Bladder Morbidity and Hepatic Fibrosis in Mixed Schistosoma haematobium and S. mansoni Infections: A Population-Wide Study in Northern Senegal

Abstract

BackgroundThe global distribution map of schistosomiasis shows a large overlap of Schistosoma haematobium- and S. mansoni-endemic areas in Africa. Yet, little is known about the consequences of mixed Schistosoma infections for the human host. A recent study in two neighboring co-endemic communities in Senegal indicated that infection intensities of both species were higher in mixed than in single infections. Here, we investigated the relationship between mixed Schistosoma infections and morbidity in the same population. So far, this has only been studied in children.Methods Schistosoma infection was assessed by microscopy. Schistosoma-specific morbidity was assessed by ultrasound according to WHO guidelines. Multivariable logistic regression models were used to identify independent risk factors for morbidity.Principal FindingsComplete parasitological and morbidity data were obtained from 403 individuals. Schistosoma haematobium-specific bladder morbidity was observed in 83% and S. mansoni-specific hepatic fibrosis in 27% of the participants. Bladder morbidity was positively associated with S. haematobium infection intensity (OR = 1.9 (95% CI 1.3–2.9) for a 10-fold increase in intensity). Moreover, people with mixed infections tended to have less bladder morbidity than those with single S. haematobium infections (OR = 0.3 (95% CI 0.1–1.1)). This effect appeared to be related to ectopic S. mansoni egg elimination in urine. Hepatic fibrosis on the other hand was not related to S. mansoni infection intensity (OR = 0.9 (95% CI 0.6–1.3)), nor to mixed infections (OR = 1.0 (95% CI 0.7–1.7)).Conclusions/SignificanceThis is the first population-wide study on the relationship between mixed Schistosoma infections and morbidity. Mixed infections did not increase the risk of S. mansoni-associated morbidity. They even tended to reduce the risk of S. haematobium-associated morbidity, suggesting a protective effect of S. mansoni infection on bladder morbidity. These unexpected results may have important consequences for schistosomiasis control in co-endemic areas and warrant further investigation.

Morbidity Associated with Schistosomiasis Before and After Treatment in Young Children in Rusinga Island, Western Kenya

“…However, children too young or small for MDA have considerable infection prevalences 5,6 in multiple African countries, where they can be exposed through bathing and other activities, 7,8 and they can be treated with no serious adverse events. [9][10][11][12][13] The morbidity pre-school-aged children (PSAC) experience from infection is not well defined, though: effects are known to include fecal occult bleeding, 14,15 hematuria, proteinuria, 16 ultrasound abnormalities, 17,18 and possibly anemia, 19,20 but clinical implications remain unclear. Thus, although these findings have prompted calls for including PSAC in MDA, 21 a 2010 WHO meeting concluded that more evidence was necessary.…”

High Schistosoma mansoni Disease Burden in a Rural District of Western Zambia

“…The milder form (LIP C) of portal fibrosis is normally seen in younger age groups. 6,35 In endemic areas, most people infected with S. mansoni present with LIP C and D forms of fibrosis, 36 whereas severe disease characterized with advanced fibrosis (LIPs E and F) is only observed in 5-10% of the people. 37 In our study population, advanced fibrosis characterized with LIPs E and F was recorded in 4.8% and 1.2% of the participants, respectively.…”

Sustainability Assessment of Large Irrigation Dams in Senegal: A Cost-Benefit Analysis for the Senegal River Valley

“…In Senegal, a parasitological survey of 857 randomly chosen individuals from the S-SRV have identified bladder morbidity caused by schistosomiasis among 83% of the studied population, liver fibrosis among 27%, and both liver and bladder morbidity among 24% (Meurs et al, 2012). According to Wright (1972), about 25% of the Schistosoma's infected persons develop a disability that reduces their productive capacity.…”