Schistosomiasis mansoni in low transmission areas: abdominal ultrasound. 
In endemic areas with low prevalence and low intensity of infection, the diagnosis of hepatic pathology due to the Schistosoma mansoni infection is very difficult.  In order to establish the hepatic morbidity, a double-blind study was achieved in Venezuelan endemic areas, with one group of patients with schistosomiasis and the other one of non-infected people, that were evaluated clinically and by abdominal ultrasound using the Cairo classification.  Schistosomiasis diagnosis was established based on parasitologic and serological tests.  The increase of the hepatic size at midclavicular and midsternal lines (in hepatometry) and the hard liver consistency were the clinical parameters able to differentiate infected persons from non infected ones, as well as the presence of left lobe hepatomegaly detected by abdominal ultrasound.  The periportal thickening, especially the mild form, was frequent in all age groups in both infected and uninfected patients.  There was not correlation between the intensity of infection and ultrasound under the current circumstances.  Our data suggest that in Venezuela, a low endemic area of transmission of schistosomiasis, the hepatic morbidity is mild and uncommon.  The Cairo classification seems to overestimate the prevalence of periportal pathology.  The specificity of the method must be improved, especially for the recognition of precocious pathology.  Other causes of hepatopathies must be investigated.