That warning comes from an international team of researchers that found Culex quinquefasciatus, also known as the southern house mosquito, already living in the islands.
West Nile has been responsible for killing vast numbers of birds in North America, and recently was reported in South America as well.
The virus can also infect humans and other mammals, along with reptiles.
“We now know that mosquitoes capable of carrying West Nile virus have a route onto the Galapagos, and once there, the virus could also spread into the local mosquito population,” said Andrew Cunningham from the Zoological Society of London.
The researchers recommend strict enforcement of insect control measures on aircraft and ships arriving in the Galapagos.