A common organic pesticide could do double duty as a cure for intestinal worms, and drag hundreds of millions of people out of poverty – provided cash can be found for human trials.
More than 1 billion people, almost all of them living below the World Bank's poverty line of $1.25 a day, are plagued by nematodes. While the worms don't usually kill, they stunt growth, cause anaemia and impair cognitive development.
All this helps to "trap the 'bottom billion' in poverty", says Peter Hotez, a specialist in tropical diseases at George Washington University in Washington DC. Existing treatments don't work well on all types of worms – and resistance is emerging.
Now Raffi Aroian at the University of California, San Diego, and colleagues have shown that the protein Cry5B, produced by the bacterium Bacillus thuringiensis and used as a crop pesticide, could act as an effective drug. An oral dose cleared around 70 per cent of the worms from infected mice.
Molecule for molecule, Cry5B is about three times as effective as tribendimidine, the other leading drug in development. And Aroian is confident of obtaining better results still.
Cry5B is largely broken down in the stomach before reaching the intestine, so his team is now working with SRI International of Menlo Park, California, to develop coatings to protect the drug from stomach acids and get higher doses to the intestine where the worms live.
The protein is known to be safe – it is one of the few pesticides used by organic farmers. The main obstacle is a dearth of funding to push the drug through human trials and begin mass treatment in the world's poorest countries. "If we don't get money this year, we will have to stop the project," Aroian warns.
Even the Drugs for Neglected Diseases initiative, launched by Médicines Sans Frontières and other partners in 2003, has not yet made intestinal worms a priority. Instead, it is concentrating on killers including malaria and sleeping sickness. "Somebody's got to step into this space," says Hotez.