2006 HUMAN HANTAVIRUS INFECTIONS IN LOS ANGELES COUNTY RESIDENTS BACKGROUND Hantavirus pulmonary syndrome (HPS) was first recognized in 1993 after an outbreak of acute respiratory failure in young people in the Four Corners area of southwestern United States

Hantavirus pulmonary syndrome (HPS) was first recognized in 1993 after an outbreak of acute respiratory failure in young people in the Four Corners area of southwestern United States (U.S.). The case fatality rate among these cases was 76% [1]. Fortunately, recent Centers for Disease Control and Prevention (CDC) surveillance data reports a decline in the case-fatality rate of 30 to 40% [2]. HPS is characterized by a febrile illness associated with bilateral diffuse interstitial edema of the lungs developing within 72 hours of hospitalization in a previously healthy person. The causative agent of HPS is Sin Nombre virus, a previously unknown hantavirus that was both documented in individuals with HPS in New Mexico and rodents within their dwellings [1]. Sin Nombre virus (SNV), a lipid enveloped single stranded RNA virus of the family Bunyaviridae, is genetically distinct from other known hantaviruses that cause hemorrhagic fever with renal syndrome in Europe and in Asia [3].