Researchers have developed a novel drug with the potential to kill a bacterium causing two of the most neglected tropical diseases that lead to blindness and severe disability and affect over 157 million people globally.

River blindness is a disease caused by a parasitic worm -- Onchocerca volvulus -- that affects the skin and eyes of people leading generally to blindness, while elephantiasis refers to a parasitic infection that causes extreme swelling in the arms and legs. 

The team from the University of Liverpool in Britain showed that the drug called AWZ1066S is based on a molecule and is effective in killing Wolbachia the bacterium, which is behind the diseases. Elephantiasis is caused by a Wolbachia-dependent parasitic worm similar to the one that causes river blindness. Thus, a cure for one could result in a cure for the other.

The new drug which can be taken orally, does not upset the gut biome and also shortened the time-scale of treatment from weeks to days, as against antibiotics which is a long treatment process, lasting up to six weeks, the researchers said.

"Our team has already shown that removing the bacteria with antibiotics results in the death of the worm, but until now we were unaware of how the bacteria protected the parasite in the first instance," said Ben Makepeace, lecturer from the varsity. 

The team found that Wolbachia bacteria inside the worm acts as a "disguise" for the parasite, resulting in the immune system reacting to it in an ineffective way. The bacteria protect the worm from the body's natural defences, but once the bacteria are removed with antibiotics, the immune system responds appropriately, releasing cells, called eosinophils, that kill the worm.

The findings, published in the journal Proceedings of the National Academy of Sciences, showed that AWZ1066S has a faster kill rate compared with other known antibiotics tested against Wolbachia in vitro. It can achieve maximum reduction of Wolbachia just after a day of drug exposure compared with the other antibiotics tested.

Currently, there is no vaccine for river blindness, but if a candidate could be identified this may help boost the immune system ahead of antibiotic treatment and reduce the length of time patients have to take the drug, Makepeace said.