 Seoul virus is found in "Rattus" species rats, most commonly "Rattus norvegicus," but occasionally "Rattus rattus".Rats do not show physiological symptoms when carrying the virus, but humans can be infected through exposure to infectious body fluids (blood, saliva, urine), exposure to aerosolized rat feces, or bites from infected rats.There is no evidence of human-to-human transmission of SEOV.