Geographic differences in hepatosplenic complications of schistosomiasis mansoni and explanatory factors of morbidity

Abstract

SummaryIn a study in three neighbouring villages of southern Madagascar, where Schistosoma mansoni is hyperendemic, ultrasound examination using the Niamey protocol showed marked differences in the burden of disease from one village to another. Hepatosplenic schistosomiasis was more frequent in the village with the highest geometric mean egg counts and the earliest onset of infections, demonstrating that the morbidity induced by S. mansoni may vary greatly within a given area. True representativeness of study populations, a keystone of epidemiological studies, is mandatory to obtain a clear picture of a wide area. Ultrasound examinations in a small number of villages, or even a single one, may be a questionable approach. Using logistic regression analysis, the explanatory variables found to be signi®cantly associated with a risk of severe hepatosplenic disease in our study were sex, age, village of residence and S. mansoni egg counts. On the other hand, a concurrent infection with an intestinal helminth seems to reduce the risk of severe hepatosplenic disease. Further studies should assess the role and possible impact of intestinal helminths on S. mansoni associated-morbidity.keywords epidemiology, intestinal helminths, Madagascar, morbidity, Schistosoma mansoni,

Morbidity due to Schistosoma mansoni: an epidemiological assessment of distended abdomen syndrome in Ugandan school children with observations before and 1-year after anthelminthic chemotherapy

“…As infections are generally lighter in Arua and Moyo, and there has been previous mass distribution of anthelminthics in Masindi and Nebbi, this might shed some light on the general patterns of lower ACR scores. Overdispersion of morbidity associated with intestinal schistosomiasis in Uganda is perhaps not unexpected given that geographic heterogeneity is known elsewhere (Boisier et al, 2001;van der Werf et al, 2002). Moreover, as this survey was based within schools, children too sick to attend class will have been missed, so the true prevalence of this syndrome within the school-age community is likely to be even higher.…”

Assessment of Ultrasound Morbidity Indicators of Schistosomiasis in the Context of Large-Scale Programs Illustrated With Experiences From Malian Children

“…47,48 The current study complements and expands previous ultrasonography-based studies within Africa on a number of issues. First, although previously published surveys 17,[49][50][51][52][53][54] have used ultrasongraphy to measure schistosomiasisassociated morbidity both in children and in adults, which is indicative of long-term chronic infections, we assessed ultrasonography in monitoring schistosomiasis morbidity in control programs focused on children. Although we recognize that measuring only children might be a limitation, if one considers the overall aim of this study, our results still contribute to assessing the suitability of ultrasonography for more recent infections and targeting age groups for future disease control programs.…”

Hepatosplenomegaly Is Associated with Low Regulatory and Th2 Responses to Schistosome Antigens in Childhood Schistosomiasis and Malaria Coinfection

“…Periportal fibrosis is thought to result from chronic immunological responses directed against Schistosoma mansoni eggs (12), and since exposure to infection over many years is associated with this pathology (6), it is detected mostly within adult members of populations in areas where S. mansoni is endemic (18,25). However, a form of S. mansoniassociated hepatosplenomegaly that can extend into adulthood is common among children, and the incorporation of ultrasonography into S. mansoni epidemiological studies has shown that this S. mansoni-associated childhood hepatosplenomegaly can occur in the absence of ultrasound-detectable fibrosis (4,41). It is therefore proposed that immunological inflammation, rather than periportal fibrosis, could be the more common cause of hepatosplenomegaly in this age group (15).…”