Objective: To investigate the effect of pre-existing Schistosoma haematobium (S. haematobium) infection on malaria disease severity. Methods: The study involved the use of twenty-five imprinting control region mice, fifteen of which were initially infected with S. haematobium. Five of the remaining ten schisto-uninfected mice together with five schisto-infected mice were infected with Plasmodium berghei (P. berghei) after four weeks (acute stage) of schistosoma infection. The remaining five schisto-uninfected mice together with five schisto-infected mice were also infected with P. berghei after seven weeks (chronic stage) of schistosoma infection. The last five schisto-infected mice were used as control group. They were then monitored for changes in P. berghei parasitaemia on Days 3, 5, 7, 9 and 11 post-infection. Records on their survivability were also taken. Results: The co-infected mice had significantly higher malaria parasitaemia, compared with the mono-infected mice during acute S. haematobium infection. In contrast, the coinfected mice had significantly lower malaria parasitaemia during chronic S. haematobium infection and a higher survival rate. Conclusions: Co-infection of mice with P. berghei during acute S. haematobium infection resulted in rapid P. berghei development and increased malaria parasitaemia. However, the co-infection resulted in slower P. berghei development and decreased malaria parasitaemia with enhanced survivability of the mice during chronic S. haematobium infection. Therefore, pre-existing chronic S. haematobium infection may provide some protection to the host by reducing parasitaemia.

Objective To assess the toxic potential of Dissotis rotundifolia (D. rotundifolia) whole plant extract in Spraque–Dawley rats within a 2-week period of administration. Methods Methanolic extract of D. rotundifolia was administered orally once daily at dose levels of 0, 100, 300 and 1 000 mg/kg body weight for 14 days. Toxicity was assessed using mortality, clinical signs, body and organ weights, hematological indices, serum chemistry parameters and histopathological analyses. Results There were no treatment-related mortalities or differences in clinical signs, hematology and serum biochemistry. This was confirmed by micrographs obtained from histopathological analysis. Conclusions The results obtained from the sub-acute toxicological assessment of D. rotundifolia extract suggest that the extract is non-toxic at doses up to 1 000 mg/kg/day administered for a period of 14 days.