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Unexpected sex between parasites

23 Jun. 2011

What we anxiously fear in the influenza virus – a cross between two strains, resulting in a new variant we have no resistance against – has occurred in another pathogen, the Leishmania parasite. This was uncovered by researchers of the Institute of Tropical Medicine (ITG). The new hybrid species might not be more dangerous than their parents, but it’s too early to know. Kenian scientist Samwel Odiwuor receives for his discovery a PhD at ITG and Antwerp University.

After malaria, leishmaniasis is the most deadly parasitic disease in developing countries. It is caused by unicellular organisms, Leishmania, transmitted by small mosquitoes (sand flies) while bloodsucking. Yearly the parasite hits two million people worldwide, of which four thousand in Southern Europe. Most victims are poor. Which means not much research is put into it: developing medicines or diagnostics costs more than it ever could bring in.
Biologically spoken, Leishmania is a remarkable organism. It is one of a few disease-causing organisms to adapt in millions of years of evolution to quite diverse environments, without making use of the normal motor of genetic innovation, sex.
During an innovative genetic analysis of Leishmania parasites from Africa and South America, Samwel Odiwuor discovered vestiges of sex between different species of Leishmania, resulting in new, hybrid varieties of the organism. It still has to be sorted out if the newcomers are ‘better’ at causing disease, as often is the case with hybrids.
If we want to understand how these parasites operate, how they can hide in animals, what they do to a human, which techniques and strategies they use to keep up against our immune system and our medicines (and it looks like they have a few tricks never before seen in biology) – then we will have to understand how they themselves are built and how they work. This research is a considerable step on that long road.