Anette Rink, Nevada Department of Agriculture director of animal disease and food safety says, "It's my understanding that the birds were picked up in a pool at a Strip casino."
Officials says a third duck carrying the rare, but more deadly St. Louis encephalitis virus was found in the same pool in June.
State officials insist there is no cause for alarm, as the virus has not transmitted to humans. They will not identify the casino from which the ducks were removed.
Viruses cannot spread from birds to humans. However, mosquitos can transmit West Nile and St. Louis encephalitis viruses by biting infected birds and then biting humans.
