Houston: Testing for the mosquito-borne Zika virus began on Monday at the Gulf Coast Regional Blood Center headquartered in Houston, the fourth-largest city in the US. The centre, which was approved for testing by the US Food and Drug Administration, can test more than 3,600 blood samples per day by using three new automated instruments and can detect the smallest amount of Zika in blood samples, Xinhua reported. Currently, there are more than 500 travel-related cases of the Zika virus in the US, according to new figures from the Centres for Disease Control and Prevention. None of them were locally transmitted by mosquitoes. As of Friday, there were 36 confirmed cases of the virus in the US state of Texas, 15 of which were reported in the Houston area. US President Barack Obama has asked Congress to allocate $1.9 billion in emergency funding to combat the spread of the virus. Zika is a disease caused by the virus of the same name which is spread primarily through the bite of an infected Aedes species mosquito. The most common symptoms of Zika are fever, rash, joint pain and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting for several days to a week after being bitten by an infected mosquito. The virus was first discovered in 1947 and is named after the Zika Forest in Uganda. In 1952, the first human cases of Zika were detected and since then, outbreaks of disease have been reported in tropical Africa, Southeast Asia and the Pacific Islands. On February 1, 2016, the World Health Organisation declared Zika virus a public health emergency of international concern.