A researcher sits in a laboratory in Indonesia, his arms extended over clear plastic boxes buzzing with mosquitoes: over the next 20 minutes, tiny bumps develop on his skin as the insects bite dozens of times.
The voluntary "feeding", at which researchers take turns, is part of a programme in the city of Yogyakarta to try to eliminate mosquito-borne diseases like dengue fever and - scientists now hope, as concerns mount about its spread across Latin America and the Caribbean - the Zika virus too.
The mosquitoes carry a bacteria called Wolbachia, which scientists introduced in earlier generations, and they will eventually be released to breed with wild mosquitoes.
The bacteria, as it spreads from one insect to another, reduces the chances of the mosquitoes passing the dengue virus on to humans.
Initial findings about the impact of the experiment on the spread of dengue have prompted Indonesian and Australian scientists to scale up this programme to include Zika.
"We already have evidence in our labs that the method that impedes the ability of dengue to grow in the mosquito also works with the Zika virus," Scott O'Neill, director of the Eliminate Dengue Program (EDP) told Reuters, adding that the research is pending reviews from peers in the scientific community.
Much remains unknown about Zika, including whether the virus causes birth defects.
The World Health Organization (WHO) declared the outbreak an international health emergency on Feb. 1, citing a "strongly suspected" relationship between Zika infection in pregnancy to microcephaly, a condition marked by abnormally small head size in babies that can result in developmental problems.
There is no treatment or vaccine and the WHO has recommended limiting people's exposure to mosquitoes.
The number of dengue cases at a test site in Yogyakarta where the bacteria method was used fell from 10 in 2015 to just one this year. However, the method has yet to show conclusive results in the field.
"I don't believe there is a single magic bullet," said Adi Utarini, who heads the research in Indonesia. "The new technology that we bring in is not intended to replace all of the existing activities ... prevention is very important."
Indonesian President Joko Widodo this week urged officials to step up preventive measures like health awareness campaigns and fogging with insecticide. The health ministry issued a travel warning for those planning to visit Latin America.
Funded partially by the Bill and Melinda Gates Foundation, EDP is also testing its methods in Vietnam. It is at the most advanced stage in Indonesia, a tropical country that has the world's second-highest number of annual dengue cases after Brazil.
Under-reported Zika cases
Limited testing capabilities and the usually mild symptoms that accompany the Zika virus have raised concern the number of people infected with the little-known disease may be hugely under-reported in Indonesia, authorities say.
The only known case in recent years was that of a man who tested positive in 2015 and is suspected to have contracted the virus locally, on Sumatra island.
"Systematic surveillance needs to be done to determine the prevalence of Zika and at the moment we might be underestimating the number of cases," said Herawati Sudoyo, deputy director of the government-funded Eijkman Institute in Jakarta, adding the health community in Indonesia is still investigating any links to birth defects.
"The scientific community may have been caught by surprise by this outbreak. We are catching up on learning about this," she added.
The Zika virus has been present in Southeast Asia for decades, but there have been no reported outbreaks. Experts say it is possible people in the region have developed an immunity to the virus, though there is no scientific evidence to support that.
In Yogyakarta, the EDP scientists hope to expand the project to test for both dengue and Zika viruses among 100,000 people this year, a 25-fold increase from their pilot tests.
But challenges remain, they say, including convincing the public the trials are safe and securing funding from the government to take the programme nationwide. It will be at least three years before they see any results in the field.
"The challenge is not necessarily including the Zika virus (in the trial)," said Utarini. "The challenge is scaling up ... which will mean much more work in the field, communicating with the public and getting the community to agree."