20 research outputs found
Ecology of bulinid snail intermediate hosts and transmission of schistosoma haematobium among school aged children in Shinyanga district, Tanzania
No full textA 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 Infections: Its Implication on Undernutrition and Anaemia among Primary Schoolchildren in Two On-Shore Communities, Northwestern Tanzania
No full textResearch 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
The Efficacy of Single-Dose versus Double-Dose Praziquantel Treatments on<i>Schistosoma mansoni</i>Infections: Its Implication on Undernutrition and Anaemia among Primary Schoolchildren in Two On-Shore Communities, Northwestern Tanzania
No full textAdministering more than one treatment may increase Praziquantel cure and egg reduction rates, thereby hastening achievement of schistosomiasis transmission control. A total of 431S. 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%) (p<0.001). The egg reduction rate was higher on repeated dose (97.54%) compared to single dose (87.27%) (p=0.0062). Geometric mean egg intensity was lower among those on repeated dose (1.30 epg) compared to single dose (3.18 epg) (p=0.036) but not at 5 (p>0.05) 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 (p<0.001). There was an increase in the mean haemoglobin levels at 8 months with no difference between the two arms (p>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 withPACTR201601001416338.</jats:p
Knowledge, attitude, and practices on intestinal schistosomiasis among primary schoolchildren in the Lake Victoria basin, Rorya District, north-western Tanzania
No full textAbstract 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
Longitudinal survey on the distribution of Biomphalaria sudanica and B. choanomophala in Mwanza region, on the shores of Lake Victoria, Tanzania: implications for schistosomiasis transmission and control
No full textBackground: Schistosomiasis is hyper-endemic in the Lake Victoria basin; with intestinal schistosomiasis plaguing communities adjacent to the lake, where the intermediate host snails live. The two intermediate host species of Schistosoma mansoni in the Mwanza region are Biomphalaria sudanica, found on the banks of the lakes, and B. choanomphala, found in the lake itself. There are few longitudinal surveys documenting changing abundance and differential transmission patterns of these Biomphalaria snails across seasons and years. We undertook 15 field surveys at 26 sites over four years to determine the parameters that influence Biomphalaria abundance, presence of S. mansoni-shedding snails and impact of schistosomiasis treatment interventions on transmission potential in the Mwanza region.
Results: Statistical analysis revealed seasonal difference in the abundance of B. sudanica with the highest number of snails found in the dry season (Kruskal-Wallis χ 2 = 37.231, df = 3, P < 0.0001). Water measurements were not associated with B. sudanica abundance; however, high levels of rainfall did have a negative effect on B. sudanica [coefficient effect -0.1405, 95% CI (-0.2666, -0.0144)] and B. choanomphala abundance [coefficient effect -0.4388, 95% CI (-0.8546, -0.0231)] potentially due to inundation of sites "diluting" the snails and influencing collection outcome. Biomphalaria sudanica snails were found at all sites whereas B. choanomphala were far more focal and only found in certain sites. Shedding Biomphalaria did not show any variation between dry and rainy seasons; however, a decrease in shedding snails was observed in year 4 of the study.
Conclusions: Biomphalaria sudanica is uniformly present in the Mwanza region whereas B. choanomphala is far more focal. Seasonality plays a role for B. sudanica abundance, likely due to its habitat preference on the banks of the lake, but not for B. choanomphala. The decrease in shedding Biomphalaria abundance in Year 4 could be linked to ongoing schistosomiasis treatment efforts in the neighbouring human populations. The highest number of shedding Biomphalaria was observed at sites with high levels of human movement. Prioritising snail control at such sites could greatly reduce transmission in these high-risk areas.Copyright: © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. The attached file is the published version of the article.NHM Repositor
Community knowledge, perceptions and water contact practices associated with transmission of urinary schistosomiasis in an endemic region: a qualitative cross-sectional study.
No full textBACKGROUND: 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
Mapping of snail intermediate host habitats reveals variability in schistosome and non-schistosome trematode transmission in an endemic setting
No full textThe 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 waterbodies 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 indirect 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
No full textThis research article was published by Proceedings of the Royal Society B: Biological Sciences Volume 291, 2024Different 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
Geographical and behavioral risks associated with Schistosoma haematobium infection in an area of complex transmission
No full textAbstract
Background
Schistosoma haematobium infection in endemic areas varies depending on the nature and complexity of the transmission networks present. Studies of micro-geographical transmission of S. haematobium infection indicate that discrepancy in prevalence between households is associated with diverse water contact behaviors and transmission that is restricted to particular sites harboring snail intermediate hosts. Detection of variations in the transmission sources with complex transmission networks of water bodies is required for optimization of malacological control. Longitudinal parasitological and malacological surveys were conducted to investigate geographical variations in transmission of urogenital schistosomiasis in Ikingwamanoti village, Shinyanga District, Tanzania.
Methods
Urine samples were collected at baseline and follow-up time points from 282 school-aged children and examined microscopically for the presence of S. haematobium eggs. Malacological surveys involved collection of Bulinus nasutus every month from 30 sites. Snails were examined for patent infections. Global positioning system was used to map household distances from S. haematobium transmission sites, while water contact behavior was assessed using a questionnaire.
Results
Schistosoma haematobium infection was observed to be prevalent among older children (12–14 years) compared to younger groups prior to treatment, but no significant difference in infection prevalence was observed at one-year. Boys were highly infected than girls at both time points. No spatial influence was observed between children’s infection and the distance from child’s residence to the nearby snail habitats nor was any significant association observed between children’s reported water contact behavior with S. haematobium infection. However, malacological surveys with cercarial shedding combined with GPS data detected significant variation among different water sources in the transmission of S. haematobium with children living in households near to ponds with high B. nasutus populations having the highest prevalence of infection.
Conclusions
Interaction between malacological surveys with cercarial shedding combined with GPS mapping in endemic settings can help detection of transmission sources even in areas with complex transmission networks. Subsequent studies are needed to determine whether the combination of GPS mapping and parasitology screens can aid the detection of transmission hotspots across varied transmission settings to enhance schistosomiasis control programmes
Longitudinal survey on the distribution of Biomphalaria sudanica and B. choanomophala in Mwanza region, on the shores of Lake Victoria, Tanzania: implications for schistosomiasis transmission and control
No full text© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. The file attached is the Published/publisher’s pdf version of the article.NHM Repositor
