Schistosoma mansoni Infection and Its Related Morbidity among Adults Living in Selected Villages of Mara Region, North-Western Tanzania: A Cross-Sectional Exploratory Study

Prevalence of human schistosomiasis in various regions of Tanzania Mainland and Zanzibar: A systematic review and meta-analysis of studies conducted for the past ten years (2013-2023)

Schistosomiasis is a significant public health problem in Tanzania, particularly for the people living in the marginalized settings. We have conducted a systematic review with meta-analysis on the prevalence of schistosomiasis to add knowledge towards the development of effective approaches to control the disease in Tanzania. Online databases namely, Pub Med, SCOPUS and AJOL, were systematically searched and a random effect model was used to calculate the pooled prevalence of the disease. Heterogeneity and the between studies variances were determined using Cochran (Q) and Higgins (I2) tests, respectively. A total of 55 articles met the inclusion criterion for this review and all have satisfactory quality scores. The pooled prevalence of the disease in Tanzania was 26.40%. Tanzania mainland had the highest schistosomiasis prevalence (28.89%) than Zanzibar (8.95%). Sub-group analyses based on the year of publication revealed the going up of the pooled prevalence, whereby for (2013-2018) and (2018-2023) the prevalence was 23.41% and 30.06%, respectively. The prevalence of the Schistosoma mansoni and Schistosoma hematobium were 37.91% and 8.86% respectively. Mara, Simuyu, and Mwanza were the most prevalent regions, with a pooled prevalence of 77.39%, 72.26%, and 51.19%, respectively. The pooled prevalence based on the diagnostic method was 64.11% for PCR and 56.46% for POC-CCA, which is relatively high compared to other tests. Cochrans and Higgins (I2) test has shown significant heterogeneity (p-value = 0.001 and I2 = 99.6). Factors including age, region, diagnostic method and sample size have shown significant contribution to the displayed heterogeneity. The pronounced and increasing prevalence of the disease suggests potential low coverage and possibly lack of involvement of some regions in the control of the disease. This, therefore, calls for an intensive implementation of control interventions in all endemic regions, preferably using an integrated approach that targets several stages of the disease lifecycle.

Parasites of the liver: A global problem?

Parasitic liver diseases can be caused by trematodes, cestodes, nematodes, and protozoa. This pathology is significant because millions of people in different parts of the world have liver parasites, which can manifest themselves in the development of inflammation, liver cysts, cholecystitis, cholelithiasis, pancreatitis and liver cirrhosis that are often threatening their lives. The International Agency for Research on Cancer considers three species of trematodes, Schistosoma haematobium, Opisthorchis viverrini and Clonorchis sinensis, to be carcinogens. Complex modern examination methods, in some cases including extensive screening of large populations, are required for diagnosing liver parasites. Treatment of parasitic liver diseases is differentiated and can involve a combination of surgical and therapeutic measures. There is no doubt that the clinical and epidemiological scale allows one to regard parasitic liver diseases as a global healthcare problem.

Predicting Schistosomiasis Intensity in Africa: A Machine Learning Approach to Evaluate the Progress of WHO Roadmap 2030

The World Health Organization (WHO) 2030 Roadmap aims to eliminate schistosomiasis as a public health issue, targeting reductions in the heavy intensity of infections. Previous studies, however, have predominantly used prevalence as the primary indicator of schistosomiasis. We introduce several machine learning (ML) algorithms to predict infection intensity categories, using morbidity prevalence, with the aim of assessing the elimination of schistosomiasis in Africa, as outlined by the WHO. We obtained morbidity prevalence and infection intensity data from the Expanded Special Project to Eliminate Neglected Tropical Diseases, which spans 12 countries in sub-Saharan Africa. We then used a series of ML algorithms to predict the prevalence of infection intensity categories for Schistosoma haematobium and Schistosoma mansoni, with morbidity prevalence and several relevant environmental and demographic covariates from remote-sensing sources. The optimal model had high accuracy and stability; it achieved a mean absolute error (MAE) of 0.02, a root mean square error (RMSE) of 0.05, and a coefficient of determination (R2) of 0.84 in predicting heavy-intensity prevalence for S. mansoni; and an MAE of 0.02, an RMSE of 0.04, and an R2 value of 0.81 for S. haematobium. Based on this optimal model, we found that most areas in the surveyed countries have not achieved the target of the WHO road map for 2030. The ML algorithms used in our analysis showed a high overall predictive power in estimating infection intensity for each species, and our methods provided a low-cost, effective approach to evaluating the disease target in Africa set in the WHO road map for 2030.

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.

Prevalence of Schistosoma mansoni infection among fishermen in Busega district, Tanzania

BACKGROUND

Schistosoma (S.) mansoni infection is endemic in all regions around Lake Victoria and affects all age groups to different degrees. In most endemic areas, less attention has been paid to determining the prevalence of infection, sanitation status, and knowledge about intestinal schistosomiasis (KIS) in fishermen. Therefore, the purpose of this study was to establish the prevalence of S. mansoni infection and associated factors among fishermen in the Busega district.

MATERIALS AND METHODS

A cross-sectional study was conducted among fishermen in July, 2020 in five fishing villages in the Busega district located along Lake Victoria. A total of 352 fishermen were interviewed with regard to their sanitation status and level of KIS. A single stool sample from fishermen was examined for S.mansoni eggs by using the Formalin-Ether Concentration technique. The potential factors associated with S. mansoni infection were explored using multivariable logistic regression.

RESULTS

The prevalence of S. mansoni infection was high (65.0%) among fishermen and varied with age, whereby fishermen aged ≤36 years had the highest prevalence. Fishermen had a low level of KIS and the majority of them reported practicing open defecation during fishing (81%). These fishermen with a low level of KIS and who reported defecating in open areas during fishing had 2.8 times (95% CI: 1.0-7.2) and 2.1 times (95% CI: 1.1-3.9) higher odds of being infected with S. mansoni than those with a high level of KIS and those who did not report defecating in open areas during fishing, respectively.

CONCLUSION

S. mansoni infection was high among fishermen in the Busega district. Furthermore, fishermen had a low level of KIS and were reported to have defecated in open areas during fishing. Infection with S. mansoni was associated with age, a low level of KIS and open defecation behaviour during fishing. Therefore, mass drug administration (MDA) with praziquantel, health education, and sanitation behaviour change interventions were needed.

Prevalence of Schistosoma mono- and co-infections with multiple common parasites and associated risk factors and morbidity profile among adults in the Taabo health and demographic surveillance system, South-Central Côte d'Ivoire

Background

Schistosomiasis remains an important public health problem, also among adults, and infected individuals not treated serve as a reservoir for continued transmission. Despite this fact, evidence on the epidemiology of schistosomiasis in adults in Côte d’Ivoire is scanty. This study aimed to determine the prevalence and risk factors of Schistosoma infection and co-infection with other helminth species and Plasmodium among adults in the Taabo region in the south-central part of Côte d’Ivoire.

Methods

A cross-sectional survey was carried out in April and May 2017 in the frame of the “Côte d’Ivoire Dual Burden of Disease Study” (CoDuBu). A total of 901 randomly selected individuals, aged 18–90 years, provided blood, stool and urine samples for the diagnosis of malaria and helminth infections. Stool samples were subjected to the Kato-Katz technique for detection of Schistosoma mansoni and soil-transmitted helminth eggs, while urine samples were examined for eggs of Schistosoma haematobium and circulating cathodic antigen of S. mansoni. Risk factors and morbidity profiles were assessed using health examination and questionnaires. Multinomial logistic regressions were employed to identify risk factors and morbidity patterns associated with S. mansoni mono- and co-infections.

Results

The prevalence of S. mansoni and S. haematobium was 23.2% and 1.0%, respectively. Most S. mansoni were mono-infections (81.3%). Independent determinants of S. mansoni infection were young age, low socioeconomic status (mono- and co-infection) and poor hygiene practices (co-infection) (P < 0.05). S. mansoni infection was independently associated with higher pain and symptom scores (mono-infection), poor self-rated health and low healthcare use (co-infection) (P < 0.05).

Conclusions

This study showed that adults represent a substantial reservoir of S. mansoni. To sustain schistosomiasis control and improve people’s wellbeing, it is important to expand preventive chemotherapy from school-aged children to adults, coupled with hygiene and health education.

Parasites of the liver - epidemiology, diagnosis and clinical management in the European context

Parasites in the liver cause significant global morbidity and mortality, as they can lead to recurrent cholangitis, cirrhosis, liver failure and cancer. Due to climate change and globalisation, their incidence is increasing, especially in Europe. The correct diagnosis of a hepatic parasite is often delayed because clinicians are unfamiliar with respective entities. Therefore, in this review, we aim to provide clinicians with a comprehensive clinical picture of hepatic parasites and to bring these neglected parasitic liver diseases to the wider attention of hepatology stakeholders in Europe and around the world.

Basic Coagulation Profiles and Platelet Count Among Schistosoma mansoni-Infected Adults Attending Sanja Primary Hospital, Northwest Ethiopia

PURPOSE

To assess basic coagulation profiles and platelet count among Schistosoma mansoni-infected and non-infected adults.

PATIENTS AND METHODS

A comparative cross-sectional study was conducted from February to April 2019 at Sanja Primary Hospital, northwest Ethiopia. A total of 200 adults (100 cases and 100 controls) were enrolled using convenient sampling technique. Both wet mount and Kato-Katz techniques were performed using a stool sample. The venous blood sample was collected to perform platelet count, basic coagulation and serological tests. The data were coded and entered into EpiData Manager (v4.4.2.1) and analyzed using SPSS version 20. Nonparametric tests were used during data analysis. P-value less than 0.05 was considered as statistically significant.

RESULTS

Prothrombin time (PT), activated partial thromboplastin time (APTT) and international normalization ratio (INR) were significantly higher while the platelet count was significantly lower in S. mansoni-infected than healthy adults (P <0.001). There were statistically significant differences in the median [IQR] value of PT, APTT, INR and platelet count between light, moderate and heavy infected groups (P <0.05). Infection intensity had a positive correlation with basic coagulation profiles and a negative correlation with platelet count (P <0.05) of S. mansoni-infected adults.

CONCLUSION

The prevalence of coagulation abnormality was higher in S. mansoni-infected adults than healthy controls. Coagulation test and platelet count should be used to monitor and manage schistosomiasis-related complications.

Can Early Diagnosis of Varices, Regular Praziquantel, and Reduction of Hepatitis Coinfection Reduce Mortality among Patients Attended for Periportal Fibrosis in Northwestern Tanzania? A Case-Control Study

Background

Schistosoma mansoni is highly endemic in the Lake Zone part of Tanzania and most people are chronically infected. Periportal fibrosis (PPF) is the commonest complication of chronic S. mansoni infection documented in up to 42% of studied participants in the community-based studies. These patients are at high risk of mortality since most of them are diagnosed late with bleeding varices. At Bugando, Schistosoma-related varices contributed to 70% of patients admitted due to vomiting blood with a two months' mortality of over 10%. Earlier studies had reported higher mortality of up to 29% among patients with PPF even with the best in-hospital care. Understanding factors that increased the risk of mortality is important clinically in devising ways that can improve the outcome of this subgroup of patients.

Methods

A retrospective analysis of patients with PPF from 2015 through 2018 was done. Their sociodemographic, clinical, laboratory, ultrasonographic, endoscopic, and survival status data were collected for analysis. STATA 13 was used for analysis, the prevalence of varices, active schistosomiasis, and hepatitis B coinfection was determined. Cumulative mortality as a major outcome was also determined, and factors associated with increased risk of mortality were assessed by a logistic regression model.

Results

In total, 250 participants were included in this analysis. Majority, 222 (88.8%; 95% CI: 84.2-92.4) had active S. mansoni infection, and 40 (16.0%; 95% CI: 11.6-21.1) had S. mansoni-HBV coinfection. Cumulatively, 39 (15.6%; 95% CI: 11.3-20.7) patients died, with most deaths, 31 (79.5%; 95% CI: 63.5-90.7) occurring within two years following the diagnosis of PPF (chi² = 6.3; p = 0.012). The odds of mortality were independently associated with fishing (OR: 10.8; 95% CI: 2.2-52; p = 0.003), upper gastro intestinal bleeding (OR: 2.4; 95% CI: 1.1-5.4; p = 0.037), HBV coinfection (OR: 3.3; 95% CI: 1.2-91; p = 0.019), and ascites (OR: 3.3; 95% CI: 1.3-8.2; p = 0.010).

Conclusions

In this, S. mansoni endemic area, varices, actives schistosomiasis, hepatitis B coinfection, and mortality are highly common. Screening for varices and initiation of prophylaxis, administration of praziquantel, and screening for hepatitis B should be part and parcel of care of these patients. The first two years of diagnosis, patients are at high risk of mortality; risk factors in this study should assist planning a closer follow-up of patients at risk of mortality to improve their long-term outcome.

Morbidity and Mortality Due to Schistosoma mansoni Related Periportal Fibrosis: Could Early Diagnosis of Varices Improve the Outcome Following Available Treatment Modalities in Sub Saharan Africa? A Scoping Review

Schistosomiasis affects about 240 million people worldwide and Schistosoma mansoni alone affects over 54 million people leaving 400 million at-risk especially in Sub Saharan Africa (SSA). About 20 million people are currently suffering from complications of chronic S. mansoni infection and up to 42% of those infected have been found with periportal fibrosis (PPF). About 0.2 million deaths are attributed to chronic S. mansoni every year, which is mainly due to varices. Death occurs in up to 29% of those who present late with bleeding varices even with the best available in-hospital care. The diagnosis of varices before incident bleeding could potentially improve the outcome of this subgroup of patients is SSA. However, there is no prior review which has ever evaluated this issue detailing the magnitude and outcome of varices following available treatment modalities among patients with Schistosoma PPF in SSA. This review summarizes the available literature on this matter and exposes potential practical gaps that could be bridged to maximize the long-term outcome of patients with S. mansoni related PPF in SSA. A total of 22 studies were included in this review. The average prevalence of varices was 82.1% (SD: 29.6; range: 11.1%–100%) among patients with PPF. Late diagnosis of varices was frequent with average bleeding and mortality of 71.2% (SD: 36.5; range: 4.3%–100.0%) and 13.6% (SD: 9.9; range: 3.5%–29%), respectively. Predictors were reported in seven (31.8%) studies including platelet count to splenic diameter ratio (PSDR) for prediction large varices in one study. Active S. mansoni infection was very prevalent, (mean: 69.9%; SD: 24.4; range: 29.2–100.0%). Praziquantel could reverse PPF and use of non-selective B-blockers reduced both rebleeding and mortality. Use of sclerotherapy for secondary prevention of variceal bleeding was associated with high rebleeding and mortality rates. Conclusions: This review shows that varices due to schistosomal PPF are a big problem in SSA. However, patients are often diagnosed late with fatal bleeding varices. No study had reported a clinical tool that could be useful in early diagnosis of patients with varices and no study reported on primary and effective secondary prevention of bleeding and its outcome. Regular screening for S. mansoni and the provision of Praziquantel (PZQ) is suggested in this review. More studies are required to bridge these practical gaps in Sub Saharan Africa.

Intestinal schistosomiasis of Ijinga Island, north-western Tanzania: prevalence, intensity of infection, hepatosplenic morbidities and their associated factors

Background

Intestinal schistosomiasis is highly endemic in Tanzania and mass drug administration (MDA) using praziquantel is the mainstay of the control program. However, the MDA program covers only school aged children and does not include neither adult individuals nor other public health measures. The Ijinga schistosomiasis project examines the impact of an intensified treatment protocol with praziquantel MDA in combination with additional public health interventions. It aims to investigate the feasibility of eliminating intestinal schistosomiasis in a highly endemic African setting using an integrated community-based approach. In preparation of this project, we report about baseline data on S.mansoni prevalence, intensity of infection, related hepatosplenic morbidities and their associated factors.

Methods

A cross sectional study was conducted among 930 individuals aged 1–95 years living at Ijinga Island, north-western Tanzania in September 2016. Single stool and urine samples were collected from each study participant and processed using Kato Katz (KK) technique and point-of-care Circulating Cathodic (POC-CCA) antigen test for detection of S.mansoni eggs and antigen respectively. Ultrasonographical examination for S.mansoni hepatosplenic morbidities was done to all participants. For statistical analyses Fisher’s exact test, chi-square test, student-t-test, ANOVA and linear regression were used where applicable.

Results

Overall based on KK technique and POC-CCA test, 68.9% (95%CI: 65.8–71.8) and 94.5% (95%CI: 92.8–95.8) were infected with S.mansoni. The overall geometrical mean eggs per gram (GMepg) of faeces was 85.7epg (95%CI: 77.5–94.8). A total of 27.1, 31.2 and 51.9% of the study participants had periportal fibrosis (PPF-grade C-F), splenomegaly and hepatomegaly. Risk factors for PPF were being male (aRR = 1.08, 95%CI: 1.02–1.16, P < 0.01), belong to the age group 16–25 years (aRR = 1.23, 95%CI: 105–1.44, P < 0.01), 26–35 years (aRR = 1.42, 95%CI: 1.21–1.67, P < 0.001), 36–45 years (aRR = 1.56, 95%CI:1.31–1.84, P < 0.001) and ≥ 46 years (aRR = 1.64, 95%CI:1.41–1.92, P < 0.001). The length of the left liver lobe was associated with being female (P < 0.03), belong to the age group 1–5 years (P < 0.013), 6–15 years (P < 0.04) and S.mansoni intensity of infection (P < 0.034). Male sex (aRR = 1.15, 95%CI:1.06–1.24, P < 0.001) and belonging to the age groups 16–25 years (aRR = 1.27, 95%CI:1.05–1.54, P < 0.02) or 26–35 years (aRR = 1.32, 95%CI:108–1.61, P < 0.01) were associated with splenomegaly.

Conclusion

Schistosoma mansoni infection and its related morbidities (hepatomegaly, splenomegaly, periportal fibrosis) are common in the study area. Age, sex and intensity of infection were associated with periportal fibrosis. The prevalence of S.mansoni was above 50% in each age group and based on the observed prevalence, we recommend MDA to the entire community.