What Is the Program?

Working to Eliminate

River Blindness & Lymphatic Filariasis

River blindness (onchocerciasis) and lymphatic filariasis (also known as LF, elephantiasis, and “bigfoot disease”) are both debilitating parasitic diseases that cause pain, suffering, and stigmatization. With sustained, annual treatment over time, transmission of both diseases can be eliminated. In the Americas, four of the six endemic countries have been verified by the World Health Organization (WHO) for eliminating river blindness. Malawi, Togo, and Yemen have been validated by WHO for eliminating LF. The Mectizan Donation Program (MDP) is committed to working with all endemic countries to end the suffering caused by these debilitating diseases. The potential to achieve this goal is not only feasible but increasingly within reach.

Lymphatic Filariasis

Also known as LF or Elephantiasis, this disease can lead to painful and disfiguring chronic enlargement of the arms, legs, breasts, and genitals.

River Blindness (onchocerciasis)

Also known as onchocerciasis, when left untreated this parasitic disease can cause severe rashes, intense itching, lesions, and—eventually—blindness.

The Medicines

How We Treat These Diseases

The drug Mectizan® (ivermectin) is effective against river blindness and LF because it kills the juvenile parasites (microfilariae) produced by the adult worm, thereby reducing the patient’s microfilarial load. 

Mectizan is distributed through a process called mass drug administration (MDA). First, a country’s ministry of health submits an application for Mectizan (see qualifying criteria here). The Mectizan Expert Committee and the Mectizan Donation Program review the application and, if approved, MDP arranges to ship the required pills to each country.

Once a shipment is received, national elimination programs work with partners to deliver Mectizan to endemic communities where specially trained community drug distributors (CDDs) assess the correct dose (based on height) and administer the annual or twice annual treatments to each eligible resident. 

A Global Effort

Where MDP Works

As of 2022, MDP has partnered with 58 countries to distribute Mectizan for river blindness and lymphatic filariasis elimination.


Established in 1987 by Merck & Co., Inc., Rahway, N.J., U.S.A.,* the Mectizan Donation Program (MDP) is the longest-running drug donation program for neglected tropical diseases (NTDs).

Our Journey

History Of The Program

In the 1970s, Dr. William Campbell of Merck Research Laboratories suggested the use of ivermectin (later named Mectizan) for river blindness in humans. Following the breakthrough lab work by Dr. Campbell (who in 2015 was named a Nobel Laureate) and his team, another Merck researcher, Dr. Mohammed Aziz, championed the clinical development of Mectizan. In the 1980s, Dr. Aziz led the collaboration with the World Health Organization (WHO) to design and implement the trials in West Africa that proved the effectiveness of the drug against river blindness.

In 1987, Merck committed to donating Mectizan—as much as needed for as long as needed—with the goal to help control river blindness.

*Merck & Co., Inc., Rahway, N.J., U.S.A., is known as MSD outside of the United States and Canada