Are the drugs working? The need to monitor deworming efficacy

3 February 2017

The World Health Organisation estimate that around 1.5 billion people are infected with soil transmitted helminths. To meet the London Declaration on NTDs target of controlling these parasitic worms by 2020 the global NTD community have sought to massively scale up deworming programmes. With the support of major drug donation programmes – by 2020 GSK alone will have donated 4.6billion tablets since 2000 - over the last four years thepercentage of infected people being treated by deworming programmes has doubled from 30% to 60% and is expected to reach 75%

There is however a risk of this strategy.  What happens if the drugs stop working? if the worms develop resistance to the anthelmintic drugs designed to kill them?

This resistance has already developed in the parasitic worms which infect our livestock, can it happen to human helminths?

Looking for signs of this anthelmintic resistance and developing tools to prevent and ultimately respond to this risk is the StarWorms Project or Stop Anthelminithic Resistant WORMS, based at Ghent University.

StarWorms, with the support of the Bill and Melinda Gates Foundation, is looking to strengthen the monitoring and surveillance of drug efficacy and anthelmintic resistance in deworming programmes. StarWorms identify three main concerns around current deworming practice:

1. Deworming programmes only rely on one drug

Deworming programmes are currently relying on just two drugs namely, albendazole or mebendazole. Both these drugs work in the same way.  Therefore if the worms develop a resistance to one it’s likely they’ll also be resistant to the other.

2. Unavailability of alternative drugs

There is a paucity of anthelmintic drugs that are licensed for the treatment of worm infections in humans. Thus, should anthelmintic resistance against albendazole or mebendazole emerge and spread there are very few alternative back up options.

3. Suboptimal doses

Currently the drugs are administered in single doses. Whilst this makes sense operationally it means that some people are not getting enough drugs to actually kill the worms. Over time this sup-optimal dosage potentially leaves the door open for the parasites to develop resistance to the deworming drugs.

Starworm through their newly relaunched website offer programme managers and researchers with a number of monitoring and planning tools to enable users to monitor drug efficiency and design cost effective deworming programmes.

Whilst there is no conclusive evidence of anthelminth resistance amongst human STH to-date, projects such as StarWorms are following the old adage that prevention is better than a cure.