Government doctors have started testing a vaccine designed to protect against all diseases spread by mosquitoes, from Zika to malaria and yellow fever.

The vaccine targets mosquito saliva in the hope that the body could push back against the bite and stop viruses or parasites from getting a foothold and starting an infection.

Mosquito-borne diseases kill hundreds of thousands of people every year. Malaria killed 438,000 people in 2015, according to the World Health Organization.

Mosquitoes spread viruses including Zika, yellow fever, dengue, West Nile virus, chikungunya and Japanese encephalitis.

There’s a good yellow fever vaccine, but it’s in short supply. And the same mosquitoes that spread yellow fever spread Zika, dengue and other viruses. Malaria spreads in many of the same regions, although it’s carried by different mosquitoes.

“Mosquitoes cause more human disease and death than any other animal,” said Dr. Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases, part of the National Institutes of Health.

“A single vaccine capable of protecting against the scourge of mosquito-borne diseases is a novel concept that, if proven successful, would be a monumental public health advance.”

The team at NIAID is starting a phase 1 trial, the earliest step in human tests, of the vaccine. It’s meant to show mainly that the vaccine is safe. If it is, the vaccine will be tested in more people to see whether it works.

The vaccine, called AGS-v, is being developed by Imutex Ltd., a joint venture of London-based pharmaceutical company SEEK and a company called hVIVO.

“The test vaccine contains four synthetic proteins from mosquito salivary glands,” NIH said.

“The proteins are designed to induce antibodies in a vaccinated individual and to cause a modified allergic response that can prevent infection when a person is bitten by a disease-carrying mosquito.”

Mosquito saliva carries chemicals to help stop blood from clotting and to open up tiny blood vessels. It stimulates an immune response, and the vaccine is designed to take advantage of that.

The NIH team will recruit human volunteers to get either two doses of the vaccine or a placebo. They’ll then have to show up again to be bitten by mosquitoes to see whether their bodies respond differently to the bites after vaccination.

“The mosquitoes will not be carrying viruses or parasites, so the participants are not at risk of becoming infected with a mosquito-borne disease,” NIH said in the statement.

“Investigators also will examine the mosquitoes after the feeding to assess any changes to their life cycle,” it added.

“Scientists suspect that the mosquitoes who take a blood meal from ASG-v-vaccinated participants may have altered behavior that could lead to early death or a reduced ability to reproduce. This would indicate that the experimental vaccine could also hinder disease transmission by controlling the mosquito population.”