[Show abstract][Hide abstract] ABSTRACT: Plasmodium ovale is a common malaria parasite in Africa, but the epidemiology of P. ovale malaria is poorly known. Exposure to malaria, parasitemia, and morbidity were monitored for 6 years among the residents of a village in Senegal. The relationship between the level of P. ovale parasitemia and fever risk were analyzed, and diagnostic criteria for clinical P. ovale malaria were established. Then the relationships between the occurrence of P. ovale clinical malaria and a series of entomological, epidemiological, and genetic factors were investigated. There was no increased risk of fever when the P. ovale parasite count was <800 parasites/microL of blood. Of 6621 episodes of illness, 114 (1.7%) were attributable to P. ovale. Although most clinical episodes occurred during early childhood, a low incidence of the disease persisted among adults. Sickle cell trait carriers had increased susceptibility to the disease.
The Journal of Infectious Diseases 10/2002; 186(5):690-5. DOI:10.1086/342395 · 6.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: During 4 months, from June to September 1990, the population of Dielmo village, Senegal, an area of intense and perennial malaria transmission, was enrolled in a follow-up study including daily clinical surveillance and bi-weekly malaria parasitaemia monitoring. Thick blood film examinations indicated that 48.5% of children (49/101) and 32.4% of adults (34/105) were infected at least once by Plasmodium ovale during the study period; 148 distinct episodes of patent parasitaemia were observed, with estimated maximum durations of 3-115 d. The mean duration at first decreased significantly with age, from 11.4 d in children under 5 years old to 4.2 d in adults aged 40-59 years, but then increased in older adults to 7.0 d. In all age groups, most infections were asymptomatic. Only high parasitaemias were significantly associated with fever; 3 clinical malaria attacks due to P. ovale were seen during the study period.
Transactions of the Royal Society of Tropical Medicine and Hygiene 09/1998; 92(5):522-5. DOI:10.1016/S0035-9203(98)90900-2 · 1.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We conducted a three-year entomologic study in Dielmo, a village of 250 inhabitants in a holoendemic area for malaria in Senegal. Anophelines were captured on human bait and by pyrethrum spray collections. The mosquitoes belonging to the Anopheles gambiae complex were identified using the polymerase chain reaction. Malaria vectors captured were An. funestus, An. arabiensis, and An. gambiae. Anopheles funestus was the most abundant mosquito captured the first year, An. arabiensis in the following years. The annual entomologic inoculation rates calculated by enzyme-linked immunosorbent assay were 238, 89, and 150 for the first, second, and third years, respectively. Each year there was a peak of transmission at the end of the rainy season, but transmission occurred year round. The heterogeneity of transmission was found at four different levels: 1) the relative vector proportion according to the place and method of capture, 2) the human biting rate and relative proportion of vectors by month and year, 3) the infection rate of each vector by year, and 4) the number of infected bites for all vectors, and for each species, for the year. Our data show that even in areas of intense and perennial transmission, there exist large longitudinal variations and strong heterogeneity in entomologic parameters of malaria transmission. It is important to take these into account for the study of the variations in clinical and biological parameters of human malaria, and to evaluate this relationship, a very thorough investigation of transmission is necessary.
The American journal of tropical medicine and hygiene 04/1997; 56(3):247-53. · 2.70 Impact Factor