Zika Transmission Documented in Florida

Pocket of Zika transmission found in Miami area

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It probably should come as no surprise that in July 2016 a part of Miami—the Wynwood neighborhood, to be exact—reported transmission of the Zika virus. After all, there are areas of the southern and western United States—like Florida, Texas, and Hawaii—where Aedes aegypti lives, and Aedes aegypti is the mosquito vector that carries the Zika virus.

Florida has been on alert and bracing itself for this inevitability of homegrown Zika transmission for some time—months before the CDC issued a travel guidance covering Florida communities in August 2016.

Furthermore in Florida, chikungunya and dengue outbreaks have occurred in the past. Both of these viruses are also carried by Aedes aegypti.

Up until now, the only Americans who were diagnosed with Zika were returning from outside the 50 states. In other words, cases of Zika were inadvertently imported to the United States. Zika virus is common in the developing nations of the Caribbean, Central and South America as well as Guam, American Samoa, and the U.S. Virgin Islands. In all these places, the Zika virus is causing crises in the form of potentially thousands of children with birth defects who are born to infected mothers. More than 1500 Americans have brought Zika back from areas where it's endemic.

What Is the Zika Virus?

The Zika virus is a flavivirus, or a (single-stranded) RNA virus. Other examples of flaviviridae include yellow fever, the West Nile virus, and the dengue virus. The Zika virus is primarily spread by the Aedes aegypti, a mosquito species that also spreads dengue and chikungunya.

Only one of five people infected with the Zika virus become symptomatic, and except for pregnant women and their unborn babies, the symptoms are mostly limited to uncomfortable aches and pains.

What Are the Symptoms of Zika Virus?

About 20 percent of people who are infected with Zika virus develop the following symptoms:

  • rash
  • joint pain
  • conjunctivitis ("pinkeye")
  • fever
  • lymphadenopathy (swollen lymph nodes)
  • muscle pains
  • headaches

These symptoms last from several days to several weeks and then go away on their own. Hospitalization for most people with such symptoms is rarely needed. A minority of people who are infected with Zika virus later go on to develop Guillain-Barré syndrome, a transient neurological condition which causes weakness of the arms and legs.

On a related note, symptoms of Zika virus infection are similar to but milder than those experienced with dengue or chikungunya, which are also transmitted by Aedes aegypti. 

The diagnosis of Zika virus is based on clinical findings and symptoms are then confirmed with diagnostic (blood or urine) testing. Currently, the CDC is performing blood tests on all Americans suspected of Zika virus infection. No quick diagnostic test exists to determine whether somebody has the disease.

Zika Virus and Microcephaly

Despite mild clinical effects in most other patient populations, Zika virus is really bad news for mothers.

Although we have yet to definitively prove a direct causal linkage between Zika virus and birth defects—and other factors may be in play—the circumstantial evidence tying this virus and thousands of cases of microcephaly among newborns in Brazil is alarming. Some countries have even gone so far as suggesting that mothers delay conception.

Evidence that helps prove a causal link between Zika and birth defects is starting to reported. In a March 2016 article published in The New England Journal of Medicine, Brazilian researchers found that 29 percent of women infected with the Zika virus exhibit birth defects, including microcephaly, on fetal ultrasound. Furthermore, in a number of these women, these defects have been confirmed at birth. 

Microcephaly is a life-threatening condition affecting newborns that presents as smallness of the head. With microcephaly, the brain is small, too, and doesn't properly develop thus resulting in a host of serious neurological problems including the following:

  • developmental delays
  • intellectual disability
  • seizures
  • hearing loss
  • vision problems
  • motor impairment

The CDC has suggested that the neurological effects of Zika virus infection are worst during the first trimester; however, evidence suggests that risk of brain damage continues into the second trimester, and more recent studies suggest that babies are at risk throughout the pregnancy, too. Major neurological development occurs during the first trimester, which is why infection during the first trimester is grave.

Brazil is a hotbed for Zika virus transmission. Brazilian medical experts are observing additional birth defects in newborns exposed to the Zika virus in utero, such as muscular abnormalities as well as eye and brain lesions.

It should be noted that many women who are infected with the Zika virus go on to have a miscarriage.

Is There a Cure for Zika Virus?

There is neither a cure nor a vaccine for Zika virus. People who develop symptoms of this infection are treated with plenty of rest, fluids and acetaminophen (Tylenol). Medications like ibuprofen or aspirin (NSAIDs) may increase the risk of bleeding and should be avoided by people with Zika virus.

The best way to deal with the Zika virus is to prevent exposure to Aedes aegypti—the mosquito that's the main vector for spread—in the first place. Specifically, this mosquito is an aggressive day-biter, and if you're traveling to an area where this sucker is endemic (like Brazil or now Florida), you should use plenty of insect repellent, wear long-sleeve clothing and pants as well as hang mosquito nets around your bed. Furthermore, you should clear your room of any stagnant water sources like ice buckets or flower pots, where this mosquito breeds.

Can Zika Virus Be Spread by Sex?

Although the Zika virus can be spread through either sex or blood transfusions, this virus is usually spread when a mosquito bites an infected person and then bites somebody without infection. Please note that if you are infected with the Zika virus, you still need to prevent mosquito bites for concern of spreading the virus others.

According to the CDC and other expert organizations, pregnant women or women planning on becoming pregnant should be a lot more cautious and avoid travel to places where Zika virus is endemic or spreading. If you are pregnant and must travel to these areas, please do your best to avoid mosquito bites. Remember that commercial insect repellents sold in the United States are safe to use while pregnant.

The Zika virus can be transmitted from one person to another before, during and after symptoms of infection develop. Thus, the CDC is recommending that people traveling to areas where ZIka is spread—like certain areas of Miami—avoid unprotected sex for 8 weeks after traveling to these areas.

Zika Virus Vaccine

Among other Zika virus research efforts, the French pharmaceutical company Sanofi is looking into a vaccine to protect people against infection. Sanofi has recently developed a vaccine that protects against dengue, a similar disease and leads research efforts in vaccines that take aim at flaviviridae. In June 2016, Sanofi announced a Cooperative Research and Development Agreement with the Walter Reed Army Institute of Research focusing on the co-development of a Zika vaccine candidate. 

Looking a bit further ahead, a vaccine could help prevent birth defects throughout the world. Although the chances are very good that a Zika vaccine will eventually be developed, the worry is that there will continue to be thousands of babies born with birth defects in the interim. Thus, time is of the essence.

Is the Average American at Risk for Zika?

Although large-scale outbreaks in the United States are certainly possible, just because a small number of people have caught Zika in Florida does note necessarily mean that the that the average American is at serious risk for catching the Zika virus.

Ultimately, the spread of Zika virus in the Miami area, although alarming, is currently limited in its greater national significance. In the end, the most parts of the United States are still not the best home for Aedes aegypti, which is more heavily distributed in tropical areas outside of continental borders.

In other words, if you're sitting on your wicker recliner in your backyard and enjoying a beautiful Syracuse, San Jose, Boston, Denver or Detroit (insert your city) evening, the chances that the mosquito bite you've been afflicted with has introduced Zika virus into your system still remains remote. Of course, if you live in Florida, please take precautions.


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McCarthy M. Zika Virus Outbreak Prompts US to Issue Travel Alert to Pregnant Women. The BMJ. 352:i306.

Zika Virus. CDC. www.cdc.gov.

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