Prevalence of Schistosomes and Soil-Transmitted Helminths and Morbidity Associated with Schistosomiasis among Adult Population in Lake Victoria Basin, Tanzania

Vaccine value profile for Hookworm

Hookworm, a parasitic infection, retains a considerable burden of disease, affecting the most underprivileged segments of the general population in endemic countries and remains one of the leading causes of mild to severe anemia in Low and Middle Income Countries (LMICs), particularly in pregnancy and children under 5. Despite repeated large scale Preventive Chemotherapy (PC) interventions since more than 3 decades, there is broad consensus among scholars that elimination targets set in the newly launched NTD roadmap will require additional tools and interventions. Development of a vaccine could constitute a promising expansion of the existing arsenal against hookworm. Therefore, we have evaluated the biological and implementation feasibility of the vaccine development as well as the added value of such a novel tool. Based on pipeline landscaping and the current knowledge on key biological aspects of the pathogen and its interactions with the host, we found biological feasibility of development of a hookworm vaccine to be moderate. Also, our analysis on manufacturing and regulatory issues as well as potential uptake yielded moderate implementation feasibility. Modelling studies suggest a that introduction of a vaccine in parallel with ongoing integrated interventions (PC, WASH, shoe campaigns), could substantially reduce burden of disease in a cost - saving mode. Finally a set of actions are recommended that might impact positively the likelihood of timely development and introduction of a hookworm vaccine.

Epidemiology and Geographical Distribution of Human Trematode Infections

Digenetic trematodes infecting humans are more than 109 species that belong to 49 genera all over the world. According to their habitat in the definitive hosts, they are classified as 6 blood flukes (Schistosoma japonicum. S. mekongi, S. malayensis, S. mansoni, S. intercalatum, and S. haematobium), 15 liver flukes (Fasciola hepatica, F. gigantica, Clonorchis sinensis, Opisthorchis viverrini, O. felineus, Dicrocoelium dendriticum, D. hospes, Metorchis bilis, M. conjunctus, M. orientalis, Amphimerus sp., A. noverca, A. pseudofelineus, Pseudamphistomum truncatum, and P. aethiopicum), nine lung flukes (Paragonimus westermani, P. heterotremus, P. skrjabini, P. skrjabini miyazakii, P. kellicotti, P. mexicanus, P. africanus, P. uterobilateralis, and P. gondwanensis), 30 heterophyid intestinal flukes (Metagonimus yokogawai, M. takahashii, M. miyatai, M. suifunensis, M. katsuradai, M. pusillus, M. minutus, Heterophyes heterophyes, H. nocens, H. dispar, Haplorchis taichui, H. pumilio, H. yokogawai, H. vanissinus, Centrocestus formosanus, C. armatus, C. cuspidatus, C. kurokawai, Procerovum calderoni, P. varium, Pygidiopsis genata, P. summa, Stictodora fuscata, S. lari, Stellantchasmus falcatus, Heterophyopsis continua, Acanthotrema felis, Apophallus donicus, Ascocotyle longa, and Cryptocotyle lingua), 24 echinostome intestinal flukes (Echinostoma revolutum, E. cinetorchis, E. mekongi, E. paraensei, E. ilocanum, E. lindoense, E. macrorchis, E. angustitestis, E. aegyptica, Isthmiophora hortensis, I. melis, Echinochasmus japonicus, E. perfoliatus, E. lilliputanus, E. caninus, E. jiufoensis, E. fujianensis, Artyfechinostomum malayanum, A. sufrartyfex, A. oraoni, Acanthoparyphium tyosenense, Echinoparymphium recurvatum, Himasthla muehlensi, and Hypoderaeum conoideum), 23 miscellaneous intestinal flukes (Brachylaima cribbi, Caprimolgorchis molenkampi, Phaneropsolus bonnei, P. spinicirrus, Cotylurus japonicus, Fasciolopsis buski, Gastrodiscoides hominis, Fischoederius elongatus, Watsonius watsoni, Gymnophalloides seoi, Gynaecotyla squatarolae, Microphallus brevicaeca, Isoparorchis hypselobagri, Nanophyetus salmincola, N. schikobalowi, Neodiplostomum seoulense, Fibricola cratera, Plagiorchis muris, P. vespertilionis, P. harinasutai, P. javensis, P. philippinensis, and Prohemistomum vivax), one throat fluke (Clinostomum complanatum), and one pancreatic fluke (Eurytrema pancreaticum). The mode of transmission to humans includes contact with cercariae contaminated in water (schistosomes) or ingestion of raw or improperly cooked food, including fish (liver flukes, heterophyid flukes, echinostomes, and throat flukes), snails (echinostomes, brachylaimids, and gymnophallid flukes), amphibia, reptiles (neodiplostomes), aquatic vegetables (fasciolids and amphistomes), and insect larvae or adults (lecithodendriids, plagiorchiids, and pancreatic flukes). Praziquantel has been proven to be highly effective against almost all kinds of trematode infections except Fasciola spp. Epidemiological surveys and detection of human infections are required for a better understanding of the prevalence, intensity of infection, and geographical distribution of each trematode species.

High Specificity but Low Sensitivity of Lab-on-a-Disk Technique in Detecting Soil-Transmitted Helminth Eggs among Pre- and School-Aged Children in North-Western Tanzania

An estimated 1.5 billion people are infected with soil-transmitted helminths (hookworms, Ascaris lumbricoides and Trichuris trichiura). These infections are targeted for elimination by the World Health Organization (WHO) by 2030, with the main interventions being mass drug administration using albendazole or mebendazole. Tanzania is one of the endemic countries; it has been implementing MDA to school-aged children for more than a decade and the infection prevalence and intensity of infection have declined. Thus, at this point, the monitoring and evaluation of infection prevalence and intensity of infections, and assessing drug efficacy is crucial and requires accurate diagnostic tests. The currently used standard diagnostic test, the Kato-Katz (KK) technique, has several limitations and the WHO is calling for the development and evaluation of new diagnostic tests. The Lab-on-a-disk (LOD) was developed and tested in the endemic areas of north-western Tanzania to evaluate its sensitivity and specificity using KK and the formol-ether concentration technique. The results showed that when using a duplicate KK slide, the LOD had a sensitivity and specificity of 37.2% (95% CI: 30.7-43.9) and 67.3% (95% CI: 63.1-71.3%). Using four KK slides as a standard technique, the overall sensitivity and specificity were 37.7% (95% CI: 33.1-42.6) and 70.7% (95% CI: 65.5-75.6). The LOD attained high specificity but low sensitivity especially in detecting eggs of Trichuris trichiura. The LOD technique has potential as a promising diagnostic test, but its sensitivity still requires improvement.

Prevalence of Schistosomiasis and Soil-Transmitted Helminthiasis and Their Risk Factors: A Cross-Sectional Study in Itilima District, North-Western Tanzania

Schistosomiasis and soil-transmitted helminthiasis remain a public health concern in Tanzania. This study investigated the prevalence and intensities of Schistosoma haematobium, S. mansoni, and soil-transmitted helminths and associated factors in Itilima district, north-western Tanzania. A cross-sectional survey was conducted between August and September 2020 among 3779 primary schoolchildren in 62 primary schools and 1122 adults in 19 villages. Urine samples were obtained from each participant and examined visually for the presence of macrohaematuria, microhaematuria, and S. haematobium eggs using a urine dipstick and urine filtration test. A single stool sample was obtained from each participant and screened for S. mansoni and soil-transmitted helminths using the Kato Katz and formalin-ether concentration techniques. A questionnaire was administered to schoolchildren to elucidate the risk factors for schistosomiasis. The overall prevalence of S. haematobium in adults was 8.1% (95% confidence interval (CI), 6.6-9.8%). In total, 3779 schoolchildren had complete results from urine testing, and the overall prevalence of S. haematobium was 10.1% (95% CI, 9.1-11.1%). The prevalence of S. mansoni and soil-transmitted helminths was relatively low among both children and adults compared to S. haematobium. Factors associated with S. haematobium infection among schoolchildren were the mother's occupation, children aged 11-15 years, and water contact behaviour. The odds of having schistosomiasis infection among children aged 11-15 are 40% higher than those aged 5-10 (95% confidence interval (CI), 10-80%, p = 0.04). Children of parents who are livestock keepers have 12.3 times higher odds of having infection compared to those who have small-scale businesses (95% CI, 1.0-5.4, p = 0.03). Children who are in contact with infested water more than three times a week have 2.1 times higher odds of having an infection compared to those who do not (95% CI, 2.1; 1.6-2.8, p < 0.001). The findings provide updated geographical information on prevalence, yielding insights into the planning and implementation of mass drug administration in rural Tanzania.

Assessing risk factors for malaria and schistosomiasis among children in Misungwi, Tanzania, an area of co-endemicity: A mixed methods study

Malaria and schistosomiasis are two major parasitic vector-borne diseases that are a particular threat to young children in Sub-Saharan Africa. In the present study, we investigated factors that are associated with malaria, schistosomiasis, and co-infection among school-aged children, using an explanatory sequential mixed-methods approach. A cross-sectional study was conducted in January 2022 in Misungwi, Tanzania, that sampled 1,122 children aged 5 to 14 years old for malaria and schistosomiasis infection. Mixed-effect logistic regression models were used to assess the association between infection prevalence or seroprevalence, and environmental determinants that create favorable conditions for vectors and parasites and social determinants that relate to disease exposure. Community mapping combined with direct field observations were conducted in August 2022 in three selected villages from the cross-sectional study to understand specific water use behaviors and to identify potential malaria mosquito larval breeding sites and freshwater snail habitat. The prevalence of malaria, seroprevalence of schistosomiasis, and co-infection in this study were 40.4%, 94.3%, and 38.1%, respectively. Individual-level factors emerged as the primary determinants driving the association with infection, with age (every one-year increase in age) and sex (boys vs girls) being statistically and positively associated with malaria, schistosomiasis, and co-infection (P<0.05 for all). Community maps identified many unimproved water sources in all three villages that were used by humans, cattle, or both. We found that children primarily fetched water, and that unprotected wells were dedicated for drinking water whereas ponds were dedicated for other domestic uses and cattle. Although not identified in the community maps, we found hand pumps in all three villages were not in use because of unpleasant taste and high cost. This study improves our understanding of individual, social and environmental factors that are associated with malaria, schistosomiasis, and co-infection, which can inform potential entry points for integrated disease prevention and control.

Cultural adaption and validation of the Explanatory Model Interview Catalogue-Community Stigma Scale in the assessment of public stigma related to schistosomiasis in lakeshore areas of Mwanza region, Tanzania

BACKGROUND

Previous qualitative studies on attitudes towards schistosomiasis demonstrated inconclusive results on the extent of stigma towards schistosomiasis in endemic communities around the world. The Explanatory Model Interview Catalogue-Community Stigma Scale (EMIC-CSS) has been used and validated for the assessment of public stigma across numerous countries in various health conditions. This study tested the performance of the scale in the context of stigma related to schistosomiasis in twelve communities in the three districts of Magu, Nyamagana and Ilemela in Mwanza region, Tanzania.

METHODOLOGY/PRINCIPAL FINDINGS

The 15-item-version of the EMC-CSS was first translated to Kiswahili language. The translation was discussed within the research team to retain the meaning of the items and implement cultural adaptations. Validation of the adapted EMIC-CSS scale was conducted following the framework of Herdman and Fox- Rushby. A pilot study with 41 participants from two communities provided the basis for testing the performance of each item and assessing the semantic and operational equivalence of the scales. In addition, eight qualitative focus group discussions (FGDs) were conducted to evaluate the conceptional equivalence of the EMIC-CSS. Finally, the performance of the adjusted scale was tested on 200 participants with a 50:50 male-female ratio from ten communities. The mean score of the EMIC-CSS M = 8.35 (SD = 6.63) shows clear indications for public stigma towards schistosomiasis. The EMIC-CSS demonstrated a good internal consistency with Cronbach's alpha α = .857 and no floor and ceiling effects.

CONCLUSION/SIGNIFICANCE

The results demonstrate that the EMIC-CSS is a useful instrument in assessing public stigma towards schistosomiasis and allow a clear recommendation of the EMIC-CSS for schistosomiasis in the Tanzanian culture. However, future studies are additionally recommended to address specific aspects and forms of the disease and how they contribute to the development of stigma towards schistosomiasis.

Burden and factors associated with ongoing transmission of soil-transmitted helminths infections among the adult population: A community-based cross-sectional survey in Muleba district, Tanzania

BACKGROUND

In Tanzania, school-based Mass Drug Administration (MDA) campaigns have been the main strategy for the prevention and control of Soil Transmitted Helminths (STH) infection. Adults are not part of the program and could remain as the reservoir of infection, favoring continuity in transmission. Water, Sanitation, and Hygiene (WaSH) issues and slow progress in community awareness promotion campaigns contribute to the persistence of STH as public health issue among target populations notwithstanding the achievements of the control interventions.

OBJECTIVE

This study aimed to determine the current prevalence and the risk factors associated with ongoing transmission of STH infection among adults in Muleba District, Tanzania.

METHODOLOGY

A household-based quantitative cross-sectional study was carried out among 552 adults in Muleba district. Through a quantitative interviewer-administered questionnaire, information was registered related to socio-demographic characteristics, level of knowledge on the disease, and WaSH factors. The prevalence of STH and estimation of its intensity were assessed by analyzing stool samples through formol-ether concentration and the Kato-Katz technique. Descriptive statistics was used to summarise data; logistic regression to determine the association between STH infection and socio-demographic and WaSH factors. A p-value < 0.05 was considered statistically significant.

RESULTS

A total of 552 adults were included in the study; 50.7% (280/552) were female. The median age was of 30 years, ranging from 18 to 73 years. A prevalence of 9.1% (50/552) for STH infection was reported; the prevalence of Hookworm Spp., Ascaris lumbricoides, and Trichuris trichiura was 7.43%, 0.91%, and 0.72%, respectively. The factors significantly associated with STH infection were farming (aOR = 3.34, 95% CI: 1.45-7.70), the habit of not wearing shoes in general (aOR = 5.11, 95% CI: 1.55-16.87), and during garden activities (aOR = 4.89, 95% CI: 1.47-16.28).

CONCLUSIONS AND RECOMMENDATIONS

We observed an aggregated prevalence of STH infections (Ancylostoma duodenale, Trichuris trichiura, and Ascaris lumbricoides) of 9.1% among the adult population, indicating a decreasing prevalence but ongoing transmission. Integrated management is needed to address practices contributing to ongoing transmission.

Test-Treat-Track-Test-Treat Strategy for Control of Schistosomiasis in Two Low-Prevalence Villages in Northwestern Tanzania

Mass drug administration of praziquantel becomes a less attractive strategy for elimination of schistosomiasis in low-prevalence areas due to cost implications and low treatment compliance. We aimed to determine the feasibility of a Test-Treat-Track-Test-Treat (5T) strategy in two low-prevalence villages; the 5T strategy has been successfully implemented in diseases such as malaria. A total of 200 school children aged 6-12 years were randomly selected from two schools and tested for Schistosoma mansoni infection using the point-of-care circulating cathodic antigen test. Schistosoma mansoni-positive children, referred to as first-generation cases (FGCs), were tracked and treated including up to five members of their families. Second-generation cases, identified by the FGCs as their close, non-relative contacts, were also tracked, tested, and treated, including up to five members of their families. The prevalence of schistosomiasis among screened FGCs was 16.5% (33/200) in both villages. Twenty-four FGCs were included in the study. Prevalence among 94 contacts of FGCs was 46.8% (44/94). The proportion was higher in Muda than Bulunga village (61.2% versus 31.1%, χ2 = 10.6611, P = 0.005). Prevalence among SGCs and their contacts was 37.5% (9/24) and 47.1% (49/104), respectively. Overall, the 5T strategy identified 102 additional cases out of 222 tracked from FGCs, 95% of whom were treated, at a total time of 52 hours. Our data demonstrate the potential of the 5T strategy in identifying and treating additional cases in the community and hence its practicality in schistosomiasis control in low-prevalence settings at relatively low time and resources investment.

Routine health check-ups for adolescents in Mwanza City, Tanzania: stakeholders' recommendations on its content, venue, and mode of delivery

BACKGROUND

Routine adolescent health screening aiming at the detection of unnoticed medical problems may increase awareness among policy makers and contribute to improved health in this population. Research is needed to inform the World Health Organization (WHO) and national health programs to provide evidence-based guidance on whether public health systems should offer comprehensive adolescent health screening, what should be included in different contexts, and how it should be delivered. We conducted formative research to define the content and delivery strategies for health check-ups to be performed in young (10-14 years) and older (15-19 years) adolescents, and to assess whether such services are likely to be acceptable and feasible in Tanzania.

METHODS

As part of a collaborative research program coordinated by WHO in Chitungwiza, Zimbabwe; Mwanza City, Tanzania; and Cape Coast, Ghana a series of key informant interviews were conducted from April to July 2020, using a semi-structured guide with purposively selected stakeholders from government departments, non-governmental and community-based organisations, schools and health facilities. Data transcripts were coded using NVivo 12 software and thematic analysis was performed.

RESULTS

We report results from 31 key informant interviews to address four main domains: proposed health conditions for routine health check-ups, health interventions to be combined with such check-ups, preferable venues, and the mode for delivering such screening activities. Stakeholders were supportive of introducing routine health check-ups among adolescents. They recommended focusing on non-communicable diseases, physical disabilities, common mental health problems, reproductive health problems, specific communicable diseases, and hygiene-related problems. They also recommended combining counselling and family planning information with these check-ups. Three venues were proposed: schools, community settings (to reach out-of-school adolescents), and youth-friendly health facilities (for conditions requiring a high level of confidentiality).

CONCLUSIONS

Stakeholders were supportive of the proposed routine health check-ups for adolescents, recommending specific health conditions to be screened for in both community and school settings. Based on the above, we plan to conduct implementation research to determine the number of new treatable conditions detected, and the costs of offering such services. In the longer term, evaluation of their health impact and cost-effectiveness will be required to guide policy.

Intestinal schistosomiasis among secondary school students in Northern Tanzania: prevalence, infection intensity and associated risk factors

Objective

Our study investigated the prevalence, infection intensity and associated risk factors of intestinal schistosomiasis among secondary school students in Shinyanga Municipal Council, Northern Tanzania.

Methods

A quantitative school-based cross-sectional study was conducted from June to August 2022 among 620 secondary students. One stool specimen per participant was collected and screened for Schistosoma mansoni ova by microscopy using the Kato-Katz technique. Ova were counted to estimate infection intensity in all positive stool samples. Participants' socio-demographic characteristics and risk factors for intestinal schistosomiasis were gathered using a structured questionnaire. Data analysis consisted of descriptive statistics, Chi-square test and logistic regression.

Results

Overall prevalence of S. mansoni was 1.9%. All infected participants had light infection intensity. Overall prevalence of other intestinal parasites was 2.7%, with Hookworm spp (17.6%) and Entamoeba coli (52.9%) the most observed intestinal helminth and protozoa, respectively. Among assessed factors, being in form II or III, visiting water sources and doing activities in water sources were statistically significantly associated with increased risk of S. mansoni transmission.

Conclusions

There is ongoing transmission of intestinal schistosomiasis among secondary students. Hence, the need for extending praziquantel administration in this group, health education provision, and improvement of water supply, sanitation and hygienic practices.

Malaria infection and anemia status in under-five children from Southern Tanzania where seasonal malaria chemoprevention is being implemented

BACKGROUND

Malaria and anemia remain major public health challenges in Tanzania. Household socioeconomic factors are known to influence these conditions. However, it is not clear how these factors influence malaria transmission and anemia in Masasi and Nanyumbu Districts. This study presents findings on malaria and anemia situation in under-five children and its influencing socioeconomic factors in Masasi and Nanyumbu Districts, surveyed as part of an ongoing seasonal malaria chemoprevention operational study.

METHODS

A community-based cross-sectional survey was conducted between August and September 2020. Finger-prick blood samples collected from children aged 3-59 months were used to test for malaria infection using malaria rapid diagnostic test (mRDT), thick smears for determination of asexual and sexual parasitemia, and thin smear for parasite speciation. Hemoglobin concentration was measured using a HemoCue spectrophotometer. A structured questionnaire was used to collect household socioeconomic information from parents/caregivers of screened children. The prevalence of malaria was the primary outcome. Chi-square tests, t-tests, and logistic regression models were used appropriately.

RESULTS

Overall mRDT-based malaria prevalence was 15.9% (373/2340), and was significantly higher in Nanyumbu (23.7% (167/705) than Masasi District (12.6% (206/1635), p<0.001. Location (Nanyumbu), no formal education, household number of people, household number of under-fives, not having a bed net, thatched roof, open/partially open eave, sand/soil floor, and low socioeconomic status were major risks for malaria infection. Some 53.9% (1196/2218) children had anemia, and the majority were in Nanyumbu (63.5% (458/705), p<0.001. Location (Nanyumbu), mRDT positive, not owning a bed net, not sleeping under bed net, open/partially open eave, thatched window, sex of the child, and age of the child were major risk factors for anemia.

CONCLUSION

Prevalence of malaria and anemia was high and was strongly associated with household socioeconomic factors. Improving household socioeconomic status is expected to reduce the prevalence of the conditions in the area.

Hand hygiene intervention to optimise soil-transmitted helminth infection control among primary school children: the Mikono Safi cluster randomised controlled trial in northwestern Tanzania

BACKGROUND

Soil-transmitted helminth (STH) infections are highly prevalent in resource-limited countries. We assessed the effect of a combination intervention aiming to enhance handwashing with soap on STH reinfection following mass drug administration among primary school children in Kagera region, Northwestern Tanzania.

METHODS

We conducted a cluster randomised trial in sixteen primary schools with known high STH prevalence. Schools were randomly assigned in a 1:1 ratio to either receive the intervention or continue with routine health education. The intervention included teacher-led classroom teaching, parental engagement sessions, environmental modifications and improved handwashing stations. The evaluation involved two cross-sectional surveys in a representative sample of students, with the end-line survey conducted 12 months after the baseline survey. The primary outcome was the combined prevalence of Ascaris lumbricoides and Trichuris trichiura infections at the end-line survey. Secondary outcomes included reported handwashing behaviour, the prevalence and intensity of individual STHs, and hand contamination with STH ova and coliform bacteria. End-line STH prevalence and intensity were adjusted for baseline differences of potential confounders.

RESULTS

At the end-line survey, 3081 school children (1566 from intervention schools and 1515 from control schools) provided interview data and stool specimens. More school children in the intervention group reported the use of water and soap during handwashing compared to school children in the control group (58% vs. 35%; aOR=1.76, 95%CI 1.28-2.43, p=0.001). The combined prevalence of A. lumbricoides and T. trichiura infections was 39% in both trial arms (aOR = 1.19; 95%CI 0.74-1.91). The prevalence of A. lumbricoides was 15% in the intervention and 17% in the control arm (aOR =1.24, 95%CI 0.59-2.59) and that of T. trichiura was 31% in both arms (aOR=1.17, 95%CI 0.73-1.88). No significant differences were found for STH infection intensity in both the main study and the hand contamination sub-study.

CONCLUSIONS

The intervention was effective in increasing reported handwashing behaviour at school, but failed to show a similar effect in the home. The intervention had no effect on STH infection, possibly due to infection in the home environment, other transmission routes such as contaminated water or food or limited changes in school children's handwashing behaviour.

TRIAL REGISTRATION

The trial was registered on June 21, 2017, by the International Standard Randomised Controlled Trial Number ( ISRCTN45013173) .

Effectiveness and safety of intermittent preventive treatment for malaria using either dihydroartemisinin-piperaquine or artesunate-amodiaquine in reducing malaria related morbidities and improving cognitive ability in school-aged children in Tanzania: A study protocol for a controlled randomised trial

BACKGROUND

In high transmission settings, up to 70% of school-aged children harbour malaria parasites without showing any clinical symptoms. Thus, epidemiologically, school aged children act as a substantial reservoir for malaria transmission. Asymptomatic Plasmodium infections induce inflammation leading to iron deficiency anaemia. Consequently, anaemia retards child growth, predisposes children to other diseases and reduces cognitive potential that could lead to poor academic performance. School aged children become increasingly more vulnerable as compared to those aged less than five years due to delayed acquisition of protective immunity. None of the existing Intermittent Preventive Treatment (IPT) strategies is targeting school-aged children. Here, we describe the study protocol of a clinical trial conducted in north-eastern Tanzania to expand the IPT by assessing the effectiveness and safety of two antimalarial drugs, Dihydroartemisinin-Piperaquine (DP) and Artesunate-Amodiaquine (ASAQ) in preventing malaria related morbidities in school-aged children (IPTsc) living in a high endemic area.

METHODS/DESIGN

The trial is a phase IIIb, individual randomized, open label, controlled trial enrolling school children aged 5-15 years, who receive either DP or ASAQ or control (no drug), using a "balanced block design" with the "standard of care" arm as reference. The interventional treatments are given three times a year for the first year. A second non-interventional year will assess possible rebound effects. Sample size was estimated to 1602 school children (534 per group) from selected primary schools in an area with high malaria endemicity. Thick and thin blood smears (to measure malaria parasitaemia using microscope) were obtained prior to treatment at baseline, and will be obtained again at month 12 and 20 from all participants. Haemoglobin concentration using a haemoglobinometer (HemoCue AB, Sweden) will be measured four monthly. Finger-prick blood (dried bloodspot-DBS) prepared on Whatman 3 M filter paper, will be used for sub-microscopic malaria parasite detection usingPCR, detect markers of drug resistance (using next generation sequencing (NGS) technology), and malaria serological assays (using enzyme-linked immunosorbent assay, ELISA). To determine the benefit of IPTsc on cognitive and psychomotor ability test of everyday attention for children (TEA-Ch) and a '20 m Shuttle run' respectively, will be conducted at baseline, month 12 and 20. The primary endpoints are change in mean haemoglobin from baseline concentration and reduction in clinical malaria incidence at month 12 and 20 of follow up. Mixed design methods are used to assess the acceptability, cost-effectiveness and feasibility of IPTsc as part of a more comprehensive school children health package. Statistical analysis will be in the form of multilevel modelling, owing to repeated measurements and clustering effect of participants.

DISCUSSION

Malaria intervention using IPTsc strategy may be integrated in the existing national school health programme. However, there is limited systematic evidence to assess the effectiveness and operational feasibility of this approach. School-aged children are easily accessible in most endemic malaria settings. The evidence from this study will guide the implementation of the strategy to provide complementary approach to reduce malaria related morbidity, anaemia and contribute to the overall burden reduction.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT03640403, registered on Aug 21, 2018, prospectively registered.Url https://www.clinicaltrials.gov/ct2/show/NCT03640403?term=NCT03640403&rank=1.

Analysis of Schistosomiasis and soil-transmitted helminths mixed infections among pupils in Enugu State, Nigeria: Implications for control

BACKGROUND

Schistosomiasis and Soil-transmitted helminthiasis cause considerable morbidity and mortality in developing countries, especially among children. To this end it, a cross-sectional survey to determine the pattern of Schistosomiasis and Soil-transmitted helminthiasis co-infection was undertaken among primary school pupils in Oduma Community in Enugu State, Nigeria.

METHODS

Fresh urine and stool samples were collected from pupils. The urine and stool samples were examined using sedimentation and Kat-Katz techniques respectively.

RESULTS

Of the 236 pupils examined, 137 (58.1%) were found positive for at least one helminth infection. Ascaris lumbricoides was the most prevalent soil-transmitted helminth (STH), with a prevalence rate of 40.3%, followed by Trichuris trichiura (15.3%) and hookworm (8.9%). Infection with Schistosoma haematobium was detected in 13.6% of the pupils while Schistosoma mansoni infection prevalence was 7.2%. Age group 4 -7 years recorded the highest prevalence for S. haematobium, A. lumbricoides, T. Trichiura and hookworm infections. Multiple infections were also recorded, with 22.9% having double infections and 2.5% having triple infections. The most common double infection was A. lumbricoides with T. trichiura (8.9%), while the most common triple infection was A. lumbricoides, S. haematobium and hookworm (1.7%).

CONCLUSION

The results from the present study revealed an evident need for the systematic and sustained administration of school-based chemotherapy program targeting the control of STH infection and Schistosomiasis using Albendazole and Praziquantel respectively in the community, instead of a one-off approach that was carried out.

Epidemiology of Trematode Infections: An Update

Digenetic trematodes infecting humans are more than 91 species which belong to 46 genera all over the world. According to their habitat in definitive hosts, they are classified as blood flukes (Schistosoma japonicum. S. mekongi, S. mansoni, S. haematobium, and S. intercalatum), liver flukes (Clonorchis sinensis, Opisthorchis viverrini, O. felineus, Metorchis conjunctus, M. bilis, M. orientalis, Fasciola hepatica, F. gigantica, Dicrocoelium dendriticum, and D. hospes), lung flukes (Paragonimus westermani, P. heterotremus, P. skrjabini, P. miyazakii, P. kellicoti, P. mexicanus, P. africanus, and P. uterobilateralis), throat fluke (Clinostomum complanatum), pancreatic fluke (Eurytrema pancreaticum), and intestinal flukes (Metagonimus yokogawai, M. miyatai, M. takahashii, Heterophyes nocens, H. heterophyes, Haplorchis taichui, H. pumilio, H. yokogawai, Centrocestus formosanus, Echinostoma revolutum, E. ilocanum, Isthmiophora hortensis, Echinochasmus japonicus, E. lilliputanus, Artyfechinostomum malayanum, A. sufrartyfex, A. oraoni, Fasciolopsis buski, Gymnophalloides seoi, Neodiplostomum seoulense, Caprimolgorchis molenkampi, Phaneropsolus bonnei, and Plagiorchis muris). The mode of transmission to humans includes contact with cercariae contaminated in water (schistosomes) and ingestion of raw or improperly cooked fish (liver and throat flukes, heterophyids, and echinostomes), snails (echinostomes and gymnophallids), amphibia, reptiles (neodiplostomes), aquatic vegetables (amphistomes), or insect larvae or adults (plagiorchiids, lecithodendriids, and pancreatic fluke). Praziquantel has been proved to be highly effective against most species of trematode infections except fascioliasis. Epidemiological surveys and detection of human infections are required for better understanding of the geographical distribution and endemicity of each trematode species.

Growth Status, Inflammation, and Enteropathy in Young Children in Northern Tanzania

Recent evidence suggests that enteropathy of the gut due to environmental conditions (i.e., environmental enteropathy [EE]) in young children is negatively associated with linear growth. Using a case-control study design, we examined the potential determinants of stunting in stunted and non-stunted children 22-28 months of age. Potential determinants included inflammation biomarkers C-reactive protein, alpha-1-acid glycoprotein (AGP), and endotoxin-core antibody (EndoCAb) measured in serum samples; enteropathy markers alpha-1-antitrypsin, neopterin, myeloperoxidase (MPO) measured in stools samples; and demographic, health, feeding, and household characteristics. We also explored the determinants of EE by testing associations of composite EE scores and individual biomarkers with potential risk factors. Fifty-two percent of children (n = 310) were found to be stunted, and mean height-for-age Z scores (HAZ) were -1.22 (standard deviation [SD] ± 0.56) among non-stunted (control) children and -2.82 (SD ± 0.61) among stunted (case) children. Child HAZ was significantly (P < 0.05) and inversely associated with AGP, and child stunting was significantly positively associated (P < 0.05) with low dietary diversity, severe household hunger, and absence of soap in the household. Alpha-1-acid glycoprotein and EndoCAb concentrations were also significantly higher (P < 0.05) among children in households with no soap. Our study documented a seemingly localized cultural practice of young children (25%) being fed their dirty bathwater, which was associated with significantly higher concentrations of MPO (P < 0.05). Alpha-1-acid glycoprotein showed the most consistent associations with child growth and hygiene practices, but fecal EE biomarkers were not associated with child growth. The lack of retrospective data in our study may explain the null findings related to fecal EE biomarkers and child growth.

Geographical and behavioral risks associated with Schistosoma haematobium infection in an area of complex transmission

BACKGROUND

Schistosoma haematobium infection in endemic areas varies depending on the nature and complexity of the transmission networks present. Studies of micro-geographical transmission of S. haematobium infection indicate that discrepancy in prevalence between households is associated with diverse water contact behaviors and transmission that is restricted to particular sites harboring snail intermediate hosts. Detection of variations in the transmission sources with complex transmission networks of water bodies is required for optimization of malacological control. Longitudinal parasitological and malacological surveys were conducted to investigate geographical variations in transmission of urogenital schistosomiasis in Ikingwamanoti village, Shinyanga District, Tanzania.

METHODS

Urine samples were collected at baseline and follow-up time points from 282 school-aged children and examined microscopically for the presence of S. haematobium eggs. Malacological surveys involved collection of Bulinus nasutus every month from 30 sites. Snails were examined for patent infections. Global positioning system was used to map household distances from S. haematobium transmission sites, while water contact behavior was assessed using a questionnaire.

RESULTS

Schistosoma haematobium infection was observed to be prevalent among older children (12-14 years) compared to younger groups prior to treatment, but no significant difference in infection prevalence was observed at one-year. Boys were highly infected than girls at both time points. No spatial influence was observed between children's infection and the distance from child's residence to the nearby snail habitats nor was any significant association observed between children's reported water contact behavior with S. haematobium infection. However, malacological surveys with cercarial shedding combined with GPS data detected significant variation among different water sources in the transmission of S. haematobium with children living in households near to ponds with high B. nasutus populations having the highest prevalence of infection.

CONCLUSIONS

Interaction between malacological surveys with cercarial shedding combined with GPS mapping in endemic settings can help detection of transmission sources even in areas with complex transmission networks. Subsequent studies are needed to determine whether the combination of GPS mapping and parasitology screens can aid the detection of transmission hotspots across varied transmission settings to enhance schistosomiasis control programmes.

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.

Prevalence and distribution of soil-transmitted helminth infections in Nigerian children: a systematic review and meta-analysis

Background

Soil transmitted helminth (STH) infections still remain a notable health problem in resource-limited countries due to difficulties in the implementation of control measures. In Nigeria for instance, despite several community-based and provincial reports, national data on prevalence, burdens and risk zones (RZs) for STH infections are lacking.

Methods

The present study employed the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) to determine the prevalence, distribution and RZs for STH infections among Nigerian children through a meta-analysis of data published between 1980 and 2015. Pooled prevalence estimate (PPE) was determined by the random-effects model while heterogeneity was evaluated using the Cochran’s Q-test.

Results

A total of 18 901 of the 34 518 Nigerian children aged 0–17 years examined across 19 Nigerian states during the period under review were infected with one or more species of STHs. The overall PPE for STH infections was 54.8% (95% CI: 54.2–55.3). PPEs for sub-groups ranged between 13.2% (95% CI: 11.5–15.1) and 80.9% (95% CI: 80.0–81.7). Highest PPEs for STH infections were observed among children within community settings (59.0%, 95% CI: 57.7–60.4) and school-aged children (54.9%, 95% CI: 54.3–55.5). Ascaris lumbricoides was the most prevalent species (44.6%, 95% CI: 44.0–45.2). Over 36% (15/41) of the studies were published from south-western Nigeria. South-western region was the only high risk zone (HRZ) for STH infections while the rest of the regions were low risk zones (LRZs).

Conclusions

STH infections involving Ascaris lumbricoides, Strongyloides stercoralis, Trichuris trichiura and hookworms are highly prevalent across Nigeria. Strategic use of anthelmintics, health education and adequate sanitation, taking into account this epidemiologic information will help in the control of these infections in Nigeria.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0451-2) contains supplementary material, which is available to authorized users.

Risk factors for mortality among patients admitted with upper gastrointestinal bleeding at a tertiary hospital: a prospective cohort study

Background

Upper gastrointestinal bleeding (UGIB) is a common gastrointestinal emergency, which is potentially fatal. Proper management of UGIB requires risk-stratification of patients which can guide the type and aggressiveness of management. The aim of this was study was identify the causes of UGIB and factors that increase the risk of mortality in these patients.

Methods

This was a prospective cohort study conducted over a period of seven months at a tertiary hospital. Adults admitted with UGIB were included in the study. Demographic data, laboratory parameters and endoscopic findings were recorded. Patients were then followed up for 60 days to identify the occurrence of mortality. Chi-square tests and cox-regression was used to determine association between risk factors and mortality in the bivariate and multivariate analysis, respectively.

Results

A total of 170 patients with UGIB were included. Males accounted for the majority (71.2%). Median age of the study population was 40.0 years. Chronic liver disease was present in 30.6% of study patients. The most common cause of UGIB among the 86 patients who underwent endoscopy was oesophageal varices (57%), followed by peptic ulcer disease (18%) and gastritis (10%). Mortality occurred in 57 patients (33.5%) and was significantly higher in patients with high white blood cell count (HR 2.45, p 0.011), raised serum alanine aminotransferase (HR 4.22, p 0.016), raised serum total bilirubin (HR 5.79, p 0.008) and lack of an endoscopic procedure done (HR 4.40, p <0.001). Rebleeding was reported in 12 patients (7.1%) and readmission due to UGIB in 4 patients (2.4%)

Conclusions

Oesophageal varices was the most common cause of UGIB. One-third of patients admitted with upper gastrointestinal bleeding died within 60 days of admission, signifying a high burden. Rebleeding and readmission rates were low. A high WBC count, raised serum ALT, raised serum total bilirubin and a lack of endoscopy were independent predictors of mortality. These findings can be used to risk-stratify patients who may benefit from early and more aggressive management.

Longitudinal survey on the distribution of Biomphalaria sudanica and B. choanomophala in Mwanza region, on the shores of Lake Victoria, Tanzania: implications for schistosomiasis transmission and control

BACKGROUND

Schistosomiasis is hyper-endemic in the Lake Victoria basin; with intestinal schistosomiasis plaguing communities adjacent to the lake, where the intermediate host snails live. The two intermediate host species of Schistosoma mansoni in the Mwanza region are Biomphalaria sudanica, found on the banks of the lakes, and B. choanomphala, found in the lake itself. There are few longitudinal surveys documenting changing abundance and differential transmission patterns of these Biomphalaria snails across seasons and years. We undertook 15 field surveys at 26 sites over four years to determine the parameters that influence Biomphalaria abundance, presence of S. mansoni-shedding snails and impact of schistosomiasis treatment interventions on transmission potential in the Mwanza region.

RESULTS

Statistical analysis revealed seasonal difference in the abundance of B. sudanica with the highest number of snails found in the dry season (Kruskal-Wallis χ ² = 37.231, df = 3, P < 0.0001). Water measurements were not associated with B. sudanica abundance; however, high levels of rainfall did have a negative effect on B. sudanica [coefficient effect -0.1405, 95% CI (-0.2666, -0.0144)] and B. choanomphala abundance [coefficient effect -0.4388, 95% CI (-0.8546, -0.0231)] potentially due to inundation of sites "diluting" the snails and influencing collection outcome. Biomphalaria sudanica snails were found at all sites whereas B. choanomphala were far more focal and only found in certain sites. Shedding Biomphalaria did not show any variation between dry and rainy seasons; however, a decrease in shedding snails was observed in year 4 of the study.

CONCLUSIONS

Biomphalaria sudanica is uniformly present in the Mwanza region whereas B. choanomphala is far more focal. Seasonality plays a role for B. sudanica abundance, likely due to its habitat preference on the banks of the lake, but not for B. choanomphala. The decrease in shedding Biomphalaria abundance in Year 4 could be linked to ongoing schistosomiasis treatment efforts in the neighbouring human populations. The highest number of shedding Biomphalaria was observed at sites with high levels of human movement. Prioritising snail control at such sites could greatly reduce transmission in these high-risk areas.

Trichuris trichiura infection and its relation to environmental factors in Mbeya region, Tanzania: A cross-sectional, population-based study

Background

The intestinal nematode Trichuris trichiura is among the most common causes of human infectious disease worldwide. As for other soil-transmitted nematodes, its reproductive success and thus prevalence and intensity of infection in a given area strongly depend on environmental conditions. Characterization of the influence of environmental factors can therefore aid to identify infection hot spots for targeted mass treatment.

Methodology

We analyzed data from a cross-sectional survey including 6234 participants from nine distinct study sites in Mbeya region, Tanzania. A geographic information system was used to combine remotely sensed and individual data, which were analyzed using uni- and multivariable Poisson regression. Household clustering was accounted for and when necessary, fractional polynomials were used to capture non-linear relationships between T. trichiura infection prevalence and environmental variables.

Principal findings

T. trichiura infection was restricted to the Kyela site, close to Lake Nyasa with only very few cases in the other eight sites. The prevalence of T. trichiura infection in Kyela was 26.6% (95% confidence interval (CI) 23.9 to 29.6%). Multivariable models revealed a positive association of infection with denser vegetation (prevalence ratio (PR) per 0.1 EVI units = 2.12, CI 1.28 to 3.50) and inverse associations with rainfall (PR per 100 mm = 0.54, CI 0.44 to 0.67) and elevation (PR per meter = 0.89, CI 0.86 to 0.93) while adjusting for age and previous worm treatment. Slope of the terrain was modelled non-linearly and also showed a positive association with T. trichiura infection (p-value p<0.001).

Conclusion/Significance

Higher prevalences of T. trichiura infection were only found in Kyela, a study site characterized by denser vegetation, high rainfall, low elevation and flat terrain. But even within this site, we found significant influences of vegetation density, rainfall, elevation and slope on T. trichiura infection. The inverse association of rainfall with infection in Kyela is likely due to the fact, that rainfall in this site is beyond the optimum conditions for egg development. Our findings demonstrate that use of remotely sensed environmental data can aid to predict high-risk areas for targeted helminth control.

Baseline prevalence and intensity of schistosomiasis at sentinel sites in Madagascar: Informing a national control strategy

BACKGROUND

Schistosomiasis affects more than 800 million people, mostly in sub-Saharan Africa. A baseline sentinel site study was conducted in the Western half of Madagascar to determine the prevalence and intensity of schistosomiasis and soil-transmitted helminth (STH) infections prior to mass drug administration, and to explore the associations between infection and school attendance, and access to water, sanitation and hygiene (WASH) facilities.

METHODS

A three-stage, cluster-randomised cross-sectional study was conducted in 29 sentinel sites in October 2015. Twenty school attending and 4 non-attending children in each of the age groups from 7 to 10 years old were randomly selected at each site for detection of Schistosoma haematobium eggs in a single urine slide by filtration, and of S. mansoni, Ascaris lumbricoides, Trichuris trichiura and hookworm eggs in duplicate Kato-Katz slides from a single stool sample. School attendance was registered individually, and school-level access to WASH facilities was scored through pre-defined observed and reported factors. Logistic regression analysis was performed, adjusting for gender, age and study site. School-level WASH status was analysed using Spearman's rank correlation coefficient.

RESULTS

A total of 1,958 children were included. The prevalence of S. haematobium infection and heavy-intensity infection was 30.5% and 15.1%, respectively. The prevalence of S. mansoni infection and heavy-intensity infection was 5.0% and 0.9%, respectively. The prevalence of any STH infection was 4.7%. There was no significant difference in prevalence of infection or heavy-intensity infection of either schistosome species between attending and non-attending children, apart from heavy-intensity S. mansoni infection that was significantly more common in children who did not attend school regularly (aOR = 7.5 (95% CI = 1.1-49.5); p = 0.037). Only a minority of schools had adequate access to WASH facilities, and in this study, we found no significant association between school-level WASH status and schistosomiasis.

CONCLUSIONS

This study found an alarmingly high prevalence and intensity of schistosomiasis, and the results warrant urgent scale-up of the national NTD control programme that will need to include both non-attending and attending school-age children in order to reach WHO roadmap targets for the control of schistosomiasis by 2020.