New insights into the biology of filarial infections

Recent successes in the control of lymphatic filariasis and onchocerciasis need continuing research in order to sustain the achievements and to develop further tools to tackle the new questions that arise when only reduced infection prevalences prevail. In this regard, in a symposium held at the Xth European Multicolloquium of Parasitology (August 2008, Paris) questions such as the impact of filarial immunosuppression, and its lack following filarial control, on the outcome of co-infections were addressed, as were new approaches to treatment with promising drugs such as moxidectin or the antibiotic chemotherapy against Wolbachia endosymbionts in filariae. In particular, longer treatment courses of doxycycline could be carried out by community-directed treatment at high coverage, thus potentially allowing its use in restricted areas with suboptimal responses to ivermectin against onchocerciasis, or in areas with co-infection by loiasis where onchocerciasis or lymphatic filariasis need to be controlled. New, more potent drugs, or eventually vaccines, will be of importance because in many vector-filarial parasite relationships worldwide, transmission efficacy increases with low numbers of ingested microfilariae, and since ivermectin may render treated hosts more susceptible to new infection.