Post by Admin on Jun 14, 2016 18:51:04 GMT
The Zika virus is a mosquito-borne illness carried by Aedes aegypti mosquitoes. Most people who are infected do not become ill, but an estimated 20 percent experience symptoms including rash, fever, joint pain, red eyes, muscle pain, and headaches. The incubation period—the time between exposure to exhibiting symptoms—is unknown, but, according to the CDC, it is likely between a few days and a week. In most cases symptoms are mild and last up to a week.
The virus was first discovered in 1947 in the Zika forest in central Uganda, but until 2007, there had only been fourteen documented cases in humans. Experts say the disease likely did not spread among humans in Uganda because the Aedes africanus mosquitoes that transmit the virus there are poorly adapted to human environments, and therefore preferred to prey on monkeys. Researchers found evidence of infections elsewhere in Africa, as well as in Asia, but local populations there appear to have developed some resistance to the virus, preventing large-scale outbreaks.
In 2007 officials confirmed forty-nine cases of Zika on the island of Yap, in the Federated States of Micronesia, in the western Pacific. In a 2013–2014 outbreak, nearly four hundred cases were confirmed in French Polynesia, more than five thousand miles southeast of Yap. Researchers say the virus likely arrived in the Americas in 2013.
Zika is primarily spread by Aedes mosquitoes. Aedes aegypti has spread most of the cases in the Americas, and its reach in the United States is generally limited to Florida and Hawaii. However scientists have also detected the virus in Aedes albopictus, known as the Asian tiger mosquito, in Mexico; it has a much wider range in the United States, reaching as far north as New York and Chicago in the summer.
A January 2016 study in the UK-based medical journal, the Lancet, found that around two hundred million people live in areas in the United States that could be affected by Zika in warmer months. CFR Senior Fellow Laurie Garrett warns that Zika could become a permanent fixture in the Western Hemisphere, like the West Nile virus, especially if it takes hold in Culex mosquitoes, which are ubiquitous in the Americas (Brazilian researchers were able to infect a Culex with Zika in a laboratory).
However CDC officials have said widespread transmission of Zika in the mainland United States is "unlikely." Researchers point to other mosquito-borne illnesses, such as dengue and Chikungunya, which have not gained traction in the mainland United States, and say the prevalence of air conditioning and window screens in the United States helps to stem the transmission. High-quality sanitation systems, which reduce exposure to standing water, also reduce the risk of transmission.