End of community-wide treatment linked to resurgence of parasitic worm infections in Malawi

Researchers at Liverpool School of Tropical Medicine have found that stopping mass drug administration for Lymphatic Filariasis (LF) was associated with an increase in infections from other parasitic worms, threatening disease control efforts. 

The study, published in PLOS Neglected Tropical Diseases, suggests that once wider community treatment programmes for LF ended, school-aged children were nearly twice as likely to be infected with the intestinal roundworm Ascaris lumbricoides. 

Ascaris lumbricoides is a species of soil-transmitted helminth, a group of parasitic worms that infect around 1 billion people worldwide, primarily in low- and middle-income countries. Infections can cause malnutrition and anaemia, as well as impaired physical and cognitive development in children. 

Starting in 2008, Malawi delivered mass drug administration to children and adults to eliminate LF, using ivermectin and albendazole. The drugs also provided an additional, indirect defence against intestinal worms by suppressing infections. Mass drug administration was ended in 2014 and the World Health Organization recognised Malawi as having eliminated LF in 2020. 

School-aged children continued to receive albendazole as part of control efforts against intestinal worms. Despite this, statistical modelling shows that children had around 1.8 times greater odds of infection with intestinal worms compared with the period of mass drug administration. This raises questions about whether community-based efforts should be resumed in areas with growing infection rates. 

Dr Faduma Farah, a PhD student at LSTM and author of the study, said: “Community-wide mass drug administration for lymphatic filariasis had an important secondary effect on intestinal worm infections. 

“When that programme ended, our analysis showed signs of resurgence in roundworm infections among school-aged children, even though school-based deworming continued.” 

Dr Farah and her PhD supervisors, Professor Mark Taylor and Dr Armelle Forrer from LSTM’s Centre for Neglected Tropical Diseases, and Dr Claudio Fronterrè from the University of Birmingham, analysed national survey data on helminth infections in Malawian schoolchildren before the lymphatic filariasis programme, during its implementation, and after it ended. 

Drawing on real-world data and supported by previous modelling studies, the research suggests community-wide mass drug administration is needed to effectively manage and reduce intestinal worm infections. However, community-wide treatment may prove difficult due to falling global investment in NTD programmes and reduced drug donations for soil-transmitted helminths, placing the financial burden on governments. 

Dr Farah added: “These findings highlight the importance of understanding how different disease control programmes interact. If community-wide treatment stops, countries may need alternative strategies to maintain the progress that has been achieved against soil-transmitted helminths.” 

The researchers emphasise the need for improved surveillance and affordable monitoring approaches, using more sensitive diagnostic tools, to track infection trends and ensure that control programmes remain effective. It also highlights the importance of adaptive control strategies that can react to changes in mass disease control programmes.