Ecology of bulinid snail intermediate hosts and transmission of schistosoma haematobium among school aged children in Shinyanga district, Tanzania

A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Life Sciences of the Nelson Mandela African Institution of Science and TechnologyThis 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

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%) (p0.05) and 8 (p>0.05) months with no difference in reinfection rate. No difference in the prevalence of stunting was observed between the two treatment regimens (p>0.05) at 8 months, but there was an increase in the prevalence of wasting among those on repeated dose (p0.05). To achieve reduction of transmission intensity and disease control in highly endemic areas, repeated treatments alone may not be sufficient. This trial was registered with PACTR201601001416338

Coinfection of intestinal schistosomiasis and malaria and association with haemoglobin levels and nutritional status in school children in Mara region, Northwestern Tanzania: a cross-sectional exploratory study.

BACKGROUND: Schistosomiasis represents a major public health problem in Tanzania despite ongoing national control efforts. This study examined whether intestinal schistosomiasis is associated with malaria and assessed the contribution of intestinal schistosomiasis and malaria on anaemia and undernutrition in school children in Mara region, North-western Tanzania. METHODS: Stool samples were collected from each of 928 school children randomly selected from 5 schools and examined for intestinal schistosomiasis using the Kato Katz method. Finger prick blood samples were collected and examined for malaria parasites and haemoglobin concentrations using the Giemsa stain and Haemocue methods, respectively. Nutritional status was assessed by taking anthropometric measurements. RESULTS: The overall prevalence and infection intensity of S. mansoni was 85.6% (794/928) and 192 (100-278), respectively. The prevalence of malaria was 27.4% (254/928) with significant differences among villages (χ 2  = 96.11, p < 0.001). The prevalence of anaemia was 42.3% (392/928) with significant differences among villages (χ 2  = 39.61, p < 0.001). The prevalence of stunting, thinness and underweight was 21, 6.8 and 1.3%, respectively. Stunting varied significantly by sex (χ 2  = 267.8, p < 0.001), age group (χ 2  = 96.4, p < 0.001) and by village (χ 2  = 20.5, p < 0.001). Out of the 825 infected children, 217 (26.4%) had multiple parasite infections (two to three parasites). The prevalence of co-infections occurred more frequently in boys than in girls (χ 2  = 21.65, p = 0.010). Mean haemoglobin concentrations for co-infected children was significantly lower than that of children not co-infected (115.2 vs 119.6; t = 0.01, p = 0.002). Co-infected children were more likely to be stunted than children who were not co-infected (χ 2  = 11.6, p = 0.003). On multivariate analysis, age group, village of residence and severe anaemia were significant predictors of stunting after adjusting for sex and infection status. CONCLUSIONS: Intestinal schistosomiasis and malaria are prevalent in Mara region. Coinfections of these parasites as well as chronic undernutrition were also common. We recommend Mara region to be included in national schistosomiasis control programmes

Community knowledge, perceptions and water contact practices associated with transmission of urinary schistosomiasis in an endemic region: a qualitative cross-sectional study

Abstract: 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

The lethal effect of soap on Schistosoma mansoni cercariae in water

Abstract 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

A novel theatre-based behaviour change approach for influencing community uptake of schistosomiasis control measures

Background: Appropriate behaviour change with regard to safe water contact practices will facilitate the elimination of schistosomiasis as a public health concern. Various approaches to effecting this change have been trialled in the field but with limited sustainable outcomes. Our case study assessed the effectiveness of a novel theatre-based behaviour change technique (BCT), in combination with cohort awareness raising and capacity training intervention workshops. Methodology: Our study was carried out in Mwanza, Tanzania and Kemise, Ethiopia. We adapted the Risk, Attitude, Norms, Ability, and Self-regulation (RANAS) framework and four phases using a mixed methods approach. Participatory project phase engagement an11 qualitative formative data were used to guide the design of an acceptable, holistic intervention. Initial baseline (BL) data was collected using quantitative questionnaire surveys with 804 participants in Tanzania and 617 in Ethiopia, followed by the theatre-based BCT and capacity training intervention workshops. Post-intervention (PI) survey was carried out after six months, with a participant return rate of 65% in Tanzania and 60% in Ethiopia. Results: The intervention achieved a significant improvement in the knowledge of schistosomiasis transmission being associated with poorly managed sanitation and risky water contact. Participants in Tanzania increased their uptake of preventive chemotherapy (Male: BL:56%; PI:73%, Female: BL:43%; PI:50%). There was a significant increase in the selection of sanitation (Tanzania: BL:13%; PI:21%, Ethiopia: BL:63%; PI:90%), safe water and avoiding/minimising contact with infested waters as prevention methods in Tanzania and Ethiopia. Some of the participants in Tanzania followed on from the study by building their own latrines. Conclusions: This study showed substantial positive behaviour changes in schistosomiasis control can be achieved using theatre-based BCT intervention and disease awareness training. With appropriate sensitisation, education and stakeholder engagement approaches, community members were more open to minimising risk-associated contact with contaminated water sources and were mobilised to implement preventive measures

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

Research Article published by BioMed Research InternationalAdministeringmore than one treatmentmay 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 40mg/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%) ( < 0.001).Theegg reduction rate was higher on repeated dose (97.54%) compared to single dose (87.27%) ( = 0.0062).Geometric mean egg intensity was lower among those on repeated dose (1.30 epg) compared to single dose (3.18 epg) ( = 0.036) but not at 5 ( > 0.05) and 8 ( > 0.05) months with no difference in reinfection rate. No difference in the prevalence of stunting was observed between the two treatment regimens ( > 0.05) at 8 months, but there was an increase in the prevalence of wasting among those on repeated dose ( < 0.001). There was an increase in the mean haemoglobin levels at 8 months with no difference between the two arms ( > 0.05). To achieve reduction of transmission intensity and disease control in highly endemic areas, repeated treatments alone may not be sufficient.This trial was registered with PACTR201601001416338

Knowledge, attitude, and practices on intestinal schistosomiasis among primary schoolchildren in the Lake Victoria basin, Rorya District, north-western Tanzania

Research Article published by BMC Public HealthBackground: 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