Increased parasitaemia and delayed parasite clearance in Schistosoma mansoni and Plasmodium berghei co-infected mice.

Identifying factors that contribute to malaria susceptibility, severity and treatment failure remains one of the major research areas in malaria control strategies. In the present study, we superinfected Schistosoma mansoni infected mice with a lethal strain Plasmodium berghei ANKA to assess whether or not infection with S. mansoni affects parasite development, parasitaemia and parasite reduction or clearance following antimalarial treatment. Mice infected with P. berghei alone were used as control. The mice were followed for parasite development and parasitaemia between days 4 and 9 post-infection. On day 9, after taking blood samples, the mice were orally treated with 100mg/kg of chloroquine and then with 10mg/kg for three consecutive days. Parasite reduction/clearance and mortality were followed between days 10 and 13 post-treatment. The results showed, that superinfection with S. mansoni enhanced P. berghei parasite development, increased parasitaemia and mortality, and delayed reduction/clearance in parasitaemia. Hence, the results postulate that co-infections with schistosome and malaria parasites would aggravate malarial severity and prolong parasite reduction or clearance after chemotherapy in humans. This would necessitate the need for considering schistosome infection in clinical as well as therapeutic management of malaria patients in areas where the two diseases are co-endemic.