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Alison Krentel

When we treat a community, who gets left behind?


Mass drug administration (MDA) is a preventative health strategy where everyone who is eligible in a population is given treatment for a disease, whether they are infected or not. It’s a strategy that is the cornerstone to eliminate five of the 21 neglected tropical diseases (NTDs) that affect 1.6 billion people worldwide.

High levels of participation in the mass drug administration are critical to its success. Despite this, there remain groups of people who are left behind in these programs, meaning that they may be untreated for infection and even may hinder elimination efforts for their whole community.

Alison Krentel, PhD, Senior Investigator at the Bruyère Research Institute and Associate Professor at the School of Epidemiology and Public Health at the University of Ottawa, studies why some people are never treated through MDA programs, whether by choice or by lack of access.

“Understanding who is being missed and why they aren’t treated is vital to public health programs that aim to treat the majority of people living in an endemic area,” said Krentel, who is also the Chair for Canadian Network for Neglected Tropical Diseases. “We need to pay attention to who is being left behind. Often, it’s the people who are living in the most vulnerable and marginalized situations in a community.”

She is among several research teams around the world currently exploring factors that contribute to individuals never being treated during MDA. One study in Indonesia found that the role of employment, health care catchment area, the perceived possibility of side effects of taking the NTD tablets, as well as difficulties in actually taking the medication were associated with the likelihood of never treatment. A recent study in Guyana showed that people who lived in a certain region in the country were more likely to be never treated than in other regions.


Alison Krentel and teamResearchers suggest that uptake can improve if community members are reassured about possible side effects and are provided with specific instructions for swallowing the tablets. A key message that emerges in many communities is that participation contributes to the benefit of the whole community’s health. This collective responsibility resounds across many geographic sites where Krentel and her colleagues have conducted research.

Krentel is also the principal investigator on a recent review of programmatic and research needs in addressing “never treatment” for lymphatic filariasis, a leading cause of global disability. The team found that never treatment followed patterns which were localized, meaning that strategies to reaching these individuals need to be context specific, quick, and focused on local solutions. Through iCHORDS, researchers are working on a toolkit to help countries identify never treatment and address it through dedicated approaches.

“NTD programs have successfully implemented MDAs for decades – often with insufficient funding and in difficult conditions – treating millions of people each year. Yet we know that we are still missing people despite our best efforts.” said Krentel. “Every country, Canada included, has its own challenges when trying to reach everybody with a public health intervention. So, it’s important that we continue to ask ourselves in our programs, who is getting left behind, why, and how do we reach them?”