Hantavirus - Complete Clinical Overview

Classification & Virology

Clinical Syndromes

Causative Viruses

• Sin Nombre virus (SNV) - major cause of HPS in western/central United States; reservoir = deer mouse (Peromyscus maniculatus)
• Andes virus - endemic to Argentina and Chile; reservoir = long-tailed rice rat (Oligoryzomys longicaudatus) - the only hantavirus capable of person-to-person transmission
• Bayou, Black Creek Canal, Monongahela, New York viruses - sporadic US cases
• Laguna Negra, Choclo viruses - South/Central America

• Hantaan virus - severe HFRS; Far East Asia
• Seoul virus - mild-moderate HFRS; worldwide (carried by domestic rats)
• Puumala virus - mild nephropathia epidemica; Europe
• Dobrava virus - Balkans

Transmission

• Primary route: Inhalation of aerosolized rodent urine, droppings, or saliva
• Other routes: Direct contact with infected rodents, rodent bites, contamination of broken skin
• Person-to-person: Documented ONLY for Andes virus (rare; requires prolonged close contact)
• High-risk activities: cleaning rodent-infested buildings, trapping rodents, hand plowing, sleeping in rodent-infested structures, camping

• Red Book 2021, p. 585-586

Hantavirus Pulmonary Syndrome (HPS) - Clinical Course

Incubation Period

Phase 1 - Prodrome (3-7 days)

• Fever, chills, headache, severe myalgia
• Nausea, vomiting, diarrhea, dizziness
• Occasional cough
• No respiratory symptoms yet - this commonly delays diagnosis

Phase 2 - Cardiopulmonary (abrupt onset)

• Sudden onset of cough and dyspnea
• Noncardiogenic pulmonary edema with bilateral interstitial and alveolar infiltrates
• Pleural effusions due to diffuse pulmonary capillary leak
• Severe hypoxemia - intubation and mechanical ventilation typically needed for 2-4 days
• Myocardial depression: low cardiac indices, low stroke volume, normal pulmonary wedge pressure, increased systemic vascular resistance - distinct from septic shock
• Hypotension, shock

Recovery

Poor Prognostic Indicators

• Persistent hypotension
• Marked hemoconcentration
• Cardiac index < 2
• Abrupt lactic acidosis with serum lactate > 4 mmol/L (36 mg/dL)
• Red Book 2021, p. 585

Laboratory Findings

5-Point Peripheral Blood Screen for HPS

1. Hemoglobin elevated for gender/age
2. Left shift of granulocytic series
3. Absence of toxic changes
4. Thrombocytopenia
5. Immunoblasts and plasma cells > 10% of lymphocytes

Diagnosis

• Serology (method of choice): Hantavirus-specific IgM and IgG - often present at disease onset. Note: IgG may be negative in rapidly fatal cases. Positive IgM results should be confirmed by CDC (Viral Special Pathogens Branch: 470-312-0094).
• Molecular (PCR): Detects virus in peripheral blood mononuclear cells during early disease; not reliably present in BAL fluid
• Viral culture: Not clinically useful
• Immunohistochemistry: Can establish diagnosis at autopsy (pulmonary capillary endothelial cells)
• Red Book 2021, p. 586

Treatment

• Immediate transfer to a tertiary care facility capable of managing respiratory failure and shock
• Mechanical ventilation for respiratory failure
• Inotropic and pressor support for myocardial depression
• ECMO should be considered when pulmonary wedge pressure and cardiac indices have deteriorated - provides short-term support for the severe capillary leak syndrome

• Red Book 2021, p. 587

Isolation Precautions

• Standard precautions in US hospitals
• Person-to-person HPS transmission not reported in the US
• Andes virus - has caused nosocomial transmission in Argentina and Chile; contact and droplet precautions warranted

Epidemiology

• ~20-40 HPS cases/year in the US; >95% west of the Mississippi River
• Over 800 total US cases reported since 1993 (Sin Nombre virus); ~1/3 fatal
• Cases in children under 10 are exceedingly rare
• American Indian/Alaska Native populations bear disproportionate burden (case fatality ~46% vs. lower in non-Native populations)
• Notable outbreak: 2012 Yosemite National Park (rodent-infested cabins)
• 2025: PAHO reported 229 HPS cases with 59 deaths across 8 Americas countries (25.7% CFR) - an increase in lethality noted in Southern Cone

🚨 Active 2026 Outbreak: Andes Virus on M/V Hondius Cruise Ship

• May 2, 2026: WHO notified of a cluster of severe acute respiratory illness aboard the Dutch-flagged cruise ship M/V Hondius in the Atlantic Ocean
• Confirmed cause: Andes virus (confirmed by PCR in South Africa)
• Index cases had traveled in Argentina and South America before boarding April 1, 2026
• As of May 18, 2026: 10 cases (8 confirmed), 3 deaths
• Illness: fever, gastrointestinal symptoms, rapid progression to pneumonia, ARDS, and shock
• Contact tracing underway across UK, South Africa, and US
• No confirmed US cases as of May 18 - risk to general US public considered extremely low
• The CDC issued a HAN Health Update (May 15, 2026) informing clinicians about Andes virus testing
• Key point for clinicians: Andes virus is the ONLY hantavirus with person-to-person transmission - consider in any patient with HPS-like illness and recent travel to South America or contact with cruise ship passengers

Prevention

• Seal rodent entry points in buildings
• Use N95 respirator when working in potentially rodent-infested enclosed spaces
• Wet-clean (don't dry-sweep) rodent droppings with dilute bleach before removing
• Avoid direct contact with rodents; use gloves when handling
• Keep campsites/cabins clean; avoid sleeping on bare ground