Scientists have discovered how the Trypanosoma parasite can overcome the body’s natural defences and cause sleeping sickness. The finding may help in the search for drugs to treat the disease in humans, as well as its equivalent in cattle.

“Our findings open up a totally new possibility to develop drugs against the parasite,” says Etienne Pays of the University of Brussels, Belgium, who led the study published today in the journal Nature.

Pays and colleagues have identified a protein present in human blood (apolipoprotein L-1), which usually attacks and destroys the parasite. But the East African and West African disease-causing strains have a molecule called SRA on their surface that disables this protein and makes them resistant to attack.

The researchers say that drugs designed to prevent SRA from binding to this defensive protein would render the parasite powerless against the body's immune response. It might also be possible to produce genetically modified (GM) cattle that are resistant to the animal version of the disease, Naguna.

“Due to Nagana, Africa only produces a fifth of what it could in terms of meat and milk and cattle for agriculture,” say Pays. “Apolipoprotein L-1 is only found in human blood, but if we could develop GM cattle that make apolipopotein, they may be resistant to Naguna.”

Transmitted to humans by the tsetse fly, sleeping sickness threatens over 60 million people in sub-Saharan Africa and is thought to cause half a million deaths every year. Although semi-eradicated in the 1960s, it is now gaining ground, particularly among rural populations who have poor access to medicines.

Link to Nature research paper

Related external links:

US Centers for Disease Control: African Trypanosomiasis
World Health Organisation: sleeping sickness