Etiology

Hantaviruses are single-stranded RNA viruses. They are carried by rodents, of which the deer mouse is the most common in the U.S. Infection usually is the result of inhalation of aerosolized excreta from rodents infected with the virus, but person-to-person transmission was documented in Argentina with infection from the Andes hantavirus. As of 2004, less than 400 cases of HPS have been identified in the U.S. The disease has had a mortality of about 35%. The incidence rises after warm, wet winters during which few rodents die. All cases originated in rural areas in people who were involved in rodent control activities, or camped or hiked in rodent-infested areas.

Symptoms

After an incubation period of about 5 to 33 days (median 18), patients usually report myalgia, fever, headache, nausea, vomiting, and diarrhea. The abrupt onset of dyspnea and nonproductive cough follows, which rapidly progresses to noncardiogenic pulmonary edema and shock. Disseminated intravascular coagulation and renal failure are common.

Diagnosis

HPS is diagnosed by clinical presentation, the presence of IgM antibodies to the virus in the blood, and Western blot enzyme-linked immunosorbent assays, among other tests.

Treatment

No effective antiviral drug therapy has been identified. Patients are given supportive care in the intensive care unit, with oxygen, mechanical ventilation, intravenous fluids, and vasopressors. Arterial blood gases, pulmonary status, neurological status, serum electrolytes and renal function, and hemodynamics are monitored closely, and airway patency maintained by careful suctioning. Fluid replacement should be based on hemodynamic monitoring. Vaccines against the virus provide a possible source of protection for persons at risk of exposure.

Patient care

People living in or visiting areas where the disease has been reported need to be educated about being careful under porches, in basements, and in attics or storage areas, where mouse droppings may be present. Mouse droppings should not be vacuumed or swept with a broom; these practices increase the risk of inhalation. Instead, individuals should cover infestations with a 10% solution of household bleach, wipe them up while wearing protective clothing and a HEPA filter mask, and place them in a bag for disposal. Dead rodents should be sprayed with a disinfectant, then double-bagged along with the cleaning material and disposed of according to local statutes. Health care providers should promptly report to state or federal public health agencies (e.g., the Centers for Disease Control and Prevention [CDC]) any disease outbreak to protect public health. Consider the possibility of bioterrorism if the disease occurs outside an endemic area, at an unusual time of year, or in an unusual pattern. Vacation cottages should be aired before anyone enters. Campers should avoid burrows and sleep on cots or mattresses rather than the bare ground. Children must be taught not to try to catch or play with deer mice, chipmunks, moles, or other rodents. A safety pamphlet is available from the Centers for Disease Control, Atlanta, Georgia. www.cdc.gov.