Humans can become infected through tick bites or through contact with the blood, feces, or urine of an infected, sick, or dead animal – most commonly, rodents. Occupational and recreational activities such as hunting or trapping may increase human risk of infection.
Transmission may also occur with no direct tick or rodent exposure as OHFV appears to be extremely stable in different environments. It has been isolated from aquatic animals and water and there is even evidence that OHFV can be transmitted through the milk of infected goats or sheep to humans.
No human-to-human transmission of OHFV has been documented but infections due to lab contamination have been described.