Vector control complements mass drug administration against bancroftian filariasis in Tirukoilur, India

Abstract

Objective To determine the role of vector control in further decreasing the transmission of bancroftian filariasis achieved by mass drug administration and the long-term impact on filariometric indices. Methods Three rounds of annual mass drug administration, with diethylcarbamazine and ivermectin, were complemented by vector control (mainly using polystyrene beads) in villages of Tirukoilur, south India, during 1995-99. Subsequently, drug administration is being carried out with diethylcarbamazine and albendazole or diethylcarbamazine alone. We evaluated the impact of mass drug administration used alone or in conjunction with vector control (from 1995 to 2005) on vector transmission indices (such as transmission intensity index, monthly biting rate, monthly transmission potential and annual transmission potential). We analysed data on filarial infection in the community to estimate the prevalence of microfilaraemia and antigenaemia using c² analysis and Fisher's exact test. Findings Vector density greatly decreased in villages where vector control was used as an adjunct to mass drug administration and almost no infective mosquitoes were found in the small numbers still remaining. Filarial antigenaemia was low and continued to decrease significantly in the age group 15-25 years in villages receiving mass drug administration with vector control in contrast to villages receiving only mass drug administration. Conclusion The gains of mass drug administration were sustained only with the integration of vector control measures. We advocate the incorporation of vector control in the Global Programme to Eliminate Lymphatic Filariasis as it can potentially decrease the time required for eliminating lymphatic filariasis. Une traduction en français de ce résumé figure à la fin de l'article. Al final del artículo se facilita una traducción al español.

Role of Vector Control in the Global Program to Eliminate Lymphatic Filariasis

“…On the other hand, including vector control would essentially, by reducing the hysteresis loop, increase the re-emergence Mf prevalence threshold. This result supports empirical evidence (73) that vector control will be crucial to the long-term sustenance of parasite elimination from treated endemic communities.…”

“…Vector control continued in the three villages where it was previously carried out. Analysis in 2006 (73) showed that vector density decreased significantly in villages where vector control was used as an adjunct to MDA, and no infective mosquitoes were found in the small numbers caught during [2003][2004][2005] (82). In the areas where vector control alone interrupted filariasis, facilitation was the vectorparasite relationship involved (72,79).…”

Insecticidal Bed Nets and Filariasis Transmission in Papua New Guinea

“…35,36 However, our study quantifies the effect of the most widely implemented vector-control measure, the use of insecticide-treated bed nets. Although vector control is not currently a part of the global strategy to eliminate lymphatic filariasis, universal bed-net distribution is now used widely for malaria control-and-elimination efforts in Papua New Guinea and sub-Saharan Africa.…”

Adult Density of Culex quinquefasciatus Say, Filarial Vector in Thapa Gaun, Jhaukhel and Lama Tole, Nagarkot VDC, Bhaktapur District

“…Lymphatic filariasis (LF) is a major cause of acute and chronic morbidity among humans causing socio economic problems in the tropical and sub-tropical areas of Asia, Africa, the Western Pacific and some parts of the Americas with an increasing prevalence worldwide (WHO 1992, Sunish et al 2007. The uncontrolled population growth, particularly in developing countries of Asia, Africa and Latin America has caused the deterioration of the ecology and environment.…”