In Washington

New requirements for the reporting of hantavirus pulmonary syndrome (HPS) were instituted in December of 2000. Since its recognition in 1993, there have been 23 reported cases of HPS in Washington through June 2002 with 8 associated deaths.

Deer mice are the primary reservoir for hantavirus in Washington State; exposure to their nests, urine, feces or saliva places individuals at risk for developing infection.  Hantavirus is not transmitted from person to person.

Purpose of Reporting and Surveillance

• To identify rodent sources of infection.
• To design more effective control or prevention methods.
• To better characterize the epidemiology of this organism.

Reporting Requirements

• Health care providers: notifiable to Local Health Jurisdiction within 3 work days
• Hospitals: notifiable to Local Health Jurisdiction within 3 work days
• Laboratories: no requirements for reporting
• Local health jurisdictions: notifiable to DOH Communicable Disease Epidemiology within 7 days of case investigation completion or summary information required within 21 days

Clinical Criteria for Diagnosis

An illness characterized by one or more of the following clinical features:

• A febrile illness (i.e., temperature greater than 101° F [greater than 38.3° C]) characterized by bilateral diffuse interstitial edema that may radiographically resemble ARDS, with respiratory compromise requiring supplemental oxygen, developing within 72 hours of hospitalization, and occurring in a previously healthy person.
• An unexplained respiratory illness resulting in death, with an autopsy examination demonstrating noncardiogenic pulmonary edema without an identifiable cause.

• Detection of hantavirus-specific immunoglobulin M or rising titers of hantavirus-specific immunoglobulin G, or
• Detection of hantavirus-specific ribonucleic acid sequence by polymerase chain reaction in clinical specimens, or
• Detection of hantavirus antigen by immunohistochemistry.

Laboratory testing should be performed or confirmed at a reference laboratory. Because the clinical illness is nonspecific and ARDS is common, a screening case definition can be used to determine which patients to test. In general, a predisposing medical condition (e.g., chronic pulmonary disease, malignancy, trauma, burn, and surgery) is a more likely cause of ARDS than HPS, and patients who have these underlying conditions and ARDS need not be tested for hantavirus.

Case Definition

• Confirmed: a clinically compatible case that is laboratory confirmed.

1. Identification

An acute zoonotic viral disease characterized by fever, myalgias and GI complaints followed by the abrupt onset of respiratory distress and hypotension. The illness progresses rapidly to severe respiratory failure and shock. An elevated hematocrit, hypoalbuminemia and thrombocytopenia are found in most cases. The crude mortality rate is approximately 40%-50%; it was 43% of the first 217 cases identified. In survivors, the recovery from acute illness is rapid, but full convalescence may require weeks to months. Restoration of normal lung function generally occurs, but pulmonary function abnormalities may persist in some individuals. Renal and hemorrhagic manifestations are usually conspicuously absent except in some severe cases.

Diagnosis is made by the demonstration of specific immunoglobulin M (IgM) antibodies by using ELISA, Western blot or strip immunoblot techniques. Most patients have IgM antibodies at the time of hospitalization. PCR analysis of autopsy or biopsy tissues and immunohistochemistry are also established diagnostic techniques in specialized laboratories.

2. Infectious Agent

3. Worldwide Occurrence

4. Reservoir

5. Modes of Transmission

6. Incubation Period

7. Period of Communicability

8. Susceptibility and Resistance

1. Preventive Measures

1. Exclude and prevent rodent access to houses and other buildings.
2. Store human and animal food under rodent proof conditions.
3. Disinfect rodent contaminated areas by spraying a disinfectant (such as dilute bleach) solution prior to cleaning.  Do not sweep or vacuum rat contaminated areas; use a wet mop or towels moistened with disinfectant.  Avoid inhalation of dust by using approved respirators when cleaning previously unoccupied areas.
4. Trap and dispose of rodents using suitable precautions.  Live trapping is not recommended.
5. In enzootic areas, minimize exposure to wild rodents and their excreta.
6. Laboratory rodent colonies, particularly Rattus norvegicus, should be tested to ensure freedom from asymptomatic hantavirus infection.

2. Control of Patient, Contacts and the Immediate Environment

1. Report to local health authority.
2. Isolation: None.
3. Concurrent disinfection: None.
4. Quarantine: None.
5. Immunization of contacts: None.
6. Investigation of contacts and source of infection: Exterminate rodents in and around the households if feasible.
7. Specific treatment: Provide respiratory intensive care management, carefully avoid overhydration that might lead to exacerbation of pulmonary edema. Use cardiotonic drugs and pressors early under careful monitoring to prevent shock. Strictly avoid hypoxia, particularly if transfer is contemplated. Ribavirin is investigational and of no proven benefit. Extracorporeal membrane oxygenation has been used with some success.

3. Epidemic Measures

4. International Measures