As cities worldwide scramble to avoid a Zika virus epidemic this summer, doctors are also working around the clock to find a cure.
But what if physicians could treat not only Zika, but also other mosquito-borne diseases including West Nile virus (which kill over a million people every year) in one fell swoop? A recent mosquito study in England shows a potential first step toward this widespread remedy.
Dr. Clive McKimmie, an immunologist at the University of Leeds, led a team examining the effects of arboviruses (viruses transmitted by mosquitoes) for a study published in the journal Immunity. While researchers have already determined that arboviruses replicate and disseminate more effectively to the blood, the Leeds team wanted to find out why this occurs.
“We know very little about what happens at the very beginning of the disease process,” Dr. McKimmie told the Observer.
To rectify this, doctors infected mice with a strain of the Semliki Forest virus, a relative of chikungunya which causes fever and joint pain in humans. When the virus was injected into the skin with a needle, none of the mice got very sick, and all survived. But when they received the strain through a bite from an infected mosquito, it spread faster through the rest of the body—four of 11 mice died from the virus.
“The mosquito bite enhances the infection,” Dr. McKimmie said. “The inflammation at the bite site helps the virus through the whole process—both the external swelling and internal factors like immune response.”
One of the main reasons for this is the infected insect’s spit— the saliva triggers inflammation as a warning that the body’s defenses have been breached, but this inflammation also keeps the blood from clotting. So instead of stopping the infection, white blood cells and other bodily defense mechanisms are infected themselves, spreading the disease further and increasing the severity.
Now that the effects of these mosquito-borne infections are clearer, Dr. McKimmie wants to find a way to contain them.
“If we can interfere with that process and block the inflammation, the virus will have no cells to replicate,” he said. “We can boost the antiviral response while suppressing the bite response.”
Any potential remedy could help treat a wide variety of arboviruses, according to Dr. McKimmie.
“Diseases like Zika and West Nile all have bite inflammation in common,” he said. “The bites define the severity of the disease, so potentially you only need to target one thing. One medicine could suppress bite inflammation for a variety of different viruses. Each virus looks very different, but it may not require its own antiviral medication.”
This cure is not imminent—Dr. McKimmie said anyone going outside this summer should still take precautions like using insect repellent and taking anti-inflammatory drugs to dull the effects of mosquito bites, in case the bugs are carrying disease.
But he also expressed hope that his team’s early experiments show a possible method to keep arboviruses from spreading.
“What we’ve identified is a potential target which could suppress inflammation in the skin and stop the virus from gaining a foothold in the body,” Dr. McKimmie concluded
