NZ research targets lungs for hookworm immunity

New Zealand researchers say they have made a breakthrough that could lead to a vaccine against hookworm, a parasite that plagues an estimated one billion people worldwide.

Their work shows the lungs are the key organ to target in efforts to provide immunity to the gut parasite.

Once in a host, hookworms suck blood voraciously from the walls of the small intestine, causing significant risk of anaemia, a decrease in red blood cells, and loss of iron and protein in the gut.

In developing countries hookworm is a leading cause of maternal and child fatalities and can cause intellectual retardation, premature births and low birth weight.

"There is an urgent need to identify the immune mechanisms that can protect against hookworm infection," said Malaghan Institute director Graham Le Gros.

Prof Le Gros said current controls for hookworm required frequent drenching with antihelminthic drugs in school-age children, but high rates of re-infection occurred soon after treatment and there was evidence of emerging drug resistance.

"Vaccination is currently viewed as the only long-term solution for reducing the enormous burden this disease imposes on developing countries,"  Prof Le Gros said.

The hookworm which affects humans is not found in New Zealand.

Malaghan researcher Marina Harvie - who did the study as part of her PhD thesis - found that the lungs were the critical site for establishing immunity against hookworm, and the team's work has just been accepted for publication in the international scientific journal "Infection and Immunity".

"Our findings imply that for a vaccine to be effective it must target the immune cells resident in the lung and stimulate a specific kind of immune response that we have not yet discovered," Prof Le Gros said.

He said the work was "intimately related" with the institute's separate work on asthma, which is known as a type of inflammatory response that can be affected by a natural infection.

The New Zealand researchers have been working with a related parasite, Nippostrongylus brasiliensis, which attacks rats, but is less infectious than human hookworms.

Scientists have noted there is usually little asthma in regions where hookworms thrive and they have also found that in a tropical African country, The Gabon, schoolchildren infected with parasitic worms have a lower allergic responses to house dust mites than children with no worms.

"It's fascinating that there is such strong connection and that we don't have a clue what it is which connects the two phenomena," Prof Le Gros said.

Mali Camberis, a senior scientist involved in the research for over a decade, said that if scientists could understand what was happening in the simpler rodent parasites, there would be scope to applying the knowledge to the human hookworms.