Browsing by Author "Angelo, Teckla"

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Community knowledge, perceptions and water contact practices associated with transmission of urinary schistosomiasis in an endemic region: a qualitative crosssectional study
(BMC Public Health, 2019-06-07) Angelo, Teckla; Kinung’hi, Safari; Buza, Joram; Mwanga, Joseph; Kariuki, Henry; Wilson, Shona
Background: In an effort to complement the current chemotherapy based schistosomiasis control interventions in Shinyanga district, community knowledge, perceptions and water contact practices were qualitatively assessed using focus group discussions and semi structured interviews involving 271 participants in one S. haematobium prevalent community of Ikingwamanoti village, Shinyanga district, Northwestern, Tanzania. Methods: In October, 2016 we conducted 29 parent semi structured interviews and 16 focus group discussions with a total of 168 parent informants. Adult participants were conveniently selected from three sub-villages of Butini, Miyu, and Bomani of Ikingwamanoti village, Shinyanga district. In March, 2017, a total of 103 children informants participated in 10 focus group discussions and 20 semi structured interviews, administered to children from standard four, five, six and seven attending Ikingwamanoti Primary School. Note taking and digital recorders were used to collect narrative data for thematic analysis of emergent themes. Results: Among participants, 75% parents and 50% children considered urinary schistosomiasis as a low priority health problem. Of the informants, 70% children and 48.3% parents had misconceptions about the cause, modes of transmission and control of schistosomiasis demonstrating gaps in their biomedical knowledge of the disease. Assessment of treatment seeking behavior for urinary schistosomiasis revealed a combination of traditional and modern health care sectors. However, modern medicines were considered effective in the treatment of urinary schistosomiasis. Lack of alternative sources of water for domestic and recreational activities and unhygienic water use habits exposed community members to high risk of acquiring urinary schistosomiasis. Conclusion: Use of Schistosoma haematobium contaminated water sources for daily domestic and recreational use facilitated contraction of urinary schistosomiasis among community members in Shinyanga district. People’s perceptions of urinary schistosomiasis as a less priority health problem promoted persistence of the disease. Future efforts to control urinary schistosomiasis should take into account integrated approaches combining water, sanitation and hygiene, health education, alternative sources of clean and safe water to facilitate behavior change.
Ecology of bulinid snail intermediate hosts and transmission of schistosoma haematobium among school aged children in Shinyanga district, Tanzania
(2020-02) Angelo, Teckla
This study investigated transmission of Schistosoma haematobium through longitudinal parasitological, malacological and human water contact surveys. Urine samples collected from school children were examined for S. haematobium infection using urine filtration method. Snail samples collected were examined for patent schistosome infections by microscopy. Multiplex PCR assessed pre-patent infections and differentiated S. haematobium from S. bovis. Water contact questionnaire, focus group discussion and semi structured interviews explored community knowledge on schistosomiasis. Pre-treatment prevalence of S. haematobium infection among school children was 34.8%. Prevalence of S. haematobium infection was higher in older children (12–14 years) compared to younger children (6-11 years) (p<0.001) with no significant variation one-year post-treatment. Boys were more infected than girls. No spatial association was observed between children‘s infection and the distance from child‘s home to the nearby snail habitats. Integration of malacological surveys linked with GPS data detected spatial association between children living in households next to ponds with high B. nasutus having the highest prevalence of S. haematobium infection. From 6202 Bulinus nasutus collected, 190 (3.06%) had patent infections. Rainfall pattern had significant impact on snail population density. Water conductivity (OR 1.23; 95%CI 1.131.34; p<0.0001) and vegetation (OR 6.84; 95%CI 2.75-16.99; P<0.0001) were significantly associated with snail population abundance. Increase of conductivity in snail habitats with vegetation reduced snail densities significantly (OR 0.76; 95%CI 0.68-0.86; P<0.0001). Increase of water temperature was associated with patent infection in pond habitats (OR 0.35; 95%CI 0.45-0.62; P<0.0001) but not rivers. Other physico-chemical parameters were not significantly associated with snail abundance. Out of 1898 B. nasutus snails for which DNA was extracted, 100 (5.17%), 291 (15.07%) and 16 (0.84%) were S. haematobium, S. bovis and S. haematobium/S. bovis co-infected, respectively. Water sources shared between humans and livestock had significantly higher S. haematobium (OR 2.53; 95%CI 1.59-4.05; p<0.0001) and S. bovis (OR 2.29; 95%CI 1.53-3.45; P<0.0001) infections. Wet season was associated with significant reduction of S. bovis infection (OR 0.17; 95%CI 0.09-0.32; P<0.0001). Molecular approach, malacological and a parasitological survey when tied together detect specific schistosome species transmitted. Measures for schistosomiasis control should take into account integrated strategies for disease elimination.
The Efficacy of Single-Dose versus Double-Dose Praziquantel Treatments on Schistosoma mansoni Infections: Its Implication on Undernutrition and Anaemia among Primary Schoolchildren in Two On-Shore Communities, Northwestern Tanzania
(Hindawi, 2017-09-28) Munisi, David; Buza, Joram; Mpolya, Emmanuel; Angelo, Teckla; Kinung’hi, Safari
Administering more than one treatment may increase Praziquantel cure and egg reduction rates, thereby hastening achievement of schistosomiasis transmission control. A total of 431 S. mansoni-infected schoolchildren were randomized to receive either a single or repeated 40 mg/kg Praziquantel dose. Heights, weights, and haemoglobin levels were determined using a stadiometer, weighing scale, and HemoCue, respectively. At 8 weeks, cure rate was higher on repeated dose (93.10%) compared to single dose (68.68%) (). The egg reduction rate was higher on repeated dose (97.54%) compared to single dose (87.27%) (). Geometric mean egg intensity was lower among those on repeated dose (1.30 epg) compared to single dose (3.18 epg) () but not at 5 () and 8 () months with no difference in reinfection rate. No difference in the prevalence of stunting was observed between the two treatment regimens () at 8 months, but there was an increase in the prevalence of wasting among those on repeated dose (). There was an increase in the mean haemoglobin levels at 8 months with no difference between the two arms (). To achieve reduction of transmission intensity and disease control in highly endemic areas, repeated treatments alone may not be sufficient.
Geographical and behavioral risks associated with Schistosoma haematobium infection in an area of complex transmission
(Parasites & Vectors, 2018) Angelo, Teckla; Buza, Joram; Kinung’hi, Safari; Kariuki, Henry; Mwanga, Joseph; Munisi, David; Wilson, Shona
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 GPSmapping 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.
Knowledge, attitude, and practices on intestinal schistosomiasis among primary schoolchildren in the Lake Victoria basin, Rorya District, north-western Tanzania
(BMC Public Health, 2017-09-21) Munisi, David; Buza, Joram; Mpolya, Emmanuel; Angelo, Teckla
Background: Globally school-age children, adolescents and young adults bear the highest burden of schistosomiasis. When developing a specific intervention to improve community’s knowledge, attitudes, and practices (KAPs), existing KAPs must be taken into account. Therefore, this study was designed to determine schoolchildren’s KAPs on schistosomiasis in the study area. Methods: A cross-sectional study was conducted in Busanga and Kibuyi villages involving 513 schoolchildren. A pre-tested questionnaire was used to collect socio-demographic data and to assess KAP on schistosomiasis among primary schoolchildren in the study area. Results: Of the 488 interviewed children, 391 (80.12%) reported to have heard of schistosomiasis, with the majority 289 (73.91%) citing school as the source of this knowledge. Swimming in the lake, worms, witchcraft, and mosquitoes were mentioned to be the cause for intestinal schistosomiasis. Fishing in the lake, drinking unboiled lake water, walking bare footed, and shaking hands were reported to be practices that may lead to contracting schistosomiasis. Only 156 (39.90%) of the study respondents reported to know the signs of intestinal schistosomiasis. Avoiding swimming in the lake, drinking unboiled water and eating unwashed fruits were mentioned as preventive measures. Nearly 85% (412) reported understanding that there was a disease known as schistosomiasis; additionally, 419 (85.86%) considered schistosomiasis as a dangerous disease and 418 (85.66%) believed that schistosomiasis was treatable. Fishermen and schoolchildren were reported to be groups most at risk of schistosomiasis infection. Visiting the lake (for swimming and other gatherings) was a common practice among study participants 471 (96.52%).Nearly 93% (451) of participants mentioned using lake water for domestic chores, and, although 407 (84.61%) reported to own a toilet at home, only 229 (55.31%) reported to always use a toilet for sanitation purposes. Conclusion and recommendation: Despite a high rate of awareness among schoolchildren regarding schistosomiasis, there was a persistent gap amongst the children regarding the causes, modes of transmission, symptoms, and preventive measures for the disease. Therefore, an appropriate health education intervention is needed in order to inculcate better knowledge, attitudes, and practices amongst schoolchildren regarding its transmission, control, and prevention as part of a successful schistosomiasis campaign.
The lethal effect of soap on Schistosoma mansoni cercariae in water
(PLOS, 2024-07-29) Zhang, Jiaodi; Pitol, Ana; Kinung’hi, Safari; Angelo, Teckla; Emery, Aidan; Cieplinski, Adam; Templeton, Michael; Braun, Laura
Background Schistosomiasis is a parasitic disease which is spread through skin contact with water containing Schistosoma cercariae. Drug treatment has been the main control method, but it does not prevent reinfection. The use of soap can be a complementary measure to reduce transmission. Therefore, this study investigates the quantitative effect of different soaps on the mortality of Schistosoma mansoni cercariae. Methodology Four soaps including two powder soaps (Kleesoft and Omo) and two bar soaps (B29 and Rungu) which are used in a schistosomiasis-endemic Tanzanian village were studied. S. mansoni cercariae were exposed to powder soaps of 0 (control), 10, 50, 75, 100 and 1000 mg/L and to bar soaps of 0 (control), 100, 500 and 1000 mg/L. The highest concentration of 1000 mg/L was selected based on the laboratory-estimated average soap concentration during handwashing. Cercariae were observed under a microscope after 0, 5, 15, 30, 45 and 60 minutes of exposure to determine their survival. Conclusions All four soaps can kill S. mansoni cercariae and this lethal effect was related to soap concentration and exposure time. At the highest concentration of 1000 mg/L, all cercariae were dead at 5 minutes post-exposure with two powder soaps and Rungu, while 100% cercarial death was achieved between 5 minutes to 15 minutes for B29. Almost all cercariae survived after being exposed to 10 mg/L powder soaps and 100 mg/L bar soaps for 60 minutes. Powder soaps were more lethal than bar soaps. Considering the widely varying concentrations of soap during real-world hygiene activities and the necessity for a very high soap concentration to eliminate all cercariae in a short 5-minute exposure, providing the efficacy of soap in preventing schistosomiasis becomes challenging. Future studies should investigate whether soap can influence alternative mechanisms such as making cercariae unable to penetrate the skin, thereby providing protection.
Mapping of snail intermediate host habitats reveals variability in schistosome and non-schistosome trematode transmission in an endemic setting
(ELSEVIER, 2025) Angelo, Teckla; Starkloff, Naima; Civitello, David; Mahalila, Moses; Kinung’hi, Safari
The intermediate snail host of Schistosoma haematobium, the etiological agent of urogenital schistosomiasis, serves as a critical sentinel for tracking the spread of associated disease risks. In addition to S. haematobium, Bulinus spp. snails also transmit S. bovis to cattle as well as several non-schistosome trematodes to cattle and wildlife. Identifying transmission foci of these multi-parasite hosts is critical for targeted and effective One Health intervention. We investigated 467 waterbodies in 86 villages across six districts in northwestern Tanzania. A total of 43,348 Bulinus nasutus were collected across three survey phases from November 2020 to August 2021. Across all snails, 0.63% were emitting schistosome cercariae. There was a significant increase in schistosome prevalence during the year, with a peak in the dry season (June-August 2021). Furthermore, of the 25,052 snails collected in the latter two phases (March to August 2021), 4.9% were infected with non-schistosome trematodes, exceeding prevalences of schistosomes at all spatial scales. Co-infections were uncommon, with only 0.05% of snails concurrently emitting both schistosome and non-schistosome parasites. These infection patterns were consistent across village and district levels. Waterbodies used by cattle had higher schistosome prevalence than waterbodies isolated for human use. Surprisingly, non-schistosome prevalence was equal in both of these waterbody types. This suggests that cattle have an indirect role in schistosome transmission, requiring the separation of waterbody usage between cattle and humans and extending snail control in dry season to water- bodies used by cattle. By contrast, water permanence and school proximity did not impact snail or parasite presence. Targeted interventions should focus on local water use dynamics, with attention to the potential in- direct role of cattle in schistosome transmission.
Spatio-temporal variability in transmission risk of human schistosomes and animal trematodes in a seasonally desiccating East African landscape
(The Royal Society, 2024-01-10) Starkloff, Naima; Angelo, Teckla; Mahalila, Moses; Charles, Jenitha; Kinung'hi, Safari; Civitello, David
Different populations of hosts and parasites experience distinct seasonality in environmental factors, depending on local-scale biotic and abiotic factors. This can lead to highly heterogeneous disease outcomes across host ranges. Variable seasonality characterizes urogenital schistosomiasis, a neglected tropical disease caused by parasitic trematodes (Schistosoma haematobium). Their intermediate hosts are aquatic Bulinus snails that are highly adapted to extreme rainfall seasonality, undergoing prolonged dormancy yearly. While Bulinus snails have a remarkable capacity for rebounding following dormancy, we investigated the extent to which parasite survival within snails is diminished. We conducted an investigation of seasonal snail schistosome dynamics in 109 ponds of variable ephemerality in Tanzania from August 2021 to July 2022. First, we found that ponds have two synchronized peaks of schistosome infection prevalence and observed cercariae, though of lower magnitude in the fully desiccating than non-desiccating ponds. Second, we evaluated total yearly schistosome prevalence across an ephemerality gradient, finding ponds with intermediate ephemerality to have the highest infection rates. We also investigated dynamics of non-schistosome trematodes, which lacked synonymity with schistosome patterns. We found peak schistosome transmission risk at intermediate pond ephemerality, thus the impacts of anticipated increases in landscape desiccation could result in increases or decreases in transmission risk with global change.
Stocking African catfish in Lake Victoria provides effective biocontrol of snail vectors of Schistosoma mansoni
(PLoS Negl Trop Dis, 2025-09-15) Proud, Roland; Allan, Fiona; Whiston, Andrew; Kayanda, Robert; Kinung'hi, Safari; Angelo, Teckla; Sylivester, Yasinta D; Mrosso, Hillary D. J.; Kashindye, Benedicto B.; Elison, Mboni; Cox, Martin J.; Yang, Yang; Chamberlin, Andrew; Boyd, Ian; Civitello, David J.; De Leo, Giulio A.; Brierley, Andrew
In areas of high infection prevalence, effective control of schistosomiasis – one of the most important Neglected Tropical Diseases – requires supplementing medical treatment with interventions targeted at the environmental reservoir of disease. In addition to provision of clean water, reliable sanitation, and molluscicide use to control the obligate intermediate host snail, top-down biological control of parasite-competent snails has recently gained increasing interest in the scientific community. However, evidence that natural predators can effectively reduce snail abundance and, ultimately, transmission risk to vulnerable human populations remains limited. In this study, we used a Before-After-Control-Intervention (BACI) design implemented in seven lakeside areas, including three intervention areas and four control areas, on the southern shores of Lake Victoria (Tanzania) in 2019–2023. We tested whether the restoration of African catfish, Clarias gariepinus, a native species of commercial value, could reduce both the abundance of Biomphalaria snails (intermediate hosts of Schistosoma mansoni) and infection intensity in school age children (SAC). Where catfish were restored, mean site-level snail counts declined by 57% (95% CI: 29.4%, 74.3%). At primary schools located within each area, SAC infection intensity (mean parasite egg count in stool samples) also decreased significantly by 55% (95% CI: 26%, 73%). This study shows that natural predators of host snails have the potential for schistosomiasis control. Scaling up to a lake-wide approach will require systemic intervention, with snail host control contributing to a broader framework for schistosomiasis management.