Incidence of tick-borne relapsing fever in west Africa: longitudinal study.

Background: The ongoing drought in sub-Saharan countries has led to the colonisation of west African Savanna by Ornithodoros sonrai; this tick acts as a vector for Borrelia crocidurae, which causes tick-borne relapsing fever (TBRF). Our aim was to ascertain the incidence of TBRF in west Africa.

Methods: From 1990 to 2003, we monitored the incidence of TBRF in Dielmo, Senegal, by daily clinical surveillance and by blood testing of individuals with a fever.

The Dielmo project: a longitudinal study of natural malaria infection and the mechanisms of protective immunity in a community living in a holoendemic area of Senegal.

The Dielmo project, initiated in 1990, consisted of long-term investigations on host-parasite relationships and the mechanisms of protective immunity in the 247 residents of a Senegalese village in which malaria is holoendemic. Anopheles gambiae s.l.

Malaria morbidity among children exposed to low seasonal transmission in Dakar, Senegal and its implications for malaria control in tropical Africa.

To measure morbidity due to malaria and to study its relationship with transmission and parasitemia in children living in an area of low malaria endemicity, a cohort study of 343 schoolchildren was undertaken during a one-year period in Dakar, Senegal. From parallel investigations on transmission and the frequency of malaria as a cause for outpatient visits, three different seasons were chosen for close monitoring of different clinical parasitologic, and sero-immunologic parameters. The daily incidence rates of malaria parasitemia and primary attacks were at a maximum level during the high transmission season (0.

Vector density gradients and the epidemiology of urban malaria in Dakar, Senegal.

The dispersion of anopheline mosquitoes from their breeding places and its impact on malaria epidemiology has been investigated in Dakar, Senegal, where malaria is hypoendemic and almost exclusively transmitted by Anopheles arabiensis. Pyrethrum spray collections were carried out along a 910-meter area starting from a district bordering on a permanent marsh and continuing into the center of the city. According to the distance from the marsh, vector density (the number of An.

Tick-borne borreliosis in west Africa.

Reported cases of tick-borne relapsing fever due to the spirochaete Borrelia crocidurae are rare in West Africa, and few epidemiological data are available. To see how common relapsing fever is in Senegal thick blood smears from cases of fever of unknown origin and from randomly selected clinic outpatients from a rural dispensary were examined for Borrelia. The prevalence of Borrelia infections in small mammals was also assessed.