International Health 3 (2011) 182–187 Contents lists available at ScienceDirect International Health journa l h o me pag e: h ttp://www.elsevier.com/ locate/inhe Monitoring lymphatic filariasis control in Tanzania: effect of repeated mass drug administration on circulating filarial antigen prevalence in young schoolchildren Paul E. Simonsen a,* , Stephen M. Magesa b,1 , Yahya A. Derua b , Rwehumbiza T. Rwegoshora b , Mwelecele N. Malecela c , Erling M. Pedersen a a DBL – Centre for Health Research and Development, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 57, 1871 Frederiksberg C, Denmark b National Institute for Medical Research, Amani Medical Research Centre, P.O. Box 81, Muheza/Tanga, Tanzania c National Institute for Medical Research, Headquarters, P.O. Box 9653, Dar es Salaam, Tanzania a r t i c l e i n f o Article history: Received 5 November 2010 Received in revised form 6 March 2011 Accepted 30 June 2011 Available online 10 August 2011 Keywords: Lymphatic filariasis Mass drug administration Control monitoring Circulating filarial antigens Children Tanzania a b s t r a c t In most countries of Sub-Saharan Africa the control of lymphatic filariasis (LF) is based on annual mass drug administration (MDA) with a combination of ivermectin and albendazole, in order to interrupt transmission. We monitored the effect of four repeated MDAs with this combination, as implemented by the Tanzanian National Lymphatic Filariasis Elimination Programme (NLFEP), on the circulating filarial antigen (CFA) status of young schoolchildren. A new batch of Standard 1 pupils from 10 rural primary schools in Tanga Municipality were examined for CFA each year in September/October (691–848 children per survey; mean age of 7.5–8.1 years), from immediately before the first MDA until eight months after the fourth MDA. The overall pre-MDA prevalence of CFA was 25.2%. Only minor and non-significant change in prevalence was seen after the first two MDAs. However, this was followed by substantial and statistically significant decreases in subsequent surveys, and eight months after the fourth MDA the prevalence was only 6.4%. Continuous entomological surveillance in a village accommodating one of the schools showed progressive decrease in transmission right from the first MDA. The usefulness of screening young schoolchildren for CFA as a tool for monitoring the impact of MDA on LF transmission is discussed. © 2011 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved. 1. Introduction Lymphatic filariasis (LF), resulting from infection with the mosquito-borne filarial nematode Wuchereria bancrofti, is a disfiguring and disabling disease. 1 It is a cause of severe suffering and a socio-economic burden in endemic com- munities. The Global Programme to Eliminate Lymphatic Filariasis (GPELF) was established in 2000, with an anchor- age in the World Health Organization, to provide guidance * Corresponding author. Tel.: +45 35331415; fax: +45 35331433. E-mail address: pesi@life.ku.dk (P.E. Simonsen). 1 Present address: RTI International, P.O. Box 6201, Kigali, Rwanda. and support to national LF control programmes. 2–4 The principal intervention measure currently recommended by GPELF for LF control is annual mass drug administration (MDA) of two-drug combinations to endemic communities. The drugs are primarily microfilaricidal and MDAs rarely completely clear the W. bancrofti infection from the treated individuals. However, it is assumed that the reduction in the microfilarial load in the endemic population will lead to a simultaneous reduction – or even elimination – of trans- mission. Hence, the term ‘transmission control’ has been adopted for this strategy. In Tanzania, with an estimated 34 million people at risk of, and six million people affected by, LF a National Lymphatic Filariasis Elimination Programme (NLFEP) was 1876-3413/$ – see front matter © 2011 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.inhe.2011.06.009 Downloaded from https://academic.oup.com/inthealth/article/3/3/182/648362 by guest on 09 May 2023