Classification of clinical falciparum malaria and its use for the evaluation of chemosuppression in children under six years of age in Liberia, west Africa

Abstract

The possible role of malaria as cause of morbidity was assessed during one year in 262 children aged 6 months to 6 years living in two villages in a rural area of Liberia. The study population was followed by weekly clinics and three-monthly surveys and the children were randomly allocated to receive either chloroquine or placebo every 3 weeks. The morbidity of the children was evaluated by criteria based on the history and the clinical condition into four different stages, in order to describe the probability that an observed clinical event could be attributed to malaria infection, based on the presence of detectable parasites in the blood, the history the previous week, and the clinical status of the child. The level of anaemia, splenomegaly and measured body temperature supported that malaria was the major contributor to the overall morbidity observed. Based on the stage classification of clinical illness, children were classified as having 'possible clinical malaria' or 'probable clinical malaria'. Malaria appeared to be an important cause of febrile episodes during both dry and rainy seasons. During the rainy season more than 60% of the children experienced at least one clinical malaria episode, and during the dry season more than 50% of the children experienced at least one clinical attack of malaria. Children receiving chemosuppression had overall fewer clinical malaria attacks, and the effect of the chemosuppression was most pronounced in the dry season, the odds ratio comparing children receiving regular chemosuppression with children receiving presumptive treatment only was estimated to 0.39 (0.25-0.62).