Source: National Center for Emerging and Zoonotic Infectious Diseases (NCEZID) — Content from the Centers for Disease Control and Prevention (public domain).
Key points
* Omsk hemorrhagic fever (OHF) is a rare disease caused by a virus spread by an infected tick or rodent.
* OHF only occurs in certain areas of Siberia, Russia.
* There is currently no treatment or vaccine for OHF.
* Most people with OHF fully recover after 1 or 2 weeks.
What it is Omsk hemorrhagic fever (OHF) is caused by Omsk hemorrhagic fever virus (OHFV). OHF was identified between 1945 and 1947 in Omsk, Russia. OHF occurs in Russia–specifically, in the western Siberia regions of Omsk, Novosibirsk, Kurgan, and Tyumen. While there is not treatment for OHF, most people recover after 1 or 2 weeks. About 5 to 30 people out of 1,000 with OHF die of the disease. OHF is rare and is unlikely to pose a public health threat to people living in the United States. 
Omsk Hemorrhagic Fever is found in western Siberia. Signs and symptoms People with OHF may experience chills, fever, headache, severe body aches, and vomiting. After 3 or 4 days, symptoms can include diarrhea and unexplained bleeding from the nose, eyes, or rectum. After being sick for 1 or 2 weeks, most people with OHF fully recover. However, some people may experience a second wave of symptoms, including fever and swelling of the brain, in the third week. Rarely, OHF can cause hearing loss, hair loss, and behavior or psychological conditions. Long-term supportive care may be needed for people with symptoms that impair their motor skills. Risk factors People in rural or outdoor settings in western Siberia have a higher risk for OHF. These people are more likely to encounter infected ticks and rodents. This includes hunters, campers, forest workers, farmers, and muskrat trappers. People are more likely to be infected during the winter months. Laboratory workers handling OHF specimens without proper personal protective equipment are also at risk. How it spreads People get OHF through tick bites or contact with the blood, feces, or urine of an infected animal, usually a rodent. Ticks that can spread OHF include Dermacentor reticulatus , Dermacentor marginatus , and Ixodes persulcatus. Rodents that can spread OHF include the muskrat, water vole, and narrow-skulled vole. People cannot spread OHF to each other. Though unusual, it is possible to get OHF without direct contact with ticks or rodents. The virus that causes OHF has been found in aquatic animals and water. The virus in the water could enter the body through broken skin or the eyes and nose. This would be extremely rare. There is even evidence that OHF can be spread by drinking the milk of goats or sheep infected with OHF. Reducing risk If you plan to spend time in rural or outdoor areas in western Siberia,
* Prevent tick bites.
* Avoid contact with muskrats, voles, and sick or dead animals.
There is no vaccine currently available for OHF. However, vaccines for another disease spread by ticks (tick-borne encephalitis) may offer some protection. These can be considered for high-risk groups, like muskrat hunters. Talk to your healthcare provider if you are traveling to the area and may have contact with animals. Diagnosis Healthcare providers can diagnose OHF with blood tests that detect the virus, like cell cultures and PCR. They may be able to tell if someone had OHF in the past by testing the blood for antibodies.