Plasmodium berghei: development of an irreversible experimental malaria model in Wistar rats

A protocol to infect five-week-old Wistar rats by Plasmodium berghei which resulted in 100% mortality was developed in this work. In order to accomplish this goal, the effect of the administration of 10(7) and 10(8) parasitized erythrocytes by i.v. and i.p. route was investigated. The animals inoculated with 10(7) parasitized red blood cells by i.p. and i.v. routes showed 25 and 50% mortality, respectively. Inoculation with 10(8) parasitized erythrocytes by both routes resulted in a 100% lethal infection. The i.v. inoculation showed less scattered results and it was preferred over the i.p. route. The suitability of the protocol developed was evaluated by treating infected Wistar rats with chloroquine (30 mg/kg/day). A decreased parasitemia after the treatment was observed until the complete eradication of the parasite, around 10 days post-inoculation. Parasitemia depression after chloroquine treatment demonstrates the utility of the model developed to test new antimalarial drugs.