementation of simple laboratory algorithms for the isolation of B. pseudomallei from clinical specimens. B. pseudomallei was most likely transferred from Asia to the Americas via Africa, which is shown by phylogenetic analyses. More data on the virulence and genomic characteristics of African B. pseudomallei isolates will contribute to a better understanding of the global evolution of the pathogen and will also help to assess potential differences in disease prevalence and outcome.

Influence of Broth Enrichment as well as Storage and Transport Time on the Sensitivity of MRSA Surveillance in the Tropics

Direct growth on blood and screening agar for methicillin-resistant Staphylococcus aureus (MRSA) at a tropical surveillance site was compared with broth enrichment and subsequent growth on selective MRSA agar after international sample transport.

In Madagascar, 1548 swabs from an MRSA surveillance study were assessed for growth on Columbia blood agar enriched with 5% sheep blood and MRSA screening agar at the surveillance site with subsequent cold storage of the samples and shipment to Germany. In Germany, 1541 shipped samples were analyzed by non-selective broth enrichment with subsequent culture on MRSA selective agar.

A total of 28 MRSA isolates were detected. Of these, 20 strains were isolated from direct culture on blood and MRSA screening agars at the surveillance site, 24 MRSA strains were isolated using the broth enrichment method in Germany, and 16 MRSA strains were identified by both approaches.

In spite of the observed die-off of individual strains due to long-term storage and transport, broth enrichment with subsequent screening on MRSA selective agar after international sample shipment led to comparable sensitivity of MRSA detection like streaking on blood and MRSA agar at the tropical surveillance site.

No serological evidence for Zika virus infection and low specificity for anti-Zika virus ELISA in malaria positive individuals among pregnant women from Madagascar in 2010

It was previously reported that a malaria infection may interfere with the specificity of a commercial ELISA test against Zika virus (ZIKV). We analyzed 1,216 plasma samples from healthy, pregnant women collected in two sites in Madagascar in 2010 for ZIKV antibodies using a commercial ELISA and for Plasmodium infection by PCR. This screen revealed six putative ZIKV-positive samples by ELISA. These results could not be confirmed by indirect immunofluorescence assays or virus neutralization tests. Four of these six samples were also positive for P. falciparum. We noted that the frequency of malaria positivity was higher in ZIKV-ELISA positive samples (50% and 100% in the two study sites) than ZIKV-negative samples (17% and 10%, respectively), suggesting that malaria may have led to false ZIKV-ELISA positives.

Prevalence of nasal colonisation by methicillin-sensitive and methicillin-resistant Staphylococcus aureus among healthcare workers and students in Madagascar

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) clones pose a significant threat to hospitalised patients because the bacteria can be transmitted by asymptomatic carriers within healthcare facilities. To date, nothing is known about the prevalence of S. aureus and MRSA among healthcare workers in Madagascar. The objective of our study was to examine the prevalence and clonal epidemiology of nasal S. aureus and MRSA among healthcare workers and non-medical University students in Antananarivo, Madagascar.

METHODS

This cross sectional study screened nasal swabs taken from students and healthcare workers for S. aureus. Multiplex PCR was performed to identify S. aureus-specific (nuc), MRSA-specific mecA and mecC genes, Panton-Valentine leukocidin (PVL) (lukF-PV), and toxic shock syndrome toxin-1 (TSST-1) specific genes in methicillin-sensitive S. aureus (MSSA) and MRSA isolates. Staphylococcus protein A gene (spa) typing was performed for all confirmed MRSA isolates. The frequency distribution of nasal S. aureus and MRSA of healthcare workers and non-medical students was compared using Pearson's χ(2) test.

RESULTS

Of 1548 nasal swabs tested, 171 (11 %) were positive for S. aureus; 20 (1.3 %) of these isolates were identified as MRSA. S. aureus was detected in 91 of 863 healthcare workers (10.4 %) and in 80 (11.8 %) of 685 students; however, 14 (1.5 %) healthcare workers carried MRSA compared with six (0.9 %) students. Nasal carriage of S. aureus and MRSA was more prevalent in women than in men, and 21 (11.7 %) S. aureus isolates were PVL-positive and 36 (21 %) were TSST-1 positive. The mecC gene was not detected in any isolates. Five different spa types were identified, with spa type t186 being the predominant MRSA clone (16/20).

CONCLUSION

The results of the present study reveal a low frequency of S. aureus and MRSA nasal carriage in both students and healthcare workers from Antananarivo, Madagascar. The predominant MRSA clone (t186) was previously described in hospitalised patients in Madagascar.

High detection rate of Rickettsia africae in Amblyomma variegatum but low prevalence of anti-rickettsial antibodies in healthy pregnant women in Madagascar

Tick-borne spotted fever group (SFG) rickettsioses are emerging infectious diseases in Sub-Saharan Africa. In Madagascar, the endemicity of tick-borne rickettsiae and their vectors has been incompletely studied. The first part of the present study was conducted in 2011 and 2012 to identify potential anthropophilic tick vectors for SFG rickettsiae on cattle from seven Malagasy regions, and to detect and characterize rickettsiae in these ticks. Amblyomma variegatum was the only anthropophilic tick species found on 262 cattle. Using a novel ompB-specific qPCR, screening for rickettsial DNA was performed on 111 A. variegatum ticks. Rickettsial DNA was detected in 96 of 111 ticks studied (86.5%). Rickettsia africae was identified as the only infecting rickettsia using phylogenetic analysis of ompA and ompB gene sequences and three variable intergenic spacers from 11 ticks. The second part of the study was a cross-sectional survey for antibodies against SFG rickettsiae in plasma samples taken from healthy, pregnant women at six locations in Madagascar, two at sea level and four between 450 and 1300m altitude. An indirect fluorescent antibody test with Rickettsia conorii as surrogate SFG rickettsial antigen was used. We found R. conorii-seropositives at all altitudes with prevalences between 0.5% and 3.1%. Our results suggest that A. variegatum ticks highly infected with R. africae are the most prevalent cattle-associated tick vectors for SFG rickettsiosis in Madagascar. Transmission of SFG rickettsiosis to humans occurs at different altitudes in Madagascar and should be considered as a relevant cause of febrile diseases.

Molecular epidemiology and seroprevalence in asymptomatic Plasmodium falciparum infections of Malagasy pregnant women in the highlands

Background

Malaria epidemiology in Madagascar is classified into four different areas, ranging from unstable seasonal transmission in the highlands to hyperendemic perennial transmission areas in the costal level. Most malaria studies in Madagascar are focused on symptomatic children. However, because of the low transmission in some areas with correspondingly low level of semi-immunity, adults are also at risk, in particular pregnant women. The objective of this study was to gain information on the genetic epidemiology of malarial infections in pregnant women in order to provide information for malaria control and elimination programmes in Madagascar.

Methods

Between May and August 2010, we carried out cross-sectional surveys targeting healthy pregnant women in six locations, three in the coastal area and three in the highlands at 850–1300 m. 1244 blood samples were screened for anti-Plasmodium falciparum antibodies by immunofluorescence test and for malarial infection by realtime-PCR. The prevalence of chloroquine and sulphadoxine-pyrimethamine resistance markers was also determined in all Plasmodium falciparum samples by PCR-RFLP as well as the multiplicity of infection through genotyping six neutral microsatellites.

Results

In the highlands, 67.4% of the women presented antibodies against Plasmodium falciparum and 9.2% were carrying parasites, at the coast 95.6% and 14.8%, respectively. In the mean, 1.2 clones were detected in infected pregnant woman in the highlands and 1.5 at the coast. A higher level of monoclonal infections was found in the highlands (85.4%) compared to the coast (61.8%). Resistance markers for sulphadoxine-pyrimethamine were present only in two sites.

Conclusion

Immunity is triggered in Malagasy highland populations when they are infected with malaria parasites, but these populations could also serve as a reservoir for epidemics.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-015-0704-5) contains supplementary material, which is available to authorized users.

Identification of nasal colonization with β-lactamase-producing Enterobacteriaceae in patients, health care workers and students in Madagascar

This study assesses the nasal occurrence of β-lactamase-producing Enterobacteriaceae both in patients in a hospital department of infectious diseases at admission and in healthy Madagascan students and health care workers. Nasal swabs from 681 students, 824 health care workers, and 169 patients were obtained in Antananarivo, Madagascar, and transferred to Germany. Screening for β-lactamase (ESBL, ampC) producing Enterobacteriaceae was performed by cultural and molecular approaches, comprising Brilliance ESBL agar, E-testing, ABCD-testing, and commercial hyplex ESBL and SuperBug ID PCR. Regarding ESBL-positive strains and strains with resistance against at least three out of the four tested bactericidal antibiotic drugs, 0.3% (five out of 1541) of the students and health care workers group showed nasal colonization, whereas colonization was observed in 7.1% (12 out of 169) of the hospitalized patients at admission. No appreciably reduced detection rates after sample storage and intercontinental transport were observed. A considerable proportion of nasal colonization with cephalosporin-resistant Enterobacteriaceae was demonstrated in Madagascan hospital patients at admission, posing a risk of developing future endogenous infections. The nasal colonization of healthy individuals was negligible. Good storage and transport stability of Enterobacteriaceae will allow for future studies even in areas difficult to access.

PCR for enteric pathogens in high-prevalence settings. What does a positive signal tell us?

BACKGROUND

Molecular methods, in particular PCR, are increasingly used for the diagnosis of enteric pathogens in stool samples. In high-endemicity settings, however, asymptomatic carriage or residual DNA from previous infections will hamper the interpretation of positive test results. We assessed the quantitative dimension of this problem in schoolchildren in the rural highlands of Madagascar.

METHODS

Stool samples were collected from 410 apparently healthy Madagascan schoolchildren and analysed by multiplex real-time PCR for enteroinvasive bacteria (Salmonella spp., Shigella spp./enteroinvasive Escherichia coli (EIEC), Campylobacter jejuni, Yersinia spp.), enteric protozoa (Entamoebea histolytica, Giardia duodenalis, Cryptosporidium spp., Cyclospora spp.), and helminths (Ascaris lumbricoides, Ancylostoma spp., Necator americanus, Strongyloides stercoralis). Symptoms of gastrointestinal disease were assessed.

RESULTS

Among the 410 samples, we detected Giardia duodenalis in 195, Campylobacter jejuni in 91, Ascaris lumbricoides in 72, Cyclospora cayetanenesis in 68, Shigella spp./EIEC in 56, and Strongyloides stercoralis and Cryptosporum spp. in 1 case each. Salmonella spp., Yersinia spp. and hookworms were not observed. Relative risk assessment suggested few and incoherent associations with pathogen detections, indicating asymptomatic carriage or DNA residuals. Only 26.1% of the schoolchildren were tested negative for all analysed pathogens.

CONCLUSIONS

The very high risk of detecting traces of asymptomatic carriage or residual DNA from previous infections limits the value of highly sensitive PCR for the causal attribution of detected enteric pathogens from stool samples to an infectious gastrointestinal disease in the high-endemicity setting. Evaluated standards for the interpretation of such results are needed both for the diagnostic routine and for epidemiological assessments.

Schistosoma mansoni in schoolchildren in a Madagascan highland school assessed by PCR and sedimentation microscopy and Bayesian estimation of sensitivities and specificities

Madagascar is an endemic area for schistosomiasis, but recent prevalence data are scarce. We investigated stool samples of 410 children aged 4-18 years from a combined primary and secondary school in a Madagascan highland village near Ambositra in order to assess the prevalence of Schistosoma mansoni using microscopy and real-time polymerase chain reaction (PCR). A high prevalence of S. mansoni of 77.1% was detected by PCR, while only 15.2% of microscopic examinations of sedimentation-enriched stools were positive. We estimated the sensitivity and specificity of stool sedimentation microscopy (19.7% and 98.8%) and of PCR (98.9% and 89.3%) using a Bayesian approach for two dependant tests in one population without a reference standard. Our Bayesian posterior estimate of the prevalence is 80.2%. Simple sedimentation technique misses about 4/5 of all PCR-confirmed infections and is insufficient to determine the prevalence of S. mansoni. A survey comparing PCR with a classical standard technique (KatoKatz) is desirable.

Seroprevalence of antibodies against Chikungunya, Dengue, and Rift Valley fever viruses after febrile illness outbreak, Madagascar

In October 2009, two-3 months after an outbreak of a febrile disease with joint pain on the eastern coast of Madagascar, we assessed serologic markers for chikungunya virus (CHIKV), dengue virus (DENV), and Rift Valley fever virus (RVFV) in 1,244 pregnant women at 6 locations. In 2 eastern coast towns, IgG seroprevalence against CHIKV was 45% and 23%; IgM seroprevalence was 28% and 5%. IgG seroprevalence against DENV was 17% and 11%. No anti-DENV IgM was detected. At 4 locations, 450-1,300 m high, IgG seroprevalence against CHIKV was 0%-3%, suggesting CHIKV had not spread to higher inland-altitudes. Four women had IgG against RVFV, probably antibodies from a 2008 epidemic. Most (78%) women from coastal locations with CHIKV-specific IgG reported joint pain and stiffness; 21% reported no symptoms. CHIKV infection was significantly associated with high bodyweight. The outbreak was an isolated CHIKV epidemic without relevant DENV co-transmission.