Rodent malaria in the natural host; irradiated sporozoites of Plasmodium berghei induce liver-stage specific immune responses in the natural host Grammomys surdaster and protect immunized Grammomys against P. berghei sporozoite challenge

The choice of the host in studying host-parasite interactions is of crucial importance, and the use of a natural host is most appropriate in answering pertinent questions related to human malaria. The Grammomys surdaster is the natural host and reservoir of the rodent malaria parasite Plasmodium berghei. This natural host is difficult to protect by irradiated sporozoite immunization, a situation comparable to what has been observed in humans with P. falciparum. This is in contrast to the complete protection that can be induced in artificial hosts like inbred mice strains. The natural host is highly susceptible to P. berghei hepatic stage infections. Immunization with irradiated sporozoites in Grammomys generates blocked hepatic stage parasites and immunized Grammomys protected upon live sporozoite challenge generate antibody and T cell proliferative responses to these hepatic stages. Associated with proliferation, cytokines are secreted into culture supernatants constituted mainly of Interferon gamma, negligible amounts of TNF-alpha, and no IL-4. Natural host-parasite interactions of Grammomys surdaster-P. berghei can help define the effector mechanism(s) in the Plasmodium falciparum-human interaction

Variation in malaria transmission intensity in seven sites throughout Uganda

Knowledge of the baseline malaria transmission in a given environment is important to guide malaria control interventions. However, in Uganda, recent information on malaria transmission intensity is lacking. Therefore, a 1-year entomological study was conducted in seven ecologically different sites throughout the country to assess spatial and temporal patterns in malaria transmission intensity. Anopheles gambiae sensu stricto was the main vector in five of the seven study sites, and An. funestus was the most important vector in the two other sites. In a peri-urban village, An. arabiensis contributed substantially to malaria transmission. Clear differences in annual entomological inoculation rates (AEIR) were observed between the study sites, ranging from 4 infective bites per person per year in the southwestern part of the country to >1,500 infective bites per person per year in a swampy area near the Nile River. Between villages with parasite prevalences of >or= 80% in children between 1 and 9 years old, a 4-fold difference in AEIR was observed. Based on the observed behavior of the vectors, insecticide-treated bed nets will be highly effective in controlling malaria. However, in the high transmission areas, additional measures will be needed to reduce the malaria burden to acceptable levels