The Zika virus has gotten a lot of press in recent months. As the suspected culprit for an unusual increase in microcephaly in Brazil's newborns, the mosquito-borne disease is now in the cross-hairs of physicians, public-health experts and scientists across the globe.
But Zika isn't the only tropical virus now arriving on new shores. As Stanford infectious disease expert Desiree LaBeaud, MD, explains in an article in this month's issue of Infectious Diseases in Children, several other diseases transmitted by mosquitoes are also making an appearance outside their usual locales, and global warming may be part of the problem:
“The world is warming,” LaBeaud said. “We have a lot of very good habitats for this vector —Aedes aegypti — so if people travel knowingly or unknowingly with the virus, they are then able to infect vectors in the new place they arrive. Also, just the fact that the world has become more urban facilitates this. Aedes aegypti has evolved with us for centuries. They are a very urban mosquito that likes to live in and around our human habitations. It is a perfect storm for these types of infections to emerge.”
An alarming component of this story, she goes on to explain, is that while Zika appears to be very damaging for babies infected in utero, it causes relatively few problems in those who aren't pregnant. The other tropical diseases now on the move are far worse:
“Zika is almost like a ‘dengue light,’ ” LaBeaud said. “It results in fever that isn’t that high for a few days, an itchy red rash, red eyes — and usually people get better within about a week. Dengue can cause an infection that presents in the same way, but patients can progress to severe dengue, which can result in vascular leak, hemorrhagic disease and shock. Dengue is called “break bone fever” because it can cause such severe myalgia and bone pain. But unlike dengue and Zika, the acute febrile illness caused by chikungunya is often manifested by arthritis and arthralgia and sometimes that’s the tip-off. Unfortunately, with chikungunya, patients can end up with severe arthritis or arthralgia for several years after the acute onset disease is finished.”
LaBeaud hopes the Zika outbreak will lead to sustained research attention for tropical diseases:
“Right now a lot of effort is focused on this infection,” LaBeaud said. “Usually these infections seem so far away, and then all of a sudden, they are at your backdoor, and people are always surprised that we don’t know everything about them.”