Malaria associated severe
anemia in children is the most important complication of Plasmodium falciparum
infection in sub-Saharan Africa. To evaluate
anemia and
malaria in an area with recurrent
malaria epidemics in the western highlands of Kenya, we conducted cross-sectional surveys in four "lowland" (1440-1660 m) and two "highland" (1960 and 2040 m) villages in 2002. Among 1314 subjects randomly selected from all age groups, the overall prevalence of
anemia (
hemoglobin, Hb < 11 g/dl) was 14% and P. falciparum
infection 17%. In children < or =5 years,
anemia prevalence ranged from 57% at 1440 m to 11% at 2040 m and correlated with altitude (r = -0.88, P < 0.05). Similarly, P. falciparum prevalence ranged from 31 to 0% and correlated with altitude (r = -0.93, P < 0.01).
Malnutrition defined by a body mass index <15th percentile characterized 39% of the population and the hookworm prevalence was 3.9%. In the lowland villages,
anemia was most common in children < or =5 years of age (34%) followed by women of childbearing age (16%). A similar pattern was also observed in the highland villages. In these vulnerable populations,
hemoglobin concentration was significantly associated with
malaria infection, but not with
malnutrition or hookworm infestation and comparisons of
anemia prevalence between highland and lowland villages revealed that two-thirds of
anemia could be attributed to
malaria infection. The prevalence of severe
anemia (Hb < 8 g/dl) was 1.5%; of these, 90% resided in lowland villages, 70% were under-fives, while 20% were women of childbearing age. In severely anemic subjects, the Hb concentration decreased further with
malnutrition (P < 0.05).
Anemia was more prevalent in the lowland villages characterized by high prevalence of P. falciparum
infection. We conclude that
malaria may also be the main cause of
anemia in the highland fringe areas of sub-Saharan Africa. Measures that reduce the prevalence of
malaria will consequently reduce
anemia in both, young children and adult women and the need for
blood transfusions associated with the risk of HIV-transmission.