Continuing to aid efforts to better health in the developing world, the Bill & Melinda Gates Foundation pledged a $21.8 million grant to the Human Hookworm Vaccine Initiative (HHVI).
"The Bill & Melinda Gates Foundation has again provided a chance for this important research to advance," said Philip Russell, the chair of HHVI's executive board. "Our team is committed to continuing the research, now in the first phase of clinical trials, and to make the funding go as far as possible toward successful development of this vaccine for the poorest populations of the developing world."
Managed by the Albert B. Sabin Vaccine Institute, the HHVI also includes the George Washington University Medical Center in Washington, the Oswaldo Cruz Foundation (FIOCRUZ) and the Butantan Institute in Brazil, the London School of Hygiene and Tropical Medicine and the Queensland Institute of Medical Research in Australia. Human hookworm infection causes large-scale blood loss, said Michael Katz, a physician at the March of Dimes, which also has contributed to the project - the daily blood loss attributable to the parasite worldwide would equal the entire blood volume of Washington. That leads to iron deficiency, anemia and protein malnutrition.
The latest funds will be used to determine a first-generation vaccine's efficacy and safety in endemic areas of Brazil, and to support its manufacturing and eventual production in that country. Labeled Na-ASP-2, the product is a recombinant protein vaccine designed to prevent larval-stage hookworms from developing into adults.
"Hookworm is one of the most common chronic infections in humans," said Peter Hotez, the vaccine's developer at George Washington University. Noting that about 740 million people worldwide are infected, about one in eight people on the planet, he added that it largely occurs "wherever you have rural poverty intersecting with a tropical climate," in places such as the Americas, sub-Saharan Africa, South China and Southeast Asia.
Despite its prevalence, it is classified by the World Health Organization as a neglected disease due to developed countries' failure to address the problem.
A. David Brandling-Bennett, of the Gates Foundation, noted that wealthy nations tend to avoid fighting such diseases because their population is not affected, and industry doesn't work toward solutions because there is no way to recoup investments from the poor who are most afflicted.
"The Human Hookworm Vaccine Initiative is a great example of the work that can be done to address these shortcomings," he said. The Seattle organization, which has an endowment of about $28.8 billion, is channeling its support through its global health program. To date, its global health funding commitments total more than $3.6 billion in areas such as HIV/AIDS, infectious disease, malaria, tuberculosis and reproductive health, among other areas.
Brandling-Bennett later added that the Gates Foundation hopes its support "will lead to similar success in the developing world" in eradicating hookworm as the Rockefeller Foundation did years ago in the U.S., where the disease was most prevalent in the Southeast. "Hookworm is an example of a disease for which a relatively modest investment in research and development could, and we expect will, affect tens of millions of lives," Brandling-Bennett said.
Currently in the U.S., Phase I safety trials of the human hookworm vaccine already are under way. The product is delivered by way of a yeast vector. Efficacy testing is scheduled to begin the first quarter of next year under the watch of FIOCRUZ.
Should the product prove effective in preventing hookworm, it would represent one of the first vaccines to work against a worm parasite, a helminth. Current deworming treatments include the use of anthelminthic drugs such as benzimidazoles - Albendazole or Mebendazole - that can reduce the amount of adult hookworms within a person's gastrointestinal tract, where they fasten onto the small intestine's inner layers and extract blood. The parasite enters humans by burrowing into the skin of the hands, arms, legs or feet, or through oral ingestion.
"The disease associated with hookworm," Hotez said, "is really a nutritional deficiency that results from the behavior of the adult parasite."
But since anthelminthic drugs do little to prevent re-infection, he noted that they are "not sufficient," and ideally, Na-ASP-2 would be used in combination with those drugs as a prevent and treat regimen.
The Sabin Vaccine Institute is headquartered in New Canaan, Conn., and also has been active in efforts to work toward vaccines for cancer, polio, rotavirus and rubella. Its hookworm support from the Gates Foundation began in 2000 with an initial grant of $18 million for HHVI, used for antigen discovery research and applied development to create the experimental hookworm vaccine. Other funding has come from the National Institutes of Health and the China Medical Board of New York.