June 19, 2013



To: Park Superintendents, Intermountain Region

From: Regional Director, Intermountain Region

Subject: Hantavirus Pulmonary Syndrome (HPS) Hazards in Parks

In an effort to protect the health of park staff, residents, and visitors, it is important to recognize both the hazards of exposure to hantavirus infection and the means to prevent such exposures.

Hantavirus Pulmonary Syndrome (HPS) is caused by exposure to one of several hantavirus strains through contact with hantavirus-infected rodents, their urine, or droppings. HPS was first recognized by the Centers for Disease Control and Prevention (CDC) in the Four Corners area of the southwest in 1993. Cases have since been verified in 34 states, including every state in the Intermountain Region.

The risks of hantavirus exposure were brought into sharp focus in 2012, when 10 visitors to Yosemite National Park came down with HPS due to their exposure to hantavirus while in the park. Three of those visitors died as a result of their exposure. The primary source of that exposure to visitors was identified as mice living in the walls of tent cabins that were rented to visitors. Failure to follow established procedures when addressing rodent infestations in park buildings is an example of the human tendency to become desensitized to the risk around us and subconsciously accept high levels of risk as being normal after continuously repeating the behavior without negative consequences. The cases at Yosemite NP are a reminder that an absence of identified cases of Hantavirus pulmonary syndrome in previous years is not an absence of risk.

Managers and supervisors need to be watchful of the tendency of employees to "normalize" risks and must implement robust management and supervisory controls to prevent this from occurring in all types of field operations. Rodent infestations must be identified and corrected which requires involvement of both Integrated Pest Management and Facilities Maintenance. All employees must be trained in the hazards associated with rodents, how to both report the presence of mice or other rodents and how to protect themselves by using appropriate personal protective equipment and approved cleanup procedures. Unsafe procedures such as use of a vacuum cleaner to clean up rodent nests and droppings must be strictly forbidden.

/s/ John Wessels Authenticated by:

SIGNED ORIGINAL ON FILE Chérry Huss, 06/19/13

John Wessels

Last updated: February 24, 2015

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