Hantavirus in Northern Arizona 2013: Peridomestic exposures as high risk

Hantavirus Pulmonary Syndrome (HPS) is of public health interest due to its high case-fatality rate (36%) and its tendency to affect previously healthy adults.  Sin Nombre virus was first isolated in 1993 in the American Southwest in mostly rural areas.  A recent outbreak at Yosemite National Park, in which three cases died, brought renewed attention to the disease.  Additional strains have been associated with cases in New York, Florida and Latin America.

An outbreak that occurred in Coconino County, Arizona in the summer of 2013 illustrates the challenges of HPS detection and prevention, particularly when occurrences are not consistent with expectations. 

On June 5, 2013, a previously healthy, 42 year-old woman who lived in an upper-middle class neighborhood presented at a hospital in Flagstaff, Arizona with nausea, body aches, shortness of breath, and fever.  The patient died the next morning.  The family denied that the case had exposure to rodents or a history of outdoor activities, e.g. hiking, camping.  Based on the clinical presentation, the hospital suspected HPS and the decedent was confirmed as a case.

Three weeks later, a previously healthy 59 year-old woman presented at a clinic with fatigue, fever, and cough and was sent home with antibiotics.  She too denied rodent exposure or outdoor activities.  Two days later, she was admitted to the hospital.  The case was transferred to a hospital in Phoenix and was confirmed with HPS.  She survived. 

Coordinated environmental, biological, and epidemiological investigations revealed that the women did not have any specific common exposures. However, both cases had spent time in enclosed areas near their homes (“peridomestic exposure”).  The first case had been in a shed and garage where rodent droppings were later found.  The second had been working in her soon-to-be-opened business, which was located in her garage.  The garage showed rodent infestation as well.

This outbreak has implications for public health and healthcare professionals.  1. Cleaning or entering enclosed areas should be considered a notable risk factor even if rodents are not observed.  2. HPS can be transmitted in many settings, including upscale neighborhoods, not just rural or recreational areas.  3. Providers should be alert for early warning signs of HPS.  4. Further research on the environmental factors encouraging the increase of the virus, rodents, and human interaction would be beneficial.