Hantavirus is a family of viruses capable of causing severe illness in humans, including Hantavirus Pulmonary Syndrome (HPS) in the Americas and Hemorrhagic Fever with Renal Syndrome (HFRS) in Europe and Asia. Despite the potential for serious health outcomes, hantavirus infections are considered rare globally. This rarity stems from specific transmission routes and the limited circumstances under which human exposure typically occurs.
Understanding Hantavirus Transmission
Hantavirus primarily spreads to humans through contact with infected rodents or their waste products. The most common route of transmission involves inhaling tiny airborne particles, known as aerosols, generated from rodent urine, droppings, or saliva. These rodents can shed the virus in their excreta for extended periods.
Less frequently, infection can occur if contaminated materials contact broken skin or mucous membranes, or through ingesting food or water tainted by rodent waste. Rodent bites or scratches are also a possible, though rare, means of transmission. With the exception of the Andes virus strain in South America, hantaviruses are not transmitted from person to person.
Global and National Incidence
Hantaviruses are present worldwide, with different strains causing distinct illnesses depending on their geographic location. HFRS is more prevalent in Europe and Asia, with European countries reporting 1,647 cases in 2020.
In the Americas, hantaviruses cause Hantavirus Pulmonary Syndrome (HPS), with approximately 200 cases reported annually across the continents. In the U.S., an average of about 28 cases are reported annually. Annually, Sin Nombre virus cases, the most common HPS-causing strain in the U.S., range between 10 and 50. Most cases, about 96%, are concentrated in states west of the Mississippi River, particularly in the Four Corners region. In Canada, the incidence is even lower, with an average of about five cases reported each year.
Factors Influencing Rarity
The rarity of hantavirus infections can be attributed to a combination of ecological and behavioral factors. Specific rodent species serve as reservoirs for different hantavirus strains; for example, the deer mouse is the primary carrier of the Sin Nombre virus in North America. Other carriers include the cotton rat, rice rat, and white-footed mouse, while common house mice and Norway rats are not associated with hantavirus transmission. These carrier rodents remain healthy despite being infected.
Human exposure is limited to specific scenarios that bring individuals into contact with environments contaminated by infected rodents. This often occurs in rural settings during activities like cleaning infrequently used structures (sheds, barns, cabins, attics, basements) or at construction sites. In these situations, disturbing accumulated rodent droppings or nesting materials can aerosolize the virus, making it inhalable. Environmental conditions also play a part; warmer winters and increased precipitation can lead to larger rodent populations, potentially increasing interactions between rodents and humans. Even with significant rodent exposure, transmission to humans remains uncommon.
Reducing Your Risk
Minimizing contact with rodents and their waste is the most effective strategy for preventing hantavirus infection. Inspect homes and garages for holes or gaps, even small ones, and seal them to prevent rodent entry. Keeping food properly stored and cleaning up spills promptly helps eliminate potential attractants for rodents.
When cleaning areas contaminated with rodent droppings, take specific precautions to prevent aerosolizing the virus:
Ventilate the area by opening doors and windows for at least 30 minutes before cleanup.
Wear rubber or plastic gloves.
Avoid sweeping or vacuuming, as these actions can stir up viral particles.
Thoroughly wet down contaminated surfaces (including urine, droppings, and dead rodents) with a bleach solution (one and a half cups of household bleach per gallon of water) or a general disinfectant, allowing it to soak for five minutes.
Wipe up the material with paper towels, then double-bag and dispose of them in a covered trash can.
Mop or sponge the cleaned area with disinfectant.
Wash hands thoroughly with soap and water after removing gloves.
For heavily infested areas, wearing a respirator may provide additional protection. Also check infrequently used vehicles for signs of rodent nesting.