Zika Virus Mosquitos Expected in United States


An outbreak of Zika virus in the United States is "likely imminent," according to a report by the Washington Post this week. To date, about a dozen cases have been reported in the United States, and none are believed to be from local infections. Those infected had been traveling in countries where the virus is currently being spread. 

The mosquito-borne virus is moving northward from South-American and Mexican zones of infection. The warning that the spread is expected in areas of the United States was issued by the World Health Organization, which expects all countries of the Americas except for Canada and Chile to ultimately be affected.

Transmission of Zika is primarily through the bite of an infected Aedes species of mosquito. Aedes is also the "vector" in the spread of dengue and chickunguya viruses of recent concern. Zika can cause symptoms ranging from no noted illness to flu-like symptoms. However the tragic secondary effect is that it can cause brain damage to the unborn children of infected mothers. Numerous cases of such effects have been reported in South America.

Because four in five infected adults do not become noticeably ill, it would be easy for a mother to have the Zika virus, which generally only lives for a few days in the bloodstream after a week or less incubation period, and not know she had been infected.  

There is also a very limited body of information supporting possible rare transmissions through sexual contact and blood transfusion. More research and cases are needed to know if these are actual routes of infection.


Two prominent means of disease spread are by vector and by fomite. A vector is a living organism such as a mosquito that takes blood or other fluids from an infected organism to another, which in-turn becomes infected. This is the case for the Zika virus. A fomite is a place where germs - viruses or bacteria - can be transferred, and then picked up later. A doorknob, faucet handle or keyboard are all examples of fomites. After being transferred to a fomite, and then to another person in this cross-contamination cycle from the original host, the germs can infect when they enter the body through ingestion or other "portals of entry." This is why handwashing and control of common touchpoints (fomites) is important in many cases.

Because the Zika virus has so far proven to spread almost exclusively by vector, the opportunity for modern cleaning for health methods to affect transmission is very limited, at least as far as the disease is understood to date. Cleaning for the most part, will not be a front-line issue in normal environments for the containment of Zika unless there is a change in transmission routes.