Shrews are small, common mammals often mistaken for mice due to their size and appearance. They possess pointed snouts, small eyes, and five clawed toes on each foot, distinguishing them from rodents. While generally shy and insectivorous, their involvement in disease transmission to humans is a public health concern.
Diseases Associated with Shrews
Shrews can host various pathogens or vectors that affect human health. Lyme disease, caused by Borrelia burgdorferi, is commonly transmitted by ticks. Shrews, particularly the northern short-tailed shrew, can harbor young, infected ticks, contributing to the population of infected ticks in some areas. Studies have found shrews to be common hosts for ticks, sometimes equally with mice.
Hantaviruses, typically associated with rodents, have also been identified in shrews globally. Shrews can serve as incidental hosts for these viruses, and distinct hantaviruses have been detected in shrew tissues. While not all shrew-borne hantaviruses cause severe human diseases like Hantavirus Pulmonary Syndrome (HPS) or Hemorrhagic Fever with Renal Syndrome (HFRS), their presence challenges the notion that rodents are the sole reservoirs.
Borna disease virus 1 (BoDV-1) is linked to the bicolored white-toothed shrew, its recognized reservoir host. This virus can cause severe neurological disease (encephalitis) in humans, though the risk of infection is low. Other pathogens found in shrews include Anaplasma phagocytophilum (anaplasmosis), Babesia microti (babesiosis), and Salmonella bacteria (salmonellosis). A newly identified Langya henipavirus (LayV) is also hypothesized to originate in shrews, causing fever and impaired kidney and liver functions in humans.
How Diseases Spread from Shrews
Diseases from shrews spread through indirect contact or vectors. Direct contact, such as bites or scratches, is rare but can transmit pathogens. Shrews are not typically aggressive unless threatened.
Indirect contact with shrew excretions or secretions is a common route. Shrews shed viruses and bacteria through their urine, feces, and saliva. When these contaminated materials dry, airborne particles can be inhaled, potentially leading to infection. This mechanism is relevant for viruses like Borna disease virus.
Vectors, such as ticks and fleas, play a significant role in transmitting diseases from shrews to humans. Ticks that feed on infected shrews can transmit pathogens like Borrelia burgdorferi (Lyme disease), Anaplasma phagocytophilum, or Babesia microti through bites. Fleas on shrews can also carry bacteria, such as those causing bubonic plague, which can then be transmitted to humans.
Reducing Your Risk of Exposure
Minimizing the risk of exposure to shrews and the diseases they might carry involves practical steps around your home. Sealing entry points into buildings is an important preventative measure. This includes repairing gaps or cracks in foundations, around pipes, windows, doors, and vents, and addressing loose siding or overlapping shingles. Use materials like caulk or copper mesh to block small openings.
Managing outdoor environments can deter shrews. Regular lawn mowing, clearing piles of leaves, wood, and other debris, and trimming overgrown vegetation reduce potential hiding spots and food sources. Removing standing water and sealing trash cans helps control insect populations, a primary food source for shrews.
When cleaning areas that may have been contaminated by shrew droppings, urine, or nests, it is important to take precautions. Avoid sweeping or vacuuming dry materials, as this can aerosolize pathogens. Ventilate the area by opening windows and doors for at least 30 minutes before cleaning. Wear rubber or plastic gloves and an N95 mask to protect yourself. Spray contaminated areas thoroughly with a disinfectant solution, such as a bleach mixture, and let it soak for at least five minutes.
Use paper towels to wipe up the materials, double-bag them, and dispose of them in a covered garbage can. After cleaning, wash gloved hands with soap and water before removing gloves, then wash bare hands thoroughly. If you encounter a shrew, avoid direct contact; consider using live traps and contacting local animal control for safe removal.