Attacking parasitic worms to cure tropical diseases

Parasitic worms, seen here, cause river blindness when transmitted to humans by flies

Researchers are developing new drug treatments to tackle river blindness and elephantiasis, which affect up to 150 million people across the world.

New funding from the Global Health Innovative Technology Fund will allow scientists from the University of Liverpool’s Department of Chemistry, together with colleagues at the Liverpool School of Tropical Medicine and Japanese pharmaceutical company, Eisai, to develop new medication which is targeted at the bacteria Wolbachia.

Parasitic worms

River blindness (onchocerciasis) and elephantiasis (lymphatic filariasis) are caused by parasitic worms, and previous attempts to cure these diseases have focused on developing drugs to kill these parasites.

Left untreated, river blindness, where the worms are transmitted by flies, can leave people robbed of their sight, whereas elephantiasis, transmitted by mosquitos, causes extreme swelling in the limbs and genitals.

However, killing the worms too suddenly can cause serious side-effects, so the research team has developed drugs which kill Wolbachia – a bacteria which lives in the worms in symbiosis and without which they cannot survive.

Attacking these bacteria causes the worms to die slowly or become sterile.  The team, known as the Anti-Wolbachia Consortium (A.WOL), has already shown that a four to six week course of the antibiotic, doxycycline can deplete Wolbachia from parasitic worms to cure infection, which has led to the adoption of this treatment in many areas of the world.

The new funding will allow the creation of drugs which can be used in children and pregnant women and can be effective over the course of a week.

Pre-clinical testing

The development of the new drugs was achieved by screening over 60,000 compounds to test their ability to kill Wolbachia. With the new funding, the most promising drug candidates will proceed through advanced rounds of chemical modification and testing to identify compounds that have a good safety and efficacy profiles, ready to move into pre-clinical testing.

Medicinal chemist, Professor Paul O’Neill from the University said: “The relationship between these worms and the bacteria is their weakness.

“By targeting the Wolbachia we can safely remove the worms and the disease, and with a quicker acting drug, we can also develop a medicine which is more useful in areas where resources are scarcer and budgets tighter.”