Mosquitoes are a public transit system for a variety of disease organisms that attack humans. The newest passenger on the mosquito express is the Zika virus. The Zika virus was originally identified in Uganda, Africa, in 1947. At that time, it seemed to be relatively harmless. Something changed. The virus now has the capability to cause serious birth defects and may cause other problems related to the nervous system. The Zika virus is primarily transmitted to humans by mosquitoes, but, according to the U.S. Centers for Disease Control, it can also be transmitted from an infected man to a woman during intercourse. And it can be acquired from a contaminated blood transfusion.
The female mosquito that carries Zika cannot successfully reproduce unless it ingests nourishment from a warm blooded animal, and that definitely includes those warm blooded animals who read newspapers and websites. The threat of extinction makes a mosquito very aggressive when it is searching for a good meal. Were it not for the need to assign scientific names to mosquitoes, they might have been named Dracula.
Historically, mosquitoes have earned their greatest notoriety for their role in transmitting malaria. Carl Zimmer writing in his book Parasite Rex says that some researchers believe that malaria has killed half of the people who have lived on planet earth. The population explosion during the past century may have changed that equation, but the estimate conveys the importance of both malaria and mosquitoes. Malaria still kills a million people every year.
The United States has many very successful mosquito abatement programs. However, according to the Department of Homeland Security, in a recent year the U.S. Customs and Border Protection service processed 360 million people into the U.S. through air terminals, seaports and land border crossings. That number includes returning U.S. citizens and foreign visitors. We should expect that some people will bring the Zika virus with them when entering the United States. The incubation time is from two to 12 days, and during that time there are no symptoms that the carrier or customs officials would notice.
This summer we will probably learn whether the Zika virus can establish itself in the United States. The primary vector for Zika virus is the Aedes aegypti mosquito. That particular type of mosquito doesn’t need a swamp or marshland. It thrives in towns and cities, depositing its eggs in any small bit of standing water. Aedes aegypti mosquitoes inhabit southern, eastern and mid-western states and part of California.
Scientists are working to develop a vaccine to protect us from the Zika virus, but, even if they succeed, the vaccine won’t be ready this summer. So, if you are where mosquitoes are trolling for dinner, wear protective clothing, use mosquito repellent and use mosquito netting if appropriate.
Jack Stevenson is now retired from military service. He served two years in Vietnam as an infantry officer and worked three years as a U.S. Civil Service employee. He also worked in Egypt as an employee of the former Radio Corporation of America (RCA).