Worm infections rebound after community treatment ends in Malawi

Researchers at the Liverpool School of Tropical Medicine have found that ending mass drug administration for lymphatic filariasis in Malawi was followed by a resurgence of other parasitic worm infections in school-aged children.

The study [1], published in PLOS Neglected Tropical Diseases, reports that children were nearly twice as likely to be infected with the intestinal roundworm Ascaris lumbricoides after community-wide treatment programmes were stopped, compared with the period when they were in place.

Ascaris lumbricoides is a soil-transmitted helminth that infects an estimated 1 billion people globally and can contribute to malnutrition, anaemia, and impaired physical and cognitive development in children.

Malawi began mass drug administration for lymphatic filariasis in 2008, treating both children and adults with ivermectin and albendazole. While the programme was primarily aimed at eliminating lymphatic filariasis, it also helped suppress intestinal worm infections across communities. The initiative ended in 2014 after Malawi was declared to have eliminated lymphatic filariasis in 2020.

Although school-based deworming with albendazole continued, statistical analysis of national survey data suggests infection rates of intestinal worms still increased after community-wide treatment stopped.

Dr Faduma Farah, lead author from LSTM, said the findings highlight the wider impact of mass treatment programmes beyond their primary target disease.

“When community-wide mass drug administration stopped, we saw signs of resurgence in roundworm infections among school-aged children, even though school-based treatment continued,” she said.

Researchers from LSTM and the University of Birmingham suggest the results support the role of community-wide treatment in sustaining control of intestinal worms, particularly in settings where transmission remains high.

However, they also note that such programmes may be difficult to maintain due to declining global funding for neglected tropical diseases and reduced drug donations, increasing pressure on national health systems.

The study highlights the need for stronger surveillance and more adaptive control strategies to ensure gains in parasite control are not lost after large-scale programmes end.

More information online

1. The impact of the termination of Lymphatic Filariasis mass drug administration on Soil-transmitted Helminth prevalence in school children in Malawi published in PLOS Neglected Tropical Diseases