Risk factors of malaria in the fringes of an evergreen monsoon forest of Arunachal Pradesh

Background, The forested hilly and foothill regions of north-east India are highly endemic for malaria and have a distinct epidemiological pattern. Ne arly half the reported cases of malaria are from these areas. A knowledge o f the risk factors in this eco-geographic entity may be helpful in formulat ing a specific control strategy. Hence, we conducted a community-based epid emiological study in a hilly, forested terrain of Arunachal Pradesh and exa mined different socio-demographic factors to identify those predisposing to the occurrence of malaria, especially Plasmodium falciparum infection, in such areas. Methods. Four epidemiological surveys were carried out during 1997 in 7 vil lages located at the fringes of a forest (total population: 1177) under Nom pong Primary Health Centre of Changlang district, Arunachal Pradesh. Blood slides were collected randomly from the inhabitants, irrespective of their fever status, ensuring at least 50% coverage. One hundred and thirty-four m icroscopically confirmed Plasmodium falciparum cases were identified and 53 6 controls were randomly selected from the list of uninfected inhabitants. Relevant socio-demographic information was obtained from both cases and con trols. The data were analysed by simple and multiple logistic regression us ing the unconditional maximum likelihood method. Results. Factors which were found to be strongly associated with Plasmodium falciparum malaria on univariate analysis were age, ethnicity, village of residence and accessibility to the nearest health care facility. However, i n multiple regression analysis, after controlling for the effects of confou nding variables, the only risk factor identified was accessibility to the n earest health care facility (adjusted odds ratio: 4.5; 95% CI: 1.8-11.3; p < 0.0001 for those at a distance of 2-8 km and adjusted odds ratio: 11.1; 9 5% CI: 4.1-30.0; p<0.0001 for those > 8 km away). Conclusion. Distance, particularly non-motorable distance, from the place o f residence to the nearest health care facility was a major risk factor for malaria in this hilly forested terrain. This indicates the need for specia l efforts to detect cases early and institute treatment promptly in such ar eas of the north-eastern region, so as to reduce the morbidity and mortalit y of malaria.