Antibiotics for worms?

In some African villages, almost all people carry the parasitic worm Mansonella perstans. Recently, scientists discovered that an old and familiar antibiotic can eliminate the little worms - in an indirect way

In some African villages, almost all people carry the parasitic worm Mansonella perstans. It is a persistent parasite that is really hard to kill due to its resistance to the usual drugs in use. Recently, scientists discovered that an old and familiar antibiotic can eliminate the little worms - in an indirect way.

The adult worms settle in the tissue surrounding the lungs, heart and stomach and from there release their offspring into the patient's blood. From the blood, the offspring are taken by a blood-sucking insect (mosquito or fly) and transferred to the next person whom they will bite. So far, the main fight against the disease has been through mosquito control. Now researchers have found another, much more targeted solution.

The worms are full of bacteria called wolbachia, and it turns out that they depend on these bacteria for their livelihood. By killing the bacteria inside the worm, doctors can kill the worms themselves. Killing bacteria is relatively easy, especially in the age of antibiotics. To test the idea, the researchers recruited carriers of the worm from four villages in Mali. The patients were divided into experimental and control groups, with 69 of them receiving a daily dose of antibiotics. After a year only two carriers remained with the worms, the rest recovered. It turns out a success of 97%.

The doxycycline antibiotic they used is the first drug that shows effectiveness in removing the worms from the blood. The parasite was not seen in the blood even three years after the six-week treatment, indicating that the treatment also had an effect on the adult worms living in the tissue surrounding the lungs, heart and stomach. They failed to kill them, but they became inactive.

About 120 million people in the world carry parasites that settle in the periphery of the body. A large part of the worms will disappear after routine treatment with antibiotics of the albendazole and ivermectin types, but the M. Perstans resistance to them. Fortunately the parasite is not as destructive as other nematodes, and it eventually leads to itching, fatigue and skin inflammation.

Using a similar method (killing the bacteria inside the parasite) the researchers were also able to treat river blindness and elephantiasis. Despite the success of the treatments, it still remains to be discovered why the parasite depends on the bacteria. Initial research showed that both creatures lacked several essential genes found in the partner.

A big advantage is that the antibiotics are cheap, less than two dollars for a six-week treatment. Although it sounds like a dizzying success, but it has a thorn in its side - in other parts of Africa, researchers have found such parasitic worms that are able to live without the bacteria, on which the antibiotics are not expected to work. Moreover, widespread flooding of the drug is problematic. This antibiotic has serious side effects on the development of teeth and bones, so it is not allowed for pregnant women or children under the age of 12. Another disadvantage is the obligation to complete all six weeks of treatment, otherwise the treatment fails.

Since the disease does not seriously affect the way of life, it is doubtful whether charitable organizations will direct their efforts to this treatment. On the other hand, the drug may be effective and useful for river blindness, which is a serious injury to the individual's ability to function on his own.

The article was published in the magazine New England Journal of Medicine October 2009.
The idea for the record came from an advertisement on the website Wired Science