Effect of missed mass drug administration on filarial infection in Malindi Sub-County, Kenya

Abstract

In 1997 Lymphatic Filariasis was identified as one of the Neglected Tropical Diseases that could be eliminated. The Global Program to Eliminate Lymphatic Filariasis, through national programs, depends on mass drug administration (MDA) of antifilarial and antihelminthic drugs to over 80% of the poputalion at-risk for a period of 4 – 6 years to interrupt transmission of the disease and control morbidity caused by LF. National programs are responsible for the distribution, control and evalatuion of MDAs. In Kenya, MDA was initiated in 2002 and MDA administered in 2002, 2003, 2005 and 2008. Parasitologic surveys were conducted in eight sentinel communities in Malindi sub-County after four annual MDAs with 6mg/kg of diethylcarbamazine in combination with 400mg albendazole. MDA was not administered to the targeted at risk-population in 2004, 2006 and 2007 due to insufficient funding. Analysis of Variance and Kruskal-Wallis tests were employed to determine quantitative differences in the study communities. The McNemars and Wilcoxon signed ranks test were used to test for the change in microfilaremia and antigenemia among the participants using paired data collection before and after the MDA at α=0.05. At baseline, 1447 participants were tested using the Immunochromatographic card test and night blood specimens were collected from all ICT positive participants. Prevalence rates were compared using a Chi-square test. Antigen prevalence among the communities ranged from 34.4% in 2002, 26.2% in 2003, 18.7% in 2004, 14.0% in 2007 and 11.4% in 2009 respectively, while the microfilaremia prevalence’s measured 20.9% in 2002, 10.5% in 2003, 7.1% in 2004, 1.9% in 2007 and 0.9% in 2009. By 2009, after four rounds of treatment, the number of mf positive individuals were 10 compared to the 297 in 2002 was statistically significant (p < 0.001). The mean value for the microfilaria count among the eight communities was at a steady decrease from 43.6 in 2002 to a 0.1 in 2009. Despite the missing of two rounds of treatment, there was a general decrease in the overall microfilaremia and antigenemia over time but no interruption of transmission. There is need for evaluation and further surveillance. There may also be need to extend the 4 – 6 year recommended period of mass treatment.