Omsk hemorrhagic fever (OHF), caused by Omsk hemorrhagic fever virus (OHFV), is an infection that occurs primarily in the western Siberia regions of Omsk, Novosibirsk, Kurgan and Tyumen. People can become infected from tick bites, or from contact with the blood, feces, or urine of an infected or dead animal (most commonly a rodent who was infected by a tick). Human exposure may also occur from contaminated water, in a laboratory setting, or through the milk of infected goats or sheep. No person-to-person transmission has been documented. The first signs and symptoms of OHF may begin between 3 to 8 days after exposure and may include chills, fever, nausea, headache, and severe muscle pain. Other symptoms that may occur 3 to 4 days after the first symptoms begin include vomiting, other gastrointestinal problems, and bleeding problems. In rare cases, OHF can cause hearing loss, hair loss, and behavioral or psychological problems.