Mosquitoes love sugar the way kids love candy. Scientists mixed a drug into a sugar solution that stops the virus from multiplying inside a mosquito. When such a mosquito bites a person, there's too little virus in its saliva to cause an infection.
In the lab, Aedes aegypti mosquitoes, which carry dengue and chikungunya fevers, were given sweet water with the drug. Some were fed before infection, others after. Two weeks later, it turned out that bait with the drug JNJ-A07 cut dengue infection from 87% to 3%, while bait with 4'-fluorouridine reduced the amount of chikungunya virus in a mosquito's body hundreds of times over.
This method doesn't kill mosquitoes, so they don't develop resistance the way they do to poisons. The next step is to check whether mosquitoes in the wild will drink such bait just as readily when there are plenty of other sugar sources around.
Aedes aegypti mosquitoes live about 27 days at 28°C, so in the 30-day survival experiment, a significant portion of mortality was natural rather than caused by the drugs.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.