Heavy schistosomiasis associated with poor short-term memory and slower reaction times in Tanzanian schoolchildren.

Cross-sectional studies of the relationship between helminth infection and cognitive function can be informative in ways that treatment studies cannot. However, interpretation of results of many previous studies has been complicated by the failure to control for many potentially confounding variables. We gave Tanzanian schoolchildren aged 9-14 a battery of 11 cognitive and three educational tests and assessed their level of helminth infection. We also took measurements of an extensive range of potentially confounding or mediating factors such as socioeconomic and educational factors, anthropometric and other biomedical measures. A total of 272 children were moderately or heavily infected with Schistosoma haematobium, hookworm or both helminth species and 117 were uninfected with either species. Multiple regression analyses, controlling for all confounding and mediating variables, revealed that children with a heavy S. haematobium infection had significantly lower scores than uninfected children on two tests of verbal short-term memory and two reaction time tasks. In one of these tests the effect was greatest for children with poor nutritional status. There was no association between infection and educational achievement, nor between moderate infection with either species of helminth and performance on the cognitive tests. We conclude that children with heavy worm burdens and poor nutritional status are most likely to suffer cognitive impairment, and the domains of verbal short-term memory and speed of information processing are those most likely to be affected.

Diagnosis of rinderpest in Tanzania by a rapid chromatographic strip-test.

A simple chromatographic strip-test based on Clearview technology, is under development as a pen-side test for the detection of rinderpest antigen in eye swabs taken from cattle in the field. An outbreak of rinderpest occurred in the northern zone of Tanzania from late February to June 1997. The affected cattle exhibited very mild clinical signs, which made clinical diagnosis difficult. One hundred and seven eye swabs were collected from cattle suspected of infection with rinderpest. These were tested in the field using a prototype of the pen-side test and 13 (12.15%) of the samples were found to be positive for the presence of rinderpest antigen. These were confirmed by ICE. The positive cases were predominantly found in the Ngorongoro district. This demonstrates the usefulness of such a simple, rapid pen-side diagnostic assay, particularly when clinically 'mild' strains of rinderpest are present.

Rinderpest antibody detected in sheep and goats before an outbreak of rinderpest reported in cattle in northern Tanzania.

In January 1997, serum samples from 1346 adult sheep and goats were tested by a competitive ELISA to determine the prevalence of rinderpest in the northern zone of Tanzania. Seroconversion rates of 20%, 13%, 9%, 7% and 3% in sheep and goats were recorded in Ngorongoro, Monduli, Hai, Arumeru and Simanjiro districts, respectively. The low profile and insidious nature of the rinderpest virus involved caused very mild disease in cattle in some of these area. The mild signs associated with this outbreak of rinderpest resulted in difficulty in its diagnosis. In these circumstances, the presence of rinderpest antibody in sheep and goats served as a valuable and effective indicator of the rinderpest outbreak in cattle.