科学美国人60秒:Viruses Hijack the Body's Response to Mosquito Bites

Chances are, you've had the opportunity to study firsthand the swollen, itchy welt left by a mosquito bite. And now—scientists have too. 

"Well, we haven't studied itching yet in our laboratory studies." Clive McKimmie, an immunologist at the University of Leeds, in England. "What we've shown is the inflammation associated with bites is not good for you as a host, and it gives a virus an advantage."

To understand why, let’s back up. To mosquito spit. "Now I know it's a little disgusting to think about, but when a mosquito bites you, they're spitting out quite a bit of saliva into your skin." That saliva can contain viruses, like zika or chikungunya. And viruses—and the tissue damage from the bite—are a rallying cry for the immune system.

McKimmie and his colleagues studied that immune response in mice. And they found that when immune cells show up at the bite the viruses infect them, and turn those immune cells into factories for further virus replication. 

"Your own immune system, which is meant to help your body defend itself against infection, seems to be inadvertently promoting an aspect of a virus infection." 

Overall, the inflammation resulted in 10 times more virus in the mice, compared to being inoculated with the virus without a bite. The study is in the journal Immunity. [Marieke Pingen et al., Host Inflammatory Response to Mosquito Bites Enhances the Severity of Arbovirus Infection]

More viruses means a higher chance they'll infect your organs—and other mosquitoes too. So McKimmie says it might be worth testing a cheap anti-inflammatory—like a topical ibuprofen cream—to see if it cuts virus numbers. "You've got to remember that these infections tend to be present in parts of the world that are economically deprived. And so we can't come up with an expensive new medication, because it's unlikely to be appropriate for that situation." 

The real beauty of this topical treatment approach, though—if it works—is its versatility: it zeroes in not on a specific disease, but that one thing they all have in common: the bite.

—Christopher Intagliata