A Colorado State University microbiologist is examining a new way to halt malaria – one of the world’s most severe public-health problems – by turning prevention on its head. He plans to give potential human victims a common antiparasitic drug that, when ingested by mosquitoes in a blood meal, kills insect vectors that spread the deadly disease.
Brian Foy, an associate professor in CSU’s Arthropod-borne and Infectious Disease Laboratory, won a coveted Grand Challenges Explorations grant of $100,000 from the Bill and Melinda Gates Foundation. The sum is small, yet the initial grant is significant for stimulating an innovative approach with the potential for more funding ahead.
Foy’s idea might seem blood simple.
Instead of stopping mosquitoes before they reach their target, with insecticide and mosquito nets, for instance, he hopes to demonstrate the effectiveness of killing mosquitoes with their target: human blood.
“I’ve always been very interested in the idea of preventing mosquito-borne disease at the bite,” said Foy, who works in the CSU Department of Microbiology, Immunology and Pathology. “Basically, the question is, ‘Can you kill a mosquito when it’s biting you with something that’s in the blood?’”
During a clinical trial in spring 2015, Foy will administer multiple doses of the common antiparasitic drug ivermectin to villagers in Burkina Faso, a West African nation hard hit by malaria. Each year, the mosquito-borne disease claims an estimated 40,000 people in the country; as in other places, most are children.
Foy offers insights on Zika virus
Brian Foy typically studies and seeks to halt malaria.
But in 2008, he unintentionally discovered, through personal experience, that Zika virus might be sexually transmitted. His case became just the second scientifically confirmed instance of infection to raise questions about the possibility for sexual transmission of Zika virus.
In 2011, the Centers for Disease Control and Prevention published Foy’s paper describing the case in its journal of Emerging Infectious Diseases.
The researcher’s experience gained international media attention starting in January 2016, as the most recent outbreak of Zika virus grew to epidemic proportions. The virus is sweeping through Latin America and has begun appearing in other parts of the world, even as scientists seek to understand the connection between Zika virus and birth defects among babies in regions hard-hit by viral infection.
Arbovirologists at CSU and elsewhere believe the Zika epidemic will continue to grow. CSU researchers hope to provide insights about mosquito-borne viruses in the global quest to better understand Zika virus and its implications for human health, said Gregory Ebel, director of the university’s Arthropod-borne and Infectious Disease Laboratory.
Ivermectin is generally safe for people – indeed, it is considered an “essential medicine” by the World Health Organization – yet makes human blood poisonous to mosquitoes that transmit the parasite that causes malaria.
The drug typically is used to treat river blindness in Africa, Latin America and elsewhere; single doses are supplied to people worldwide each year to kill parasites and to protect those at risk of disease.
Foy’s approach is different in several ways. He will examine ivermectin’s use in prevention, rather than treatment; against a different type of disease-causing parasite; administered in a higher number of doses than villagers now receive; and given during the critical springtime transition from dry season to rainy season, when mosquito populations explode.
“Dr. Foy is a creative and imaginative investigator who has managed to get two of these highly competitive awards with innovative approaches to stopping deadly human disease,” said Dr. Sue VandeWoude, associate dean for research in the CSU College of Veterinary Medicine and Biomedical Sciences. “This strategy has been used in veterinary medicine for prevention of heart worms and other parasitic diseases in animals. Brian is the first researcher I know of to adapt the strategy for human medicine.”
Foy, who has traveled to West Africa frequently to study mosquito-borne disease, is pursuing his idea based on evidence that malaria-carrying mosquitoes significantly decline after villagers receive ivermectin and other drugs to protect against elephantiasis and river blindness.
His upcoming clinical trial also will involve more standard approaches to preventing malaria, including use of insecticide-treated bed nets to protect people from mosquito bites as they sleep.
Collaborating with Foy are the Burkina Faso Ministry of Health and the country’s Institut de Recherche en Sciences de la Santé.
Foy and fellow researchers hope their strategy with ivermectin will be particularly effective in killing infected adult female Anopheles mosquitoes that transmit the disease to humans. Females of the species often seek human blood meals to produce eggs; insects infected with malaria parasites transmit the parasites through their bites.
Children are especially susceptible to developing potentially fatal infectious disease, with symptoms including fever, vomiting and seizures. New controls are needed in part because mosquitoes have developed resistance to traditional insecticide use.
“Our hypothesis is that giving ivermectin more often will kill off the adult female mosquitoes. Then kids will get malaria less often because they are being bit less often by the mosquitoes transmitting the parasites,” said Foy. His department is well-known for expertise in mosquito-borne disease.
More than 200 million people are infected with malaria each year, making it one of the most difficult to treat infectious diseases globally. Of those who become ill, about 650,000 people die of malaria each year; most are children, and most are in Africa, according to the World Health Organization.
CSU and the Gates Foundation
Over the past decade, CSU has received 37 grants totaling about $14.5 million from the Bill and Melinda Gates Foundation for a variety of research projects, including studies targeting tuberculosis, another globally devastating infectious disease. Earlier this year, the Gates Foundation funded a CSU effort to develop a diagnostic breath test for TB.
Jeff Dodge contributed to this report.