Singapore could become the first dengue-free country in the tropics, according to Verily, Alphabet’s life sciences unit, if the government decides to use its technology citywide to combat the mosquito-borne disease.
Dengue claims 300 million victims each year, with 90 million serious cases and tens of thousands of deaths, most of them children. In Singapore, cases have risen this year, with the average weekly number in early December 20 percent higher than normal, according to the National Environment Agency.
But in some residential neighborhoods where NEA and Verily have conducted field tests, the story is different. Verily’s technology fights dengue Aedes aegypti mosquitoes with the release of others raised in facilities wolbachian–aedes mosquitoes. The NEA has reported up to 98 percent suppression of the Aedes aegypti population and an 88 percent reduction in dengue cases after at least a year of releases under Project Wolbachia, which Truly joined in 2018.
“We could do Singapore the first dengue-free country in the tropics,” said Linus Upson, who runs Verily’s Debug Project out of California and previously worked at Google. “We are making sure that our [island-wide] proposal is scientifically and economically sound. . . and I will make you a proposal [the Singapore government] in the coming months.”
Projects to sterilize insects have been around for decades and Verily has tested the technology elsewhere, such as California, but Singapore’s high density is seen as a particularly ambitious opportunity to test an entire country.
Businesses, including resorts and hotels in hot, tropical locations, could eventually be customers of the technology, though concerns remain about the environmental impact, as insects are pollinators that affect plant growth. There are also questions about whether the poorer governments of Southeast Asia could afford to replicate the project of wealthy Singapore.
Aedes aegypti it is the main vector driving dengue transmission in Singapore and can also transmit yellow fever, chikungunya and Zika viruses.
The key to eradicating it is to use wolbachian — common bacteria that naturally occur in 50 percent of insect species — for suppression. Verily’s highly automated facility in Singapore and a team of scientists, engineers and specialists breed mosquitoes, sort them according to sex and then release the males to mate with wild females. Verily males have wolbachianwhile wild Aedes aegypti females do not, making them incompatible. The females lay eggs, but never hatch.
“The concept is quite interesting because they are adding to the total number of mosquitoes to reduce the population. It has worked here and elsewhere, although we need to determine if the overall benefit is worth the environmental impact and cost,” said a science professor from the city-state, who asked to speak anonymously because it is a government project.
Other projects that do not focus on repression have also been successful. The Global Mosquito Program, which works in 12 countries from Australia to Brazil and Fiji, breeds and releases wolbachian-Mosquitoes infected weekly for a period of up to 20 weeks. After one year, the wild population in the target area becomes infected and the bacteria can block the replication of viruses, including dengue.
“We immunized them effectively,” said Cameron Simmons, director of global implementation for the Global Mosquito Program and director of the Vector-Borne Diseases Institute at Monash University. There were no more and no fewer mosquitoes with the WMP method, he said. Nor was it necessary to repeat it and it did not require large industrial and automated facilities.
The WMP trial in Yogyakarta, Indonesia showed a 77% reduction in dengue cases and an 86% reduction in dengue hospitalizations in wolbachian-treated areas compared to untreated areas.
“High-income countries like Singapore or US states can afford the male mosquito method used by Verily. But in cities like Jakarta, Bangkok or Ho Chi Minh City, both the mosquito and human populations are much higher, making it more difficult and expensive. [That technology] it has not been tested at scale,” added Simmons. “We do not solve the problem of people who are bitten. The mosquitoes are still there, but we solved the health problem”.
Proponents argue that suppression techniques remain cheaper than the cost of public health in the long run. Research by the NEA estimated the economic impact of dengue at between $1 billion and $2.2 billion between 2010 and 2020.
Upson agreed that any interference had an environmental impact, but said the problem of invasive mosquito species like Aedes aegypti — which is not native to Southeast Asia — had become increasingly serious for governments and health systems.
The cost of Verily’s program in Singapore “would be less than the direct costs of dengue care,” he argued.
