Declining malaria parasite prevalence and trends of asymptomatic parasitaemia in a seasonal transmission setting in north-western Burkina Faso between 2000 and 2009–2012

Abstract

BackgroundMalaria transmission was reported to have declined in some East African countries. However, a comparable trend has not been confirmed for West Africa. This study aims to assess the dynamics of parasite prevalence and malaria species distribution over time in an area of highly seasonal transmission in Burkina Faso. The aim was also to compare frequency of asymptomatic parasitaemia between wet and dry season by parasite density status and age group.MethodsDuring the years 2009–2012, six cross-sectional studies were performed in the rural village Bourasso in the Nouna Health District in north-west Burkina Faso. In subsequent rainy and dry seasons blood samples were collected to assess the parasite prevalence, species, density and clinical parameters. In total, 1,767 children and adults were examined and compared to a baseline collected in 2000.ResultsThe microscopical parasite prevalence (mainly P. falciparum) measured over the rainy seasons decreased significantly from 78.9% (2000) to 58.4%, 55.9% and 49.3%, respectively (2009–2011; p <0.001). The frequency of Plasmodium malariae infections (mono- and co-infections) decreased parallel to the overall parasite prevalence from 13.4% in 2000 to 2.1%, 4.1% and 4.7% in 2009–2011 (p <0.001). Comparing parasite-positive subjects from the rainy season versus dry season, the risk of fever was significantly reduced in the dry season adjusting for parasite density (grouped) and age group.ConclusionsThe results of this study suggest a decline of malaria transmission over the rainy seasons between 2000 and 2009–2011 in the region of Nouna, Burkina Faso. The decreased transmission intensity was associated with lower prevalence of P. malariae infections (both mono-infections and co-infections). Asymptomatic parasitaemia was more frequent in the dry season even adjusting for parasite density and age group in a multivariate regression. Possible reasons for this observation include the existence of less pathogenic Plasmodium falciparum genotypes prevailing in the dry season, or the effect of a reduced incidence density during the dry season.

Impact of long-lasting insecticidal nets on prevalence of subclinical malaria among children in the presence of pyrethroid resistance in Anopheles culicifacies in Central India

“…However, on the contrary, no major difference in age and parasite density among subclinical and total malaria cases was observed in the present study. Asymptomatic parasitemia is usually higher in the dry season as compared to the rainy season 35 and the presence of gametocyte density in the dry season probably acts as a source of infection in the next cycle of malaria transmission 36 . In the Keshkal sub district, malaria transmission is seasonal and malaria incidence usually peaks in the post monsoon season.…”

Substantial increase in mutations in the genes pfdhfr and pfdhps puts sulphadoxine–pyrimethamine‐based intermittent preventive treatment for malaria at risk in Burkina Faso

“…The parasite prevalence was 55.4% at the end of the rainy season (October 2009–2011) and 30.7% at the end of the dry season (April 2010–2012) (Geiger et al . ).…”

“…The study design and the demographics are described in more detail elsewhere (Geiger et al . ). In short, a random list of all households was generated using the data from the Health and Demographic Surveillance System (HDSS), and all household members were invited to participate in the study until the target number of participants per survey was achieved (inclusion criterion above 6 months of age).…”

Plasmodium species occurrence, temporal distribution and interaction in a child-aged population in rural Burkina Faso

“…In fact, only a few studies even report the prevalence of the last two species across human population [5,19-21]. Most of these studies were done in the past decade before the scale up of interventions such as the availability of artemisinin combination therapy (ACT) or the mass distribution of insecticide-treated bed nets (ITNs).…”