Environmental factors as determinants of malaria risk. A descriptive study on the northern coast of Peru.
We conducted a series of studies on the northern Pacific coast of Peru to determine environmental risk factors for malaria. We report in this paper the results of both a descriptive study of incidence and a prevalence survey of malaria. Both studies showed that the area was at low risk for malaria. The malaria incidence rate was 40/1000 p.a. during the study period, and the prevalence of infection was 0.9% (95% CI: 0.4-1.7) before and 1.4% (95% CI: 0.8-2.2) after the high incidence period. However, the risk of malaria varied according to season, village and even house within a single village. Incidence rates increased from February (2.6/1000 p.a.) to May (12.9/1000 p.a.) and decreased during the second part of the year. Most of the cases were clustered in four villages that constituted only 21% of the total population of the area. Houses where multiple cases were recorded were often located near a source of water. Our observations suggested that environmental factors, and particularly the presence of water for irrigation around villages and houses, played a major role in determining the risk of malaria. These observations were extended through an entomological study and a case-control study, to be published elsewhere.
Guthmann
J P
JP
Infectious and Tropical Disease Department, Infectious Disease Epidemiology Unit, London School of Hygiene and Tropical Medicine, England. jguthmann@epicentre.msf.org
Llanos-Cuentas
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Palacios
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Hall
A J
AJ
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004777:Environment; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D016778:Malaria, Falciparum / Q000453:epidemiology*; D016780:Malaria, Vivax / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D010568:Peru / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D012621:Seasons