Click here to return to the issue index.

Eradicable differences

Interview by Valerie Gregg

Eric Ottesen, MD, new director of the Lymphatic Filariasis Support Center at RSPH, has led the Lymphatic Filariasis Elimination Program at the World Health Organization for the past seven years. Before that, he spent 22 years at the National Institutes of Health as an infectious disease scientist. He brings a unique expertise to RSPH along with a commitment to finding creative new ways to attack the public health problems of developing countries. He recently spoke to Public Health magazine about lymphatic filariasis (LF), the realities of disease eradication, and new partners in global health.

PH: What makes lymphatic filariasis eradicable?
Ottesen: To eradicate a disease, first you must have a good way to detect it, and second, you must be able to treat it and halt its spread. There must also be a commitment to follow through with the effort. LF was generally not a public health priority before the early 1990s—even in terms of recognizing the economic and social impact of the disability it caused. But now the public health community is paying more attention to disability and quality-of-life issues. And new tools out of the lab in the past few years have given us the means to make eradicating LF entirely possible.

We can now test for infection with a simple finger prick blood test for LF antigens. In the old days, we had to take blood for examination between the hours of 10 pm and 2 am—in most countries, the only time when the parasite larvae (microfilariae) circulate in the blood. So diagnosis was literally a nightmare. Public health workers had to wander through villages in the middle of the night, wake people up, and ask to bleed them and their children. Teams of parasitologists were chased out of villages as vampires or evil spirits. It just wasn’t culturally acceptable, and beside that, it was miserably inconvenient. Because of that we never knew exactly where the disease was. We could tell only years after initial infection, when elephantiasis or hydrocoeles became evident, but we really didn’t know how many people or children were infected. Because of the new diagnostic test, we now know that children are often infected as early as age 2, 3, or 4. And simpler, new drug regimens that keep the LF parasite from producing microfilariae can now be administered to entire communities once a year, for four to six years. If there are no larvae circulating in the bloodstream, then they cannot be spread via mosquitoes to other people. The generosity of pharmaceutical companies to donate these drugs for as long as necessary makes elimination of LF possible in developing nations.

PH: The new LF Support Center at RSPH is part of the Global Alliance for the Elimination of Lymphatic Filariasis, yet we speak of LF as an eradicable disease. What is the difference between eradication and elimination?
Ottesen: When a disease is eradicated, it’s gone forever, from everywhere, so you no longer need either intervention or monitoring. Smallpox is a disease that has been eradicated. Elimination of a disease involves more of a regional concept. When a disease is eliminated, you no longer need treatment or intervention in that area. But you must still maintain surveillance for it, because it’s out there somewhere. The 1997 World Health Assembly resolution calls for the global elimination of LF as a public health problem, which means bringing it to the level where it may still be in the background but is not a big public health issue.

PH: What can be done for those already infected with the LF parasite?
Ottesen: We now have good, reliable drug regimens to treat entire communities where LF is a problem. These drugs clear the larval parasites out of the blood, and they can kill or sterilize the adult-stage parasites that are damaging the lymphatic system. WHO used to recommend 12 days of the drug diethylcarbamazine (DEC) to treat LF. This drug can induce inflammation, fever, rashes, and liver pain, as the body clears parasites from the blood. It can be tough to take for 12 days, and convincing a whole community to adhere to that regimen wasn’t easy. But recent research has shown that a single dose of DEC works as well as 12 doses! So it has become much easier to convince entire villages to accept it.

Recent research has shown that a drug initially used for river blindness—ivermectin (Mectizan)—also works for LF. Furthermore, when people take DEC along with either ivermectin or albendazole, the microfilariae are cleared from the blood for a far longer time period than after the single dose of DEC. In African countries where river blindness is endemic, we can’t use DEC because the post-treatment inflammatory reactions can damage the eye. There, ivermectin and albendazole are used together. It doesn’t kill the adult worms as effectively, but it stops the adult worm from producing more microfilariae. In the rest of the world, DEC and albendazole are given in a single dose, once a year. That keeps the level of larvae in the blood so low that transmission is interrupted.

Are infected people actually cured? Kind of. DEC kills about half of the worms in an infected person. What we don’t know is how many people are totally rid of the worms after treatment and how many continue to carry a small number. It’s as if some parts of the parasite’s life cycle are sensitive to the drug and other parts are not. With repeated treatment over four to six years, the parasites are either killed by the drug or die of old age, and further damage to the lymph system is prevented.

When patients maintain careful hygiene, recurrent bacterial infections are prevented, the progression of the disease is greatly slowed or halted, and patients report feeling much better.

PH: The Global Alliance for the Elimination of Lymphatic Filariasis is an unusual coalition of academia, corporations, government agencies, and nonprofits. What can this effort teach us about combatting disease in developing countries?
Ottesen: It’s the same kind of public health initiative that is now being organized around HIV/AIDS. These kinds of problems require huge resources, expertise, and the authority to act across borders. Only coalitions of organizations can accomplish all of these things. The pharmaceutical companies have been tremendously important in this effort. GlaxoSmithKline has agreed to provide enough albendazole to treat as many as a billion people yearly for four to six years. That’s up to 6 billion tablets—a tremendous donation. Merck has donated enough ivermectin for all of Africa and expanded its donation of Mectizan to include all countries where LF and river blindness are both endemic. Forging public-private partnerships is an important new way of approaching public health problems, and it’s especially effective in developing countries. The private sector has the money; the government sector has the problems and can be a conduit for money to flow to the problems. The possibilities in Atlanta for expanding these kinds of partnerships make the Rollins School of Public Health an especially good place to work now.


Autumn 2001 Issue | In Brief | La Mano de Obra: The Hand of the Worker
Forgotten Disease of Forgotten People | Age-Old Questions | Alumni News | WHSC | RSPH
Copyright © Emory University, 1999. All Rights Reserved.
Send comments to hsnews@emory.edu.