Thursday, January 28, 2016

Zika Virus

Zika virus is spread to people through mosquito bites, currently from the Aedes species mosquitoes. There is no vaccine to prevent or medicine to treat Zika. Outbreaks of Zika have occurred in areas of Africa, Southeast Asia, the Pacific Islands, and the Americas. In May 2015, the first local transmission of Zika virus infection (Zika) was reported in Brazil from there it spread to the rest of South America, to Central America, Caribbean and now appeared in Puerto Rico and Hawaii. The Center for Disease Control and Prevention (CDC) has issued a travel alert for people traveling to Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, Venezuela, and the Commonwealth of Puerto Rico and recommended for pregnant women to avoid the areas.

This alert follows reports in Brazil of microcephaly, babies born with abnormally underdeveloped heads, and other poor pregnancy outcomes in babies of mothers who were infected with Zika virus while pregnant. A few months after the introduction of Zika virus (ZIKV) infection into Brazil, there was an increase in congenital microcephaly occurrence. The incidence of congenital microcephaly increased by twenty times. This increase raises questions about the possible role of the Zika infection in congenital microcephaly, though there is currently only ecological evidence of an association between the two events, because there is no test for the presence of the Zika antibodies to confirm past infection. A possible causative nature of the association cannot be ruled out and more research needs to be done. The CDC has taken down its article on the possible association, but you can read the article from the European Center for Disease Control.

The disease symptoms are usually mild and last for 2 to 7 days. Infection may go unrecognized or are misdiagnosed as dengue, chikungunya or other viral infections that cause fever and rash. Asymptomatic infections are also reported to be common. According to the CDC about one in five people infected with Zika virus will develop symptoms, which include fever, rash, joint pain, and conjunctivitis (pink eye). Other commonly reported symptoms include myalgia, headache, and pain behind the eyes. Severe disease requiring hospitalization is uncommon and case fatality is low.

During the Zika virus outbreak in French Polynesia, in 2013, 74 patients who had Zika symptoms, later developed neurological or autoimmune syndromes - out of them, 42 were diagnosed as Guillain–Barré syndrome. In the current Brazil outbreak , 121 cases of neurological manifestations and Guillain–Barré syndrome (GBS) have been reported, all with a history of Zika-like symptoms. Guillain-Barré syndrome (GBS) is a disorder in which the body's immune system attacks part of the peripheral nervous system. The first symptoms of this disorder include varying degrees of weakness or tingling sensations in the legs. In many instances the symmetrical weakness and abnormal sensations spread to the arms and upper body. These symptoms can increase in intensity until certain muscles cannot be used at all and, when severe, the person is almost totally paralyzed. Most people will have good recovery from even the most severe cases, although some continue to have a certain degree of weakness.

The Zika virus orginated in Africa and some disease specialists believe it was introduced in Brazil during the World Cup. These same scientists modeled the vectors to spread the disease have warned that the Brazil 2016 Summer Olympics could serve as a catalyst for the virus to spread the disease to the rest of the world.

Because the Aedes species mosquitoes that spreads the Zika virus are found throughout the world, it is likely that outbreaks will continue spread to new countries. In December 2015, Puerto Rico reported its first confirmed Zika virus case. Locally transmitted Zika has not been reported elsewhere in the United States, but cases of Zika have been reported in returning travelers. There is no widely available test for Zika, a blood or tissue sample from the first week of the infection can be used with advanced molecular testing. It is also possible that due to Zika’s close relation to two dengue and yellow fever it may react with the antibody tests for those viruses.

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