They don’t kill, so they don’t make many headlines. But river blindness and elephantiasis cause untold suffering for tens of millions of people worldwide, leaving many unable to provide for themselves and their families, and locking them into a cycle of poverty.

The diseases may soon be history, though, thanks in large part to Charles Mackenzie, a professor of veterinary pathology at Michigan State University.

“It’s important not to just look at diseases that kill people, but also those that debilitate and prevent them from making a living,” says Theresa Bernardo, an associate professor of epidemiology, “and Charles has made a tremendous contribution there.”

A former director of pathology at the London School of Hygiene and Tropical Medicine, Mackenzie has long been a key player in the international fight against the diseases, which are caused by parasitic worms transmitted by mosquitoes and black flies. The worms reproduce quickly within a person’s body and cause intense itching when the worms die.

One variety of worm causes lymphatic filariasis, commonly called elephantiasis, an often-excruciating disease that can damage the kidneys and lymphatic system. It results in severe swelling of the legs, arms and genitals, and the accompanying stigma leaves many infected people extremely depressed. More than 120 million people are infected worldwide—40 million of whom are incapacitated or disfigured—and a fifth of the world’s population is at risk.

Mackenzie heads MSU’s involvement in the Global Alliance to Eliminate Lymphatic Filariasis, a public-private partnership among the ministries of health in participating countries, the World Health Organization (WHO) and dozens of other institutions and private donors.

Instrumental to the group’s efforts were commitments by pharmaceutical giants GlaxoSmithKline and Merck and Co. to donate as many doses of anti-elephantiasis drugs as needed for as long as it takes to eliminate the disease. Mackenzie helped secure the donations, which, at more than $1 billion, are the biggest ever.

Grants from the Bill and Melinda Gates Foundation have also been crucial in the battle against lymphatic filariasis. Equally important, Mackenzie says, is the active role of the Tanzanian government, which now pays more than 80 percent of the costs of fighting the disease within its borders.

“This was, from the very beginning, an elimination program,” says Mackenzie. “We’re going to eliminate this parasite from the world.”

The WHO has resolved to do just that by 2020, which means workers must distribute the drug annually for at least five years to every at-risk person in the world, many of whom live in the remotest of rural villages.

That may seem next to impossible, but the results so far have been dramatic; since 2000, when Mackenzie took a one-year sabbatical to run the African lymphatic filariasis donation program for the drug companies, he and others have treated 19 million of the target population of 28 million people in Tanzania. In a coastal region of the country where 70 percent of inhabitants were infected at the program’s outset, now only 6 percent are, and no new cases have been reported.

If that weren’t enough, the successful treatments have come with some encouraging side effects, Mackenzie says. For one, the donated drugs kill the parasitic worms more slowly than earlier treatments did, which means less skin irritation and swelling. And, surprisingly, the treatment reverses swelling in many patients. Doctors have known that frequent washing of irritated areas could prevent bacterial infections and reduce swelling, but with the new treatment, swollen limbs shrink even when patients don’t wash.

“That’s an extraordinarily good thing,” says Mackenzie. “Because, as I like to say, patients are why we do these things.”

Mackenzie has also worked extensively toward the elimination of onchocerciasis, better known as river blindness for the permanent loss of sight that follows the death of a worm in a person’s eye. The disease has blinded some 300,000 people, mostly in Africa, but also on the Arabian Peninsula and in Latin America. Yet it seems that river blindness, like elephantiasis, is no match for Mackenzie and others dedicated to destroying it.

In 1990, testing in Ecuador revealed that more than 90 percent of people living in high-risk areas had suffered some degree of eye damage or infection from onchocerciasis.

A partnership soon formed to distribute drugs, also donated by Merck, to stamp out the disease. Mackenzie was brought on to aid the coalition, which was led by the WHO, the Georgia-based Carter Center and other groups.

And now?

“As a clinical disease, it’s totally gone from Ecuador,” says Mackenzie.

Still, it’s unlikely that the worms that cause the disease will ever be wiped out completely, so continued monitoring and treatment of isolated cases are needed to prevent future outbreaks.

But it’s a task Mackenzie is equal to, according to Bernardo.

“Charles has shown remarkable dedication throughout his career and has stuck with these programs through their ebbs and flows,” she says. It’s also a task he relishes.

“I think I’m extremely lucky,” he says. “I’m a terrible tourist, but I’ve been more places than most people.”

But it’s not about adventure for Mackenzie, who still remembers names of people he treated years ago. It’s about people.

“Seeing those patients get better in Tanzania when they weren’t supposed to,” he says—“that was one of the most thrilling things in my life.”