Year-to-Year Variation in the Age-Specific Incidence of Clinical Malaria in Two Potential Vaccine Testing Sites in Mali With Different Levels of Malaria Transmission Intensity

Abstract

To explore the feasibility of field sites for malaria vaccine trials, we conducted a prospective study of clinical malaria incidence during two consecutive transmission seasons in children and young adults living in two areas of Mali with different entomologic inoculation rates (EIRs). Approximately 200 subjects (3 months to 2 years of age) were enrolled per site and followed weekly. Malaria smears were performed monthly in all participants and when symptoms or signs of malaria were present. In Sotuba (annual EIR < 15 infective bites per person), the incidence of clinical malaria was comparable across all age groups but varied significantly between the 2 years. In contrast, in Donéguébougou (annual EIR > 100 infective bites per person), incidence rates decreased significantly with increasing age but remained stable between years. Our results suggest that, although the age distribution of clinical malaria depends on transmission intensity, the total burden of disease may be similar or higher in settings of low transmission.

Development of Clinical Immunity to Malaria in Highland Areas of Low and Unstable Transmission

“…12,14,[23][24][25][26] Early studies in western Uganda suggested that at high altitudes, the parasite rate in persons less than 20 years of age old was nearly twice as high as in those persons 20 years of age.…”

Spatial Patterns of Plasmodium falciparum Clinical Incidence, Asymptomatic Parasite Carriage and Anopheles Density in Two Villages in Mali

“…Malaria incidence in 2000 was 0.8 in 0-5 year olds and 1.3 in 6-10 year olds. 17 Kollé is situated 55 km south of Bamako and is a typical rural Savannah village with a population of ∼2,500 (Figure 1; Sotuba and 176 mm in Kollé, during the subsequent dry season hardly any rain fell with on average 5 mm and 3 mm, respectively.…”

In Vivo Efficacy and Parasite Clearance of Artesunate + Sulfadoxine–Pyrimethamine Versus Artemether–Lumefantrine in Mali

“…The entomological inoculation rate is 4-12 infective bites per person per year. 17 Kolle is a village of 2,500 inhabitants located 57 km southwest of Bamako in the Sudan savanna area and 9 km away from the Niger River. The entomological inoculation rate is nearly identical to the level of Banambani.…”

“…The entomological inoculation rate is 137-167 infective bites per person per year. 17 Sotuba is a peri-urban area of Bamako with 6,472 inhabitants. The entomological inoculation rate is 4-12 infective bites per person per year.…”

“…The entomological inoculation rate is nearly identical to the level of Banambani. 17 Study volunteers were recruited between October 2010 and January 2011 in Sotuba and Kolle and between January 2013 and January 2014 in Banambani.…”