Introduction
Hantavirus Pulmonary Syndrome (HPS) is a severe and sometimes fatal respiratory disease caused by hantaviruses, a group of viruses primarily transmitted to humans through contact with infected rodents. First identified in the United States in 1993, HPS has since been recognized as a significant public health concern, especially in rural areas where rodent populations are more prevalent.
Causes and Transmission
Rodent carriers
Hantavirus pulmonary syndrome is a human disease found only in North and South America. Each strain of the hantavirus has a preferred rodent carrier.
The deer mouse is the most common carrier of the virus in North America and Central America. In the United States, most of the infections occur in the states west of the Mississippi River.
Other carriers in North America include the rice rat and cotton rat in the Southeast and the white-footed mouse in the Northeast. Rodent carriers in South America include the rice rat and the vesper mouse.
Transmission
The virus is present in the rodent’s urine, feces or saliva. You can come in contact with the virus in the following ways:
- Inhaling viruses — the most likely form of transmission — when they become airborne from disturbed rodent droppings or nesting materials
- Eating food contaminated with mouse saliva, urine or droppings
- Touching things contaminated with the virus, such as a nest, and then touching your mouth, eyes or nose
- Being bitten or scratched by an infected rodent
Person-to-person transmission of the virus has only been recorded with a strain of the virus found in South America called the Andes virus.
Effect of the virus
When hantaviruses reach the lungs, they invade tiny blood vessels called capillaries, eventually causing them to leak. Your lungs fill with fluid (pulmonary edema), resulting in severe dysfunction of the lungs and heart.
Related disease
Another disease caused by different strains of the hantavirus is called haemorrhagic fever with renal syndrome, which causes severe kidney disease. These variants of the virus have other animal carriers in Africa, Asia and Europe.
Risk factors
In the United States, hantavirus pulmonary syndrome is most common in rural areas of the West. However, any exposure to rodent habitats can increase the risk of disease.
Common sites for exposure to rodent nests, urine and droppings include:
- Farm buildings
- Infrequently used buildings, such as storage sheds
- Campers or seasonal cabins
- Camp sites or hiking shelters
- Attics or basements
- Construction sites
Activities that can increase the risk of exposure to the hantavirus include:
- Opening and cleaning long unused buildings
- Cleaning up rodent nests or droppings without appropriate precautions
- Working in a field that increases exposure to rodents, such as construction, utility work, pest control and farming
Symptoms and Diagnosis
The incubation period for HPS ranges from one to eight weeks, with most cases developing symptoms within two to four weeks after exposure. The disease typically progresses through two distinct phases:
Early Phase
During the early phase, which lasts for about three to five days, patients may experience flu-like symptoms, including:
- Fever
- Chills
- Muscle aches
- Headaches
- Fatigue
- Dizziness
- Stomach pain, nausea, vomiting, and diarrhea may also occur in some cases.
Late Phase
The late phase of HPS, which can develop rapidly, is characterized by severe respiratory distress and may include:
- Shortness of breath
- Rapid respiration
- Coughing
- Fluid buildup in the lungs (pulmonary edema)
- Low blood pressure (hypotension)
- Reduced heart function
In severe cases, HPS can lead to respiratory failure and death. The mortality rate for HPS is approximately 38%, making early diagnosis and treatment critical.
Diagnosis
Diagnosing HPS can be challenging due to the non-specific nature of early symptoms, which can resemble those of other viral infections. However, healthcare providers may suspect HPS based on a history of potential rodent exposure and the presence of characteristic symptoms. Diagnostic tests for HPS include:
- Serological tests to detect antibodies against hantavirus
- Polymerase chain reaction (PCR) tests to identify viral RNA in blood or tissue samples
- Chest X-rays to detect pulmonary edema and other lung abnormalities
Treatment and Prognosis
There is no specific antiviral treatment for HPS. Instead, supportive care is the mainstay of treatment, focusing on managing symptoms and complications. This may include:
- Supplemental oxygen therapy to alleviate respiratory distress
- Mechanical ventilation in severe cases of respiratory failure
- Intravenous fluids to maintain blood pressure and hydration
- Intensive care monitoring for complications such as cardiac dysfunction
Early recognition and prompt medical intervention are crucial for improving the prognosis of HPS patients. With appropriate supportive care, many patients can recover fully, although the recovery process may be prolonged.
Prevention
Preventing HPS involves minimizing exposure to rodents and their excreta, particularly in areas where hantavirus-carrying rodents are known to live. Key preventive measures include:
- Sealing holes and gaps in homes and other buildings to prevent rodent entry
- Keeping food in rodent-proof containers to deter rodents
- Maintaining cleanliness and reducing clutter in and around living areas to eliminate rodent nesting sites
- Avoiding contact with rodent droppings, urine, and nesting materials
- Using protective gear, such as gloves and masks, when cleaning areas contaminated by rodent droppings or urine
- Ventilating enclosed spaces before cleaning to reduce the risk of inhaling airborne particles
- Following safe and humane rodent control methods
For those working in high-risk occupations or recreational activities that may increase contact with rodents, additional precautions such as using rodent-proof tents and practicing good hygiene are recommended.
REFERENCES
- American Lung Association. Hantavirus Pulmonary Syndrome (HPS) https://www.lung.org/lung-health-diseases/lung-disease-lookup/hantavirus-pulmonary-syndrome.
- Arthropod-Borne and Rodent-Borne Viral Diseases. In: Riedel S, Hobden JA, Miller S, et al., eds. Jawetz, Melnick, & Adelberg’s Medical Microbiology, 28th Edition. McGraw Hill; 2019.
- Barlam TF. Approach to the Acutely Ill Infected Febrile Patient. In: Loscalzo J, Fauci A, Kasper D, et al., eds. Harrison’s Principles of Internal Medicine, 21st Edition. McGraw Hill; 2022.
- Centers for Disease Control and Prevention. Hantavirus Pulmonary Syndrome (HPS) (https://www.cdc.gov/hantavirus/hps/index.html).
- Chest Foundation. Hantavirus Pulmonary Syndrome (HPS) (https://foundation.chestnet.org/patient-education-resources/hantavirus-pulmonary-syndrome/).
- Merck Manual. Hantavirus Infection https://www.merckmanuals.com/home/infections/arboviruses-arenaviruses-filoviruses/hantavirus-infection.
- National Organization for Rare Disorders. Hantavirus Pulmonary Syndrome (https://rarediseases.org/rare-diseases/hantavirus-pulmonary-syndrome/).
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