Antimalarial plant ‘kills worms that cause bilharzia’

[BEIJING] Chinese scientists say a derivative of the shrub Chinese wormwood (Artemisia annua) can prevent and treat bilharzia — a disease caused by parasitic worms called schistosomes.

The scientists say the compound could help tackle the growing problem of parasite resistance to current drugs.

According to lead researcher Li Chuan of the Shanghai Institute of Materia Medica, experiments in the laboratory and on animals showed that the compound can kill both juvenile and adult schistosomes and is harmless to mammals.

The compound, called SM618, works by disrupting the schistosome’s metabolism, says Li.

Different forms of bilharzia — also known as schistosomiasis — occur throughout the tropics. Together, they kill 15,000 people each year, according to the World Health Organization.

The disease is caused by five species of worm that enter humans through their skin as juveniles, then mature and reproduce in the blood vessels. The worm eggs are usually evacuated from the body in urine or stools but some remain in the body leading to disease symptoms, which include damage to the kidneys, spleen and bladder.

Until now, the main drug used to treat bilharzia has been praziquantel. But Li says “it is quite urgent for us to find alternatives” because after 30 years of praziquantel use, there is evidence that some parasites are becoming resistant to it.

Li says that while praziquantel kills only adult schistosomes, tests on infected rats showed that SM618 also kills juveniles.  

He adds that the production of SM618 should pose fewer risks to health or the environment than praziquantel manufacture, which involves using toxic chemicals such as potassium cyanide.

The researchers are now testing the compound on rabbits and dogs. Li says the animal research should be finished by the end of this year, and an application for clinical trials in people will be submitted to China’s State Food and Drug Administration (SFDA) early next year.

Although the compound itself has been patented, Li’s team need to secure other patents, such as one for the production technique, to protect their intellectual property rights before publishing their findings.

“We have prepared large amounts of data, and once the clinical trial is approved, we will publish them both domestically and internationally,” said Li.

Li Ying, who began the Institute of Materia Medica’s research on SM618 nearly 30 years ago, says some drug manufacturers showed initial interest in investing in it after arthemeter, also derived from Chinese wormwood, proved lucrative when the World Health Organization recommended using it to treat malaria.

But, says Li, because bilharzia is a disease mostly affecting the poorest in China, the drug companies lost interest in investing.

“This has greatly delayed the research process,” says Li Ying, adding that the current studies are funded by the state and the institute’s own money.

Bilharzia has spread rapidly in China in recent years. About one million Chinese are infected with the schistosome parasite and 50 million live in areas where the disease is common.