New hookworm vaccine passes clinical trials in Brazil

The new vaccine’s active ingredient comes from hookworms themselves, a protein from a common species of adult hookworm (Photo: Shutterstock)

A clinical trial of a permanent vaccine for hookworm has been completed in Brazil, giving hope for a permanent end to a problem that affects 600 million people worldwide. US-based Sabin Vaccine Institute, which has developed the vaccine, has called hookworm "one of the most pervasive neglected tropical diseases (NTD) affecting the world’s poor."

Hookworms are aptly named for how nasty they are. The parasites mainly live in the small intestine, feeding from blood leached from the intestine walls they hook into. They can also live in the lungs. Some of the problems associated with a hookworm infection are anemia and nutritional deficiencies and a lack of protein and iron. Small children can suffer worse complications, such as stunted growth and slowed mental development.

The only possible upside might be a link between protecting against asthma and other allergies and hookworms. And whilst far greater attention is now being paid to the importance of gut bacteria in humans the blood leaching hookworms are not really considered the "good" kind.

They are, however, a relatively treatable problem. Getting rid of an infection is not especially difficult; treatments can take only a few days. However prevention is preferable. Hookworm infections are the most common in the tropics and other warmer areas with poorer sanitation. Typically infections occur when the larvae hatch from eggs in feces and travel through the skin and into the bloodstream and then lungs or small intestine and basic prevention methods include wearing shoes when outside and ensuring human defecation is limited to certain areas, so the eggs and hatching larvae are not widely spread.

The vaccine’s active ingredient comes from hookworms themselves, a protein from a common species of adult hookworm. When exposed to it, patients develop antibodies that recognize the protein and can later mobilize against should the body be infected with hookworms at some point.

"Developing lasting solutions for hookworm and other NTDs trapping people in poverty requires comprehensive collaboration, cutting-edge science and leadership among health and policy leaders in endemic countries," Peter Hotez, president of Sabin, has said.

The problem with hookworm is repeat infections, from contaminated water. It is hoped that this drug can be streamed into the nation’s vaccination programs to provide lasting immunity rather than burden the health system with multiple trips to the doctor for free single dose treatments.

Whilst offering hope for the developing world it may still take time. Though Phase 1 clinical trials were completed in August in two cities of the Brazilian state of Minas Gerais, over a period of three and a half years and involving 102 participants, a license may not be forthcoming until 2020. More trials are expected to start in Gabon soon, a nation with a three-in-ten rate of hookworm infection.

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