A team of scientists based in Ireland has made a potentially significant advance in the fight against a parasite which kills tens of thousands of people around the world each year and makes hundreds of millions sick.
The group found that infection levels from the intestinal roundworm, Ascaris lumbricoides, differ depending on the type of proteins they are exposed to in the liver.
The researchers think this discovery may in time assist with the development of a preventative treatment against Ascaris.
The parasite infects around a billion people globally each year, and is thought to play a role in around 60,000 deaths, mostly in the developing world.
The damage done by the worm includes growth retardation, and impaired cognitive development.
Ascaris infection is treatable, but individuals who have overcome the infection naturally or with the help of drugs do not develop resistance and can be easily re-infected.
The study, published in the journal PLoS Neglected Tropical Diseases, was led by biology lecturer Dr James Carolan, from Maynooth University, and Professor of Zoology Celia Holland, from Trinity College Dublin, as well as collaborators from Queen Mary University in London.
The scientists built on earlier research which found that among susceptible and resistant groups of mice, Ascaris severity varies considerably, with the difference in that vulnerability first becoming evident in the infected mice’s livers.
If resistant mice are infected with Ascaris, they show an earlier immune response and more speedy tissue repair in the liver than mice which are susceptible that have been infected with a similar number of eggs.
By examining in detail the range of proteins in the livers of both sets of mice, the scientists were able to identify substantial differences between the two strains, including when Ascaris eggs were not even present.
The findings around host resistance lay out a pathway for potential future research, which could in time lead to preventative medicines against the parasite.
Hookworm infection, also known as hookworm disease, is an infection by a parasitic bloodsucking roundworm. Hookworm infections include ancylostomiasis and necatoriasis.
These worms live in the small intestine of their host, which may be a bird or a mammal such as a dog, cat, or human. Hookworm infection in pregnancy can cause retarded growth of the fetus, premature birth and a low birth weight. Hookworms in children can cause intellectual, cognitive and growth problems.
Two species of hookworms commonly infect humans: Ancylostoma duodenale and Necator americanus.
A. duodenale predominates in the Middle East, North Africa, India and (formerly) in southern Europe, while N. americanus predominates in the Americas, Sub-Saharan Africa, Southeast Asia, China, and Indonesia.
A. tubaeforme infects cats, A. caninum infects dogs and A. braziliense and Uncinaria stenocephala infect both cats and dogs.
Hookworms are much smaller than the giant roundworms Ascaris lumbricoides and so cause less tissue damage and obstruction.
The most significant risk of hookworm infection is anemia, secondary to loss of iron (and protein) in the gut. The worms suck blood voraciously and damage the mucosa. However, the blood loss in the stools is not visibly apparent.