A Very High Infection Intensity of Schistosoma mansoni in a Ugandan Lake Victoria Fishing Community Is Required for Association with Highly Prevalent Organ Related Morbidity

et al. (2013) A Very High Infection Intensity of Schistosoma mansoni in a Ugandan Lake Victoria Fishing Community Is Required for Association with Highly Prevalent Organ Related Morbidity. PLoS Negl Trop Dis 7(7): e2268. doi:10.1371/ journal.pntd.0002268 A Very High Infection Intensity of Schistosoma mansoni in a Ugandan Lake Victoria Fishing Community Is Required for Association with Highly Prevalent Organ Related Morbidity Edridah M. Tukahebwa 0 Pascal Magnussen 0 Henry Madsen 0 Narcis B. Kabatereine 0 Fred Nuwaha 0 Shona Wilson 0 Birgitte J. Vennervald 0 Simon Brooker, London School of Hygiene and Tropical Medicine, United Kingdom 0 1 Vector Control Division, Ministry of Health , Kampala , Uganda , 2 DBL- Centre for Health Research and Development, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark , 3 School of Public Health, Makerere University , Kampala , Uganda , 4 Department of Pathology, University of Cambridge , Cambridge , United Kingdom Background: In schistosomiasis control programmes using mass chemotherapy, epidemiological and morbidity aspects of the disease need to be studied so as to monitor the impact of treatment, and make recommendations accordingly. These aspects were examined in the community of Musoli village along Lake Victoria in Mayuge district, highly endemic for Schistosoma mansoni infection. Methodology and Principal Findings: A cross sectional descriptive study was undertaken in a randomly selected sample of 217 females and 229 males, with a mean age of 26 years (SD 616, range 7-76 years). The prevalence of S. mansoni was 88.6% (95% CI: 85.6-91.5). The geometric mean intensity (GMI) of S. mansoni was 236.2 (95% CI: 198.5-460.9) eggs per gram (epg) faeces. Males had significantly higher GMI (370.2 epg) than females (132.6 epg) and age was also significantly associated with intensity of infection. Levels of water contact activities significantly influenced intensity of infection and the highest intensity of infection was found among people involved in fishing. However, organomegaly was not significantly associated with S. mansoni except for very heavy infection (.2000 epg). Liver image patterns C and D indicative of fibrosis were found in only 2.2% and 0.2%, respectively. S. mansoni intensity of infection was associated with portal vein dilation and abnormal spleen length. Anaemia was observed in 36.4% of the participants but it was not associated with S. mansoni infection intensity. Considering growth in children as one of the morbidity indicators of schistosomiasis, intensity of S. mansoni was significantly associated with stunting. Conclusion: Although organ-related morbidity, with the exception of periportal fibrosis, and S. mansoni infections were highly prevalent, the two were only associated for individuals with very high infection intensities. These results contrast starkly with reports from Ugandan Lake Albert fishing communities in which periportal fibrosis is more prevalent. - Funding: This study was funded by the Commission of the European Communitys Science and Technology for Development Programme (INCO-DEV Contract No: 517733 (MUSTSchistUKEMA)), coordinated by DBL-Centre for Health Research and Development. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. In Uganda, schistosomiasis is mainly caused by Schistosoma mansoni [1] and affects more than 10% of the population [2,3]. It is one of the Neglected Tropical Diseases (NTDs) which perpetuate poverty. The distribution of schistosomiasis has increased due to environmental changes, water development projects and migration of people from endemic to non-endemic areas, spreading to urban areas in developing countries [4,5]. Schistosome eggs trapped in the host tissue are the major cause of morbidity. Eggs trapped in the liver cause granulomatous reactions and lead to formation of fibrotic lesions with hepatosplenic enlargement which may in turn cause portal hypertension and hepatosplenic schistosomiasis [6,1,7,810]. Hepatosplenic schistosomiasis is common in children and adolescents and may affect up to 80% of the infected individuals [6,9] and in the Kenyan study it was exacerbated by malaria otherwise, its severity is related to the intensity of infection [11] and duration of exposure to contaminated water [8]. However, not all infected individuals experience morbidity and the level of schistosomiasis related morbidity differs among affected communities and endemic areas. Other manifestations of schistosomiasis include anaemia [12] and physical retardation [13,14]. However, other parasitic infections may interact on schistosomiasis-related morbidity. For instance, Schistosoma mansoni infection is one of the Neglected Tropical Diseases (NTDs) that perpetuate poverty, especially in Sub Saharan Africa. It is associated with hepatomegaly, splenomegaly or hepatosplenomegaly, liver fibrosis and anaemia. Control of schistosomiasis is now a priority in most endemic countries in Africa as a component of integrated control of NTDs using mass drug administration (MDA). Other than the new WHO strategic plan to eliminate schistosomiasis as a public health problem in WHO Africa region by 2020, the major target in the control of schistosomiasis has for a long time been reduction of its related morbidity. Epidemiological and morbidity studies are key in monitoring the impact of an intervention. However, epidemiology of schistosomiasis and its related morbidity have been shown to vary in different endemic areas and communities. We report on the epidemiology of S. mansoni infection and related morbidity in a community in Mayuge District along Lake Victoria in Uganda. malaria may act synergistically with schistosomiasis in the development of hepatosplenomegaly [1517] and anaemia is associated with malaria [18] and hookworm [19] infections. Previously, epidemiological and morbidity data have been reported from the Lake Albert region [1,11], however such data from Lake Victoria in Uganda are few [20]. This study was carried out to describe the epidemiology of S. mansoni infection and its related morbidity among communities living along Lake Victoria. Materials and Methods Study Area and Population The study was conducted in Musoli village along Lake Victoria, Mayuge district in South East Uganda. The district lies at an altitude of 1161 m above sea level, with temperatures ranging from 1927uC and receives annual rainfall in the range of 600 1100 mm [21]. Like other lakes in Uganda, transmission of schistosomiasis in Lake Victoria is stable and intense throughout the year. Musoli village is inhabited by two ethnic groups; the Bantu and Nilotics. The level of literacy is high as compared to other fishing communities in Uganda and most children go to school. Other than subsistence farming, fishing (...truncated)