Lymphatic Filariasis (LF) in Ivory Coast

Overview

The recommended treatment for elimination of LF in sub-Saharan Africa is annual mass drug administration (MDA) with single dose Albendazole (ALB) plus Ivermectin (IVM) given for at least 5-7 years. However, in areas where LF is co-endemic with a related filarial parasite, Loa loa, co-infection with L. loa represents a serious barrier to LF elimination because IVM used in LF MDA can result in severe reactions and even death in individuals with high microfilaria (mf) levels of L. loa. Screening for heavy L. loa infection is problematic. To overcome this problem, monotherapy with ALB is possible, since this drug has little or no effect on circulating mf and thus would not cause adverse effects in people with heavy L. loa infections. Moreover ALB has been shown to have embryostatic or embryocidal effects in female adult worms resulting in decreased mf levels with time as natural attrition of circulating mf occurs. Thus this open-label, randomized clinical trial will examine treatment with ALB monotherapy administered twice per year over a period of 3 years with the primary endpoint being the proportion of individuals with total clearance of mf at 36 months and Alere antigen test negativity (a more sensitive circulating antigen test of filarial infection). Two of the treatment arms will include ALB at two different doses, 400mg or 800mg (fixed dose twice yearly) as compared to standard treatment of ALB (400 mg) plus IVM (150-200 µg/kg) administered annually. Observations from an ongoing clinical trial in Papua New Guinea suggest that a single dose of triple therapy with ALB + IVM + DEC may be highly effective in sterilizing adult female worms. Therefore to confirm and expand these important preliminary observations in a different population, a fourth arm will be included in the current clinical trial in which subjects will receive all three drugs. The clinical trial will be performed in a region of Cote d'Ivoire where onchocerciasis and loiasis are not endemic.

Lymphatic filariasis (LF) is a deforming and disabling infectious disease that causes elephantiasis and genital deformity (especially hydroceles). The infection affects some 120 million people in 81 countries in tropical and subtropical regions with well over 1 billion people at risk of acquiring the disease. LF is caused by Wuchereria bancrofti and Brugia spp. (B. malayi and B. timori), nematode parasites that are transmitted by mosquitoes. The World Health Organization (WHO) developed a plan for LF elimination that is based on using novel approaches to rapidly map endemic areas and 4 to 6 annual rounds of MDA with antifilarial medication. A recent summary from WHO reported that more than 4 billion doses of MDA were distributed between 2000 and 2012. Thus, the Global Program to Eliminate Lymphatic Filariasis (GPELF) is the largest infectious disease intervention program attempted to date based on MDA (Ottesen, Hooper et al. 2008). MDA has worked better in some areas than others. There are a number of challenges faced by GPELF. These include (among others) inability to conduct MDA programs in areas of Africa where L. loa is coendemic because of the unacceptable risk of Serious Adverse Events (SAE's) with IVM in persons with heavy L. loa infections (Hoerauf, Pfarr et al. 2011), the limited macrofilaricidal activity of current MDA regimens (especially ALB + IVM) that necessitate repeated annual rounds of MDA (Geary and Mackenzie , Hoerauf, Pfarr et al. 2011), and the difficulty of achieving high compliance rates for MDA over a period of years (Hoerauf, Pfarr et al. 2011). It is clear that new (or reformulated) drugs and/or dosing schedules for LF MDA have the potential to greatly improve the number of countries that will successfully eliminate LF by the WHO target date of 2020. This is especially important for areas of Central and West Africa where MDA has not been implemented because of the possible co-infection with L. loa and logistical and financial challenges to delivering annual doses of IVM + ALB MDA to millions of individuals over multiple years.