Mass drug administration (MDA)

Mass drug administration (MDA) is one of the world’s most effective tools for protecting whole communities from parasitic infections. By providing treatment to entire communities—whether or not they show symptoms, MDA helps people stay healthy, stay in school, and thrive.

At Unlimit Health, we work with countries to strengthen and scale these programmes, so that one is left behind.

What is mass drug administration

Mass drug administration is a public health strategy in which all eligible people living in areas where parasitic infections are common, receive treatment, regardless of whether they currently show symptoms. This approach is crucial for reducing transmission of parasitic infections, which disproportionally affect children and communities living in poverty.

Preventive chemotherapy: the foundation of MDA

MDA is built on a World Health Organization (WHO)‑recommended approach called preventive chemotherapy (PC), defined by WHO as:

“the large-scale delivery of safe, single‑administration, quality‑assured medicines, either alone or in combination, at regular intervals, to entire population groups.” [who.int]

WHO recommends this strategy because it is proven to reduce infection, improve health outcomes, and lower disease transmission.

Why MDA matters

• Targets entire at‑risk populations — ensuring both symptomatic and asymptomatic infections are treated.
• Reduces community‑wide disease transmission — improving long‑term health and wellbeing.
• Cost‑effective — recognised globally as one of the “best buys” in public health.
• Builds healthier futures — reducing school absenteeism and improving quality of life for children.

This approach is essential to tackling diseases such as schistosomiasis (SCH) and soil‑transmitted helminth infections (STH), which affect some of the world’s most marginalised communities. WHO recommends treating at‑risk populations once or twice a year, depending on infection levels. [who.int]

Who delivers MDA?

Programmes targeting parasitic worm infections are designed and led by national governments, ensuring that treatment strategies reflect local needs and priorities.

At Unlimit Health, we are proud to work as independent technical advisors, providing research, analysis, and programme expertise to help countries scale up, strengthen, and optimise their national strategies.

Who receives treatment?

MDA targets everyone who is eligible in areas where infections are common. This typically includes:

• School‑age children (5–14 years), who often carry the highest burden
• Women of child‑bearing age
• Children under five, depending on national guidelines
• Adults in high‑risk occupations or environments that involve water contact such as farming, fishing

Reaching whole communities helps ensure that treatment is equitable and that even those without symptoms are protected.

Where and how is MDA delivered?

Most MDA campaigns take place in schools or within communities, delivered by trained teachers or community drug distributors (CDDs). CDDs are often trusted local volunteers nominated by their communities and trained by national programmes to ensure treatment is delivered safely and effectively.

Medicines donated by partners

The medicines used in MDA—including praziquantel for schistosomiasis and albendazole or mebendazole for STH—are donated every year by pharmaceutical partners, enabling millions of people to access life‑changing treatment at no cost.

Can preventive chemotherapy eliminate worm infections?

Preventive chemotherapy through MDA has dramatically reduced the burden of parasitic infections worldwide and remains one of the most impactful health interventions available.

However, MDA alone cannot eliminate these diseases entirely. To break transmission, WHO recommends combining MDA with:

• Water, sanitation and hygiene (WASH) improvements
• Environmental and One Health measures
• Behaviour‑change initiatives that reduce exposure to infection. [who.int]
• These combined approaches tackle both the infections and their root causes.

Our role: How Unlimit Health supports MDA

Unlimit Health works in close partnership with governments to strengthen national programmes. We do not run parallel systems — we support countries to lead. We:

• Provide technical expertise, research, and analysis
• Help scale up high‑quality MDA campaigns
• Strengthen programme monitoring and decision‑making
• Support cross‑sector approaches aligned with the WHO Neglected Tropical Diseases road map. Our 2023–2028 organisational strategy is fully aligned with this shift.

Our impact (2024-25)

Supporting high‑quality treatment through MDA remains a cornerstone of our mission.

• We supported the delivery of 30 million treatments for schistosomiasis and soil transmitted helminthiases reaching 21 million people across partner countries.
• Expanding treatment access -as a member of the Paediatric Praziquantel Consortium, we are contributing to the development of a child‑friendly formulation of praziquantel—critical for protecting pre‑school‑aged children, who are currently underserved.