What are the symptoms of hantavirus infection in individuals exposed to rodents?

Hantavirus Symptoms

Hantavirus infection causes two distinct clinical syndromes: Hantavirus Pulmonary Syndrome (HPS) in the Americas with severe respiratory failure and approximately 60% mortality, and Hemorrhagic Fever with Renal Syndrome (HFRS) in Europe and Asia with kidney failure and variable mortality depending on viral strain.

Hantavirus Pulmonary Syndrome (HPS) - Americas

Early Phase Symptoms

• Fever is universal and marks disease onset 1, 2
• Myalgias (muscle aches) occur prominently in the early phase 1
• Fatigue and malaise develop as initial presenting symptoms 2
• Headache accompanies the febrile illness 2
• Gastrointestinal symptoms including nausea, vomiting, abdominal pain, and diarrhea are common 2

Cardiopulmonary Phase (Life-Threatening)

• Severe, noncardiogenic pulmonary edema develops rapidly as the hallmark of HPS 1, 2
• Respiratory failure requiring mechanical ventilation occurs in most severe cases 2
• Myocardial depression with decreased cardiac function 1
• Hypotension or shock develops as vascular permeability increases 1, 2
• Cardiogenic shock can accompany the pulmonary manifestations 2

The pathophysiology involves T cells acting on heavily infected pulmonary endothelium, with gamma interferon and tumor necrosis factor causing reversible increases in vascular permeability 1. This is an immunopathologic disease where the immune response itself drives clinical manifestations 1.

Hemorrhagic Fever with Renal Syndrome (HFRS) - Europe and Asia

Classic Five-Phase Presentation

HFRS progresses through distinct clinical phases 3:

1. Fever phase: High fever, headache, myalgias, and malaise 3
2. Hypotensive phase: Shock and vascular leak, particularly in the retroperitoneum 1, 3
3. Oliguric phase: Acute kidney injury with decreased urine output 3
4. Polyuric phase: Recovery of kidney function with excessive urination 3
5. Convalescent phase: Gradual return to baseline 3

Systemic Manifestations

• Prominent retroperitoneal vascular leak is a major site of pathology 1
• Tubular necrosis affecting the kidneys 1
• Myocardial depression similar to HPS 1
• Hemorrhagic manifestations in severe cases 2

Severity Variation by Viral Strain

• Hantaan and Dobrava viruses: Cause severe HFRS with up to 10% mortality 4
• Seoul virus: Causes mild HFRS with <1% mortality 4
• Puumala virus: Causes nephropathia epidemica (NE), a mild form with <1% mortality 4

Critical Clinical Recognition Points

Timing of Symptom Onset

• Workers should seek medical attention within 45 days of last potential rodent exposure if they develop febrile or respiratory illness 4
• Symptoms typically develop after inhalation of aerosolized rodent excreta 5, 6

Overlapping Features Between Syndromes

Both HPS and HFRS share several common features despite being distinct clinical entities 2:

• Fever as the initial presenting symptom
• Myocardial depression
• Hypotension or shock
• Increased vascular permeability as the central pathogenic mechanism
• Immunopathologic disease process

High-Risk Exposure History

Suspect hantavirus infection in patients with compatible symptoms and history of 4:

• Occupying or cleaning previously vacant cabins with rodent infestation
• Cleaning barns and outbuildings
• Disturbing rodent excreta or nests
• Handling mice without gloves
• Hiking or camping in endemic areas
• Hand plowing or planting in rural settings

Diagnostic Approach

When to Test

• Any febrile or respiratory illness within 45 days of potential rodent exposure warrants immediate evaluation 4
• Blood samples should be obtained and forwarded to state health departments for hantavirus antibody testing 4

Available Diagnostic Methods

• IgM-capture tests are the primary serologic method 7, 3
• RT-PCR detection of viral RNA from blood, plasma, or respiratory specimens 7, 3
• Viral RNA has been detected in whole blood, lymphocyte fractions, and occasionally plasma during acute HPS 4

Critical Pitfalls to Avoid

• Do not dismiss respiratory symptoms in patients with recent rodent exposure - HPS mortality is approximately 60%, and early recognition is crucial for survival 2
• Brief exposure is sufficient for infection - as little as 5 minutes in areas with infected rodents can cause disease 4, 5
• Subclinical infection appears uncommon - most infections result in clinically apparent disease 4
• Person-to-person transmission does not occur with North American hantaviruses, unlike some other viral hemorrhagic fevers 4