ESTIMATES OF MALARIA ATTRIBUTABLE FREACTION AMONG CHILDREN IN ONA ARA LOCAL GOVERNMENT AREA, OYO STATE

Abstract

Malaria remains a major public health problem particularly in the tropics and about 90% of malaria in Africa occur in young children who are more vulnerable than adults. Fever is one of the major symptoms of malaria; however, not all fever cases is a result of malaria. Therefore this study estimated the proportion of fever cases that can be attributed to malaria among children in south west Nigeria. The study period was from February 2011 to June 2011. Participants who have been residing in the community for six months or more who gave written or verbal informed consent were enrolled into the study. Records of all children (≤ 12yrs) eligible for the study were used for the analysis. Malaria attributable fraction (MAF) was estimated using 3 approaches: Classical method parametric regression method such as logistic regression model and Non parametric regression method such as local linear smoothing. The mean age of the respondents was 5.6±3.2 years. According to age group, the proportion of children with fever increased during the first 3 years of life and thereafter decreased but was not significant with age. The prevalence of Parasitemia also decreased with increasing age as those with age < 3years of age had the largest Parasitemia of 56.4% and those with age ≥ 10years had the lowest Parasitemia of 39.3%. The proportion of MAF obtained from the classical method was 0.2652(95% CI. 0.1784-0.3520), the logistic estimate for those with parasite density less than 1000μ1 was 0.0385 (95% CI:0.0105- 0.0665) and for those with parasite density ≥1000μ1 was 0.3215 (95% Cl, 0.2738- 0.3691 ). The non parametric estimate of the MAF obtained was 0.2447 (95% Cl, 0.1785- 0.3119) . The prevalence of malaria disease and fever during childhood remained high. The study observed that fever rates increases sharply for low exposures and also approaches 1 for high exposures, it also suggests a monotone pattern of the conditional probability of P(Y = 1/X = x). However, other causes of fever should be considered in the case of management of febrile illnesses during childhood. The logistic estimate for parasite density category of 2:1000μ1 gave the highest malaria attributable fraction and had the smallest Confidence interval followed by the local linear estimate. Therefore the logistic method is a better estimate while classical method behaved the worst.