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Article

Epidemiological Survey of Human Zoonotic Fascioliasis and Schistosomiasis in the Lake Victoria and Southern Highland Ecological Zones of Tanzania

by
Godlisten Shedrack Materu
1,2,3,*,
Jahashi Nzalawahe
1,
Mita Eva Sengupta
4,
Anna-Sofie Stensgaard
4,
Abdul Katakweba
5,
Yasinter Silvester
2,
Gerald P. Mwing’a
6,
Birgitte J. Vennervald
4 and
Safari Kinung’hi
2
1
Department of Veterinary Microbiology, Parasitology and Biotechnology, College of Veterinary Medicine and Biomedical Sciences, Sokoine University of Agriculture, Morogoro P.O. Box 3019, Tanzania
2
National Institute for Medical Research (NIMR), Mwanza Research Centre, Mwanza P.O. Box 1462, Tanzania
3
National Institute for Medical Research (NIMR), Tukuyu Research Centre, Mbeya P.O. Box 538, Tanzania
4
Department of Veterinary and Animal Sciences, University of Copenhagen, DYRLAEGEVEJ100.2, DK-1870 Frederiksberg C, Denmark
5
Institute of Pest Management, Sokoine University of Agriculture, Chuo Kikuu, Morogoro P.O. Box 3110, Tanzania
6
National Institute for Medical Research (NIMR), Dodoma Research Centre, Dodoma P.O. Box 805, Tanzania
*
Author to whom correspondence should be addressed.
Zoonotic Dis. 2025, 5(4), 29; https://doi.org/10.3390/zoonoticdis5040029
Submission received: 14 June 2025 / Revised: 13 August 2025 / Accepted: 26 August 2025 / Published: 5 October 2025
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Simple Summary

Zoonotic fascioliasis and schistosomiasis are emerging snail-borne trematode infections worldwide with a great spreading capacity linked to animal and human interaction and movements, climate change, and population dynamics of snail hosts. The aim of the current study was to determine the burden of fascioliasis and schistosomiasis among community members in Tanzania who were not involved in mass drug administration programme. Understanding the burden of zoonotic fascioliasis and schistosomiasis in the two age groups will help in planning and implementation of mass drug administration. This will also serve as a wake-up call for the Neglected Tropical Disease control program of the Ministry of Health to incorporate diagnosis and treatment in routine health care services.

Abstract

Background: Zoonotic fascioliasis and schistosomiasis, caused by trematode parasites transmitted by freshwater snails, are neglected tropical diseases of both medical and veterinary importance. There are critical knowledge gaps regarding the transmission dynamics of these infections in humans and animals, particularly in endemic African communities. Therefore, the current study aimed to determine the burden of human zoonotic schistosomiasis and fascioliasis among different age groups, focusing on the Lake Victoria zone and the Southern Highlands of Tanzania. Methods: A cross-sectional study was conducted among preschool-aged children, school-aged children, and adults. A total of 1557 stool and urine samples were collected, 400 from preschool children, 804 from school-aged children, and 353 from adults. Stool samples were processed using the Kato–Katz technique and the formol-ether concentration method to detect Schistosoma mansoni and Fasciola spp., respectively. Urine samples were examined for Schistosoma haematobium infection using the urine filtration method. Data were analyzed using Stata version 17. The t-tests or one-way ANOVA were used to assess statistical differences in the mean egg counts of S. mansoni and S. haematobium between exposure groups. Results: The overall prevalence of S. haematobium was 4.9%, S. mansoni was 1.2% with no significant differences across age groups, but with a statistically significant difference between sexes 1.8%. Males had a higher prevalence of both S. haematobium and S. mansoni infections compared to females. The prevalence of Fasciola infection was 0.9%, with the highest prevalence found in adults (≥18 years). Conclusions: Zoonotic schistosomiasis and fascioliasis are prevalent in the study area, affecting individuals across all age groups. This is the first study to report the presence of Fasciola infection in both the Lake Victoria zone and the Southern Highlands of Tanzania. These findings call for the Ministry of Health, through the Tanzania NTD Control Program, to recognize fascioliasis as a high-priority disease and include it in the national master plan.

1. Introduction

Schistosomiasis is the most important trematode/blood fluke infection of humans [1]. Two major schistosome species are prevalent in the African region, namely Schistosoma mansoni and Schistosoma haematobium, causing intestinal and urogenital schistosomiasis, respectively [2,3]. Tanzania is endemic for both S. mansoni and S. haematobium, where the prevalence of human schistosomiasis ranges from 12.7 to 87.6% [4]. The country ranks second after Nigeria in terms of schistosomiasis burden in sub-Saharan Africa [4]. Prevalence is highest in rural areas, where access to clean water, sanitation, and hygiene facilities is limited [4].
Transmission of schistosomiasis depends on several factors: contamination of water with viable schistosome eggs, the presence of suitable snail intermediate hosts, and frequent human contact with infested water sources [5]. S. mansoni infection is associated with hepatosplenic disease, often presenting as hepatosplenomegaly and progressive periportal fibrosis. These complications can lead to portal hypertension, irregularities of the liver surface, esophageal varices, and haematemesis [6,7,8]. S. haematobium infection is associated with anaemia, nutritional deficiencies, and lesions in the urogenital tract, such as the kidneys, urinary bladder, and ureters, and cervix in women. If left untreated, chronic infections can progress to urinary bladder cancers such as squamous cell carcinoma [9].
Worldwide, it is estimated that approximately 779 million people are at risk of schistosomiasis, where 250 million people are mainly from sub-Saharan Africa [3,10]. Annual mortality from schistosomiasis is highly controversial, and estimates to be over 200,000 people worldwide [11].
Preventive chemotherapy (PC) using mass drug administration (MDA) of praziquantel targeting primary school-aged children in schools is the main strategy for controlling schistosomiasis in Tanzania [12]. However, adults and pre-school-aged children at any level of transmission risk are excluded from mass PC [13]. The major drawback of this approach is the exclusion of community members outside the school setting, many of whom carry the highest burden of hepatosplenic disease [6]. In addition, untreated individuals sustain transmission within the environment and serve as a reservoir of infection for treated schoolchildren [6]. To reach the global targets of eliminating schistosomiasis by 2030, as part of the Sustainable Development Goals and the commitment to “leave no one behind, “public health interventions must be integrated and reach the entire community [14].
Fascioliasis is caused by the liver fluke of the genus Fasciola [15]. These parasites have a two-host life cycle involving an intermediate gastropod host and a final ruminant host (e.g., cattle, sheep, or buffalo). Two species are known to infect humans, namely Fasciola hepatica and Fasciola gigantica, the latter being less widespread globally but more pathogenic [16,17]. Humans are infected by eating raw or undercooked liver or raw, poorly washed aquatic plants with metacercaria or drinking water from contaminated sources. Acute fascioliasis symptoms include abdominal pain, loss of appetite, and fever, while chronic infections may lead to hepatomegaly and portal cirrhosis [15].
Approximately 2.4 million people worldwide are infected with fascioliasis, while 180 million people are at risk of infection [18]. Trematode infections overall affect more than 10% of the global population, resulting in an estimated 14 million disability-adjusted life years lost annually [19]. Human fascioliasis is known to be endemic throughout Africa; however, most documented cases are from Egypt, Morocco, Tunisia, Algeria, Nigeria, and South Africa [20]. Aside from schistosomiasis, most human trematode infections remain understudied [21].
Currently, the only schistosomiasis control intervention in Tanzania is school-based mass drug administration with praziquantel (PZQ). Despite evidence of disease among pre-school-aged children, they are excluded from treatment [13]. Fascioliasis, on the other hand, is not included in Tanzania’s Neglected Tropical Diseases (NTD) Control Master Plan [22]. It is not routinely diagnosed in health facilities, which may result in a large number of undetected or “hidden” cases. Moreover, very few studies on human fascioliasis have been conducted in Tanzania, despite the known higher prevalence of the disease in animals [23]. This is concerning, given that fascioliasis is a zoonotic disease and animals share the same environment and water sources with humans [23]. The current study aimed to examine the burden of zoonotic schistosomiasis and fascioliasis to generate evidence that will support the planning and implementation of targeted control interventions.

2. Materials and Methods

2.1. Study Design

This was a cross-sectional study, conducted from March to May 2023 in Misungwi, Bariadi, and Iringa districts in Tanzania. Misungwi District is located in the Mwanza Region, while Bariadi District lies within the Simiyu Region, both in the Lake Zone area of Tanzania. Iringa District is located in the Iringa Region, within the Southern Highlands of the country. In Misungwi District, the study was conducted in the villages of Kanyelele, Koromije, and Ibongoya B. In Bariadi District, data were collected from Pugu and Itubukilo A villages. In Iringa Rural District, the study was carried out in Lupembelwasenga, Usengelindeti, and Migori villages (See Figure 1). The selection of study districts and villages was purposive, based on population density, historical reports of Fasciola infections in cattle, known disease burden of schistosomiasis and fascioliasis, and epidemiological data obtained from local District Medical Offices.
Bariadi and Misungwi District Councils are located in the northwestern part of Tanzania, southeast of Lake Victoria. Bariadi District has an elevation of approximately 1272 m above sea level, while Misungwi ranges from 1165 to 1250 m. Both districts receive between 700 mm and 950 mm of rainfall annually [23]. Average temperatures in the two districts range from 19 °C to 29 °C [23].
Iringa Rural District Council, located in the Southern Highlands, is characterized by varied topography, from highlands to midlands. The altitude ranges from 900 to 2300 m above sea level. Highland areas receive between 500 mm and 2700 mm of rainfall annually, whereas lowland areas receive less than 600 mm [23].

2.2. Study Population and Eligibility Criteria

This study recruited preschool-aged children (≤6 years), school-aged children (7–17 years), and adults (≥18 years) in selected villages located along Lake Victoria and the Southern Highlands zones of Tanzania. Eligible participants included children aged ≤17 years and adults aged ≥18 years residing in the study villages, regardless of sex, who provided informed consent either personally or through a parent/guardian.

2.3. Sample Size and Sampling Strategies

The sample size was determined using the single population proportion formula: n   =   ( Z α 2 2 P 1 − P d 2 ) , where P is the prevalence (%) of human schistosomiasis of 21% [24], the desired absolute precision (d) of 2%, and the standard normal deviate (Z) corresponding to the level of significance of 1.96 at a 95% confidence interval (CI) was used. Using these parameters, a total sample size of 1593 participants was calculated.
The sampling strategy used in this study has been described elsewhere [25]. Briefly, a random selection of 150–200 preschool-aged and school-aged children was conducted from the list of registered students in the school attendance book on the day of sample collection. The selection was based on probability proportional to the size of the school and the class population. Systematic sampling was employed, using class registers as the sampling frame. After determining the sampling interval and selecting a random starting point from a table of random numbers, the required number of children was selected from each class. For adult participants, 50 individuals per school/village were invited to participate in the study.

2.4. Data Collection

2.4.1. Collection of Participants’ Demographic Information and Samples

A data collection form was used to collect demographic information, including age, sex, village, district, and height, for preschool-aged children, school-aged children, and adults. For preschool-aged children, a structured questionnaire was administered to their caregivers (parents or guardians). The data collection form was translated into Kiswahili and then back-translated into English before being entered into the database. Fresh stool samples (~10 g) and urine samples (20 mL) were collected from each enrolled participant. Samples for Bariadi and Misungwi District participants were placed in appropriate leak-proof primary containers and transported under chilled conditions to the National Institute for Medical Research, Mwanza Centre, Parasitology Laboratory, on the day of sampling. Samples for Iringa Rural District participants were transported on the day of sampling to the Tanzania Veterinary Laboratory Agency in Iringa Municipality.

2.4.2. Examination for Schistosoma mansoni Using the Kato Katz Technique

Duplicate Kato–Katz thick smears were prepared from a single stool sample collected from each participant, including preschool-aged children, school-aged children, and adults [26]. A 41.7 mg template was used to make the thick smears, which were examined by two independent laboratory technicians trained on the Kato–Katz technique. Ova of S. mansoni appeared yellowish white with a lateral spine shape against a greenish background. For quality assurance, 20% of both positive and negative Kato–Katz smears were re-examined by a third laboratory technician, who was blinded to the initial results.

2.4.3. Examination for Schistosoma haematobium Infection Using the Urine Filtration Method

A single urine sample was collected from each preschool-aged child, school-aged child, and adult participant in the study. The urine filtration method [26] was used to screen urine samples, and the resulting filters were examined under light microscopy. The presence of S. haematobium eggs was identified by their characteristic terminal spine and orange staining [27]. Each sample was examined independently by two medical laboratory technicians. For quality control, 20% of both positive and negative samples were re-examined at the end of each fieldwork day by a third laboratory technician blinded to the initial results.

2.4.4. Examination for Fasciola sp. Infection Using the Formal-Ether Concentration Method

The Formal-Ether Concentration method was used according to Uga et al. [28] and Sato et al. [29] with minor modifications. Briefly, the procedure was followed to prepare a sediment whereby 30 μL was examined on a slide under a light microscope, completely and systematically. Fasciola spp. were confirmed by measuring egg morphology, where an average of 50 eggs from each positive sample was measured, and the average size was calculated (Figure 2).

2.5. Data Management and Analysis

Data were double-entered into a Microsoft Excel sheet for simple cleaning before being exported to STATA version 17 for further management and analysis. Continuous variables (age, egg intensities) were summarized using mean and median as appropriate. The categorical variables were summarized by frequencies and percentages/proportions. The Pearson Chi-square (χ2) test was used to examine associations between the prevalence of human zoonotic fascioliasis and schistosomiasis at different levels of predictor variables. An independent sample t-test for two groups and one-way analysis of variance (ANOVA) for more than two groups were used to assess the difference in mean egg counts of S. mansoni by sex and age groups. However, the arithmetic mean egg counts were obtained from the counts of four Kato Katz smears and multiplied by 24 to get the individuals’ eggs per gram of faeces. The intensity of S. mansoni infection was categorized according to WHO criteria: 1–99 epg, 100–399 epg, and ≥400 epg, defined as low, moderate, and heavy intensity infections, respectively [30]. For S. haematobium, infection intensities were classified into two categories as per WHO recommendation, light infection (<50 eggs/10 mL of urine) and heavy infection (≥50 eggs/10 mL of urine) [31].

2.6. Ethical Considerations

The National Health Research Ethics Committee (NATREC) of the National Institute for Medical Research (NIMR) approved the study (ethics clearance certificate number NIMR/HQ/R.8a/360). The methods used to collect the presented data followed the recommended standard operating procedures (SOPs). The study received further permission from the regional and district authorities of the Misungwi, Bariadi, and Iringa rural districts, Tanzania. Parents and guardians of preschool and school-aged children received information through the village government and school leadership, respectively. Written informed assent and consent forms were obtained from children and parents/guardians before participation in the study. Furthermore, children provided verbal assent to ensure that their participation was voluntary. If a parent or guardian refused, the child’s name was removed from the list of participants. Confidentiality was maintained throughout the study. Those participants diagnosed with either S. haematobium, S. mansoni, and Fasciola were treated with PZQ at 40 mg/kg and Triclabendazole at 10 mg/kg, respectively, following WHO recommendations.

3. Results

3.1. Demographic Characteristics of the Study Participants

A total of 1557 participants were recruited from Bariadi (n = 400), Iringa (n = 563), and Misungwi (n = 594) District Councils. Of these 353 (22.7%) were adults, 804 (51.6%) were school-aged children, and 400 (25.7%) were preschool-aged children. The median age of the school-aged and preschool-aged children was 12 years (IQR: 6–15). More than half of the participants—812 (52.2%)—were female (Table 1).

3.2. Prevalence and Infection Intensity of Schistosoma haematobium Infection

The overall prevalence of S. haematobium based on the urine filtration technique was 4.9% (95% CI: 0.4–6.1%) (Table 2). The prevalence of S. haematobium was higher in adults (≥18 years), 5.1% [95% CI: 3.3–8.0%] compared with other age groups. However, this difference was not statistically significant (ꭓ2 (2) = 0.20, p = 0.905 (Table 2). Moreover, the prevalence of S. haematobium was significantly higher in males, 7.7% [ꭓ2 (1) = 23.81, 0.000], than in females (Table 2). Concerning S. haematobium infection intensity, 3.2% (50/1557) and 1.7% (26/1557) of the participants had light and heavy infection intensity, respectively. The overall geometric mean eggs/10 mL of urine was 25.7 eggs/10 mL (95% CI: 17.3–38.1) with no significant differences among males and females (t = 0.53, p = 0.60) (Table 3).

3.3. Prevalence and Intensity of Schistosoma Mansoni Infection

The prevalence of S. mansoni infection was 1.2% (95% CI: 0.7–1.9%) with no age difference but with a significant difference among sex groups 1.8% [ꭓ2 (1) =4.47, 0.034. The prevalence of S. mansoni was higher in preschool children (≤6 years) compared with other age groups. However, this difference was not statistically significant (ꭓ2 (2) =1.48, p = 0.477 (Table 2). Moreover, the prevalence of S. mansoni was significantly higher in males, 1.8% [ꭓ2 (1) =4.47, 0.034], than in females (Table 2). The overall geometric mean number of epg per gram of faeces (epg) was 2.94 epg (95% CI: 1.9–4.5). No difference in mean epg of faeces was observed among sex and age groups (t = −0.01, p = 0.33, and f = 0.73, p = 0.17, respectively) (Table 3)

3.4. Prevalence and Intensity of Fasciola Infection

The overall prevalence of Fasciola infection was 0.9% (95% CI: 0.4–1.5%). The highest prevalence of Fasciola infection was observed in adults (≥18 years) 1.4% [95% 0.6–3.4%] but no significant difference among age groups [ꭓ2 (2) = 3.47, 0.176]. There were no significant differences in prevalence among males and females [ꭓ2 (1) = 3.56, 0.059] (Table 2).

3.5. The Distribution of Schistosoma haematobium, Schistosoma mansoni, and Fasciola Infection Across Study Villages from Each District

Overall, infections of schistosomiasis and Fasciola by villages were highly observed in the Bariadi district, with the highest prevalence of S. haematobium infection observed in Pugu and Itubukilo villages (14.3%) and (12.3%), respectively. Likewise, the prevalence of S. mansoni was highest in Itubukilo village (2.2%) compared to other villages in other districts (Figure 3). Surprisingly, two children in the same village of Itubukilo found to have co-infection with one of them (a female of 6 years old) having triple infection of S. haematobium, S. mansoni, and Fasciola. The S. haematobium infection was more prevalent in all the villages in the Misungwi district compared to other districts. However, there were no Fasciola infections observed in Ibongoya B and Kanyelele villages of the Misungwi district. Villages from the Iringa district had a lower prevalence of these infections compared to villages from other districts. Generally, S. haematobium infection was the most prevalent trematode infection across all districts. S. mansoni infections were relatively low compared to other infections in all districts, and Fasciola infection was the least prevalent trematode infection across all three districts (Figure 3).

4. Discussion

The present study examined the burden and distribution of human zoonotic trematode infections, namely schistosomiasis and fascioliasis, across different age groups in two ecological zones of Tanzania. To the best of our knowledge, this is the first study to demonstrate the presence and transmission of both fascioliasis and schistosomiasis among various age groups in the study areas. The observed prevalence was 4.9% for S. haematobium, 1.2% for S. mansoni, and 0.9% for Fasciola spp., indicating that these infections are present in the region [32].
The prevalence of Fasciola, S. haematobium, and S. mansoni varied across districts and villages, with the highest rates observed in areas within the Lake Victoria ecological zone. These findings are consistent with earlier studies on the endemicity of S. haematobium, S. mansoni, and Fasciola spp. infections in Tanzania [24,33,34,35,36]. However, this is the first study to report the presence of Fasciola infection in both Lake Victoria and the Southern Highlands of Tanzania. Differences in prevalence between settings may be attributed to the abundance and competence of snail intermediate hosts, local human activities, livestock rearing practices, and environmental contamination with human faeces [37,38]. The overall prevalence of S. haematobium in our study population aligns with findings from previous research conducted in Zanzibar [39], Mtera [36], and Masasi [40]. However, it was higher than the 0.83% reported by Mazigo et al. [24] in Nyasa District, in the Southern Highlands. In contrast, the observed prevalence of S. haematobium in the present study remained lower than that of 32.8% in Morogoro municipality [41] and Northwestern Tanzania, 34.8% [37]. Such variations can be explained by the focal distribution of S. haematobium, proximity to transmission sites, effectiveness of control interventions such as MDA, and environmental sanitation levels [25,37,38]. In this study, S. haematobium prevalence was significantly lower in preschool and school-aged children compared to adults. Further, males were more infected with S. haematobium than other groups, consistent with the findings from studies in Ethiopia and Senegal [42,43], which showed that males often have higher infection intensities. This may be due to behaviors such as swimming in ponds, rivers, and lakes, which are more common among males.
The overall prevalence of S. mansoni was lower than in previous studies, likely due to effective community response to control interventions, reduced snail populations, and community distance from transmission sites. [24,35,44,45].
The prevalence of S. mansoni infection was associated with age in line with previous studies [46]. This trend is typical in endemic areas, where S. mansoni infection peaks between the ages of 6–19, then declines with increasing age [47]. The present study also detected S. mansoni infections in children under 6 years of age, indicating early exposure and supporting the inclusion of younger children in treatment programs [45,48].
The overall prevalence of fascioliasis observed in the present study was 0.9% which is lower compared to the previous studies in Tanzania [49,50] and elsewhere [51,52,53]. These differences may be due to ecological variation, dietary habits, hygiene practices, or diagnostic methods used. Further, low fecal egg counts have been reported among acutely infected individuals presenting with abdominal symptoms [54,55].
The epidemiological classification set for human fascioliasis endemicity is categorized as hypo-endemic (<1%), meso-endemic (1–10%), and hyper-endemic (>10%) [56]. Hence, the Lake Victoria and Southern Highlands ecological zone of Tanzania could be regarded as the hypo-endemic regions for human fascioliasis. Underreporting of fascioliasis in humans is common, often due to limited clinical and research attention, especially in developing countries like Tanzania. This highlights the need to prioritize fascioliasis as a public health concern. The current study had several limitations. First, the geographical coverage was limited, meaning the findings may not be generalizable to other regions. The prevalence and distribution of schistosomiasis and human fascioliasis vary across localities, ecology, and population dynamics of snail intermediate hosts. Second, due to the purposive selection of study districts, the results reflect the presence and distribution of infections by age and sex, but not the actual regional prevalence. Finally, it remains unclear whether the fascioliasis cases detected were transmitted from livestock or through human-to-human transmission. Further research, including molecular studies, is needed to explore the role of humans in the transmission cycle and to investigate possible species hybridization.

5. Conclusions

This study demonstrates that zoonotic schistosomiasis and fascioliasis are prevalent among preschool-aged children, school-aged children, and adults in the Lake Zone and Southern Highlands of Tanzania. These findings highlight the need for the Ministry of Health and the national NTD control program to recognize fascioliasis as a priority disease. Efforts should include the integration of Fasciola diagnosis into routine health services, training of laboratory technicians, and inclusion of both preschool children and adults in mass drug administration programs. In addition, more research, surveillance, and targeted investment are urgently needed to address fascioliasis, which remains significantly underreported despite its public health and economic impact. There is also a need for continuous public and healthcare provider education on fascioliasis, along with improvements in diagnostic and disease reporting systems.

Author Contributions

G.S.M., S.K., J.N., A.K., Y.S., G.P.M., M.E.S., A.-S.S. and B.J.V. conceptualized and designed the study; G.S.M., S.K., Y.S. and J.N. planned and conducted the field work; G.S.M. and J.N. collected and examined the fecal specimens; G.S.M. and G.P.M. analyzed the data and drafted the manuscript; and G.S.M., G.P.M., J.N., Y.S., A.K., S.K., M.E.S., A.-S.S. and B.J.V. revised and improved the final version of the manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

This research reported in this publication was funded partly by the PREPARE4VBD project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101000365. MES and ASS are grateful to the Knud Højgaards Foundation for its support of The Research Platform for Disease Ecology, Health and Climate (grant numbers 16-11-1898 and 20-11-0483).

Institutional Review Board Statement

This research was a part of a project called “PREPARE4VBDs” aimed at identifying, predicting, and preparing for emerging vector-borne diseases. The study adhered to the ethical approval guidelines set forth by the Medical Research Coordination Committee (MRCC) of the National Institute for Medical Research (NIMR), which serves as the national ethics review board in Tanzania (ethics clearance certificate number NIMR/HQ/R.8a/Vol. IX/3860, approved on 3 December 2021.

Informed Consent Statement

Informed consent was obtained from all study participants.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Acknowledgments

The authors express their gratitude to the Regional Commissioners of Mwanza, Simiyu, and Iringa regions, the District Executive Directors and the District Medical Officers of Bariadi, Misungwi, and Iringa Rural districts, and the Village and Sub-village leaders for their cooperation during field data collection. All participants are highly acknowledged. Salim Bwata, Revocatus Silayo, Aruni Haruya, Martin Anditi, and Kalebu Kihongosi are highly acknowledged for their technical assistance during field and laboratory work.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Administrative map of Tanzania (A) showing the study areas, Bariadi District Council (B), Iringa Rural District Council (C), and Misungwi District Council (D).
Figure 1. Administrative map of Tanzania (A) showing the study areas, Bariadi District Council (B), Iringa Rural District Council (C), and Misungwi District Council (D).
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Figure 2. Microscopic view of Fasciola eggs showing size measurement.
Figure 2. Microscopic view of Fasciola eggs showing size measurement.
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Figure 3. Prevalence of Schistosoma haematobium, Schistosoma mansoni, and Fasciola by village in each district.
Figure 3. Prevalence of Schistosoma haematobium, Schistosoma mansoni, and Fasciola by village in each district.
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Table 1. Demographic characteristics of the study population.
Table 1. Demographic characteristics of the study population.
CharacteristicsNumber of ParticipantsPercent (%)
Age group
Pre-school children (≤6 years)40025.7
School-aged children (7–17 years)80451.6
Adult (≥18 years)35322.7
Sex
Male74547.9
Female81252.2
Village
Ibogoya B20012.9
Itubukilo35022.5
Kanyelele19412.5
Koromije20012.9
Lupembelwasenga18912.1
Migoli18812.1
Pugu503.2
Usengelindete18612.0
District
Bariadi DC40025.7
Iringa DC56336.2
Misungwi DC59438.2
Table 2. Prevalence of Schistosoma mansoni, Schistosoma haematobium, and Fasciola stratified by age and sex.
Table 2. Prevalence of Schistosoma mansoni, Schistosoma haematobium, and Fasciola stratified by age and sex.
CharacteristicsSchistosoma mansoniSchistosoma haematobiumFasciola
Infected N (%)ꭓ2, p-ValueInfected N (%)ꭓ2, p-ValuePositive N(%)ꭓ2, p-Value
Age (years)
Children (≤6 years)7 (1.8)ꭓ2 (2) = 1.48, p = 0.47718 (4.5)ꭓ2 (2) = 0.2, p = 0.9055 (1.3)ꭓ2 (2) = 3.47, p = 0.176
School-aged children (7–17 years)8 (1.1)40 (5.0)4 (0.5)
Adult (≥18 years)3 (0.9)18 (5.1)5 (1.4)
Sex
Male13 (1.8)ꭓ2 (1) = 4.47, p = 0.03457 (7.7)ꭓ2 (1) = 23.81, p = 0.0003 (0.4)ꭓ2 (1) = 3.56, p = 0.059
Female5 (0.6)19 (2.4)11 (1.4)
ꭓ2 (1): Chi-square test with 1 degree of freedom, ꭓ2 (2): Chi-square test with 2 degrees of freedom.
Table 3. The relationship between the geometric mean of intensity of infection (GMI) in Schistosoma mansoni and Schistosoma haematobium among study participants by age and sex.
Table 3. The relationship between the geometric mean of intensity of infection (GMI) in Schistosoma mansoni and Schistosoma haematobium among study participants by age and sex.
CharacteristicsSchistosoma mansoniSchistosoma haematobium
N InfectedGMI (95% CI)F/t, p-ValueN InfectedGMI (95% CI)F/t, p-Value
Age group
Children (≤6 years)73.87 (1.96–7.65)f = 0.73, p = 0.171865.35 (26.92–158.65)f = 9.33, p = 0.0002
School-aged children (7–17 years)82.25 (1.20–4.21)4029.80 (18.44–48.15)
Adult (≥18 years)33.17 (0.87–11.53)187.25 (4.04–13.00)
Sex
Male132.59 (1.54–4.36)t = −1.01, p = 0.335727.28 (17.29–43.06)t = 0.53, p = 0.60
Female84.09 (1.38–12.13)1921.40 (9.12–38.07)
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Materu, G.S.; Nzalawahe, J.; Sengupta, M.E.; Stensgaard, A.-S.; Katakweba, A.; Silvester, Y.; Mwing’a, G.P.; Vennervald, B.J.; Kinung’hi, S. Epidemiological Survey of Human Zoonotic Fascioliasis and Schistosomiasis in the Lake Victoria and Southern Highland Ecological Zones of Tanzania. Zoonotic Dis. 2025, 5, 29. https://doi.org/10.3390/zoonoticdis5040029

AMA Style

Materu GS, Nzalawahe J, Sengupta ME, Stensgaard A-S, Katakweba A, Silvester Y, Mwing’a GP, Vennervald BJ, Kinung’hi S. Epidemiological Survey of Human Zoonotic Fascioliasis and Schistosomiasis in the Lake Victoria and Southern Highland Ecological Zones of Tanzania. Zoonotic Diseases. 2025; 5(4):29. https://doi.org/10.3390/zoonoticdis5040029

Chicago/Turabian Style

Materu, Godlisten Shedrack, Jahashi Nzalawahe, Mita Eva Sengupta, Anna-Sofie Stensgaard, Abdul Katakweba, Yasinter Silvester, Gerald P. Mwing’a, Birgitte J. Vennervald, and Safari Kinung’hi. 2025. "Epidemiological Survey of Human Zoonotic Fascioliasis and Schistosomiasis in the Lake Victoria and Southern Highland Ecological Zones of Tanzania" Zoonotic Diseases 5, no. 4: 29. https://doi.org/10.3390/zoonoticdis5040029

APA Style

Materu, G. S., Nzalawahe, J., Sengupta, M. E., Stensgaard, A.-S., Katakweba, A., Silvester, Y., Mwing’a, G. P., Vennervald, B. J., & Kinung’hi, S. (2025). Epidemiological Survey of Human Zoonotic Fascioliasis and Schistosomiasis in the Lake Victoria and Southern Highland Ecological Zones of Tanzania. Zoonotic Diseases, 5(4), 29. https://doi.org/10.3390/zoonoticdis5040029

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