Aedes aegypti mosquitoes are seen at the Laboratory of Entomology and Ecology of the Dengue Branch of the U.S. Centers for Disease Control and Prevention in San Juan, March 6, 2016. REUTERS/Alvin Baez 
 
 CHICAGO (Reuters) - The Florida health department said on Wednesday it was investigating another two cases of Zika not related to travel to a place where the virus is being transmitted, raising the possibility of local Zika transmission in the continental United States. 
 
 The Florida health department said it has identified an additional case of Zika in Miami-Dade County, where it was already investigating a possible case of Zika not related to travel, and another case in Broward County, where it has been investigating a non-travel related case. 
 
 “Evidence is mounting to suggest local transmission via mosquitoes is going on in South Florida,” said CDC spokesman Tom Skinner said. 
 
 “These cases fit similar transmission patterns for mosquito-borne diseases such as Chikungunya that we’ve seen in South Florida in years past.” 
 
 To confirm whether Zika is being transmitted locally, epidemiologists must survey households and neighbors within a 150-yard radius around the residence of the person who has Zika, which constitutes the flying range of the mosquitoes that carry the virus. 
 
 According to the U.S. Zika response plan, Zika transmission is defined as two or more cases not due to travel or sex with an infected person that occur in a 1-mile diameter over the course of a month. Evidence of the virus in local mosquito populations can also be used to confirm local transmission. 
 
 Florida heath department officials said investigations into the new cases begins today. The state is urging residents and visitors to participate in requests for urine samples by the department in the areas of investigation. These results will help the department determine the number of people affected. 
 
 In addition to the possible cases of non-travel related transmission, Florida on Wednesday reported 328 travel-related cases of Zika. The state is monitoring 53 pregnant women who had Zika infections. ||||| Fearing Zika, FDA Asks 2 Florida Counties To Halt Blood Donations 
 
 Enlarge this image toggle caption Chris O'Meara/AP Chris O'Meara/AP 
 
 There's been a looming fear that mosquitoes would start spreading the Zika virus in the U.S. Now that possibility seems increasingly real. 
 
 On Thursday, senior officials at the Food and Drug Administration said they have asked blood donation centers in two Florida counties, Miami-Dade and Broward, to stop collecting blood for the time being. 
 
 The move came after investigators ruled out travel as the cause of four cases of Zika virus in those counties. Florida health officials announced the cases last week. The people hadn't traveled to places where Zika is endemic and don't appear to have contracted it through sex, leaving a possibility that they got the virus from being bitten by infected mosquitoes in the U.S. 
 
 If they did acquire the virus from domestic mosquitoes, it could mean that others in the area also may have acquired Zika virus locally, and may have donated blood without knowing it was infected. 
 
 In an effort to "help ensure the safety of the nation's blood supply," Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, said in a statement that blood collections shouldn't resume in the area until the centers can test each incoming blood donation for Zika virus. 
 
 The agency suggested that neighboring counties do the same, and that at-risk counties across the U.S. screen donors before collecting blood. 
 
 "These may be the first cases of local Zika virus transmission by mosquitoes in the continental United States," said the statement. The Florida Department of Health has yet to confirm how the people acquired the virus.
– The US may have just joined the other 67 countries and territories worldwide where mosquitoes are spreading the Zika virus, Popular Science reports. Up until now, all 1,600 Zika cases in the US were people who either traveled elsewhere to contract it or had sex with someone who did. But on Wednesday, the Florida health department announced four cases in Florida in which officials have ruled out both travel and sex. That means it's possible mosquitoes in Miami-Dade and Broward counties are spreading the virus. Officials are surveying people within a 150-yard radius of the four cases, Reuters reports. That's the distance Zika-spreading mosquitoes are able to fly. So far, officials have interviewed about 200 people and asked for urine samples. They're also testing local mosquitoes. On Thursday, the FDA asked both Miami-Dade and Broward counties to stop all blood donations as a precaution, according to NPR. It's recommending neighboring counties do the same.