Mass Drug Administration
Over the duration of the program, the WHO standard of tablet-based mass drug administration (MDA) has been our principal tool for halting LF transmission in Haiti. We use two drugs in concert, both proven to be safe and effective microfilaricides: diethylcarbamazine (DEC) at a dosage of 6 mg/kg and albendazole at a constant dosage of 400 mg. DEC is purchased from WHO-recommended foreign suppliers, while albendazole is donated by GlaxoSmithKline. These drugs primarily destroy juvenile LF worms (microfilariae), but studies using ultrasound and biopsies of post-treatment nodules indicate that when given in single doses of 6 mg/kg or more, DEC also kills a proportion of adult worms. Albendazole is effective in ridding the body of other helminths, such as hookworms, that can cause deadly anemia. Combining lymphatic filariasis eradication efforts with treatment for intestinal helminths dramatically increases the benefit to treated populations and bolsters community support for the MDA.
Due to the fact that the adult female LF worms can live in the body up to eight years, in order to eliminate the disease, drugs must be administered annually to destroy progeny worms until the females die naturally. However, since the circulating juvenile worms are the form of LF parasite available for mosquitoes to transmit, killing these worms halts transmission of the infection, so each treatment has a significant effect. In our pilot MDA in the Leogane commune in 2000, we treated 109,000 people, 70% of the at-risk population, and subsequently detected a 56% reduction in microfilaremia prevalence.
LF is truly a national disease in Haiti, present in 118 of 140 communes, making 84% of the country a potential risk zone. Current WHO models suggest that drug coverage of approximately 80% of the eligible population in endemic areas is needed to stop transmission and eliminate the disease. Full country coverage became a reality in 2012. The entire population of Haiti has had the opportunity to participate in MDAs annually since 2012. MDA has been halted in some communes due to low prevalence. The use of co-fortified salt can be helpful in maintaining the prevalence rates below the infection transmission threshold. In 2014, 71% of the country’s population received life-changing drugs through Mass Drug Administration. Recent research reveals that adding salt-delivered coverage in highly endemic regions must be a priority to effectively halt transmission and address areas of non-compliance. With continued support and resources, we can continue to use our momentum to permanently lift the scourge of this disease from Haiti.