A well-known medicine for animal health could stop the epidemics of malaria and Zika virus

04 July 2018

Medications given to pets to kill fleas and ticks could be effective in preventing epidemics of malaria, zika fever and other insect-borne diseases that infect millions of people around the world. by scientists at Calibr, a nonprofit drug research institute closely affiliated with Scripps Research and TropIQ Health Sciences, a Dutch social enterprise.

The researchers discovered a class of drugs called isoxazolines, sold in veterinary products such as fluvan. ) and afoxolaner (NexGard) to protect animals against fleas and ticks, and also kill disease-carrying mosquito species that feed on human blood.

The research team, led by Koen Dechering of TropIQ, Ph.D. and Matt Tremblay, Ph.D., of Calibr, have determined through experimental studies on mosquitoes and computer modeling that they are the only ones in the world. by administering isoxazolines to less than one-third of the population in regions prone to seasonal epidemics of insect-borne diseases, up to 97% cases of infection. The results of the study were published today in the Proceedings of the National Academy of Sciences .

"Infectious insect-borne diseases remain the leading causes of serious illness and death worldwide. these diseases are essential, "said Peter Schultz, Ph.D., chief executive officer of Calibr and Scripps Research. "Our results suggest that isoxazolines may be effective in controlling outbreaks of mosquito and other insect-borne diseases in areas with limited medical infrastructure."

Millions of people contract each year malaria, zika fever and other insect-borne diseases. prevalent in tropical and subtropical regions. In 2016, about 216 million people became infected with malaria worldwide and 445,000 died of the disease (mainly children in the African Region), according to the US Centers for Disease Control. Zika, a mosquito-borne disease that can cause birth defects in infants born to infected mothers, has spread rapidly around the planet in recent years and is now found in 90 countries.

Mosquitoes are not the only vectors of these diseases. Leishmaniasis, caused by protozoan parasites transmitted by sandflies, is endemic in parts of Africa, South America, the Middle East, and India. Although less common than malaria, forms of leishmaniasis that affect internal organs can be fatal if left untreated.

"Research on insect-borne diseases focuses primarily on the control of insect populations., But these approaches have not been fully effective in controlling outbreaks," said Koen Dechering , CEO of TropIQ Health Sciences. "Vaccines are largely lacking for most diseases and drugs to treat people who have contracted the disease lose their effectiveness due to emerging resistance."

The Research Team International is studying a new strategy, the possibility of administering isoxazolines by insect vectors.Isoxazolines are sold in veterinary products such as fluralaner (Bravecto) and afoxolaner (NexGard) that protect animals from fleas and ticks.

When administered orally, drugs absorb blood circulation and spread throughout the body. Three months, although well tolerated in dogs and cats, drugs kill blood-sucking fleas and ticks that feed on the blood of treated animals by damaging the nervous system of insects.

Scientists Calibr and TropIQ and their collaborators tested two drugs, fluralaner and afoxolaner, and discovered that they were also killing disease-carrying mosquito and sandfly species that were feeding on human blood infused with insecticides. . The drugs have also been effective against insect strains resistant to common insecticides.

Based on existing data from animal drug studies, the researchers estimated that a single human dose of drugs would have an insecticidal effect against mosquitoes and sand. "In many areas where seasonal epidemics are endemic, the medical infrastructure is such that the delivery of medical care is intermittent," said Matt Tremblay, PhD, chief operating officer of Calibr and Scripps. Research and a senior author on PNAS paper. "Isoxazolines can be administered before the onset of seasonal outbreaks to provide protection until the threat decreases at the end of the season."

Drugs may not work as vaccines because a person being treated can still contract a disease. insect bite. But an insect biting an infected person who takes the drugs would die before he could pass the disease on to other people, an effect that, when multiplied over a large population, would reduce the total number of people who were sick. ; infections.

College London, UK, the team of researchers used models of computer epidemiology to estimate that giving drugs to only 30% of the population in an area where fever Zika is common could prevent more than 97% of cases. With regard to the incidence of malaria, their modeling has shown that in areas with low seasonal transmission, such as Senegal, Sudan, Madagascar, Namibia, Botswana and Zimbabwe, 30% of the isoxazolines could prevent more 70% of infections. 19659003] Regions with more cases and year-round outbreaks will see a smaller percentage reduction, but the overall reduction in these areas could be dramatic. The Democratic Republic of Congo has, for example, between 16 and 20 million malaria cases a year, so a 30 percent reduction would prevent up to 6 million cases.

According to safety studies on the use of isoxazoline in animals, the drugs have a good chance of being safe if re-used for human use . The research team plans to evaluate the effectiveness of drugs in humans and predicts that these studies will take about two years.