Key points
- Hantaviruses are a family of viruses that cause serious illness and sometimes death in people worldwide.
- The viruses are spread by infected rodents through their urine, feces, and saliva.
- Some hantaviruses cause hantavirus pulmonary syndrome (HPS).
- Early symptoms of HPS in people resemble many other respiratory illnesses, making HPS difficult to diagnose at illness onset.
- Healthcare providers should test a person for hantavirus if they have HPS-compatible symptoms and have had contact with rodents.
Overview
Hantaviruses are spread by rodents' body fluids and excrement. People mostly contract hantavirus by breathing in the virus. Most hantaviruses found in North, Central, and South America can cause hantavirus pulmonary syndrome (HPS). Andes virus, which is found in South America, has reportedly had person-to-person transmission.
Different hantaviruses are found in the United States. Most of these cause HPS, which primarily affects the lungs. Non-HPS hantavirus infection can also occur, where patients experience non-specific viral symptoms, but no cardiopulmonary symptoms. The hantaviruses that are found throughout the United States are not known to spread between people.
HPS initially causes flu-like symptoms that can progress to more severe illness where people have trouble breathing. It's important for people with HPS to begin treatment as early as possible to improve their chances of recovery. HPS is fatal in nearly 4 in 10 people who are infected.
Exposure risks
Anyone who has contact with hantavirus-carrying rodents, or their droppings, urine, saliva or nesting material is at risk of HPS. Rodent infestation in and around the home remains the primary risk for hantavirus exposure. Even healthy individuals are at risk for HPS infection if they have contact with the virus.
How it spreads
Each hantavirus has one primary rodent that carries the disease. The most common hantavirus that causes HPS in the U.S. is spread by the deer mouse.
People can contract hantavirus if they have contact with urine, feces or saliva of a rodent carrying the virus. This can occur when people:
- Breathe in hantavirus-contaminated air when cleaning up after rodents.
- Touch contaminated objects and then touch their nose or mouth.
- Are bitten or scratched by an infected rodent.
- Eat food contaminated with hantavirus.
Cases normally occur in rural areas where forests, fields, and farms offer habitats for rodents. The animals can get into homes and barns, where they may leave urine or feces.
Dogs and cats are not known to become infected with hantavirus in the United States. Pets may bring infected rodents to people or into homes.
Testing and diagnosis
Assessing patients for hantavirus can be difficult early in the infection because symptoms are non-specific and resemble many other viral infections like influenza, legionnaire's, leptospirosis, mycoplasma, and Q fever. Because hantavirus resembles these infections, a blood test is often the only way to officially diagnose it.
To diagnose hantavirus or HPS, clinicians should understand:
- Disease symptoms and rodent exposure history
- Testing guidelines to identify the virus
- How to request testing support from CDC if needed, and
- How to report cases to CDC
Clinicians with a patient experiencing symptoms compatible with HPS and a potential rodent exposure should contact their state, tribal, local, or territorial health department.
CDC is available to consult or provide diagnostic testing. Clinicians can reach out by calling the CDC Emergency Operations Center at 770-488-7100 and requesting the on-call epidemiologist that handles hantavirus.
Testing
CDC uses an enzyme-linked immunosorbent assay (ELISA) to detect IgM antibodies and diagnose acute infections with hantaviruses. This diagnostic method is used to diagnose both HPS and HFRS. Diagnostic testing can be performed at:
- CDC
- State labs running the CDC-developed assay
- State public health labs using other diagnostic assays
- Commercial labs
The criteria to report hantavirus-positive cases are based on the national case definition, which includes clinical symptoms (HPS or non-HPS) and acute laboratory diagnostic results, such as:
- IgM positive
- IgG positive with rising titers
- Immunohistochemistry positive, or
- PCR positive
Testing suspected hantavirus specimens at CDC
Treatment and recovery
There is no specific treatment for hantavirus infection. If HPS is suspected, the patient needs emergency medical care immediately, preferably in the intensive care unit, even before diagnosis.
Early intensive medical care is critical because patients who have sudden acute disease can rapidly become severely sick and die. If a patient is experiencing full distress, it is less likely the treatment will be effective.
Patient management should include:
- Monitoring and adjustment of cardiac function
- Carefully administering fluids
- Providing supplemental oxygen
- Intubating and ventilating if needed
Suspected HPS patients should receive appropriate broad-spectrum antibiotic therapy, even if you're still waiting for diagnosis. Care should also include fever reducers and pain relievers.
While HPS can be quite severe, it has a short duration of critical disease. The cardiopulmonary dysfunction seen in HPS is most likely due to circulating inflammatory mediators. Autopsies performed on fatal cases did not show significant tissue damage.
Initiating extracorporeal membrane oxygenation (ECMO) at the earliest sign of decompensation has an 80 percent survival rate in patients despite cardiopulmonary collapse.
Within 24 hours of initial evaluation, most HPS patients develop some degree of hypotension. They also experience progressive evidence of pulmonary edema and hypoxia, usually requiring mechanical ventilation.
Patients with fatal infections often appear to have severe myocardial depression that progresses to sinus bradycardia with subsequent electromechanical dissociation, ventricular tachycardia, or fibrillation.
In patients with HPS, poor prognostic indicators include a plasma lactate of greater than 4.0 mmol/L or a cardiac index of less than 2.2 L/min/m2.
Pulmonary edema and pleural effusions are common, but multiorgan dysfunction syndrome is rarely seen. However, HPS patients sometimes have mildly impaired renal function. Survivors frequently become polyuric during convalescence and improve rapidly.
Intravenous ribavirin, a guanosine analogue, has been tested in patients with HPS. However, it was not shown to be effective for treatment of HPS.
Without adequate treatment, most deaths occur in patients with HPS within 24 to 48 hours of the cardiopulmonary phase onset.
Related diseases
Some hantaviruses cause kidney symptoms more than lung damage. When this occurs, it is called hemorrhagic fever with renal syndrome (HFRS).