Clinical trials of a vaccine for parasitic intestinal worms showed that it is effective and safe, informed the U.S. Company HOOKVAC, which is responsible for its development.
The trials were conducted in the city of Belo Horizonte, and the rural settlement of Americaninhas, both located in eastern Brazil, where hookworm infection risk is very high.
Hookworm parasites infect more than 600 million people worldwide, attaching themselves to the intestines to feed on blood. Infection can lead to iron deficiency and capillary damage, and may retard children’s growth and mental development.
Researchers from the Sabin Vaccine Institute Product Development Partnership found that the vaccine doses were well tolerated by 102 healthy volunteers and blood tests showed that they developed an immune response. None of them had ever been exposed to hookworm before.
David Diemert, Sabin’s director of clinical trials, said: “A vaccine able to induce long-lasting immunity, which could be incorporated into existing vaccination programs in countries like Brazil, would provide a sustainable solution to the problem of hookworm.”
The vaccine’s active ingredient is a protein from the adult Necator americanus hookworm, the species that most commonly infects people. When patients are exposed to a harmless form of the protein, they develop antibodies that recognize it. In theory these would then be able to recognize the proteins — and mobilize the immune system — if the person was subsequently infected with worms.
Researchers say the vaccine could be an alternative way to deal with repeat infections. Brazil’s public health system distributes single dose anti-hookworm drugs to local people for free, but they are often reinfected by contaminated water. In theory, the vaccine could treat existing infections and provide lasting immunity.
Although the vaccine raises hopes of having a better hookworm control, it will still be several years before the vaccine has undergone all the tests necessary to be approved for use, says Diemert. But he hopes to have a licensed vaccine by 2020.
The Sabin initiative is part of the wider HOOKVAC consortium that is developing the vaccine. Another trial is expected to start this month in Gabon, where three in ten people have hookworms.
Ronaldo Scholte, a senior consultant at the Brazilian Health Ministry, said that any future vaccine would be an important tool to control hookworm infections. However, he pointed out that “basic sanitation is as important as new drugs to treat waterborne diseases”.
Manoel Victor Lemos, an applied biologist at Sao Paulo State University, Brazil, says a vaccine would be the “most sustainable control of hookworm we have ever had.”
Through: SciDev.Net
