Seasonal variations in Malaria transmission in a peri-urban area of the Cameroon: Entomological, Parasitological and Clinical investigations

A cross-sectional transversal study on the malaria transmission was carry out in the Mangoum village, situated in the Mountain western region of Cameroon in October 2005 and May 2006. The parasite and spleen rates, biting habits and entomological inoculation rate of parasites and Anopheles species were investigated during dry and rainy seasons. Mosquitoes were collected by night landing catches on volunteers and indoor pyrethrum spray catches. Members of the An. gambiae complex and molecular forms were identified using PCR method. Infection intensity was determined by counting the number of infected red blood cells against 200 leucocytes. A total of 1195 Anopheles was collected, 183 and 1012 respectively in the dry and rainy seasons. Two Anopheles species were identified; An. gambiae s.l. and Anopheles funestus. An. gambiae s.s. was the only member of the An. gambiae complex found and the main malaria vector in this region. The sporozoite rate of An. gambiae was higher in the rainy season (9%). The average inoculation rate was 90 infective bites per man per year. A total of 699 children were examined. Two parasites species were identified: Plasmodium falciparum and P. malariae. The mean parasite rate was 41, 3%. In the age range of 2–9 years, the parasite rate were respectively 49% in the dry season and 34, 7% in the rainy season. The mean spleen rate of the age range (2–9 years) was 24, 7% with 26, 7% in rainy season and 22, 3% in the dry season.