New sleeping sickness drug hope

British scientists have discovered a new way of tackling the fatal parasitic disease African sleeping sickness which they say could pave the way for the development of safe, effective drugs to treat it.

The scientists, whose study was published in the journal Nature, said new drugs could be ready for human clinical trials in around 18 months.

"This is one of the most significant findings made in recent years in terms of drug discovery and development for neglected diseases," said Professor Paul Wyatt, director of the Drug Discovery for Tropical Diseases programme at Dundee University, who led the research.

The World Health Organisation estimates that between 50 000 and 70 000 people in sub-Saharan Africa are infected with the sleeping sickness, or human African trypanosomiasis (HAT), which is spread by the bite of the tsetse fly. Left untreated, it is usually fatal.

Wyatt said his team had discovered a compound that disrupts an enzyme called N-myristoyl transferase, or NMT, which is essential for the survival and growth of the parasites injected into the victim by the tsetse fly's bite.

Their study showed this NMT-inhibitor compound leads to rapid killing of trypanosomes in laboratory tests and cures trypanosomiasis in mice.

Sleeping sickness often deadly

The disease, called sleeping sickness because of the disruption to the sleep cycle caused by parasites infecting the brain, has two stages, the second of which begins when the parasites have penetrated the central nervous system.

The second stage is particularly difficult to treat in poor rural areas where many victims live, the scientists said.

Of the two drugs currently available, one - based on arsenic - has fatal side effects in around one in 20 patients, and the other, eflornithine from Sanofi Aventis, requires prolonged hospital treatment and is not effective against all forms of the disease.

Research offers treatment hope

Increasing reports of treatment failures with these drugs have raised fears that soon there may be no effective treatment. Wyatt said he hoped his team's research would change that.

"We now have a valid drug target for HAT and have found leads for drugs which can be dosed orally. These two findings represent significant strides in the development of a full-blown drug against sleeping sickness suitable for clinical trials."

African sleeping sickness is one of a group known as "neglected tropical diseases" which often struggle to attract research attention from large pharmaceutical firms.

These firms fear investment in research will not pay off as most sufferers live in poor countries and cannot afford to buy expensive medicines.

GlaxoSmithKline, Merck & Co, Pfizer and others recently announced new initiatives involving collaborating more closely in the search for treatments for neglected diseases. - (Reuters Health, April 2010)