Twenty-Year Summary of Surveillance for Human Hantavirus Infections, United States - CANCELLED

BACKGROUND:  Several hantaviruses are endemic to North America, and infections in humans continue to occur where they come into contact with infected rodents. Hantavirus pulmonary syndrome (HPS) is by far the most common form of hantavirus infection in the United States, causing severe respiratory distress and death in 36% of cases. Although several hantavirus species are endemic in the United States, Sin Nombre virus (SNV), carried by the deer mouse (Peromyscus maniculatus) is the most common cause of HPS. The objectives of this presentation are to summarize the spectrum and distribution of human hantavirus infections in the United States in the past two decades.

METHODS:  National surveillance for HPS began in 1993, and HPS became nationally notifiable in 1995. Cases both met the clinical HPS case definition and were laboratory confirmed via serology, PCR, or immunohistochemistry assays. Standardized case information was collected, which included rodent exposures, clinical details, laboratory results, and outcome. Additionally, cases of hantavirus infection that did not meet the criteria to be HPS were also recorded.

RESULTS:  In the past 20 years of hantavirus surveillance, 624 cases of HPS have been reported, 96% of which occurred in states west of the Mississippi river. Twelve HPS cases were confirmed by PCR analysis to be caused by hantavirus species other than SNV, including Bayou virus (5 cases), Black Creek Canal virus (1 case), New York virus (2 cases), and Monongahela virus (4 cases). There were 10 laboratory confirmed cases of acute, domestically acquired hantaviral infection that did not fit the clinical case definition of HPS. Because these patients did not have pulmonary symptoms, they were not included in the national HPS case counts. This presents a missed opportunity in understanding the full spectrum of hantaviral disease, and reduced awareness of where and how persons are exposed to hantaviruses. Seoul virus, a hantavirus causing hemorrhagic fever with renal syndrome (HFRS), is also present in the United States, and 4 domestically acquired cases have been reported. Imported cases of HPS and HFRS have also occurred over the years.

CONCLUSIONS:   In summary, we have found that while HPS caused by SNV continues to be the predominant form of hantaviral infection in the United States, we must continue to consider hantaviruses as a cause of disease in patients with rodent exposures that are outside the western United States, differ from the usual clinical presentation of pulmonary disease, or are not associated with deer mouse exposure.