The Nobel Prize 2015: The fight against parasitic diseases continues
Artemisinin and Avermectin/Ivermectin – the discoveries that were awarded this year’s Nobel Prize in Medicine or Physiology – have saved millions of lives from malaria, river-blindness and elephantiasis. The fight against the diseases continues – here in Karolinska Institutet’s laboratories too.
A large percentage of the annual 500,000 estimated victims of malaria are babies; older children and adults in malaria-ridden areas have had time to build up an immunity to the disease. Professor Anna Färnert is studying this immunity.
“We’ve shown that people continuously infected with several parasite strains have better immunity against the disease. This suggests that a future malaria vaccine should contain several components if it is to provide decent protection.”
Färnet’s clinical research in Sweden has changed the medical view of immunity to severe malaria. It is not, as once though, permanent.
“Patients originally from Africa but who have lived for a long time in other parts of the world lose this protection,” she says.
Ambitious moves against malaria
Senior professor Anders Björkman has been researching malaria since the 1980s. One of his research tracks is Zanzibar, off the coast of Tanzania, where ambitious moves against malaria have long been in progress.
“We’re dealing with a combination of Artemisinin, impregnated mosquito net and other measures,” he says. “One and a half million people live on these islands and these efforts have reduced the incidence of malaria by 97 per cent.”
Professor Akira Kaneko is also interested in islands, and has managed to make and keep the Pacific island of Aneityum, with its 700-strong population, entirely malaria-free. He now intends to repeat her successes in Lake Victoria.
“We’re looking at four islands and part of the mainland,” he says. “We’ll be launching a pilot study on a small island in January with a combination of measures, including drug therapy, for all 60,000 people in the area. Population mobility will bring new cases into the area, but we hope our strategy will bring the incidence of the disease down from 30 per cent to less than 1 per cent in four years.”
Resistence a serious concern
All these malaria researchers share a serious concern about the growing resistance to artemisinin. Pedro Gil is one of many devoting his research to this threat.
“We’re researching the molecular mechanisms behind resistance in order to find optimal combinations of drugs for this,” he says. “We hope to find combinations of components that the parasite won’t be able to develop comprehensive resistance to; in other words, to put it in a Catch 22 situation – develop a resistance to A and be attacked by B, or vice versa. We’re planning clinical trials in Mali for next year.”
Another way of dealing with the effects of resistance is to develop new drugs.
“We’ve produced a candidate called Sevuparin, which operates according to a new principle: blocking a receptor to prevent the parasite from entering the red blood cells,” explains Professor Mats Wahlgren. “We’ve recently completed a phase I/II study and have just sent the results in for publishing.”
Countries will be free from the diseases
Resistance can also become a problem for the antiparasitic drug Ivermectin, says researcher Susanne Nylén.
“There are no clear indications of resistant parasites in humans yet, but there are in livestock,” she says. “But then again, Ivermectin is used much more for animals, so the pressure to develop resistance has been much greater there.”
So far, she notes, Ivermectin has been a very successful weapon in the battle against river blindness and lymphatic filariasis (elephantiasis): many countries are, or will soon be, free from the diseases, which might eventually be eradicated completely.
Malaria, however, is much harder to combat.
“We aim to have completely eradicated the disease by 2050, which is an enormous undertaking,” says Professor Mats Wahlgren.
Text: Anders Nilsson