The Dangers of the Zika virus in America

As of 9 March 2016, according to the U.S. Centers for Disease Control (CDC), there have been 193 travel-associated cases of Zika in the United States, but no locally-acquired cases. For now, what that means is that you probably can’t get Zika in the U.S. from mosquitos. You could get Zika if you travel to a Zika affect area. You could also get Zika from a person who contracted Zika in another country. Zika is transmitted by mosquitos, but can also be sexually-transmitted. Florida, California, Texas, and New York lead the pack with the most travel-associated cases of Zika. See this list and map: CDC: Zika in the United States.

What about U.S. territories? The story changes: 1 travel-associated case in Puerto Rico, and 173 locally-acquired cases: Puerto Rico (159), the U.S. Virgin Islands (1), and American Samoa (13). So you can contract Zika if you travel to a U.S. territory. Here’s a CDC map of Zika affected places in the Americas:

How bad is a case of Zika virus? Well, the answer is complicated. Most persons recover, after a week of flu-like symptoms, with no serious consequences. However, Zika can cause severe birth defects in pregnant women. Zika can also cause or precipitate a case of Guillain-Barré syndrome (a severe neurological disease).

Is there a vaccine? No. Will there be one soon? Probably not.

“There are no Zika vaccines in advanced development, although a number of existing flavivirus vaccine platforms could presumably be adapted, including flavivirus chimera or glycoprotein subunit technologies. Zika vaccines would, however, face the same problem as vaccines for chikungunya, West Nile, St. Louis encephalitis, and other arboviruses: since epidemics appear sporadically and unpredictably, preemptively vaccinating large populations in anticipation of outbreaks may be prohibitively expensive and not cost-effective, yet vaccine stockpiling followed by rapid deployment may be too slow to counter sudden explosive epidemics.” [New England Journal of Medicine]

How do I know if I have Zika? You probably won’t know. There are no symptoms in most cases:

“Infection with Zika virus is asymptomatic in an estimated 80% of cases, and when Zika virus does cause illness, symptoms are generally mild and self-limited. Recent evidence suggests a possible association between maternal Zika virus infection and adverse fetal outcomes, such as congenital microcephaly, as well as a possible association with Guillain-Barré syndrome. Currently, no vaccine or medication exists to prevent or treat Zika virus infection. Persons residing in or traveling to areas of active Zika virus transmission should take steps to prevent Zika virus infection through prevention of mosquito bites” []

Guillain-Barré syndrome

Guillain-Barré syndrome “is a rare disorder in which your body’s immune system attacks your nerves. Weakness and tingling in your extremities are usually the first symptoms. These sensations can quickly spread, eventually paralyzing your whole body…. Most people recover from Guillain-Barre syndrome, though some may experience lingering effects from it, such as weakness, numbness or fatigue.” [Mayo Clinic]

A new study, soon to be published in the internationally-renowned medical journal The Lancet, provides evidence that the Zika virus is associated with acute onset of Guillain-Barré syndrome (a severe neurological ailment). The study is available online in advance of print publication. The study authors analyzed data from a previous outbreak of Zika:

“Between October, 2013, and April, 2014, French Polynesia experienced the largest Zika virus outbreak ever described at that time. During the same period, an increase in Guillain-Barré syndrome was reported, suggesting a possible association between Zika virus and Guillain-Barré syndrome.” [The Lancet]

In the study, patients diagnosed with Guillain-Barré syndrome all (100%) had neutralizing antibodies against Zika virus, and 98% had antibodies against the Zika virus, indicating recent past exposure to Zika. However, most persons who contracted Zika did NOT fall ill with Guillain-Barré syndrome. Only a small percentage of persons infected with Zika subsequently had Guillain-Barré syndrome. In the study, symptoms of Guillain-Barré syndrome began about 4 to 10 days after the symptoms of the Zika virus infection.

Medical researchers do not know the exact cause of Guillain-Barré syndrome. But it sometimes occurs after a recent viral or bacterial infection, only for certain viruses and bacteria — now including Zika.

Your Odds

If you don’t travel outside of the 50 U.S. States, and you don’t have sex with someone who has traveled to a Zika infected area, you are very unlikely to contract Zika. Eventually, it might make its way into the mosquito population in the States, but not soon.

If you contract Zika, most of the time there is no real problem. You recover and are probably immune to a second infection with the virus.

Zika has been in the news a lot recently. But for U.S. residents, the risks are very low. You are more likely to die from bees, sharks, or the flu than from Zika. That said, keep an eye on this disease as it could become a major problem in the not-too-distant future.

– Thoreau

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