Malaria and urbanization in Central Africa: the example of Brazzaville

Abstract

The current incidence of pernicious attacks and of mortality due to malaria were studied in Brazzaville. The results of this study, which concerned all the medical units of the town, were analysed in terms of previous studies on the epidemiology of malaria transmission in the various districts of the town. It was estimated that the annual incidence of pernicious attacks in children in Brazzaville is 1.15 per thousand between 0 and 4 years, 0.25 per thousand between 5 and 9 years and 0.05 per thousand between 10 and 14 years. The annual mortality due to malaria was estimated at 0.43 per thousand between 0 and 4 years and 0.08 per thousand between 5 and 9 years. These values are about 30 times lower than those expected from the results of previous studies of the mortality due to malaria in intertropical Africa. Whereas considerable differences in intensity of malaria transmission exist in the different districts of Brazzaville, the incidence of pernicious attacks and the resulting mortality are remarkably unvarying whatever the level of transmission. In particular, similar results were observed for the sector Mfilou-Ngamaba-Ngangouoni, where malaria is holoendemic with over 100 infective bites per person per year and a parasite rate of 80.95% in schoolchildren, and the central sector of Poto-Poto-Ouenze-Moungali, where malaria is hypoendemic with less than one infective bite per person every three years and a parasite rate of less than 4% in schoolchildren. These results are discussed in terms of previous observations in urban and surrounding rural areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic polymorphism of merozoite surface protein 2 and prevalence of K76T pfcrt mutation in Plasmodium falciparum field isolates from Congolese children with asymptomatic infections

“…These semi-urban divisions with about 6,000 inhabitants are located in the southern part of Brazzaville along the Congo River where malaria is transmitted throughout the year [12]. Plasmodium falciparum is the main plasmodial species and Anopheles gambiae the main mosquito vector.…”

“…Makélékélé is an administrative division in the south-eastern part of Brazzaville (Republic of Congo), and has been well characterized as a highly endemic area with perennial malaria transmission [11,12]. However, there is a paucity of information on the genetic diversity of P. falciparum populations.…”

Plasmodium falciparum: Differential Selection of Drug Resistance Alleles in Contiguous Urban and Peri-Urban Areas of Brazzaville, Republic of Congo

“…The urban and peri-urban districts from which patients were recruited are in very close proximity to each other, in places separated by only a few hundred meters, and the parasitological, epidemiological and entomological differences between them were previously described in detail by Trape et al (1987) [35], [37], [38], [39], [40]. The urban areas are characterized by low malaria transmission rates (2–12 infective mosquito bites per person per year [37]) and meso-endemicity (parasite prevalences of ∼39%, as determined by active case detection of school children within Bacongo in 1984 [37], and the peri-urban areas by high transmission rates (∼50 infective mosquito bites per person per year [40]) and hyper-endemicity (parasite prevalences of >80%, as determined by active case detection of school children resident in the peri-urban area of Makélékélé [39]).…”

Measuring Changes in Plasmodium falciparum Transmission

“…In mosquitoes, the effective contact rate with humans and factors influencing the susceptibility of mosquitoes to malaria infection determine κ. The susceptibility of anophelines to malaria infection differs between mosquito strains as a result of differences in mosquito innate immunity (Blandin et al, 2004, Molina-Cruz et al, 2012, Smith et al, 2004, Trape et al, 1987). and midgut microbiota (Cirimotich et al, 2011).…”

“…However at high transmission levels, incidence does not exceed that observed at intermediate transmission levels, partly due to acquired immunity and multiple infections (Ghani et al, 2009, Trape and Rogier, 1996). Therefore as transmission falls, a threshold must be crossed before a significant reduction in cases and hospital admissions is observed (Smith et al, 2004, Trape et al, 1987). Incidence estimated using hospital admissions will be unreliable if over-diagnosis leads to an overestimation of the number of cases presenting to health facilities, and cases in the community are missed.…”