A national survey of the prevalence of schistosomiasis and soil transmitted helminths in Malawi

Female genital schistosomiasis burden and risk factors in two endemic areas in Malawi nested in the Morbidity Operational Research for Bilharziasis Implementation Decisions (MORBID) cross-sectional study

BACKGROUND

Female genital schistosomiasis (FGS), caused by the parasite Schistosoma haematobium (Sh), is prevalent in Sub-Saharan Africa. FGS is associated with sexual dysfunction and reproductive morbidity, and increased prevalence of HIV and cervical precancerous lesions. Lack of approved guidelines for FGS screening and diagnosis hinder accurate disease burden estimation. This study evaluated FGS burden in two Sh-endemic areas in Southern Malawi by visual and molecular diagnostic methods.

METHODOLOGY/PRINCIPAL FINDINGS

Women aged 15-65, sexually active, not menstruating, or pregnant, were enrolled from the MORBID study. A midwife completed a questionnaire, obtained cervicovaginal swab and lavage, and assessed FGS-associated genital lesions using hand-held colposcopy. 'Visual-FGS' was defined as specific genital lesions. 'Molecular-FGS' was defined as Sh DNA detected by real-time PCR from swabs. Microscopy detected urinary Sh egg-patent infection. In total, 950 women completed the questionnaire (median age 27, [IQR] 20-38). Visual-and molecular-FGS prevalence were 26·9% (260/967) and 8·2% (78/942), respectively. 6·5% of women with available genital and urinary samples (38/584) had egg-patent Sh infection. There was a positive significant association between molecular- and visual-FGS (AOR = 2·9, 95%CI 1·7-5·0). 'Molecular-FGS' was associated with egg-patent Sh infection (AOR = 7·5, 95% CI 3·27-17·2). Some villages had high 'molecular-FGS' prevalence, despite <10% prevalence of urinary Sh among school-age children.

CONCLUSIONS/SIGNIFICANCE

Southern Malawi carries an under-recognized FGS burden. FGS was detectable in villages not eligible for schistosomiasis control strategies, potentially leaving girls and women untreated under current WHO guidelines. Validated field-deployable methods could be considered for new control strategies.

An assessment of implementation and effectiveness of mass drug administration for prevention and control of schistosomiasis and soil-transmitted helminths in selected southern Malawi districts

Background

Mass drug administration (MDA) is one of the key interventions recommended by WHO for prevention and control of neglected tropical diseases (NTD). In Malawi, MDA is widely carried out annually since 2009 for prevention and control of schistosomiasis and soil-transmitted helminths (STH). No study has been carried out to assess effectiveness of the MDA approach and to document perceptions of health providers and beneficiaries regarding use of MDA. This study was done to understand how well MDA is being implemented and to identify opportunities for improvement in MDA delivery in Malawi.

Methods

Designed as a cross-sectional and multi-methods research, the study was carried out in three southern Malawi districts of Chiradzulu, Mangochi and Zomba. In each district, four health centres and 16 villages were randomly selected to participate. A mixed-methods approach to data collection focusing on quantitative data for coverage and knowledge, attitudes and practices assessments; and qualitative data for assessing perceptions of health providers and beneficiaries regarding MDA was used. Quantitative data were processed and analyzed using IBM SPSS software version 26 while qualitative data were analysed using NVivo 12 for Windows.

Results

Knowledge levels about schistosomiasis and STH in the districts varied according to disease aspects asked about. Majority are more knowledgeable about what schistosomiasis is (78%) and whether STH are treatable with drugs (97%); with least knowledgeable about the organism that transmits schistosomiasis (18%), types of schistosomiasis (11%) and what causes STH (20%). In 2018 and 2019 the districts registered high coverage rates for praziquantel and albendazole using community-based MDA (73–100%) and using school-based MDA (75–91%). Both the health authorities and community members perceived the MDA approach as good because it brings treatment closer to people.

Conclusion

With the high MDA coverage obtained in communities and schools, the effectiveness of MDA in the target districts is satisfactory. There are, however, several challenges including disproportionate knowledge levels, which are hampering progress towards attainment of the 2030 global NTD goals. There is a need for promotion of community participation and partnerships as well as implementation of other recommended interventions for sustainable prevention and control of schistosomiasis and STH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-07925-3.

Epidemiology of soil-transmitted helminths following sustained implementation of routine preventive chemotherapy: Demographics and baseline results of a cluster randomised trial in southern Malawi

Malawi has successfully leveraged multiple delivery platforms to scale-up and sustain the implementation of preventive chemotherapy (PCT) for the control of morbidity caused by soil-transmitted helminths (STH). Sentinel monitoring demonstrates this strategy has been successful in reducing STH infection in school-age children, although our understanding of the contemporary epidemiological profile of STH across the broader community remains limited. As part of a multi-site trial evaluating the feasibility of interrupting STH transmission across three countries, this study aimed to describe the baseline demographics and the prevalence, intensity and associated risk factors of STH infection in Mangochi district, southern Malawi. Between October-December 2017, a community census was conducted across the catchment area of seven primary healthcare facilities, enumerating 131,074 individuals across 124 villages. A cross-sectional parasitological survey was then conducted between March-May 2018 in the censused area as a baseline for a cluster randomised trial. An age-stratified random sample of 6,102 individuals were assessed for helminthiasis by Kato-Katz and completed a detailed risk-factor questionnaire. The age-cluster weighted prevalence of any STH infection was 7.8% (95% C.I. 7.0%-8.6%) comprised predominantly of hookworm species and of entirely low-intensity infections. The presence and intensity of infection was significantly higher in men and in adults. Infection was negatively associated with risk factors that included increasing levels of relative household wealth, higher education levels of any adult household member, current school attendance, or recent deworming. In this setting of relatively high coverage of sanitation facilities, there was no association between hookworm and reported access to sanitation, handwashing facilities, or water facilities. These results describe a setting that has reduced the prevalence of STH to a very low level, and confirms many previously recognised risk-factors for infection. Expanding the delivery of anthelmintics to groups where STH infection persist could enable Malawi to move past the objective of elimination of morbidity, and towards the elimination of STH. Trial registration: NCT03014167.

Resource-Efficient Characterisation of Pit Latrine Sludge for Use in Agriculture

Resource recovery through reuse of by-products of the sanitation chain presents a great potential towards ensuring universal access to safely managed sanitation. Many developing countries are faced with uncertainty over public and environmental health concerns associated with use of faecal sludge in agriculture. Due to resource constraints, limited data exists on the characteristics of faecal sludge to inform proper and safe use in agriculture. Despite predictive characterisation being demonstrated to be a resource-efficient approach to generate data in other fields, its application in agricultural resource recovery from faecal sludge is lacking in the literature. This paper explored predictive modelling as a less resource-intensive approach for characterisation of nutrients and pathogens in faecal sludge. Specifically, it investigated the extent to which gravimetric parameters could predict nutrients and pathogens in pit latrine sludge from informal settlements in the cities of Malawi. The study explored predictive models to estimate total ammoniacal nitrogen (TAN), total phosphorus (TP), E.coli and helminth eggs from gravimetric parameters (total solids [TS] and total volatile solids [TVS]) in pit latrine sludge. The models developed in the study allow substantially reliable estimation of TAN (R2pred = 75.4%) and TP (R2pred = 78.2%); they also provide moderately reliable predictions for E.coli (R2pred = 69.1%) and helminth eggs (R2pred = 74.3%) from total solids. Since total solids are easy and inexpensive to measure, the models present an option that can reduce resource requirement for characterisation of pit latrine sludge for informed decision-making when using pit latrine sludge in agriculture. In the absence of data on faecal sludge characteristics at the national level, the models provide a starting point for estimation of pathogens and nutrients in sludge for agricultural use. However, stepwise refinement of the models needs to be done through their validation for different types of sludge and inclusion of spatially available demographic, technical and environmental (SPA-DET) data.

Population Attributable Fraction of Anemia Associated with P. falciparum Infection in Children in Southern Malawi

Anemia is a leading cause of morbidity in sub-Saharan Africa. The etiologies of anemia are multifactorial, and it is unclear what proportion of anemia is attributable to malaria in children of different ages in Malawi. We evaluated the population attributable fraction (PAF) of anemia due to malaria using multiple cross-sectional surveys in southern Malawi. We found a high prevalence of anemia, with the greatest proportion attributable to malaria among school-age children (5-15 years) in the rainy season (PAF = 18.8% [95% CI: 16.3, 21.0], compared with PAF = 5.2% [95% CI: 4.0, 6.2] among young children pooled across season [< 5 years] and PAF = 9.7% [95% CI: 6.5, 12.4] among school-age children in the dry season). Malaria control interventions will likely lead to decreases in anemia, especially among school-age children.

An outbreak of intestinal schistosomiasis, alongside increasing urogenital schistosomiasis prevalence, in primary school children on the shoreline of Lake Malawi, Mangochi District, Malawi

BACKGROUND

Intestinal schistosomiasis was not considered endemic in Lake Malawi until November 2017 when populations of Biomphalaria pfeifferi were first reported; in May 2018, emergence of intestinal schistosomiasis was confirmed. This emergence was in spite of ongoing control of urogenital schistosomiasis by preventive chemotherapy. Our current study sought to ascertain whether intestinal schistosomiasis is transitioning from emergence to outbreak, to judge if stepped-up control interventions are needed.

METHODS

During late-May 2019, three cross-sectional surveys of primary school children for schistosomiasis were conducted using a combination of rapid diagnostic tests, parasitological examinations and applied morbidity-markers; 1) schistosomiasis dynamics were assessed at Samama (n = 80) and Mchoka (n = 80) schools, where Schistosoma mansoni was first reported, 2) occurrence of S. mansoni was investigated at two non-sampled schools, Mangochi Orphan Education and Training (MOET) (n = 60) and Koche (n = 60) schools, where B. pfeifferi was nearby, and 3) rapid mapping of schistosomiasis, and B. pfeifferi, conducted across a further 8 shoreline schools (n = 240). After data collection, univariate analyses and Chi-square testing were performed, followed by binary logistic regression using generalized linear models, to investigate epidemiological associations.

RESULTS

In total, 520 children from 12 lakeshore primary schools were examined, mean prevalence of S. mansoni by 'positive' urine circulating cathodic antigen (CCA)-dipsticks was 31.5% (95% confidence interval [CI]: 27.5-35.5). Upon comparisons of infection prevalence in May 2018, significant increases at Samama (relative risk [RR] = 1.7, 95% CI: 1.4-2.2) and Mchoka (RR = 2.7, 95% CI: 1.7-4.3) schools were observed. Intestinal schistosomiasis was confirmed at MOET (18.3%) and Koche (35.0%) schools, and in all rapid mapping schools, ranging from 10.0 to 56.7%. Several populations of B. pfeifferi were confirmed, with two new eastern shoreline locations noted. Mean prevalence of urogenital schistosomiasis was 24.0% (95% CI: 20.3-27.7).

CONCLUSIONS

We notify that intestinal schistosomiasis, once considered non-endemic in Lake Malawi, is now transitioning from emergence to outbreak. Once control interventions can resume after coronavirus disease 2019 (COVID-19) suspensions, we recommend stepped-up preventive chemotherapy, with increased community-access to treatments, alongside renewed efforts in appropriate environmental control.

Schistosomiasis among obstetric fistula patients in Lilongwe, Malawi

Background

Schistosoma haematobium infection has been documented as an uncommon cause of vesicovaginal fistula (VVF) and can result in impaired wound healing of urogenital tissues. For these reasons, it could potentially be linked to an increased rate of obstetric fistula among women who experience obstructed labor and/or in a higher failure rate of fistula repair. Therefore, the primary objective of our study was to determine the prevalence of S. haematobium infection among women undergoing obstetric VVF repair in Lilongwe, Malawi. Our secondary objectives were to assess if S. haematobium infection could be a risk factor for obstetric fistula development or unsuccessful VVF repair in our patient population.

Methods

From July to October 2013, we conducted S. haematobium testing via urine microscopy on 96 patients undergoing obstetric VVF repair surgery at the Fistula Care Centre in Lilongwe, Malawi.

Results

The prevalence of S. haematobium infection among women undergoing obstetric VVF repair was 2% (n=2). Both women with S. haematobium had successful VVF repairs.

Conclusions

Although S. haematobium has the potential to be a risk factor for obstetric VVF formation or unsuccessful VVF repair, it was uncommon among the women in our clinic with obstetric VVF.

A prevalence survey of enteral parasites in preschool children in the Mangochi District of Malawi

BACKGROUND

Helminthic and protozoan infections are common, particularly in low- or middle-income countries. Although an association between parasite carriage and markers of poor growth have been shown in some studies, systematic reviews have suggested only a modest impact of clearing carriage. The prevalence of these pathogens and the effect that they have on growth in preschool children has never been investigated in Malawi.

METHODS

One hundred ninety-three children aged 0-72 months were randomly recruited from rural villages in the Mangochi district of Malawi. Formol-ether concentration was performed on stool and the samples examined with a light microscope. Anthropometric data was taken for each child and the haemoglobin measured with a point of care test.

RESULTS

The mean age of the children was 2 years 4 months. Overall prevalence of intestinal parasite infection was 37.3%. Protozoa were found in 28.5% of children, while helminths were found in 8.8%. The most commonly found organisms were Giardia lambia (12.4%), Entamoeba coli (10.4%) and Hookworm species (3.6%). Stunting was seen in 47.8% of children, 12.9% were underweight and 5.0% were wasted. No significant association was found between markers of poor growth and infection with any intestinal parasite.

CONCLUSIONS

We found that prevalence of helminth infection was low in preschool children living in the Mangochi district compared to international standards. However a significant proportion of the preschool population are infected with protozoa, particularly Giardia lambia. In this cohort, despite a significant prevalence of stunting, helminth infection was not significantly associated with any markers of poor growth. The significance of protozoal carriage and contribution to growth restriction in this context creates further avenues for future research.

Hematobium schistosomiasis control for health management of labor force generation at Nkhotakota and Lilongwe in the Republic of Malawi-assumed to be related to occupational risk

Background

In Malawi, hematobium schistosomiasis is highly endemic. According to previous studies, countermeasures have been conducted mainly in school-aged children. In this study, we focused on the age groups, which are assumed to be major labor force generation. Hematobium schistosomiasis is supposed to be related to occupational activities in schistosome-endemic countries because of its infectious route. We chronologically followed the transition of schistosome egg-positive prevalence before and after mass drug administration of praziquantel (MDA) by using a urine filtering examination. We also analyzed the effectiveness of urine reagent strips from the cost perspective.

Results

The egg-positive prevalence was 34.3% (95% CI 28.5–40.5) just before MDA in June 2010 and the highest prevalence was in the age of twenties. The egg-positive prevalence reduced to 12.7% (95% CI 9.2–17.3, p < 0.01) 8 weeks after the first MDA and the prevalence reduced to 6.9% (95% CI 4.6–10.0, p < 0.01) after the second MDA in August 2011. The egg-positive prevalence after MDA in 2013 was reduced from 3.8% (95% CI 2.1–6.9) to 0.9% (95% CI 0.3–3.4) and p value was 0.050. Using urine reagent strips after MDA, the positive predictive value decreased, but the negative predictive value remained high. The cost of one urine reagent strip and one tablet of praziquantel were US$0.06 and US$0.125 in 2013 in Malawi. If the egg-positive prevalence is 40%, screening subjects for MDA using urine reagent strips, the cost reduction can be estimated to be about 24%, showing an overall cost reduction.

Conclusions

MDA of praziquantel can assuredly reduce schistosome egg-positive prevalence. The combination of MDA and urine reagent strips could be both a practical and cost-effective countermeasure for hematobium schistosomiasis. It is key to recognize that hematobium schistosomiasis could be considered a disease that is assumed to have some concern with occupational risk at Nkhotakota and Lilongwe in Malawi. From this point of view, it is very important to manage workers’ health; the sound labor force generation is vital for economic growth and development in these areas and countries.

A comparative cross-sectional study of prevalence and intensity of soil-transmitted helminthic infection between healthy and severe acutely malnourished pre-school aged children in Kano, Northern Nigeria

BACKGROUND

Soil-transmitted helminthic (STH) infections are common in Sub-Saharan Africa. One method used for control of these helminths is mass anti-helminthic administration in populations at risk of STH infections. In this regard, empiric treatment of children with Severe Acute Malnutrition (SAM) for STH infection is practiced in this region. It is however unclear if children with SAM suffer more from STH infection than healthy children. The objective of this study was to compare prevalence and intensity of STH infection between pre-school aged children with SAM and healthy children.

METHODS

We approached 1114 pre-school aged children attending care in two health facilities in Kano, Nigeria to partake in this study. Of this number, we recruited 620 (55.7%) children, comprising 310 well-nourished children from well-baby clinics and 310 children with SAM from Community Management for Acute Malnutrition (CMAM) centres in these facilities. We assessed their nutritional status using World Health Organisation (WHO) growth charts and collected stool samples which we analysed using Formal-Ether Concentration technique to identify STH infection and Stoll's technique to assess intensities of STH infection. We fitted a logistic regression model to determine if there was any association between nutrition status and helminthic infection, adjusting for the confounding effects of socio-economic status and age. We compared intensity of STH infection (measured as eggs per gram of faeces) between both nutrition groups using the independent t-test.

RESULTS

Overall STH prevalence in our population was low (2.7%) and we found no significant association between nutritional status and presence of STH infection (OR = 1.10, 95% CI 0.38 to 3.21). Majority of our study participants had either low or moderate (94.2%) and there was no statistically significant difference between intensity of STH infection (t value = - 1.52, P value = 0.13) in children with SAM and those who were well-nourished.

CONCLUSIONS

The overall STH prevalence among pre-school children was low in Kano and we did not find prevalence and intensity of STH infection to differ significantly between preschool children with SAM and well-nourished children. Our findings confirm the WHO recommendation that at low levels of prevalence and intensity, interventions to control STH are unnecessary.

Schistosoma mansoni infection and its association with nutrition and health outcomes: a household survey in school-aged children living in Kasansa, Democratic Republic of the Congo

Introduction

Schistosomiasis (SCH) is an important public health problem in developing countries and school-aged children are the most affected. This study explored health and nutritional status and their correlation with SCH in children attending primary school (3rd to 6th class) living in the area of Kasansa in the Democratic Republic of Congo.

Methods

Across-sectional household survey was carried out in Kasansa health area in February 2011. Children whose parents reported to attend primary school (3^rd to 6^th class) were included. Socio-demographic characteristics, information on morbidity history and risk factor were collected using a semi-structured questionnaire. S. mansoni and malaria infection were assessed using the Kato-katz technique and rapid diagnostic test, respectively. Haemoglobin concentration was also performed using a portable HemoControl device. Bivariate and multiple logistic regressions were used to assess risk factors for S. mansoni.

Results

A total of 197 school aged children participated in the study with a median age of 12 years and 53.8% of them were boys. The overall health status of the children was poor with very high prevalences of S. mansoni infection (89.3%), malaria infection (65.1%), anaemia (61.4%) and stunting (61.0%). Regular contact with river water was the most important risk factor (OR: 11.7; p<0.001) related to SCH infection. A low haemoglobin concentration was significantly associated with a SCH infection (OR: 12.3; p=0.003) and egg load was associated with stunting (OR: 12.4; p=0.04). Children from farmers were more at risk for low school performance (OR: 5.3; p=0.03).

Conclusion

High prevalence of Schistosoma mansoni and malaria infection was observed in the study population living in Kasansa area. Moreover, they presented a high burden of anaemia, chronic malnutrition and low school performance. An integrated disease control and management of these diseases and their consequences, endorsed by surveillance, is needed.

Biosocial Determinants of Persistent Schistosomiasis among Schoolchildren in Tanzania despite Repeated Treatment

Schistosomiasis is a parasitic disease endemic to Tanzania and other countries of the global south, which is currently being addressed through preventive chemotherapy campaigns. However, there is growing recognition that chemotherapy strategies will need to be supplemented to sustainably control and eventually eliminate the disease. There remains a need to understand the factors contributing to continued transmission in order to ensure the effective configuration and implementation of supplemented programs. We conducted a cross-sectional questionnaire, to evaluate the biosocial determinants facilitating the persistence of schistosomiasis, among 1704 Tanzanian schoolchildren residing in two districts undergoing a preventive chemotherapeutic program: Rufiji and Mkuranga. A meta-analysis was carried out to select the diagnostic questions that provided a likelihood for predicting infection status. We found that self-reported schistosomiasis continues to persist among the schoolchildren, despite multiple rounds of drug administration.Using mixed effects logistic regression modeling, we found biosocial factors, including gender, socio-economic status, and water, sanitation, and hygiene (WASH)-related variables, were associated with this continued schistosomiasis presence. These findings highlight the significant role that social factors may play in the persistence of disease transmission despite multiple treatments, and support the need not only for including integrated technical measures, such as WASH, but also addressing issues of poverty and gender when designing effective and sustainable schistosomiasis control programs.

Estimating the Health Risk Associated with the Use of Ecological Sanitation Toilets in Malawi

Use of Ecological Sanitation (EcoSan) sludge is becoming popular due to increasing price of organic fertilizers in Malawi; however, there is little evidence on the associated risks. Quantitative microbiological risk assessment (QMRA) was done to determine health risks associated with use of EcoSan. Pathogens considered included Escherichia coli (E. coli), Salmonella, and soil transmitted helminths (STHs). Exponential and Beta Poisson models were used to estimate the risk from helminthic and bacterial pathogens, respectively. Main exposure pathways were through poor storage of sludge, contamination of foods during drying, walking barefoot on the ground contaminated with sludge, pit emptying without protection, and application of sludge in the fields. Estimated annual risk for Ascaris lumbricoides, Taenia, and hookworms was approximately over 5.6 × 10⁻¹ for both Fossa Alternas (FAs) and Urine Diverting Dry Toilet (UDDTs). Risk from E. coli and Salmonella was 8.9 × 10⁻² and above. The risks were higher than WHO acceptable risk for use of faecal sludge in crops of 10⁻⁴ infections per year. Promoters and users of EcoSan latrines need to consider advocating for strict guidelines to reduce the risk.

Short-Term Changes in Anemia and Malaria Parasite Prevalence in Children under 5 Years during One Year of Repeated Cross-Sectional Surveys in Rural Malawi

In stable transmission areas, malaria is the leading cause of anemia in children. Anemia in children is proposed as an added sensitive indicator for community changes in malaria prevalence. We report short-term temporal variations of malaria and anemia prevalence in rural Malawian children. Data from five repeated cross-sectional surveys conducted over 1 year in rural communities in Chikwawa District, Malawi, were analyzed. Different households were sampled per survey; all children, 6–59 months, in sampled household were tested for malaria parasitemia and hemoglobin levels using malaria rapid diagnostic tests (mRDT) and Hemocue 301, respectively. Malaria symptoms, recent treatment (2 weeks) for malaria, anthropometric measurements, and sociodemographic details were recorded. In total, 894 children were included from 1,377 households. The prevalences of mRDT positive and anemia (Hb < 11 g/dL) were 33.8% and 58.7%, respectively. Temporal trends in anemia and parasite prevalence varied differently. Overall, unadjusted and adjusted relative risks of anemia in mRDT-positive children were 1.31 (95% CI: 1.09–1.57) and 1.36 (1.13–1.63), respectively. Changes in anemia prevalence differed with short-term changes in malaria prevalence, although malaria is an important factor in anemia.

Is there a difference in prevalence of helminths between households using ecological sanitation and those using traditional pit latrines? A latrine based cross sectional comparative study in Malawi

Background

Studies have shown that households using sludge from human excreta for agriculture are at an increased risk of soil transmitted helminths. However, while use of ecological sanitation (EcoSan) latrines is increasing in most African countries including Malawi, few studies have been done to check whether use of such sludge could potentially increase the prevalence of helminthic infections among household members as a results of exposure to faecal sludge/compared to use of traditional latrines.

Methods

A cross sectional study was done targeting households using EcoSan and traditional pit latrines. Samples were collected from both types of latrines in Chikwawa (rural) and Blantyre (urban) districts. These two districts have a high number of EcoSan latrines in southern region of Malawi. 156 latrines were sampled (n = 95 traditional; n = 61 EcoSan), and processed following standard guidelines using modified triple floatation method. Identification of helminth ova (Ascaris lumbricoides, hookworms, Trichuris trichiura, Taenia spp. and Diphyllobothrium latum) was done using standard microscopy methods. The difference between the prevalence and mean concentration of helminths between the two types of latrines was tested using Chi Square and t test respectively.

Results

Of the total latrines tested, 85.9% (n = 134) had at least one species of helminth while 84.6% (n = 132) had at least a STH, with 82.0% (n = 50) in EcoSan and 86.3% (n = 82) in traditional pit latrines. There was no significant difference between the prevalence of helminths in EcoSan and traditional pit latrines [χ² = 0.43 (1), P = 0.5]. The prevalence of Ascaris lumbricoides was significantly higher in EcoSan than in traditional pit latrines [χ² = 5.44 (1) p = 0.02] while prevalence of hookworms was significantly higher in traditional pit latrines than in EcoSan latrines [χ² = 13.98 (1) p < 0.001]. The highest concentration of helminths per gram of faecal sludge was in traditional pit latrines [31.2 (95% CI 19.1–43.2)] than in EcoSan latrines [26.4 (95% CI 16.5–36.3)].

Conclusion

There was no significant difference between overall prevalence of helminths between households using EcoSan and those using traditional pit latrines. However, Ascaris lumbricoides was significantly higher in households using EcoSan latrines. EcoSan users need awareness on safe ways of handling faecal sludge in order to reduce chances of reinfection from Ascaris lumbricoides. Further research should be undertaken on household members to identify those infected and potential routes of infection to enable preventive targeting.

Urinary schistosomiasis among preschool children in Malengachanzi, Nkhotakota District, Malawi: Prevalence and risk factors

AIM

This study was designed to determine the prevalence of and risk factors for schistosomiasis among a group of preschool children in Malawi. Schistosomiasis burden among preschoolers in Malawi is not well documented in the literature.

METHODS

This study used field research (in the form of a snail survey), laboratory work (urinalysis and microscopy for parasite identification), and questionnaire-guided interviews to determine the prevalence of and risk factors for urinary schistosomiasis among children, aged between 6 and 60 months, in Malengachanzi, Nkhotakota District, Malawi.

RESULTS

Urinary schistosomiasis prevalence among preschool children was 13%. Of the factors evaluated, only age (P = 0.027) was statistically significantly associated with urinary schistosomiasis risk. Four-year-old preschool children were five times more likely to contract urinary schistosomiasis than twoyear-old children (odds ratio [OR] = 5.255; 95% confidence interval [CI] = 1.014-27.237; P = 0.048). Increased contact with infested water among older children likely explains much of their increased risk. Infestation was evidenced by the presence of infected Bulinus globosus snails in the water contact points surveyed. Multiple regression analysis showed that visiting water contact sites daily (OR = 0.898, 95% CI = 0.185-4.350, P = 0.894), bathing in these sites (OR = 9.462, 95% CI = 0.036-0.00, P = 0.430) and lack of knowledge, among caregivers, regarding the causes of urinary schistosomiasis (OR = 0.235, 95% CI = 0.005-1.102, P = 0.066) posed statistically insignificant risk increases for preschoolers contracting urinary schistosomiasis.

CONCLUSIONS

Urinary schistosomiasis was prevalent among preschool children in Malengachanzi, Nkhotakota District. Contact with infested water puts these children and the general population at risk of infection and reinfection. Inclusion of preschool children in treatment programmes should be considered imperative, along with safe treatment guidelines. To prevent infection, the population in the area should be provided with health education and safe alternative water sources.

Prevalence and distribution of Schistosoma haematobium infection among school children living in southwestern shores of Lake Malawi

BACKGROUND

The prevalence of Schistosoma haematobium infection has been shown to be about 23.7% among children living in the lakeshore areas of Malawi, with reinfection rates of about 30% to 40%. This study aimed to determine the current prevalence and distribution of S. haematobium infection in school children along the southwestern shores of Lake Malawi and examine the control interventions present in the area.

METHODS

This prospective cross-sectional study was conducted in primary schools. School children were enrolled, demographic data were collected, and urine samples were submitted for analysis on macrohaematuria, microhaematuria, and S. haematobium eggs. A questionnaire was administered to 3 health facilities on diagnosis and treatment of schistosomiasis, as well as the control interventions against it.

RESULTS

Four hundred children (174 males and 226 females) were enrolled from 7 primary schools. Mean participant age was 9.57 years (range 7 to 12 years). Fifty children (12.5%) had S. haematobium eggs detected in their urine, with the mean egg count being 15/10 mL. The highest infection intensity category (≥ 50 eggs/10mL) was seen in 10 children (2.5%). Prevalence varied significantly between the schools, with rates ranging from 0% to 20%. Schools with higher prevalence rates were located farther away from the nearest public hospital that provides treatment free of charge. Prevalence correlated with previous history of mass chemotherapy in schools. Mass chemotherapy, health education, and improved water supply and sanitation were some of the interventions that contributed to lower prevalence rates in some areas.

CONCLUSIONS

Schistosomiasis prevalence around southwestern Lake Malawi was lower than previously reported, owing to control interventions focusing on health education, improved water supply, sanitation, and mass chemotherapy. Consistent and uniform interventions can reduce prevalence further and sustain control. As prevalence falls, diagnostics can identify high transmission areas, monitor disease trends, and guide evidence-based control strategies.

Extent of morbidity associated with schistosomiasis infection in Malawi: a review paper

Data on the extent of the burden due to schistosomiasis is sparse in most Sub-Saharan African countries. However, this data is crucial for triggering medical attention. A review of extent of morbidity and determinants associated with schistosomiasis in Malawi was therefore conducted to quantify the infection in order to concretise the need for medical intervention. A systematic and traditional search strategy was used to find literature for the review, whilst exclusion and inclusion criteria were used to identify appropriate articles. Logistic regression curves of epidemiological model Y = (a + bx (c) )/(1 + bx (c) ) and the recommendation that schistosomiasis prevalence can be used to estimate morbidity were employed to quantify morbidity at various infection stages. Morbidity was quantified as a direct proportion of the population and the respective national schistosomiasis prevalence. Findings showed that both S. mansoni and S. haematobium are present in Malawi with the latter highly prevalent (50%). Furthermore, out of the estimated population of 16,829 million, approximately 8.4 million have schistosomiasis, with about 4.4 million of these aged 18 years and below. The most frequent manifestation is Katayama syndrome, while ascites is the lowest, impacting about 3.0 million and 960 individuals, respectively. Localised studies on association of schistosomiasis infection to risk factors such as occupation, age and gender found odds ratio (OR) ranging from 1.29 to 5.37. Morbidity due to schistosomiasis is high in Malawi. It is therefore recommended that a more detailed study on the determinants of high schistosomiasis and re-evaluation of the current control measures be conducted if the current morbidity statistics are to be remarkably reduced.

Urban schistosomiasis and associated determinant factors among school children in Bamako, Mali, West Africa

BACKGROUND

Schistosomiasis is classically described as a rural disease that occurs in areas with poor sanitary conditions. However, over recent decades, there has been an expansion of schistosomiasis foci towards urban areas faced with a rapid and disordered urbanization. In Bamako, Mali, the impact of environmental change on vector-borne diseases such as schistosomiasis is not well known. This study sought to identify the presence of schistosomiasis transmission hotspots in Bamako. Using this perspective, we aimed to describe the risk factors of the endemization and maintenance of schistosomiasis.

MATERIALS AND METHODS

A cross-sectional study was carried out in the six municipalities (communes) in Bamako. Environmental information was obtained from earth observation satellites in order to maximize ecological contrasts. Twenty-nine blocks of 200 m x 200 m were identified. We selected a school inside or nearest to each block for urine and stool samples examination. The study cohort was school children aged between eight and 15 years. The Kato-Katz technique and filtration were used for Schistosoma mansoni and S. haematobium ova research in stools and urine, respectively. The schools and snail breeding sites were georeferenced. Four malacological surveys were conducted between October 2011 and February 2012. Bivariate analysis was used to identify independent predictors of being infected with schistosomiasis.

RESULTS

The prevalence rate of S. haematobium was 14.7% (n = 1,761) and that of S. mansoni 1.5% (n = 1,491). Overall, the urinary form was endemic in 76.6% of schools. The infection significantly varied between the municipalities (p < 0.001). It was also more prevalent on the left side of the Niger River than the right side (17.4% vs. 9.5% respectively; p < 0.001). The vicinity to snail breeding sites (OR = 3.677; 95% IC [2.765-4.889]; p < 10 (-3) ) and parents' occupations (OR = 7.647; 95% IC [2.406-24.305]; p < 0.001) were the most important risk factors associated with S. haematobium infection exposure. Biomphalaria pfeifferi, Bulinus truncatus, and B. globosus were the intermediate hosts captured. The schistosome natural infection rates (SNIRs), which were low or nil in October and November, rose to 2.8% in January and 8.3% in February for B. pfeifferi and B. truncatus, respectively.

CONCLUSION

Our findings show that there is a high transmission risk for schistosomiasis in Bamako. Appropriate integrated control measures need to be introduced to control the transmission of this disease in the study area.

Schistosomiasis in Malawi: a systematic review

INTRODUCTION

Schistosomiasis remains an important public health problem that undermines social and economic development in tropical regions of the world, mainly Sub-Saharan Africa. We are not aware of any systematic review of the literature of the epidemiology and transmission of schistosomiasis in Malawi since 1985. Therefore, we reviewed the current state of knowledge of schistosomiasis epidemiology and transmission in this country and identified knowledge gaps and relevant areas for future research and research governance.

METHODS

We conducted computer-aided literature searches of Medline, SCOPUS and Google Scholar using the keywords: "schistosomiasis", "Bilharzia", "Bulinus" and "Biomphalaria" in combination with "Malawi". These searches were supplemented by iterative reviews of reference lists for relevant publications in peer reviewed international scientific journals or other media. The recovered documents were reviewed for their year of publication, location of field or laboratory work, authorship characteristics, ethics review, funding sources as well as their findings regarding parasite and intermediate host species, environmental aspects, geographical distribution, seasonality of transmission, and infection prevalence and intensities.

REVIEW

A total of 89 documents satisfied the inclusion criteria and were reviewed. Of these, 76 were published in international scientific journals, 68 were peer reviewed and 54 were original research studies. Most of the documents addressed urinary schistosomiasis and about two thirds of them dealt with the definitive host. Few documents addressed the parasites and the intermediate hosts. While urinary schistosomiasis occurs in most parts of Malawi, intestinal schistosomiasis mainly occurs in the central and southern highlands, Likoma Island and Lower Shire. Studies in selected communities estimated prevalence rates of up to 94.9% for Schistosoma haematobium and up to 67.0% for Schistosoma mansoni with considerable geographical variation. The main intermediate host species are Bulinus globosus and Bulinus nyassanus for urinary schistosomiasis and Biomphalaria pfeifferi for intestinal schistosomiasis. Seasonality of transmission tends to vary according to geographical, environmental, biological and behavioural factors.

CONCLUSION

Transmission of schistosomiasis in Malawi appears to be highly focal, with considerable variation in space and time. Many locations have not been covered by epidemiological investigations and, thus, information on the transmission of schistosomiasis in Malawi remains fragmented. Functional infection risk assessment systems based on systematic investigations and surveillance are required for developing informed prevention and control strategies.

Zero adjusted models with applications to analysing helminths count data

Background

It is common in public health and epidemiology that the outcome of interest is counts of events occurrence. Analysing these data using classical linear models is mostly inappropriate, even after transformation of outcome variables due to overdispersion. Zero-adjusted mixture count models such as zero-inflated and hurdle count models are applied to count data when over-dispersion and excess zeros exist. Main objective of the current paper is to apply such models to analyse risk factors associated with human helminths (S. haematobium) particularly in a case where there’s a high proportion of zero counts.

Methods

The data were collected during a community-based randomised control trial assessing the impact of mass drug administration (MDA) with praziquantel in Malawi, and a school-based cross sectional epidemiology survey in Zambia. Count data models including traditional (Poisson and negative binomial) models, zero modified models (zero inflated Poisson and zero inflated negative binomial) and hurdle models (Poisson logit hurdle and negative binomial logit hurdle) were fitted and compared.

Results

Using Akaike information criteria (AIC), the negative binomial logit hurdle (NBLH) and zero inflated negative binomial (ZINB) showed best performance in both datasets. With regards to zero count capturing, these models performed better than other models.

Conclusion

This paper showed that zero modified NBLH and ZINB models are more appropriate methods for the analysis of data with excess zeros. The choice between the hurdle and zero-inflated models should be based on the aim and endpoints of the study.

[Prevalence of geohelminth infections in children living in Kinshasa]

BACKGROUND

Data on geohelminth infections in children in the Democratic Republic of Congo are sparse. The objective of this study was to document and compare the profile and prevalence in children living in Kinshasa.

METHODS

A prospective cohort study was conducted from May to October 2009 in children in the Biyela health area in Kinshasa, Democratic Republic of Congo. Stool samples were collected from representative members of these two populations and analyzed for geohelminths (GH) using the Kato-Katz technique.

RESULTS

In this series, 438 school-age children were included. There were 235 children recruited in schools and 203 in households (77.8%). Overall prevalence of geohelminths was 66.9%. The specific prevalence was 69.4% in children recruited in schools and 64.0% in children recruited in households. The frequency of Ascaris lumbricoides, Trichuris trichiura, and Ancylostoma species were, respectively, 56.2%, 38.7%, and 1.7% in schools and 39.9%, 51.7%, and 1.0% in households. A. lumbricoides was significantly more prevalent in schools (56.2% vs 39.9%; OR=2.0; 95%CI: 1.3-3.0), T. trichiura was significantly less prevalent in schools (38.7% vs 51.7%; OR=0.6; 95% CI: 0.4-0.9). There were no significant differences in the prevalence of Ancylostoma between schools and households.

CONCLUSION

GH is a health problem among Biyela children. Preventive measures and education of the population need to be emphasized in attempts to reduce the prevalence of geohelminths in these children.

Schistosomiasis in pre-school-age children and their mothers in Chikhwawa district, Malawi with notes on characterization of schistosomes and snails

BACKGROUND

To complement ongoing schistosomiasis control within national control programmes (NCPs) that administer praziquantel to school-age children, assessing the risk and extent of schistosomiasis in pre-school-age children (PSAC) is important.

METHODS

In June 2012, schistosomiasis in Chikhwawa district, Malawi was assessed across 12 villages examining pre-school-age children (PSAC) and their mothers by serological and parasitological diagnosis, as supplemented with urine-antigen and questionnaire-interview methods. Urinary tract morbidity was inferred by haematuria and albuminuria assays.

RESULTS

In total, 49.5% (CI₉₅ 42.6-56.4) of 208 PSAC and 94.5% (CI₉₅ 90.9-98.1) of 165 mothers were seropositive for schistosomiasis, in 2 villages seroprevalence exceeded 75% in PSAC. Egg-patent urogenital and intestinal schistosomiasis was observed; 17.7% (CI₉₅ 12.4-23.2) of PSAC and 45.1% (CI₉₅ 37.4-52.8) of mothers having active schistosomiasis by parasitological and urine-antigen testing combined. PSAC often had extensive daily water contact and many (~25%) had haematuria and albuminuria. As eggs with an atypical morphology of Schistosoma haematobium were observed, a general selection of schistosome eggs was characterized by DNA barcoding, finding Group I S. haematobium and Group IV and V S. mansoni. Malacological surveys encountered several populations of Bulinus globosus but failed to find Biomphalaria.

CONCLUSIONS

Both PSAC and their mothers appear to be at significant risk of schistosomiasis and should be considered for treatment within the NCP of Malawi.

Epidemiological study on Schistosoma mansoni infection in Sanja area, Amhara region, Ethiopia

Background

The epidemiology of schistosomiasis is well documented and its geographic distribution has been mapped and there is an ongoing mapping in Ethiopia. Nevertheless, new transmission foci have been discovered in different parts of the country. The objective of this study was to assess the establishment of transmission and determine the prevalence of Schistosoma mansoni infection in school children from Sanja Town, northwest Ethiopia.

Methods

A cross-sectional parasitological survey involving 384 school children in two primary schools of Sanja Town was conducted between February and April 2013. Stool specimens were collected and microscopically examined using Kato-Katz and Sodium acetate-acetic acid-formalin (SAF) concentration methods. Malacological survey was also carried out to identify snail intermediate hosts and larval infection rate in the snail. The snails collected were checked for trematode infection by shedding. Observation was also made on water contact habits of the study population.

Results

The prevalence of Schistosoma mansoni infection using Kato-Katz method was high among male (79.5%) children in Sanja Primary school while it was high among female (75%) children in Ewket Amba Primary school. The prevalence of Schistosoma mansoni infection among Sanja Primary school children in the age groups 5–9 and 10–14 years were 84.6% and 75.2%, respectively while in Ewket Amba Primary school, the prevalence was 66% and 77.9% in the age groups 5–9 and 10–14 years respectively. The prevalence of schistosome infection in Biomphalaria pfeifferi was 16.9% and 0.027% during February and April, respectively. S. mansoni infection was successfully established in laboratory mice and adult worms were harvested after six weeks of laboratory maintenance. Observations made on water contact activities showed swimming, bathing and washing in the river and the stream as the high risk activities for Schistosoma mansoni infection.

Conclusion

The study has shown establishment of transmission of schistosomiasis mansoni in Sanja Town. Therefore, appropriate integrated control measures need to be introduced to reduce morbidity in the population and also to control the transmission of schistosomiasis in the study area.

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.

Analysis of Schistosomiasis haematobium infection prevalence and intensity in Chikhwawa, Malawi: an application of a two part model

Background

Urinary Schistosomiasis infection, a common cause of morbidity especially among children in less developed countries, is measured by the number of eggs per urine. Typically a large proportion of individuals are non-egg excretors, leading to a large number of zeros. Control strategies require better understanding of its epidemiology, hence appropriate methods to model infection prevalence and intensity are crucial, particularly if such methods add value to targeted implementation of interventions.

Methods

We consider data that were collected in a cluster randomized study in 2004 in Chikhwawa district, Malawi, where eighteen (18) villages were selected and randomised to intervention and control arms. We developed a two-part model, with one part for analysis of infection prevalence and the other to model infection intensity. In both parts of the model we adjusted for age, sex, education level, treatment arm, occupation, and poly-parasitism. We also assessed for spatial correlation in the model residual using variogram analysis and mapped the spatial variation in risk. The model was fitted using maximum likelihood estimation.

Results and discussion

The study had a total of 1642 participants with mean age of 32.4 (Standard deviation: 22.8), of which 55.4 % were female. Schistosomiasis prevalence was 14.2 %, with a large proportion of individuals (85.8 %) being non-egg excretors, hence zero-inflated data. Our findings showed that S. haematobium was highly localized even after adjusting for risk factors. Prevalence of infection was low in males as compared to females across all the age ranges. S. haematobium infection increased with presence of co-infection with other parasite infection. Infection intensity was highly associated with age; with highest intensity in school-aged children (6 to 15 years). Fishing and working in gardens along the Shire River were potential risk factors for S. haematobium infection intensity. Intervention reduced both infection intensity and prevalence in the intervention arm as compared to control arm. Farmers had high infection intensity as compared to non farmers, despite the fact that being a farmer did not show any significant association with probability of infection.

These results evidently indicate that infection prevalence and intensity are associated with risk factors differently, suggesting a non-singular epidemiological setting. The dominance of agricultural, socio-economic and demographic factors in determining S. haematobium infection and intensity suggest that disease transmission and control strategies should continue centring on improving socio-economic status, environmental modifications to control S. haematobium intermediate host snails and mass drug administration, which may be more promising approaches to disease control in high intensity and prevalence settings.

Schistosomiasis is one of the great causes of morbidity among school aged children in the tropical region and Sub Saharan Africa in particular. It's mainly transmitted through contact with water infested with intermediate host snail Cercariae. Currently, over 200 million people are estimated to be infected in SSA alone. Here, we used robust and contemporary statistical methods in a two part application to analyse risk factors for S. haematobium infection intensity and prevalence. We found that S. haematobium was more common in younger children as compared to older children, thus making the infection and prevalence age dependent. We also found that mass chemotherapy reduced both infection prevalence and intensity. We found that dominance of agricultural, socio-economic and demographic factors in determining S. haematobium infection risk in the villages carries important implications for disease surveillance and control strategies. Therefore disease transmission and control strategies centered on improving strategies involving socio-economic status, environmental modifications to control S. haematobium intermediate host snails and mass drug administration may be more promising approaches to disease control in high intensity and prevalence settings.

Comparative analysis of urinary schistosomiasis among primary school children and rural farmers in Obollo-Eke, Enugu State, Nigeria: implications for control

OBJECTIVE

To determine the prevalence, sex-age related intensity of urinary schistosomiasis and to compare such parameters among rural school children and rural farmers in selected communities in Obollo-Eke located in Southeast, Nigeria.

METHODS

A cross-sectional survey involving 1 337 school children and farmers was conducted in Obollo-Eke community between September 2006 and July 2007. Demographic data of subjects was collected using a questionnaire prepared for this purpose. Urine samples were collected and examined for haematuria and ova of Schistosoma haematobium (S. haematobium) using Medi-test Combi 9 and sedimentation technique respectively.

RESULTS

The prevalence of urinary schistosomiasis based on microscopic examination of the urine sediment for the ova of S. haematobium was 17.5% while the prevalence of haematuria was 15.6%. Infection intensity varied from light to heavy. In general, the prevalence was higher among males (20.8%) than females (14.6%; P>0.05) and was slightly higher among primary school children (18.0%; n=762) than farmers (16.9%; n=575; P>0.05). The age-specific prevalence of schistosomiasis among the study subjects ranged from 8.3% to 21.2% in 0-5 years and 11-15 years age groups respectively.

CONCLUSIONS

Haematuria and mean egg/10 mL urine (r = 0.95; P<0.01) showed that both procedures are reliable for the diagnosis of the disease and can be used to ascertain the prevalence of the disease in any community. The comparative analysis of urinary bilharziasis among primary school children and rural farmers demonstrated that the infection is moderately high in these two risk population groups at Obollo-Eke. A robust intervention strategy is clearly needed.

Associations between peripheral Plasmodium falciparum malaria parasitemia, human immunodeficiency virus, and concurrent helminthic infection among pregnant women in Malawi

Approximately 2 billion persons worldwide are infected with schistosomiasis and soil-transmitted helminths (STH), many in areas where endemic malaria transmission coexists. Few data exist on associations between these infections. Nested within a larger clinical trial, primigravid and secundigravid women provided blood samples for human immunodeficiency virus (HIV) testing and peripheral malaria films and stool and urine for evaluation of STH and Schistosoma spp. during their initial antenatal clinic visit. The most common parasitic infections were malaria (37.6%), S. haematobium (32.3%), and hookworm (14.4%); 14.2% of women were HIV-infected. S. haematobium infection was associated with lower malarial parasite densities (344 versus 557 parasites/μL blood; P < 0.05). In multivariate analysis, HIV and hookworm infection were independently associated with malaria infection (adjusted odds ratio = 1.9 and 95% confidence interval = 1.2-3.0 for HIV; adjusted odds ratio = 1.9 and 95% confidence interval = 1.03-3.5 for hookworm). Concurrent helminthic infection had both positive and negative effects on malaria parasitemia among pregnant women in Malawi.

Multiparasitism a neglected reality on global, regional and local scale

This review focuses on the issue of multiparasitism, with a special emphasis on its characteristics, its extent in eastern Asia and its significance for infectious disease control. Multiparasitism is pervasive among socially and economically disadvantaged or marginalised communities, particularly in tropical and subtropical areas. Intestinal parasites are the most numerous group, but an array of parasites is located elsewhere than in the human gastrointestinal tract. Although multiparasitism has been recognised for decades, in-depth studies are rare, and its public health and economic implications have yet to be fully elucidated. The assessment of multiparasitism is hampered by a lack of sensitive broad-spectrum diagnostic tools and the need to collect multiple biological samples for detailed appraisal. Non-specific symptoms and mainly subtle effects complicate the appreciation of its influence on cognitive and physical development, health, economic productivity and general well-being. Multiparasitism has been reported from virtually every eastern Asian country, and studies regarding the extent of multiparasitism and its effects on child health have been implemented in the region. However, new research is needed, as no comprehensive evaluations of multiparasitism in eastern Asia could be identified. Two case studies pertaining to multiparasitism at the local and regional scale are presented. Multiparasitism was rampant in an ethnic minority village in southern People's Republic of China where the challenges associated with its thorough evaluation are illustrated. The results from a cross-sectional survey covering 35 villages highlight the significance of its evaluation for the design of locally adapted and sustainable parasite control and poverty alleviation programmes. We conclude by listing a set of research needs for future investigations.

Sentinel surveillance of lymphatic filariasis, schistosomiasis soil transmitted helminths and malaria in rural southern Malawi

BACKGROUND

Baseline prevalence and knowledge, attitude and perception (KAP) survey is a prerequisite for mass drug administration for the control of Lymphatic filariasis (LF) and other neglected tropical diseases.

METHODS

In preparation for the first mass drug administration for LF elimination, a baseline survey was conducted in six sentinel sites in the southern Malawi, amongst participants aged five years or more. A standard questionnaire was used to obtain data on socio-demographic factors, ownership and use of bed nets, previous ingestion of ivermectin and KAP toward hydrocele and lymphoedema. Finger prick blood samples were collected from 22:00 to 01:00 hours for LF microscopy, malaria and haemoglobin examination. Stool and urine samples were collected for internal helminths and schistosomiasis respectively.

RESULTS

A total of 1, 903 participants were enrolled. Knowledge on the cause of hydrocele and lymphoedema was low in all the sentinel sites (16%-42%, 10%-24% (respectively). Sexual intercourse with a menstruating woman, bad weather and HIV/AIDS were perceived causes of hydrocele. Microfilaraemia prevalence was 1.5% and varied little between sentinel sites (1.0%-2.1%). Childhood urinary schistosomiasis was common in Phalombe (94.9%) and Blantyre (26.9%).

CONCLUSION

Integrated approach and understanding of the community KAP is vital or successful implementation of LF elimination programme.

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.

Effect of transmission setting and mixed species infections on clinical measures of malaria in Malawi

Background

In malaria endemic regions people are commonly infected with multiple species of malaria parasites but the clinical impact of these Plasmodium co-infections is unclear. Differences in transmission seasonality and transmission intensity between endemic regions have been suggested as important factors in determining the effect of multiple species co-infections.

Principal Findings

In order to investigate the impact of multiple-species infections on clinical measures of malaria we carried out a cross-sectional community survey in Malawi, in 2002. We collected clinical and parasitological data from 2918 participants aged >6 months, and applied a questionnaire to measure malaria morbidity. We examined the effect of transmission seasonality and intensity on fever, history of fever, haemoglobin concentration ([Hb]) and parasite density, by comparing three regions: perennial transmission (PT), high intensity seasonal transmission (HIST) and low intensity seasonal transmission (LIST). These regions were defined using multi-level modelling of PCR prevalence data and spatial and geo-climatic measures. The three Plasmodium species (P. falciparum, P. malariae and P. ovale) were randomly distributed amongst all children but not adults in the LIST and PT regions. Mean parasite density in children was lower in the HIST compared with the other two regions. Mixed species infections had lower mean parasite density compared with single species infections in the PT region. Fever rates were similar between transmission regions and were unaffected by mixed species infections. A history of fever was associated with single species infections but only in the HIST region. Reduced mean [Hb] and increased anaemia was associated with perennial transmission compared to seasonal transmission. Children with mixed species infections had higher [Hb] in the HIST region.

Conclusions

Our study suggests that the interaction of Plasmodium co-infecting species can have protective effects against some clinical outcomes of malaria but that this is dependent on the seasonality and intensity of malaria transmission.

Early detection of Schistosoma mansoni infection by touchdown PCR in a mouse model

A detection assay for Schistosoma mansoni DNA in mouse serum samples based on touchdown PCR was developed and evaluated. The serum samples could be assayed directly without the need to extract DNA. No cross reactions between S. mansoni and related species inducing human schistosomiasis were observed. After the infection, mouse sera and feces were collected for 8 weeks. Anti-worm antigen IgG and anti-soluble egg antigen IgG were detected in the sera at 6 weeks post-infection by ELISA. The parasite's eggs were detected in the feces at 8 weeks. In contrast, S. mansoni DNA was detected in the sera at 2 weeks post-infection. These data suggest that touchdown PCR is a potential tool for the early diagnosis of S. mansoni infection.

Schistosomiasis and water resources development: systematic review, meta-analysis, and estimates of people at risk

An estimated 779 million people are at risk of schistosomiasis, of whom 106 million (13.6%) live in irrigation schemes or in close proximity to large dam reservoirs. We identified 58 studies that examined the relation between water resources development projects and schistosomiasis, primarily in African settings. We present a systematic literature review and meta-analysis with the following objectives: (1) to update at-risk populations of schistosomiasis and number of people infected in endemic countries, and (2) to quantify the risk of water resources development and management on schistosomiasis. Using 35 datasets from 24 African studies, our meta-analysis showed pooled random risk ratios of 2.4 and 2.6 for urinary and intestinal schistosomiasis, respectively, among people living adjacent to dam reservoirs. The risk ratio estimate for studies evaluating the effect of irrigation on urinary schistosomiasis was in the range 0.02-7.3 (summary estimate 1.1) and that on intestinal schistosomiasis in the range 0.49-23.0 (summary estimate 4.7). Geographic stratification showed important spatial differences, idiosyncratic to the type of water resources development. We conclude that the development and management of water resources is an important risk factor for schistosomiasis, and hence strategies to mitigate negative effects should become integral parts in the planning, implementation, and operation of future water projects.