According to a statement from the British Equine Veterinary Association (BEVA), Culex modestus—a type of mosquito capable of transmitting West Nile virus (WNV)—has been found in marshes in southeast England. West Nile—while often identified in African, Eastern European, and West Asian horses, among other populations—has never been found in the U.K. in any species, the release said.

"Cx. modestus has not been seen in the U.K. since 1945, when only a handful were recorded," the statement said, adding that the mosquitoes were found and identified by Centre for Ecology & Hydrology (CEH) and University of Oxford post-graduate student, Nick Golding. Golding found the mosquitoes living in marshes north of Kent and south of Essex, the statement said.

Golding said, in the statement, that it’s not clear how long the mosquitoes have been living and breeding in the U.K., however he believes the species "arrived fairly recently."

"No one knows for certain how these mosquitoes got to the U.K.," the BEVA statement relayed. "They can’t fly far so probably didn’t travel from mainland Europe under their own steam. It’s more likely they were accidentally transported by ship, especially given the number of international shipping terminals in the area where Cx. modestus now seems to be established