Occurrence of myocarditis in rodents infected with Schistosoma mansoni.

Myocarditis is a complication of Schistosoma mansoni infection, although the literature does not provide much information regarding the frequency of myocarditis. In order to analyze the relationship between myocarditis and S. mansoni infection, different laboratory animals were infected with different dose of cercariae. At different weeks of post infection the hearts of infected animals were collected and processed for histopathological examination. Myocarditis was characterized by interstitial inflammatory cell infiltration with or without granuloma. ddY and ICR infected mice showed eosinophilic egg-granuloma in the heart where as neither eosinophil nor egg-granuloma were observed in the heart of infected gerbils. Higher number of eosinophils and greater size of the granuloma were found in the ddY mice than ICR mice. The number of eosinophils was significantly higher in severe myocarditis. Incidence of myocarditis was higher in ddY mice (69% with 100) than ICR mice (35%) and gerbils (23%). The results indicate that ddY mice were more susceptible to S. mansoni infection in the development of myocarditis and myocardial severity was associated with greater eosinophil infiltration. These findings suggest that eosinophils might be involved in the development of myocarditis, although the involvement of immunological reaction can not be ruled out.