Zika is a virus first discovered in 1947 and named after the Zika forest in Uganda. The first human cases of Zika were detected in 1952, but until last year there had been only isolated outbreaks occurring mainly in tropical locales.
Zika is spread primarily through the bite of an infected Aedes aegypti or Aedes albopictus mosquito. Mosquitoes become infected by drinking the blood of a person infected with Zika, and then spread the disease to other people.
A man infected with Zika can transmit the virus through sexual intercourse. Also, people can be infected if they are given a blood transfusion tainted with Zika.
Four out of five people infected with Zika do not develop any symptoms. Those who do most often suffer from mild symptoms that include fever, rash, joint pain or red eyes.
The true risk of Zika is to a developing fetus. The U.S. Centers for Disease Control and Prevention has confirmed that Zika can cause terrible birth defects if a pregnant woman is infected with the virus.
Microcephaly is the most common birth defect caused by Zika, and it involves abnormally small development of the head and brain. Zika also causes other brain-related birth defects, and can result in miscarriage, according to the CDC. Not every fetus exposed to Zika develops a birth defect but no one knows what the odds are that a birth defect will occur.
Women of child-bearing age who live in an active Zika region should protect themselves from mosquito bites by wearing long-sleeved shirts and long pants, using mosquito repellent when outside, and staying indoors as much as possible. Women should use condoms or refrain from sex with a male partner if they are living in an active Zika area. They also should follow these precautions for a least 8 weeks if the man has traveled to an active Zika area, or for at least 6 months if the man has been diagnosed with Zika.
There is no cure or vaccine for Zika. Pregnant women infected with Zika will be monitored by doctors, who will closely tract fetal development. The CDC has said there’s no evidence that a past Zika virus infection will endanger future pregnancies. It appears that once the virus has been cleared from a person’s bloodstream, it poses no risk to any subsequent pregnancies.
Zika has been associated with Guillain-Barre syndrome (GBS), a rare disease of the nervous system in which a person’s immune system attacks nerve cells. The disease causes muscle weakness and, less frequently, paralysis. Most people recover fully, but some have permanent damage and about one in 20 die.
Zika already is active in the territory of Puerto Rico, where one death has been reported, as well as American Samoa and the U.S. Virgin Islands. Public health officials expect Zika to strike first in the continental United States in Florida, Louisiana or Texas, once the mosquito season gets underway. The A. aegypti mosquito can range as far north as San Francisco, Kansas City and New York City, although health officials have said infections that far north are unlikely.
As I noted in last week’s blog, the spread of Zika is related to global warming. The cases we’ve seen so far in the continental U.S. have been imported but that will change this summer. Look for this virus to spread over a much wider portion of the country that this report would indicate.
The Bottom Line:
Take these precautions seriously. We know very little about this virus and nothing about the long term effects. All viral infections remain within the body, even if they are “cleared from the blood stream.”
May 9, 2016 National Institutes of Health
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