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 evaluate the antimalarial and antioxidant properties of stem bark extracts of Haematostaphis barteri (H. barteri). Methods: The prophylactic activity of the plant was performed by dosing mice with sulfadoxine-pyrimethamine (1.2 mg/kg), aqueous extract (30, 100, 300 mg/kg) and dichloromethane/methanol (D/M) (30, 100, 300 mg/kg) extracts of H. barteri for 3 days. On the 4th day, the mice were inoculated with Plasmodium berghei. The parasite density was estimated for each mouse 72 h post-parasite inoculation. The curative activity of the plant was also performed by inoculating mice with Plasmodium berghei. Three days later, they were treated with artemether-lumefantrine (4 mg/kg), aqueous and D/M extracts of H. barteri stembark for 5 days. The in vitro antioxidant property of the aqueous extractwas determined by using the reducing power, nitric oxide and total antioxidant capacity assays. Results: The aqueous extract exerted significant (P < 0.05) curative and prophylactic antimalarial activities. The D/M extract exhibited significant curative (P < 0.05) but not prophylactic antiplasmodial effect. The aqueous extract exhibited in vitro antioxidant property with IC