Bayer drug raises hope for 1.5bn people with worm diseases

More than 1.5 billion people around the world are infected with soil-transmitted helminths (STHs), parasitic worms that damage their health and are a leading cause of malnutrition in children.

While drugs such as albendazole, mebendazole, and ivermectin are available to treat STH infections, cure rates are not high, particularly for whipworm (Trichuris trichiura). Moreover, both access to and compliance with treatment can be patchy, and resistance has started to emerge.

Now, a new therapy developed by Bayer has shown greatly improved efficacy against whipworm as well as hookworm (Ancylostoma duodenale and Necator americanus) infections in phase 2 trials, and the drugmaker has joined forces with Switzerland’s Public Health Institute (Swiss TPH) to carry out large-scale efficacy studies.

Bayer’s drug – called emodepside – is already marketed as a treatment for parasitic veterinary infections and is also under development for river blindness (onchocerciasis) in humans.

In a pair of phase 2a studies carried out by Swiss TPH on the Tanzanian island of Pemba in the Indian Ocean, a single oral dose of emodepside was able to cure 83% to 92% of whipworm infections, while the cure rate in a placebo group was 10%.

Treatment with albendazole – which has to be taken over three days – only achieved a cure rate of 17% in the study, although it is known to be less effective for this infection than mebendazole, which has historical cure rates of 40% to 75%.

“Such a high cure rate of patients infected with whipworm has not been observed so far with the current anthelminthic drugs,” according to Swiss TPH’s Professor Jennifer Keiser, principal investigator of the study.

For hookworm, emodepside had a curate of 32% at the lowest dose (5mg) and 95% at the highest dose (15mg), compared to 14% for placebo and 70% with albendazole.

STH infections are transmitted by eggs present in human faeces, which contaminate the soil in areas where sanitation is poor, with the highest prevalence reported from sub-Saharan Africa, Asia, and South America.

Transmission occurs either when eggs are ingested or larvae penetrate the skin – for example, when walking barefoot – and the worms feed on host tissues, impairing the nutritional status of patients.

Heavy infestations can cause diarrhoea and abdominal pain, malnutrition, malaise and weakness, and in children can impair their growth and physical development. In severe cases, it can even cause blockages in the intestine that may require surgery.

While major programmes are already in place to provide treatments to areas where STHs are common, the World Health Organization (WHO) has said that there is a pressing need to reduce the number of tablets needed to prevent and treat infections.

Public domain image from CDC Public Health Image Library via Wikimedia.