Malaria in Zimbabwe: comparisons of IFAT levels, parasite and spleen rates among high, medium and lower altitude areas and between dry and rainy seasons.

OBJECTIVES

To study the extent of malaria prevalence among children at various elevations above sea level and in children during the dry and rainy seasons in Zimbabwe.

DESIGN

Cross sectional.

SETTING

Primary and secondary schools.

SUBJECTS

The number of children (aged about eight years in Grade Three and 13 years in Form One) examined in November 1992 was 103 in Chitungwiza (above 1,200 m), 94 in Gokwe (900 to 1,200 m) and 96 in Sasame (under 900 m). In April 1993 it was 86 in Chitungwiza, 78 in Gokwe and 81 in Sasame.

MAIN OUTCOME MEASURE

Indirect Fluorescent Antibody Test (IFAT) levels, parasite and spleen rates.

RESULTS

No splenomegaly was detected in children in schools above 900 m. While no parasitaemia was detected in children in schools above 1200 m, one (0.6%, 95% CI to -0.6 to 1.7) child and 37 (20.9%, 95% CI 14.9 to 26.9) children in schools between 900 and 1,200 m and below 900 m, respectively, had parasitaemia. The IFAT levels were lowest in children in areas above 1,200 m and increased significantly with decreasing altitude (x2 for linear trend 332, p < 0.001). The parasite rate in the rainy season (39.5%, 95% CI 28.9 to 50.2) was significantly (p < 0.001) higher than that in the dry season (5.2%, 95% CI 0.8 to 9.7). No significant differences in the IFAT levels (p = 0.208) and in the spleen rates (p = 0.180) were observed between the dry and rainy seasons. Sixty five percent of all children in schools above 1,200 m visiting rural areas used no protective measures against malaria. All children in schools under 900 m reported that their homes were sprayed, but very few other prophylactic measures (seven children used antimalarial drugs and 15 children used a net) were reported.

CONCLUSIONS

Malaria acquisition is uncommon above 900 m and the people in these areas are highly vulnerable to malaria.