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Hantaviruses are a group of viruses that are found in certain rodents which are specific hosts for the virus.  The most important hantavirus in the United States is the Sin Nombre virus, for which deer mice (Peromyscus maniculatus) are the host.  Infection with this virus can cause Hantavirus Pulmonary Syndrome (HPS), a severe, sometimes fatal, respiratory disease in humans.  Humans can become infected through inhalation of aerosolized virus from urine or droppings from infected rodents, or through direct contact with the animals or their excretions.   Other rodents that carry hantaviruses in the U.S. are the cotton rat (Black Creek Canal virus), rice rat (Bayou virus), and white-footed mouse (New York virus).  No person-to-person transmission of HPS has occurred in the U.S., but rare instances have been reported in Chile and Argentina with Andes Virus. 

Symptoms of HPS usually develop between 1 and 8 weeks after exposure to infected rodents.  Early symptoms of HPS include fatigue, fever, and muscle aches, especially in the larger muscle groups.  Some individuals may also experience headaches, dizziness, chills, nausea, vomiting, diarrhea, and abdominal pain.  Late symptoms of HPS arise 4 to 10 days after the initial phase and include coughing and shortness of breath, with the sensation of chest tightening due to lungs filling with fluid.  The mortality rate for HPS is 38%. 

Hantavirus infection is reportable in Orange County within one (1) working day of identification.  To report a case, health care providers/facilities should call OCHCA Epidemiology at 714-834-8180 or fax records to 714-560-4050. Less than three (3) cases hantavirus infection were reported in California each year between 2011 and 2016, with the exception of 2012 when 10 cases were reported in conjunction with an outbreak at Yosemite National Park.  Orange County had one case in 2012 in a resident who had visited Yosemite during the outbreak period but has had no other cases since then.

For more information about hantavirus, see

For information about deer mice in Orange County, see the Orange County Mosquito and Vector Control website

Last reviewed December 6, 2018