Public Health Advisory - Hantavirus (5/12/2026)

Dear Colleagues:

This advisory summarizes key guidance on hantavirus pulmonary syndrome (HPS), in light of the recent Andes virus cluster linked to international cruise travel. Risk to Marin County remains very low, but awareness is recommended for patients with compatible illness and exposures.

Background

As of May 8, 2026, the WHO reports 8 cases (6 confirmed) and 3 deaths linked to a cruise departing Argentina. The Andes virus (ANDV) is notable for its rare person-to-person transmission, which requires close, prolonged contact. California is following 4 people who had close contact with exposed individuals. No U.S. cases have been identified to date. 

Local Context 

• U.S. cases are typically due to Sin Nombre virus (SNV)
• ANDV and SNV both cause Hantavirus Pulmonary Syndrome (HPS), a severe illness characterized by rapid progression to respiratory failure and a high case fatality rate.
• Transmission: inhalation of aerosolized rodent excreta (especially deer mice)
• No person-to-person spread with U.S. hantaviruses
• Exposure settings: cabins, sheds, garages, rodent-infested spaces, usually in rural settings

When to Consider HPS

Compatible illness + rodent exposure or travel to endemic areas within the prior 42 days

Symptoms

• Early: fever, myalgia, fatigue ± GI symptoms
• Late: cough, dyspnea, rapid respiratory decline 

Risk factors

• Rodent exposure (most common)
• Travel/contact linked to cruise cluster
• Close contact with symptomatic Andes virus case 

Testing

• Test for more common causes of respiratory illness (e.g., COVID-19, influenza, RSV)  
• Coordinate with Marin County Public Health (MCPH) for hantavirus testing (serology ± PCR through public health laboratory)
• Early testing may be negative; repeat testing in consultation with MCPH if suspicion remains high

Management

• No proven specific antiviral therapy is available
• Monitor closely; rapid clinical deterioration can occur
• Refer to the Emergency Department immediately if there are signs of clinical deterioration (e.g., worsening dyspnea, hypoxia, or hemodynamic instability); contact the ED in advance to ensure readiness to receive the patient

Reporting and coordination

• Notify Marin County Public Health (MCPH) immediately of suspected or confirmed cases.  Call 415-473-4163, After Hours Call 415-479-5305
• For ED cases, notify MCPH to support transfer and coordination with state health authorities

Infection Control 

• Single room; AIIR if available (especially for aerosol-generating procedures)
• Standard + droplet precautions: mask, eye protection, gown, gloves
• N95 for aerosol-generating procedures

Resources

• CDPH
• CDC
• CDC Health Alert (May 8)