People at high risk of contracting malaria might be protected by taking a combination of simple, inexpensive antibiotics. That is the finding of a new study by researchers who say the drugs rally the body's immune system against the mosquito-borne parasite.
Malaria infects an estimated three million people around the world each year and causes as many as one million deaths - most of them children in sub-Saharan Africa.
So far, experimental vaccines offer only partial protection against malaria, which causes high fever, chills, body aches and at worst, brain complications leading to death.
But a team of researchers has found that a combination of two widely available and inexpensive antibiotics - clindamycin and azithromycin - provided laboratory mice with protection against the parasitic illness.
Researchers say the antibiotic cocktail, given once a week at the height of malaria season, has the potential to protect people living in endemic areas and may even offer life-long protection the same way a vaccine would.
Steffen Borrmann is with the Heidelberg University School of Medicine in Germany and the Kenya Medical Research Institute in Kilifi.
"Here we would only give a drug periodically, as in peak transmission seasons in malaria endemic areas," said Steffen Borrmann. "And the hope is that this would generate protection for subsequent reinfections."
The antibiotics stimulate a strong protective immune response against the malaria parasite while it is in the liver of an infected individual, the symptomless first stage in the parasite's life cycle.
Borrmann says the immune reaction causes cellular changes that make it impossible for parasitic spores released into the bloodstream to infect red blood cells, the second stage of the life-cycle that causes life-threatening malaria symptoms.
The parasite then dies because it cannot infect the red blood cells it needs for sustenance.
Borrmann says that in an experiment with mice, those treated with antibiotics were protected when scientists exposed them to the parasite.
"It prevented [the conversion] to the pathogenic [the symptomatic] blood stage," he said. "That's the one thing that's been known for some time. We have established that this is the mode of action. But secondly, for subsequent reinfections again via the mosquito route, the animals are protected."
Borrmann says he is not concerned that frequent and widespread use of the antibiotics, including azithromycin, might lead to drug resistant strains of malaria. He points to the use of the drug in the treatment of trachoma, a serious bacterial infection of the eye.
"So far, when, for instance, azithromycin has been used for mass treatment of trachoma in African countries over a year, there wasn't any evidence for the emergence of bacterial resistance," said Borrmann. "But that has yet to be seen, of course. That will be seen as part of one of the first clinical studies."
Borrmann says the trials could begin almost immediately because the drugs are easily available at very little cost.
The study demonstrating antibiotic protection against malaria is published in the journal Science Translational Medicine.