Soil-transmitted helminths (STHs) are a group of parasitic worms that infect millions of children in sub-tropical and tropical countries, resulting in malnutrition, growth stunting, intellectual retardation and cognitive deficits. To control the morbidity due to these worms, school-based deworming programs are implemented, in which anthelminthic drugs are administered to children without prior diagnosis. The continued fight against these worms is aided by the London Declaration on Negelected Tropical Diseases, which helps sustain and expand global drug donation program, resulting in an unprecedended growth of deworming programs. to illustrate, in the last four years the coverage of drug administration has doubled from 30 to 60%, and ongoing global efforts are made to ultimately reach the milestone of 75% by 2020.
While the laudable long-term aim is to eliminate STHs as a public health problem by 2020, and to eventually declare targeted geographical areas free from infections, this high degree of drug pressure makes deworming programs vulnerable to the development of anthelmintic resistance because of the following reasons:
1. The programs only rely on one drug
Current deworming programs rely on either albendazole or mebendazole, both of which share a common mode of action. Therefore, the development of anthelmintic resistance against one drug will most likely be accompanied by poor anthelmintic drug efficacy of the other drug.
2. Suboptimal doses
The drugs are currently administered in single doses. Although this practice is operationally justified, it never achieves 100% efficacy. The wide distribution of suboptimal doses over a significant period of time may further encourage the development of anthelmintic resistance in parasite populations.
3. Unavailability of alternative drugs
There is a paucity of licensed anthelmintic drugs that are licensed for the treatment of worm infections in humans. If anthelmintic resistance against albendazole or mebendazole were to eventually emerge and spread, drug-based control of STHs would therefore be even more limited than is presently the case, with few acceptable alternative options.