Athens, Ga. – Researchers from the University of Georgia have been awarded a three-year, $1.1 million grant from the National Institutes of Health to determine how two commonly administered drug combinations work to remove larvae from the bloodstream of people infected with lymphatic filariasis, also known as elephantiasis.

Elephantiasis  of leg due to filariasis/CDC
Elephantiasis of leg due to filariasis/CDC

Elephantiasis is a serious human tropical disease caused by several species of parasitic roundworm and is transmitted to humans by infected mosquitos. More than 120 million people are infected with elephantiasis, and 1.3 billion people in 73 countries are at risk of the disease. 

Often, elephantiasis is contracted during childhood. A person’s lymphatic system, kidneys and immune system may be permanently damaged long before he or she begins to show physical symptoms. As the disease progresses, it can cause extreme swelling in the extremities and other body parts, resulting in severe pain and, often, permanent disability. 

In addition to the physical pain, the victims can suffer social and financial losses. Worldwide, roughly 40 million people have been disfigured or incapacitated by this disease.

In parts of the world where the disease is common, it is controlled by giving a single dose of two drug combinations to the entire at-risk population every year: albendazole with diethylcarbamazine citrate if just elephantiasis is present, and lbendazole with ivermectin if “river blindness,” which is caused by a different parasite, is also present. This is part of an ambitious project, led by the World Health Organization, to eliminate the disease by 2020.

“Billions of doses of these drugs have been distributed, yet we do not know how diethylcarbamazine citrate works against the parasites, and it is likely that our previous ideas of how ivermectin works against these parasites may be wrong,” said Adrian Wolstenholme, the principal investigator on the project. 

Wolstenholme is a professor of infectious diseases in the UGA College of Veterinary Medicine and a faculty member within the UGA Center for Tropical and Emerging Global Diseases.

The drug combinations eliminate larvae from the patient’s bloodstream, which prevents the larvae from being transmitted to mosquitos and thus to other people. However, the drugs have a limited impact on the adult worms, which can live up to eight years inside the infected patient. This means that at least five consecutive years of annual treatments are required to prevent new infections before the existing adult parasites die, which can be difficult to achieve in some areas of the world.

“Understanding how our current drugs work, especially if they allow the infected person’s own immune system to eliminate the parasite, will help us to use them in the most effective way possible. It may also help us think of new ways in which to kill the adult parasites, and to ensure that this horrible disease is removed from the face of the earth as early as possible,” said Wolstenholme.

The other researchers on the elephantiasis project, in the UGA department of infectious diseases, are Ray Kaplan, a parasitologist and professor of infectious diseases; Balazs Rada, an immunologist and assistant professor of infectious diseases; Barbara Reaves, a cell biologist and associate research scientist; and Andrew Moorhead, a parasitologist and assistant research scientist. Walter Lorenz, an assistant research scientist in the UGA Warnell School of Forestry and Natural Resources and a member of the Institute of Bioinformatics’ Quantitative Biology Consulting Group, will help the researchers analyze the large amount of data generated by the project.