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Hantavirus

Two major groups of hantaviruses are recognized based on their clinical presentation. The first group includes Sin Nombre Virus (SNV), which causes hantavirus pulmonary syndrome. A second group of hantaviruses includes Seoul, Hantaan, Dobrava, and Puumala viruses. This group of hantaviruses causes hemorrhagic fever with renal syndrome, which is not commonly seen in the United States.

Hantavirus pulmonary syndrome was first described in 1993 during an outbreak of unexplained fever and the acute respiratory distress syndrome among members of the Navajo tribe at the northern border between New Mexico and Arizona. Since 1993, a total of 728 cases have been reported by the Centers for Disease Control and Prevention.

Hantavirus pulmonary syndrome (HPS) is an acute, zoonotic viral disease that is spread by contact with infected rodents, primarily deer mice (Peromyscus maniculatus). Most persons with HPS are infected by breathing in small viral particles from rodent urine or droppings that have been stirred up into the air. Sin Nombre virus causes the majority of infections in the United States. The majority of HPS cases occur in spring and summer; however, the seasonality of HPS can vary by elevation, location, and biome. The fatality rate is 30 to 40%.

The incubation period for HPS is typically 2 to 4 weeks after exposure, with a range of a few days up to 6 weeks. Hantavirus pulmonary syndrome (HPS) typically begins as severe headache, high-grade fever, chills, myalgia, cough and gastrointestinal symptoms in a previously healthy person. Characteristic laboratory abnormalities include thrombocytopenia, leukocytosis, hemoconcentration, hypoalbuminemia, and elevated serum lactate dehydrogenase. The prodromal phase is followed by an abrupt progression to the cardiopulmonary phase, which is characterized by productive cough with nonpurulent secretions and dyspnea with severe respiratory distress. Chest radiographs reveal bilateral diffuse interstitial pulmonary edema which can resemble acute respiratory distress syndrome. There is no specific treatment available, but early recognition and administration of supportive care greatly increase the chance of survival. Fatality rate is 40%.

Laboratory testing of patients with symptoms consistent with HPS is required to confirm the diagnosis. Serologic testing for hantavirus-specific IgM is the most commonly performed diagnostic test, because almost all infected persons will have hantavirus-specific IgM at the onset of clinical symptoms. Hantavirus-specific IgG is often also present in the blood shortly after the onset of illness and can persist for months to years after the acute illness has occurred.

Because it is a reportable disease in the United States, clinicians suspecting HPS should notify their state health department. For additional information about HPS symptoms and diagnosis, please go to the CDC’s Hantavirus webpage at: http://www.cdc.gov/hantavirus/technical/hps/index.html

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