The lowly mosquito has always been the number one biting pest responsible for transmitting diseases to people. Malaria has been killing people for a long time, but thankfully not in this country. Yet here in the Northeastern U.S., we’ve got West Nile virus (WNV) and Eastern Equine Encephalitis (EEE) to worry about, and our dogs can get dog heartworm from mosquitoes. In other parts of the U.S., chikungunya, dengue fever, and other encephalitis viruses are all mosquito-transmitted diseases of concern.

Now health officials in the southern U.S. are bracing for the introduction of a new mosquito disease, ZIKV, better known as Zika virus. Zika is related to West Nile virus and dengue fever. Most people who get it have very mild or no symptoms at all. Some people have flu-like symptoms and usually recover quickly.

Zika was first discovered in 1947 but wasn’t perceived to be much of a threat until 2007 when its spread throughout Micronesia French Polynesia was connected to a 20-fold increase in cases of Guillain-Barre syndrome, an autoimmune disease of the central nervous system.

A Connection Between Zika Virus and Birth Defects?

Alarm increased in 2015 when Zika appeared in Brazil and nine other countries in Central and South America. The disease spread rapidly in Brazil with 85,000 known infections in its first year. Then things got even stranger as an increase in babies born in Brazil with microcephaly were found to also harbor the Zika virus. Microcephaly is a rare birth defect where the brain doesn’t develop normally. In 2015 in Brazil there was a 10-fold increase in cases of microcephaly. Recently, babies born to Polynesian mothers who tested positive for Zika virus were also found to have unusual nervous system defects. It is believed that when a mosquito infected with Zika virus bites a pregnant woman, she gets the virus (she may not even know it) that then also infects her developing fetus.

There is still no confirmation that Zika virus is the causative agent for these health conditions. But in December 2015, the Pan American Health Organization issued an alert to its member states to take preventive measures and plan for a possible epidemiological crisis. On January 15, 2016, the Centers for Disease Control (CDC) issued an alert advising pregnant women to avoid traveling to Brazil or one of the more than a dozen other countries in South and Central America where Zika transmission has occurred.

We Have the Mosquitoes, But Not Yet the Disease

It is believed that Zika virus is transmitted by the yellow fever mosquito, Aedes aegypti, which is common in the southeastern U.S., the Gulf states, and is found as far north as New York state. Like dengue and chikungunya, Zika transmission is human-to-human and does not involve infected birds like West Nile virus. For this reason, it is hoped that any spread into the U.S. may be slow and controllable. So far, the few U.S. cases have been in travelers returning from infected areas.

This new year may result in a Zika virus outbreak in the U.S., or not. Only time will tell. For more on mosquito-transmitted diseases in our region, see these Colonial blogs:

• Mosquito-Transmitted Diseases on the Increase
• Should I Be Worried About Chikungunya?
• It’s Late Summer…Are Mosquitoes Still a Disease Threat?
• Mosquito Bites Are the Cause of Dog Heartworm