Altitude-dependent and -independent variations in Plasmodium falciparum prevalence in northeastern Tanzania

J Infect Dis. 2005 May 15;191(10):1589-98. doi: 10.1086/429669. Epub 2005 Apr 7.


Background: Effective malaria control requires information about intensity of transmission across large areas and populations. Estimates based on entomological factors lack precision and are not cost-effective to obtain. We tested altitude and rainfall measurements as correlates of transmission intensity in different ecological settings.

Methods: We conducted 2 cross-sectional surveys of approximately 12,000 people (1-45 years old) in 6 altitude transects (150-1800 m) in the Kilimanjaro and Tanga regions of Tanzania. Data were analyzed for associations with altitude and rainfall estimates by use of appropriate regression models.

Results: Plasmodium falciparum prevalence showed a negative relationship with altitude (19% and 21% decrease/100-m altitude increase, respectively, in children in Kilimanjaro and Tanga) and rainfall during the 3 months before the survey (46% decrease/100-mm rainfall increase in children in Kilimanjaro). Mean hemoglobin concentrations increased with altitude (0.05 and 0.09 g/dL/100-m altitude increase, respectively, in children in Kilimanjaro and Tanga) and rainfall (0.17 g/dL/100-mm rainfall increase in children and adults in Kilimanjaro).

Discussion: Altitude and rainfall were correlated with parasite prevalence and mean hemoglobin concentration; however, the relationship varied according to ecological setting. Climatological variables alone cannot predict malarial outcomes. Local variations in seasonality of malaria transmission--together with vector species composition, topography, host and parasite genetics, and socioeconomic factors--may influence malaria prevalence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Altitude*
  • Animals
  • Child
  • Child, Preschool
  • Cross-Sectional Studies
  • Female
  • Humans
  • Infant
  • Malaria, Falciparum / epidemiology*
  • Malaria, Falciparum / transmission
  • Male
  • Middle Aged
  • Rain
  • Tanzania / epidemiology