Control of urinary schistosomiasis: an investigation into the effective use of questionnaires to identify high-risk communities and individuals in Niger State, Nigeria

Diagnostic tests for human Schistosoma mansoni and Schistosoma haematobium infection: a systematic review and meta-analysis

BACKGROUND

Accurate diagnosis is pivotal for implementing strategies for surveillance, control, and elimination of schistosomiasis. Despite their low sensitivity in low-endemicity areas, microscopy-based urine filtration and the Kato-Katz technique are considered as reference diagnostic tests for Schistosoma haematobium and Schistosoma mansoni infections, respectively. We aimed to collate all available evidence on the accuracy of other proposed diagnostic techniques.

METHODS

In this systematic review and meta-analysis, we searched PubMed, Embase, the Cochrane Library, and LILACS for studies published from database inception to Dec 31, 2022, investigating the sensitivity and specificity of diagnostic tests for S haematobium and S mansoni infections against Kato-Katz thick smears or urine microscopy (reference tests) involving adults (aged ≥18 years), school-aged children (aged 7 to 18 years), or preschool-aged children (aged 1 month to 7 years). We extracted raw data on true positives, true negatives, false positives, and false negatives for the diagnostic tests and data on the number of participants, study authors, publication year, journal, study design, participants' age and sex, prevalence of Schistosoma infection, and treatment status. To account for imperfect reference tests, we used a hierarchical Bayesian latent class meta-analysis to model test accuracy.

FINDINGS

Overall, we included 121 studies, assessing 28 different diagnostic techniques. Most studies (103 [85%] of 121) were done in Africa, 14 (12%) in South America, one (1%) in Asia, and one (1%) in an unknown country. Compared with the reference test, Kato-Katz thick smears, circulating cathodic antigen urine cassette assay version 1 (CCA1, 36 test comparisons) had excellent sensitivity (95% [95% credible interval 88-99]) and reasonable specificity (74% [63-83]) for S mansoni. ELISA-based tests had a performance comparable to circulating cathodic antigen, but there were few available test comparisons. For S haematobium, proteinuria (42 test comparisons, sensitivity 73% [62-82]; specificity 94% [89-98]) and haematuria (75 test comparisons, sensitivity 85% [80-90]; specificity 96% [92-99]) reagent strips showed high specificity, with haematuria reagent strips having better sensitivity. Despite limited data, nucleic acid amplification tests (NAATs; eg, PCR or loop-mediated isothermal amplification [LAMP]) showed promising results with sensitivity estimates above 90%. We found an unclear risk of bias of about 70% in the use of the reference or index tests and of 50% in patient selection. All analyses showed substantial heterogeneity (I2>80%).

INTERPRETATION

Although NAATs and immunological diagnostics show promise, the limited information available precludes drawing definitive conclusions. Additional research on diagnostic accuracy and cost-effectiveness is needed before the replacement of conventional tests can be considered.

FUNDING

WHO and Luxembourg Institute of Health.

Human schistosomiasis in Nigeria: present status, diagnosis, chemotherapy, and herbal medicines

Schistosomiasis is a neglected tropical disease caused by a parasitic, trematode blood fluke of the genus Schistosoma. With 20 million people infected, mostly due to Schistosoma haematobium, Nigeria has the highest burden of schistosomiasis in the world. We review the status of human schistosomiasis in Nigeria regarding its distribution, prevalence, diagnosis, prevention, orthodox and traditional treatments, as well as snail control strategies. Of the country's 36 states, the highest disease prevalence is found in Lagos State, but at a geo-political zonal level, the northwest is the most endemic. The predominantly used diagnostic techniques are based on microscopy. Other methods such as antibody-based serological assays and DNA detection methods are rarely employed. Possible biomarkers of disease have been identified in fecal and blood samples from patients. With respect to preventive chemotherapy, mass drug administration with praziquantel as well as individual studies with artemisinin or albendazole have been reported in 11 out of the 36 states with cure rates between 51.1 and 100%. Also, Nigerian medicinal plants have been traditionally used as anti-schistosomal agents or molluscicides, of which Tetrapleura tetraptera (Oshosho, aridan, Aidan fruit), Carica papaya (Gwanda, Ìbẹ́pẹ, Pawpaw), Borreria verticillata (Karya garma, Irawo-ile, African borreria), and Calliandra portoricensis (Tude, Oga, corpse awakener) are most common in the scientific literature. We conclude that the high endemicity of the disease in Nigeria is associated with the limited application of various diagnostic tools and preventive chemotherapy efforts as well as poor knowledge, attitudes, and practices (KAP). Nonetheless, the country could serve as a scientific base in the discovery of biomarkers, as well as novel plant-derived schistosomicides and molluscicides.

Improving Access to Diagnostics for Schistosomiasis Case Management in Oyo State, Nigeria: Barriers and Opportunities

Schistosomiasis is one of the Neglected Tropical Diseases that affects over 200 million people worldwide, of which 29 million people in Nigeria. The principal strategy for schistosomiasis in Nigeria is a control and elimination program which comprises a school-based Mass Drug Administration (MDA) with limitations of high re-infection rates and the exclusion of high-risk populations. The World Health Organization (WHO) recommends guided case management of schistosomiasis (diagnostic tests or symptom-based detection plus treatment) at the Primary Health Care (PHC) level to ensure more comprehensive morbidity control. However, these require experienced personnel with sufficient knowledge of symptoms and functioning laboratory equipment. Little is known about where, by whom and how diagnosis is performed at health facilities within the case management of schistosomiasis in Nigeria. Furthermore, there is a paucity of information on patients’ health-seeking behaviour from the onset of disease symptoms until a cure is obtained. In this study, we describe both perspectives in Oyo state, Nigeria and address the barriers using adapted health-seeking stages and access framework. The opportunities for improving case management were identified, such as a prevalence study of high-risk groups, community education and screening, enhancing diagnostic capacity at the PHC through point-of-care diagnostics and strengthening the capability of health workers.

Schistosomiasis: from established diagnostic assays to emerging micro/nanotechnology-based rapid field testing for clinical management and epidemiology

Schistosomiasis is a neglected invasive worm disease with a huge disease burden in developing countries, particularly in children, and is seen increasingly in non-endemic regions through transfer by travellers, expatriates, and refugees. Undetected and untreated infections may be responsible for the persistence of transmission. Rapid and accurate diagnosis is the key to treatment and control. So far, parasitological detection methods remain the cornerstone of Schistosoma infection diagnosis in endemic regions, but conventional tests have limited sensitivity, in particular in low-grade infection. Recent advances contribute to improved detection in clinical and field settings. The recent progress in micro- and nanotechnologies opens a road by enabling the design of new miniaturized point-of-care devices and analytical platforms, which can be used for the rapid detection of these infections. This review starts with an overview of currently available laboratory tests and their performance and then discusses emerging rapid and micro/nanotechnologies-based tools. The epidemiological and clinical setting of testing is then discussed as an important determinant for the selection of the best analytical strategy in patients suspected to suffer from Schistosoma infection. Finally, it discusses the potential role of advanced technologies in the setting near to disease eradication is examined.

Impact of Single Dose Praziquantel Treatment on Schistosoma haematobium Infection among School Children in an Endemic Nigerian Community

Schistosomiasis is prevalent in Nigeria, and the foremost pathogen is Schistosoma haematobium, which affects about 29 million people. Single dose of the drug praziquantel is often recommended for treatment but the efficacy has not been documented in certain regions. Therefore, this study was designed to assess the impact of single dose praziquantel treatment on S. haematobium infection among school children in an endemic community of South-Western Nigeria. Urine samples were collected from 434 school children and 10 ml was filtered through Nucleopore filter paper before examination for egg outputs by microscopy. The prevalence was 24.9% at pre-treatment. There was no statistically significant difference for the prevalence of infection between males (14.7%) and females (10.2%), although the mean egg count for the females (9.87) was significantly more (P < 0.05) than the males (6.06). At 6 and 12 months post-treatment there was 74.4% and 86.4% reduction in the mean egg count, respectively. Interestingly, an increased prevalence of infection from 2.1% at 6 months to 7.7% at 12 months post-treatment was observed, nonetheless the mean egg count was reduced to 0.27 at 12th month from 1.98 at 6 months post-treatment. Resurgence in the prevalence rate between 6 and 12 months post-treatment with praziquantel is herein reported and the need for a follow-up treatment in endemic areas for adequate impact on schistosomiasis control is discussed.

Comparison of sensitivity and specificity of three diagnostic tests to detect Schistosoma mansoni infections in school children in Mwanza region, Tanzania

Background

Schistosomiasis remains one of the most prevalent parasitic infections in the world and has significant economic and public health consequences, particularly in poor communities. Reliable and accurate diagnosis plays a key role in surveillance, prevention and control of schistosomiasis. Currently, the microscopic Kato Katz (KK) stool thick smear technique is the most commonly used method to diagnose Schistosoma mansoni infections in epidemiological surveys. It is well-known that the sensitivity of this parasitological method decreases when infection intensities are moderate to low, however. The urine-based Point-of Care Circulating Cathodic Antigen (POC-CCA) test has been extensively evaluated as a further diagnostic tool. Several studies have shown that the POC-CCA test is more sensitive but less specific than the KK method. However, to clarify the meaning of inconsistent results between KK and POC-CCA tests in clinical routine, this study compares the accuracy of microscopy and POC-CCA versus real-time polymerase chain reaction (real-time PCR) results of urine and faecal samples from African school children participants.

Methodology

This was a school-based cross-sectional study conducted in 2015 among 305 school children aged 7–16 years from two primary schools located in Ilemela and Magu Districts, north-western Tanzania. Single stool and urine samples were collected from each participant and examined for the presence of Schistosoma mansoni eggs, parasite antigen, and parasite DNA using KK thick smears, POC-CCA tests, and real-time PCR, respectively.

Principal findings

The prevalence of S. mansoni infection, calculated by KK was 85.2%, by real-time PCR 92.9% and by POC-CCA 94.9%. In comparison to KK, the POC-CCA and real-time PCR tests had sensitivities of 89.7% and 99.5% and specificities of 22.73% and 29.55%, respectively. However, due to the known limitations of the KK assay, we also used latent class analysis (LCA) that included POC-CCA, KK, and schistosome-specific real-time PCR results to determine their sensitivities and specificities. The POC-CCA test had the highest sensitivity (99.5%) and a specificity of 63.4% by LCA and the real-time PCR test had a sensitivity of 98.7% and the highest specificity (81.2%).

Conclusion

In moderate and high prevalence areas, the POC-CCA cassette test is more sensitive than the KK method and can be used for screening and geographical mapping of S. mansoni infections. Real-time PCR is highly sensitive and also shows the highest specificity among the 3 investigated diagnostic procedures. It can offer added value in diagnosing schistosomiasis.

Urogenital Schistosomiasis among Schoolchildren and the Associated Risk Factors in Selected Rural Communities of Kwara State, Nigeria

Urogenital schistosomiasis is a chronic parasitic disease that causes severe morbidity among schoolchildren in many poor-resource communities in Nigeria. We investigated the prevalence, intensity, and risk factors of the infection in three communities of Kwara State to ascertain the current status of the disease. Of the 724 urine samples screened, using filtration method, 332 (45.6%) school-aged children were infected with average intensity and mean population eggs load of 127.9 eggs/10 ml of urine and 0.794, respectively. Prevalence and intensity of infection varied with communities: high in Ajase-Ipo (57.1%; X = 100.7 ± 23.01 eggs/10 ml) and low in Shonga (37.5%; X = 91.4 ± 78.0). Infection was significantly (P < 0.05) higher in males (50.8%) than the females (42.4%). Similarly, infection significantly (P < 0.05) increased with increasing age. Multivariate logistic analysis of risk factors revealed that lack of portable drinking water (adjusted odd ratio (aOR) = 4.76; 95% CI = 2.64-5.98), unemployment (aOR = 2.23; 1.87-2.294), lack of knowledge of infection (aOR = 2.16; 0.59-3.83), and frequent contact with contaminated water bodies (aOR = 2.01; 1.45-2.70) were important predictors of urinary schistosomiasis. Therefore, continuous evaluation of the intervention strategies that address risk factors must compliment Mass Drug Administration to curtail the transmission and debilitating health consequences of infection in endemic settings.

Maternal urogenital schistosomiasis; monitoring disease morbidity by simple reagent strips

Background

Urine analysis is one of the recommended antenatal guidelines for early diagnosis of pregnancy-associated complications. While in practice, urine analysis by dipstick had been used to provide useful information on other urinary tract infections, its applications for early detection of urogenital schistosomiasis in pregnant women is often times not given due attention in most endemic areas. Our study therefore assessed the performance of some common urinalysis parameters in the diagnosis of maternal urogenital schistosomiasis in endemic rural communities of Nigeria.

Methodology/Principal findings

The cross-sectional epidemiologic survey of urogenital schistosomiasis was conducted among pregnant women in Yewa North Local Government, Ogun State, Nigeria. The women were microscopically examined for infection with Schistosoma haematobium, visually observed for macrohematuria, and screened for microhematuria and proteinuria using standard urine chemical reagent strips. Of 261 volunteered participants, 19.9% tested positive for S. haematobium infection. The proportion of microhematuria (23.8%) was significantly higher than that of macrohematuria (3.8%) and proteinuria (16.8%) (P<0.05). Microhematuria with sensitivity (82.7%) and specificity (89.0%) was the best diagnostic indicator of urogenital schistosomiasis. Macrohematuria with the least sensitivity (11.8%) was however the most specific (98.1%) for diagnosing urogenital schistosomiasis in pregnant women. Maximum microhematuria sensitivity (100.0%) was observed in women between 15–19 years but sensitivity was consistently low in older age groups. Maximum sensitivity, specificity and predictive values (100.0%) were recorded for microhematuria in first trimester women. Diagnostic efficiency of proteinuria and macrohematuria was also better in the first trimester women except the 25.0% specificity recorded for proteinuria. The overall diagnostic performance of microhematuria and proteinuria was better in secundigravidae.

Conclusions/Significance

Microhematuria can be used for early detection of urogenital schistosomiasis in endemic areas especially in younger women. However because microhematuria is a condition that occurs during pregnancy and in several other diseases, it is necessary to compliment the diagnosis with other diagnostic tools such as microscopy and serology. Treatment with praziquantel is recommended for the women in their late trimesters after follow up test in order to avert associated adverse pregnancy outcomes.

Urinary schistosomiasis in school aged children of two rural endemic communities in Edo State, Nigeria

BACKGROUND

Urinary schistosomiasis is endemic in many rural communities of Nigeria and school aged children are mostly affected. A cross-sectional study was carried out to assess the prevalence and intensity of urinary schistosomiasis infection among 251 school aged children in two communities of Ovia South West LGA of Edo State, Nigeria, as well as their knowledge on the control/elimination measures.

METHODS

Urine samples were collected and examined by microscopy using filtration technique. In addition, a questionnaire survey was conducted among school-aged children and health care providers, probing their knowledge, attitude and practices on on-going control activities.

RESULTS

The prevalence of urinary schistosomiasis among the school-aged children was 65.3%. The prevalence was generally higher among females (68.8%) and children in the age groups 10-14 (69.9%). The intensity of infection ranged from 1 to 5044 (mean=449.8) eggs/10ml of urine with a higher proportion having heavy infections (76.8%, P<0.05). Water contact was attested by 123 (49.0%) of the children; of these 123, 74 (60.1%) were infected. The children's knowledge on urinary schistosomiasis was deficient.

CONCLUSION

The high prevalences reported in these communities require integrated approach to control which essentially should incorporate the provision of safe water supply and sanitary facilities, and health education in addition to the annual mass praziquantel distribution, to reduce transmission.

Meta-analysis of the diagnostic efficiency of the questionnaires screening for schistosomiasis

Schistosomiasis is the second widespread tropical disease that affects the health of over 240 million people of 78 countries. Questionnaires have been commonly used to diagnose schistosomiasis, while no meta-analysis of their efficacy had been reported previously. This meta-analysis was conducted to assess their diagnostic accuracy of schistosomiasis. Studies published prior to December 1, 2014, that had used questionnaires as a diagnostic tool were searched in PubMed, Medline, EMBASE, and China National Knowledge Infrastructure (CNKI) database. A total of 32 studies with 72,812 cases were identified for the meta-analysis. The best diagnostic odds ratio (DOR) was obtained from Schistosoma haematobium (67.68, 95 % confidence interval (CI) = 31.48 to 145.54), followed by Schistosoma japonicum (11.74, 95 % CI = 4.59 to 30.05) then Schistosoma mansoni (2.98, 95 % CI = 1.95 to 4.54). Pooled sensitivity and specificity were respectively 0.82, 0.88, and 0.46, and 0.59, 0.86, and 0.81 for S. japonicum, S. haematobium, and S. mansoni. The multivariable subgroup analyses showed that the questionnaires which had been pretested and standardized had better diagnostic performance. The result suggested that questionnaires can be used to diagnose schistosomiasis with moderate sensitivity and specificity and the questionnaires for diagnosing S. haematobium performed best.

Circulating antigen tests and urine reagent strips for diagnosis of active schistosomiasis in endemic areas

BACKGROUND

Point-of-care (POC) tests for diagnosing schistosomiasis include tests based on circulating antigen detection and urine reagent strip tests. If they had sufficient diagnostic accuracy they could replace conventional microscopy as they provide a quicker answer and are easier to use.

OBJECTIVES

To summarise the diagnostic accuracy of: a) urine reagent strip tests in detecting active Schistosoma haematobium infection, with microscopy as the reference standard; and b) circulating antigen tests for detecting active Schistosoma infection in geographical regions endemic for Schistosoma mansoni or S. haematobium or both, with microscopy as the reference standard.

SEARCH METHODS

We searched the electronic databases MEDLINE, EMBASE, BIOSIS, MEDION, and Health Technology Assessment (HTA) without language restriction up to 30 June 2014.

SELECTION CRITERIA

We included studies that used microscopy as the reference standard: for S. haematobium, microscopy of urine prepared by filtration, centrifugation, or sedimentation methods; and for S. mansoni, microscopy of stool by Kato-Katz thick smear. We included studies on participants residing in endemic areas only.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data, assessed quality of the data using QUADAS-2, and performed meta-analysis where appropriate. Using the variability of test thresholds, we used the hierarchical summary receiver operating characteristic (HSROC) model for all eligible tests (except the circulating cathodic antigen (CCA) POC for S. mansoni, where the bivariate random-effects model was more appropriate). We investigated heterogeneity, and carried out indirect comparisons where data were sufficient. Results for sensitivity and specificity are presented as percentages with 95% confidence intervals (CI).

MAIN RESULTS

We included 90 studies; 88 from field settings in Africa. The median S. haematobium infection prevalence was 41% (range 1% to 89%) and 36% for S. mansoni (range 8% to 95%). Study design and conduct were poorly reported against current standards. Tests for S. haematobium Urine reagent test strips versus microscopyCompared to microscopy, the detection of microhaematuria on test strips had the highest sensitivity and specificity (sensitivity 75%, 95% CI 71% to 79%; specificity 87%, 95% CI 84% to 90%; 74 studies, 102,447 participants). For proteinuria, sensitivity was 61% and specificity was 82% (82,113 participants); and for leukocyturia, sensitivity was 58% and specificity 61% (1532 participants). However, the difference in overall test accuracy between the urine reagent strips for microhaematuria and proteinuria was not found to be different when we compared separate populations (P = 0.25), or when direct comparisons within the same individuals were performed (paired studies; P = 0.21).When tests were evaluated against the higher quality reference standard (when multiple samples were analysed), sensitivity was marginally lower for microhaematuria (71% vs 75%) and for proteinuria (49% vs 61%). The specificity of these tests was comparable. Antigen assayCompared to microscopy, the CCA test showed considerable heterogeneity; meta-analytic sensitivity estimate was 39%, 95% CI 6% to 73%; specificity 78%, 95% CI 55% to 100% (four studies, 901 participants). Tests for S. mansoni Compared to microscopy, the CCA test meta-analytic estimates for detecting S. mansoni at a single threshold of trace positive were: sensitivity 89% (95% CI 86% to 92%); and specificity 55% (95% CI 46% to 65%; 15 studies, 6091 participants) Against a higher quality reference standard, the sensitivity results were comparable (89% vs 88%) but specificity was higher (66% vs 55%). For the CAA test, sensitivity ranged from 47% to 94%, and specificity from 8% to 100% (4 studies, 1583 participants).

AUTHORS' CONCLUSIONS

Among the evaluated tests for S. haematobium infection, microhaematuria correctly detected the largest proportions of infections and non-infections identified by microscopy.The CCA POC test for S. mansoni detects a very large proportion of infections identified by microscopy, but it misclassifies a large proportion of microscopy negatives as positives in endemic areas with a moderate to high prevalence of infection, possibly because the test is potentially more sensitive than microscopy.

Spatial distribution of urinary schistosomiasis in Cross River State, Nigeria using geographical information system and school based questionnaire

Urinary schistosomiasis is a serious disease in Cross River State, Nigeria. Dearth of information on its distribution has hampered the implementation of focused control of the disease. The availability of a rapid method for mapping the disease necessitated this research to provide data for control of Urinary schistosomiasis in Cross River State, Nigeria. The study used a rapid validated school-based questionnaire method in mapping schistosomiasis. Geographical information system (GIS) software tools were used to produce a spatial map for prevalence of infection and areas at risk for urinary schistosomiasis in Cross River State. Data analysis with SPSS package revealed that 9,993 (10.2%) female and 10,328 (10.0%) male pupils in 218 schools passed blood in urine in one month out of 199,794 pupils interviewed. There was no statistically significant difference in the prevalence between male and female pupils with infection (p < 0.005). The prevalence of urinary schistosomiasis using questionnaire method correlated positively with the filtration method used in determining the egg output (r = 0.71, p < 0.001). Endemic schools were distributed in thirteen Local Government Areas of Cross River State, Nigeria. Yala and Yakurr LGAs had the highest number of schools that reported schistosomiasis with 39 (59%) and 13 (59%), respectively. Odukpani LGA had the lowest prevalence of 1 (0.2%). The overall results showed a mean urinary schistosomiasis prevalence of 10.2% for Cross River State, Nigeria. The findings of this study would guide Government and other relevant agencies in the implementation of control strategies for the treatment of urinary schistosomiasis in Cross River State, Nigeria.

Urogenital schistosomiasis and urological assessment of hematuria in preschool-aged children in rural communities of Nigeria

OBJECTIVE

The study evaluates the prevalence of urogenital schistosomiasis and diagnostic performance of chemical reagent strips used for disease diagnosis in preschool-aged children (≤ 5 years) in Nigeria rural communities.

PATIENTS AND METHODS

Urine samples from 419 children were observed microscopically for Schistosoma haematobium and screened for hematuria using standard urine chemical reagent strips.

RESULTS

Prevalence and intensity of infection were 9.8% and 14.4 eggs/10 ml of urine, respectively. Prevalence of infection was similar in girls (10%) and boys (9.6%) (p > 0.05). The intensity of infection was higher in boys (17.1 eggs/10 ml of urine) than in girls (12.8 eggs/10 ml of urine); however, this was not gender dependent (p > 0.05). The occurrence of hematuria was not associated with gender (p > 0.05), but was associated with prevalence of infection (p < 0.05).

CONCLUSION

Infection with S. haematobium occurs early in life in the communities and although intensity of infection is low, it could have serious implications in disease transmission. Hematuria, although moderately sensitive to infection, is an important morbidity indicator of urogenital schistosomiasis in the study population.

Prevalence and intensity of urinary schistosomiasis among school children in the district of Niakhar, region of Fatick, Senegal

BACKGROUND

Urinary schistosomiasis is a parasitic disease that exists in all regions of Senegal. It is a major public health issue in this country. This study was carried out to determine the prevalence and intensity of this parasitosis in 12 villages of Niakhar (Fatick, Senegal).

METHODS

A total of 210 schoolchildren, aged 7 to 15 years, were enrolled in this study, and urine samples were examined for Schistosoma haematobium eggs using a standard urine filtration technique.

RESULTS

Of these children, 121 (57.6%) were found to be infected with a mean geometric count of 185 eggs per 10 ml of urine. The disease was present in all surveyed villages, and the prevalence ranged from 14.3% to 92.8%. The prevalence of infection was significantly correlated with increasing age and was higher in boys. Infection intensity was significantly higher in boys but did not significantly differ with age. Significant relationships between i) water contact or access to running water and ii) the prevalence or intensity of urinary schistosomiasis were also noted.

CONCLUSIONS

The district of Niakhar is endemic for urinary schistosomiasis, with a high intensity of infection. A control program to decrease the prevalence and intensity should be implemented in this area to improve community health.

High levels of urinary schistosomiasis among children in Bunuso, a rural community in Ghana: an urgent call for increased surveillance and control programs

We investigated the occurrence of urinary schistosomiasis and estimated predictors for risk of infection among children in the Bunuso community of Ashanti Region of Ghana, West Africa. The cross-sectional survey was conducted between June and December 2009. Information was obtained on socio-demographic characteristics, schistosomiasis symptoms and other risk factors through interviews and questionnaires. Urine samples were analysed for Schistosoma haematobium ova using centrifugation and sedimentation, filtration and microscopy. Bivariate estimations and multiple logistic regression modelling with odds ratios (OR) were used to assess risk factors for S. haematobium infections. Inspections at River Nanakwaw revealed snail vectors, Bulinus truncatus. Overall, 95 out of 100 (95 % confidence interval [CI] 88.8-97.6) children tested positive for S. haematobium infection. The mean ova density (eggs/10 ml of urine) of infections was 58.12 (95 % CI 31.3-71.6) and varied significantly between age-group distributions (P value = 0.001; Post Hoc, P > 0.05 for ≤8 vs 15-17 years, and 9-11 vs 12-14 years), sources of house-hold water (P value = 0.019; Post Hoc, P < 0.05 for Borehole vs River Nanakwaw), children activities in River Nanakwaw (P value = 0.001), and haematuria (P value = 0.007). Independent variables significantly associated with S. haematobium infections were the use of River Nanakwaw as source of household water (OR 12.54; 95 % CI 3.932-42.12, P value = 0.003), engaging activities in River Nanakwaw (OR 8.76; 95 % CI 1.759-31.871; P value = 0.008) and haematuria (OR 36.71; 95 % CI 10.18-48.47; P value = 0.001). The passage of blood urine was prognostic of urinary schistosomiasis with a positive predictive value of 97.5 %. Our results demonstrate the endemicity of urinary schistosomiasis in Bunuso. Schistosomiasis remains a disease of great public health importance in Ghana, and there is the urgent need to intensify surveillance and control programs in remote riparian communities.

Schistosomiasis infection among primary school students in a war zone, Southern Kordofan State, Sudan: a cross-sectional study

BACKGROUND

Schistosomiasis is a major health problem adversely affecting the health of vulnerable populations in Sudan.

METHODS

We conducted a school-based survey to estimate the prevalence of schistosomiasis in 36 villages in Southern Kordofan (SK) State. A total of 2,302 primary school students were recruited. Each student completed a questionnaire and submitted one urine and one stool sample.

RESULTS

The prevalence of schistosomiasis haematobium was 23.7%, while schistosomiasis mansoni was not detected among the study participants. S. haematobium infection was identified in all areas, with the highest prevalence in the western locality of SK State. The infection was associated with the distance between home/school and open water sources. In addition, S. haematobium infection was associated with the existence of and distance to open water sources, higher frequency of contact with open water, absence of a health advocacy group in the school and history of schistosomiasis treatment.

CONCLUSIONS

This study highlights schistosomiasis as a public health problem in SK State. The findings will guide the schistosomiasis Control Program of the State Ministry of Health in developing and applying treatment plans for schistosomiasis in SK State.

Schistosoma haematobium infections in preschool children from two rural communities in Ijebu East, south-western Nigeria

There is an urgent need for information on schistosomiasis in preschool children, who are often excluded in mass treatment programmes. The prevalence and intensity of Schistosoma haematobium infection were determined in preschool children aged ≤ 6 years in two rural communities in Ijebu East, south-western Nigeria. Two urine samples each were collected from 83 preschool children from the two communities, tested for microhaematuria using reagent strips and then processed and examined with a microscope for S. haematobium eggs. Focus group discussions on perceptions of the disease and water contact practices were held in the communities with their guardians, caregivers and preschool children, using an interview guide. The prevalence of S. haematobium in the two communities was 14 (16.9%), with no significant differences (P = 0.661) in infection rate between boys (18.4%) and girls (14.7%). Both prevalence and intensity of infection did not increase significantly with age in both Korede and Obada community. However, there were significant differences in prevalence of infection between the two communities (P = 0.035). There was no association (P = 0.750) between intensity in boys (0.176 eggs/10 ml urine) and girls (0.110 eggs/10 ml urine). Focal group discussions with guardians and caregivers revealed that preschool children acquired infection early in their lives through exposure to infected stream water by their mothers, while the older children visit the stream for playing, bathing and swimming. It has therefore become imperative for preschool children to be included in the planning of schistosomiasis intervention programmes as a means of reducing transmission.

The use of bivariate spatial modeling of questionnaire and parasitology data to predict the distribution of Schistosoma haematobium in Coastal Kenya

BACKGROUND

Questionnaires of reported blood in urine (BIU) distributed through the existing school system provide a rapid and reliable method to classify schools according to the prevalence of Schistosoma haematobium, thereby helping in the targeting of schistosomiasis control. However, not all schools return questionnaires and it is unclear whether treatment is warranted in such schools. This study investigates the use of bivariate spatial modelling of available and multiple data sources to predict the prevalence of S. haematobium at every school along the Kenyan coast.

METHODOLOGY

Data from a questionnaire survey conducted by the Kenya Ministry of Education in Coast Province in 2009 were combined with available parasitological and environmental data in a Bayesian bivariate spatial model. This modeled the relationship between BIU data and environmental covariates, as well as the relationship between BIU and S. haematobium infection prevalence, to predict S. haematobium infection prevalence at all schools in the study region. Validation procedures were implemented to assess the predictive accuracy of endemicity classification.

PRINCIPAL FINDINGS

The prevalence of BIU was negatively correlated with distance to nearest river and there was considerable residual spatial correlation at small (~15 km) spatial scales. There was a predictable relationship between the prevalence of reported BIU and S. haematobium infection. The final model exhibited excellent sensitivity (0.94) but moderate specificity (0.69) in identifying low (<10%) prevalence schools, and had poor performance in differentiating between moderate and high prevalence schools (sensitivity 0.5, specificity 1).

CONCLUSIONS

Schistosomiasis is highly focal and there is a need to target treatment on a school-by-school basis. The use of bivariate spatial modelling can supplement questionnaire data to identify schools requiring mass treatment, but is unable to distinguish between moderate and high prevalence schools.

Schistosomiasis and soil-transmitted helminths among an adult population in a war affected area, Southern Kordofan state, Sudan

Background

Schistosomiasis remains a major health problem at global and national levels, contributing to the vulnerability of the poor people in Sudan. Southern Kordofan is affected by Schistosomiasis but the disease prevalence was unknown.

Methods

1826 adults were recruited in a community-based survey. Each recruited subject submitted at least 10 ml urine and one stool sample; they were also interviewed and filled in a questionnaire.

Results

1826 adults were recruited in a community-based survey. Each recruited subject submitted at least 10 ml urine and one stool sample; they were also interviewed and filled in a questionnaire. The prevalence of S. haematobium was 6.9 % among the adult population. We estimated S. mansoni prevalence as 0.0 %. S. haematobium infection was focally distributed at the village level. The infection was associated with non preference of latrine use – if available, use of open water source for household affairs such as cleaning and also with the history of schistosomiasis treatment. The prevalence of soil transmitted helminths (STH) was also reported as high at 7.8 %, and two species were identified; Hymenolepis nana and Giardia lamblia.

Conclusion

Schistosomiasis is a significant health problem among the adult population in Southern Kordofan. The estimated prevalence will serve as a guide in developing a Schistosomiasis Control Program and applying treatment plans.

A simple approach improving the performance of urine reagent strips for rapid diagnosis of urinary schistosomiasis in Nigerian schoolchildren

In Nigeria, schistosomiasis, caused predominantly by the species Schistosoma haematobium, is highly endemic in resource-poor communities. We performed a school-based survey in two rural communities in Osun State (Southwestern Nigeria) and assessed macrohaematuria, microhaematuria and proteinuria as indirect indicators for the presence of disease. Urine samples were inspected macroscopically for haematuria and screened for microhaematuria and proteinuria using urine reagent strips. The microscopic examination of schistosome eggs was used as the gold standard for diagnosis. In total, 447 schoolchildren were included in this study and had a 51% prevalence of urinary schistosomiasis. The sensitivity of microhaematuria (68%) and proteinuria (53%) for infection with S. haematobium was relatively low. In patients with a heavy infection (>or= 500 eggs/10 mL), the sensitivity of microhaematuria was high (95%). When the presence of macrohaematuria and the concomitant presence of microhaematuria and proteinuria were combined, it revealed a sensitivity of 63%, a specificity of 93% and a positive predictive value of 91%. Macrohaematuria also showed high specificity (96%) and a positive predictive value of 92%, while sensitivity was < 50%. These data show that combining urine reagent strip tests (presence of proteinuria and microhaematuria) and information on macrohaematuria increased the accuracy of the rapid diagnosis of urinary schistosomiasis in an endemic rural West African setting. This simple approach can be used to increase the quality of monitoring of schistosomiasis in schoolchildren.

Rapid mapping of schistosomiasis and other neglected tropical diseases in the context of integrated control programmes in Africa

There is growing interest and commitment to the control of schistosomiasis and other so-called neglected tropical diseases (NTDs). Resources for control are inevitably limited, necessitating assessment methods that can rapidly and accurately identify and map high-risk communities so that interventions can be targeted in a spatially-explicit and cost-effective manner. Here, we review progress made with (1) mapping schistosomiasis across Africa using available epidemiological data and, more recently, climate-based risk prediction; (2) the development and use of morbidity questionnaires for rapid identification of high-risk communities of urinary schistosomiasis; and (3) innovative sampling-based approaches for intestinal schistosomiasis, using the lot quality assurance sampling technique. Experiences are also presented for the rapid mapping of other NTDs, including onchocerciasis, loiasis and lymphatic filariasis. Future directions for an integrated rapid mapping approach targeting multiple NTDs simultaneously are outlined, including potential challenges in developing an integrated survey tool. The lessons from the mapping of human helminth infections may also be relevant for the rapid mapping of malaria as its control efforts are intensified.

Cost comparison of rapid questionnaire screening for individuals at risk of clonorchiasis in low- and high-prevalence communities in northern Vietnam

Clonorchiasis is an emerging food-borne trematode infection in Vietnam. Due to the absence of cost-effective preventive measures its control largely relies on morbidity reduction by chemotherapy with praziquantel. We performed a comparative cost estimation of three different diagnostic and intervention approaches in areas of high and low prevalence of clonorchiasis in northern Vietnam in order to select more cost-effective chemotherapy. Our study confirmed that a questionnaire investigating the habit of eating raw, freshwater fish was a rapid, cost-effective and operationally feasible tool for identifying individuals at risk of clonorchiasis in both high-prevalence and low-prevalence areas. The cost of diagnosis and intervention per person and per true positive case was 20-fold higher in low-prevalence areas, regardless of the type of approach. Geographical mapping of high-risk areas prior to screening is, therefore, recommended to maximize the cost-effectiveness of the intervention activities.

Prevalence distribution and risk factors for Schistosoma hematobium infection among school children in Blantyre, Malawi

BACKGROUND

Schistosomiasis is a public health problem in Malawi but estimates of its prevalence vary widely. There is need for updated information on the extent of disease burden, communities at risk and factors associated with infection at the district and sub-district level to facilitate effective prioritization and monitoring while ensuring ownership and sustainability of prevention and control programs at the local level.

METHODS AND FINDINGS

We conducted a cross-sectional study between May and July 2006 among pupils in Blantyre district from a stratified random sample of 23 primary schools. Information on socio-demographic factors, schistosomiasis symptoms and other risk factors was obtained using questionnaires. Urine samples were examined for Schistosoma hematobium ova using filtration method. Bivariate and multiple logistic regressions with robust estimates were used to assess risk factors for S. hematobium. One thousand one hundred and fifty (1,150) pupils were enrolled with a mean age of 10.5 years and 51.5% of them were boys. One thousand one hundred and thirty-nine (1,139) pupils submitted urine and S. hematobium ova were detected in 10.4% (95%CI 5.43-15.41%). Male gender (OR 1.81; 95% CI 1.06-3.07), child's knowledge of an existing open water source (includes river, dam, springs, lake, etc.) in the area (OR 1.90; 95% CI 1.14-3.46), history of urinary schistosomiasis in the past month (OR 3.65; 95% CI 2.22-6.00), distance of less than 1 km from school to the nearest open water source (OR 5.39; 95% CI 1.67-17.42) and age 8-10 years (OR 4.55; 95% CI 1.53-13.50) compared to those 14 years or older were associated with infection. Using urine microscopy as a gold standard, the sensitivity and specificity of self-reported hematuria was 68.3% and 73.6%, respectively. However, the positive predictive value was low at 23.9% and was associated with age.

CONCLUSION

The study provides an important update on the status of infection in this part of sub-Saharan Africa and exemplifies the success of deliberate national efforts to advance active participation in schistosomiasis prevention and control activities at the sub-national or sub-district levels. In this population, children who attend schools close to open water sources are at an increased risk of infection and self-reported hematuria may still be useful in older children in this region.

Age and gender effects in self-reported urinary schistosomiasis in Tanzania

OBJECTIVES

To characterize age-gender prevalence profiles of urinary schistosomiasis according to the questionnaire responses, compare the profiles to field survey data from selected regions, and determine if the profiles varied spatially throughout Tanzania.

METHODS

In 2004, a national school-based questionnaire survey for self-reported schistosomiasis and blood in urine (BIU) was conducted in all regions of mainland Tanzania, to assist targeted mass distribution of praziquantel. Field survey data were collected in six north-western and five coastal regions using microscopic examination of urine samples for the presence of Schistosoma haematobium eggs and assessment of micro-haematuria with chemical reagent strips. Bayesian logistic regression models were created to calculate age-gender profiles adjusted for demographic and ecological covariates and spatial correlation in the questionnaire data. Separate odds ratios (OR) for age-gender effects were calculated in each administrative area.

RESULTS

Data were obtained from > 2.5 million schoolchildren. Boys had higher prevalence of self-reported schistosomiasis and BIU than girls. In boys, prevalence according to the questionnaire and field surveys followed similar age profiles. However, in girls, prevalence according to the field surveys increased in older age groups, but flattened out or decreased according to the questionnaire, indicating the latter underestimated prevalence in older girls. In the models, little spatial correlation was evident in the OR for the age-gender effects, suggesting that these did not vary spatially.

CONCLUSION

Age-gender patterns of urinary schistosomiasis were consistent in different geographical areas of Tanzania. Because the questionnaire underestimated prevalence in older girls, we propose that upward calibration of observed prevalence is done for older females only.

Geographical information system and predictive risk maps of urinary schistosomiasis in Ogun State, Nigeria

Background

The control of urinary schistosomiasis in Ogun State, Nigeria remains inert due to lack of reliable data on the geographical distribution of the disease and the population at risk. To help in developing a control programme, delineating areas of risk, geographical information system and remotely sensed environmental images were used to developed predictive risk maps of the probability of occurrence of the disease and quantify the risk for infection in Ogun State, Nigeria.

Methods

Infection data used were derived from carefully validated morbidity questionnaires among primary school children in 2001–2002, in which school children were asked among other questions if they have experienced "blood in urine" or urinary schistosomiasis. The infection data from 1,092 schools together with remotely sensed environmental data such as rainfall, vegetation, temperature, soil-types, altitude and land cover were analysis using binary logistic regression models to identify environmental features that influence the spatial distribution of the disease. The final regression equations were then used in Arc View 3.2a GIS software to generate predictive risk maps of the distribution of the disease and population at risk in the state.

Results

Logistic regression analysis shows that the only significant environmental variable in predicting the presence and absence of urinary schistosomiasis in any area of the State was Land Surface Temperature (LST) (B = 0.308, p = 0.013). While LST (B = -0.478, p = 0.035), rainfall (B = -0.006, p = 0.0005), ferric luvisols (B = 0.539, p = 0.274), dystric nitosols (B = 0.133, p = 0.769) and pellic vertisols (B = 1.386, p = 0.008) soils types were the final variables in the model for predicting the probability of an area having an infection prevalence equivalent to or more than 50%. The two predictive risk maps suggest that urinary schistosomiasis is widely distributed and occurring in all the Local Government Areas (LGAs) in State. The high-risk areas (≥ 50% prevalence) however, are confined to scatter foci in the north western part of the State. The model also estimated that 98.99% of schools aged children (5–14 years) are living in areas suitable for urinary schistosomiasis transmission and are at risk of infection.

Conclusion

The risk maps developed will hopefully be useful to the state health officials, by providing them with detailed distribution of urinary schistosomiasis, help to delineate areas for intervention, assesses population at risk thereby helping in optimizing scarce resources.

Bayesian spatial analysis of a national urinary schistosomiasis questionnaire to assist geographic targeting of schistosomiasis control in Tanzania, East Africa

Spatial modelling was applied to self-reported schistosomiasis data from over 2.5 million school students from 12,399 schools in all regions of mainland Tanzania. The aims were to derive statistically robust prevalence estimates in small geographical units (wards), to identify spatial clusters of high and low prevalence and to quantify uncertainty surrounding prevalence estimates. The objective was to permit informed decision-making for targeting of resources by the Tanzanian national schistosomiasis control programme. Bayesian logistic regression models were constructed to investigate the risk of schistosomiasis in each ward, based on the prevalence of self-reported schistosomiasis and blood in urine. Models contained covariates representing climatic and demographic effects and random effects for spatial clustering. Degree of urbanisation, median elevation of the ward and median normalised difference vegetation index (NDVI) were significantly and negatively associated with schistosomiasis prevalence. Most regions contained wards that had >95% certainty of schistosomiasis prevalence being >10%, the selected threshold for bi-annual mass chemotherapy of school-age children. Wards with >95% certainty of schistosomiasis prevalence being >30%, the selected threshold for annual mass chemotherapy of school-age children, were clustered in north-western, south-western and south-eastern regions. Large sample sizes in most wards meant raw prevalence estimates were robust. However, when uncertainties were investigated, intervention status was equivocal in 6.7–13.0% of wards depending on the criterion used. The resulting maps are being used to plan the distribution of praziquantel to participating districts; they will be applied to prioritising control in those wards where prevalence was unequivocally above thresholds for intervention and might direct decision-makers to obtain more information in wards where intervention status was uncertain.

The effects of quarry mining on the epidemiology of Schistosoma haematobium in schoolchildren, in Ishiagu, south-eastern Nigeria

Over the last two decades there has been a noticeable increase in the activities of quarry-mining companies in the Ishiagu area of south-eastern Nigeria. These activities have produced an ever-growing number of abandoned quarry pits that usually quickly fill with water and appear to become suitable habitats for the freshwater snails that may act as intermediate hosts of Schistosoma haematobium. To examine the potential role of quarry mining on the prevalence of urinary schistosomiasis caused by S. haematobium, urine samples were collected from 1819 schoolchildren in northern Ishiagu (an area with intense mining activities and many quarry pits) and from 252 schoolchildren in southern Ishiagu (an area with no mining activity or quarry pits). When these 2071 samples were checked for schistosome eggs, 1005 (48.5%) were found positive and 252 (25.1%) of the infected children showed visible haematuria. The children from northern Ishiagu were much more likely to be infected than the children from the south (53.3% v. 13.9%; P<0.001). Curiously, only the children from northern Ishiagu showed a gender-related difference in prevalence that was statistically significant, with boys more likely to be infected than girls (60.9% v. 38.5%; P<0.001). Although the 'children' investigated varied in age from 5 to 20 years, no statistically significant increase or decrease in prevalence with age was apparent. Four species of snails (Bulinus globosus, B. rohlfsi, B. forskalii and B. senegalensis) were found in the overall study area but B. globosus was only found in the quarry pits in northern Ishiagu and never in the water bodies of southern Ishiagu. It does appear that quarry-mining activity in the Ishiagu area is a factor in the local epidemiology of urinary schistosomiasis, with the water bodies that form in the abandoned quarry pits serving as the principal foci of transmission.

Ill-health reported by schoolchildren during questionnaire surveys in Ghana, Mozambique and Tanzania

BACKGROUND

Insufficient attention has been paid to the health problems of school-age children in sub-Saharan Africa. A questionnaire administered to schoolchildren about their ill-health has been developed to identify schools in which urinary schistosomiasis occurs. The data collected during the interviews can also be used to assess other common health problems.

OBJECTIVES

To analyse data collected during health questionnaires in schools to assess how schoolchildren perceive their own health, and to compare the findings between three countries in sub-Saharan Africa.

METHODS

Questionnaires asking about recent health problems were administered by teachers to schoolchildren in 120 primary schools in Mozambique, 52 primary schools in Tanzania and 298 primary schools in Ghana. A total of 67 002 children aged 8-15 years took part.

RESULTS

Of the 10 health problems asked about in all questionnaires, the average number reported by each child was 3.9 in Ghana, 3.4 in Mozambique and 3.1 in Tanzania. The distributions of the prevalence of each condition among schools were similar and the prevalence of all conditions showed a similar ranking. For most conditions a greater percentage of girls than boys reported each health problem.

CONCLUSIONS

Schoolchildren in Ghana, Mozambique and Tanzania do not perceive themselves to be healthy. The pattern of reported health problems was similar in each country. School health questionnaires are worthy of further study and validation.

Urinary schistosomiasis in preschool children in settlements around Oyan Reservoir in Ogun State, Nigeria: implications for control

We determined the prevalence of urinary schistosomiasis in preschool children below the age of 5 years in three settlements around Oyan Reservoir in Ogun State, Nigeria. Of 209 children screened, 150 (71.8%) had an infection, with no significant difference between males and females; 42.9% of infants were infected. Both prevalence and intensity of infection increased significantly with age (P < 0.005). Most (62.7%) infections were light (<50 eggs/10 ml urine). A 17.7 percentage of the children had visible haematuria, which increased with age (P < 0.005). Focus group discussions (FGDs) with adult men and women revealed that infection in preschool children was primarily because of exposure occasioned by the mothers' domestic (washing and bathing) and occupational (fishing) activities, while older children could go swimming on their own. Although the participants claimed that using a different water supply may not be effective in combating the disease, as their entire existence was tied to the reservoir, we propose that health education geared towards changing behaviour and attitudes is necessary. As preschool children are a source of both contamination and transmission, control programmes must take them into account.

Screening for schistosomiasis with questionnaires

New schistosomiasis control initiatives have been launched to reduce significantly the current global burden of this disease, mainly through regular administration of praziquantel to schoolchildren living in endemic areas. Because schistosomiasis is distributed focally, epidemiological tools for rapid and inexpensive identification of communities at highest risk of morbidity are required to target praziquantel most efficiently. This article outlines the development and validation of simple questionnaires for screening of Schistosoma haematobium and Schistosoma mansoni in sub-Saharan Africa.

Reinfection with Schistosoma haematobium following school-based chemotherapy with praziquantel in four highly endemic villages in Côte d'Ivoire

We present the comparative evaluation of school-based chemotherapy with praziquantel on Schistosoma haematobium reinfection patterns, 6, 12, 18 and 24 months after systematic treatment of schoolchildren in four villages of south-central Côte d'Ivoire. At baseline, very high S. haematobium infection prevalences of 88-94% were found in Taabo Village, located adjacent to a large man-made lake, and in Batera and Bodo, where small dams were constructed. In Assinzé, a village with no man-made environmental alterations, the baseline infection prevalence was significantly lower (67%). The parasitological cure rate, assessed 4 weeks after praziquantel administration in the village with the highest prevalence and intensity of infection, was high (82%), and showed a clear association with infection intensity prior to treatment. Six months after chemotherapy, significant reductions in the prevalence and intensity of infection were observed in all villages. However, infection prevalence was again high in Taabo Village (63%) and in Batera (49%). Different patterns of reinfection occurred in the four villages: rapid reinfection in Taabo Village to reach almost baseline infection prevalence 12 months post-treatment; slow but gradual increase in the prevalence and intensity of infection in Bodo; marked increase in prevalence and intensity of infection during the second year of the follow-up in Assinzé; and prevalence and intensity of infection that remained almost constant between 6 and 24 months post-treatment in Batera. Our study confirms that S. haematobium reinfection patterns largely depend on the local epidemiological setting, which is of central importance to tailoring treatment strategies that are well adapted to these different settings.

Schistosomiasis: a critical review

Precise data on epidemiology, morbidity, post-treatment resolution, reinfection, and resurgence of schistosomiasis could be helpful in establishing purposeful treatment plans for the disease in endemic populations. Here we give a concise overview of recent publications on bilharziasis. A main emphasis is placed on studies on the prevalence of schistosomiasis, partly including long term surveillance of morbidity following treatment with praziquantel. As genito-urinary schistosomiasis may be a risk factor for the spread of HIV, the involvement of the reproductive tract has become another focus in research on the disease. A novel diagnostic tool, eosinophil cationic protein (ECP), is proposed to correlate with the degree of inflammation of the genito-urinary tract.