Rodent-borne Diseases

(This page is part of a series. For information on other illnesses that can affect NPS employees, volunteers, commercial use providers, and visitors, please see the NPS A–Z Health Topics index.)

Deer Mouse (Peromyscus maniculatus)

NPS

THE BASICS
Humans: Rodents directly transmit a number of pathogens that can cause human disease in the United States, including hantavirus, leptospirosis, rat bite fever, and salmonellosis. These pathogens can infect humans through various routes, including direct handling, bites, or contact (such as through breathing in air or eating food) with feces, urine, or saliva. They also serve as the hosts for ectoparasite vectors (such as ticks or fleas) that transmit other diseases, including Lyme disease, plague, tularemia, murine typhus, and tickborne relapsing fever. Burrows and nests of some rodent species may serve as a reservoir for kissing bugs (e.g., triatomines) that transmit Trypanosoma cruzi, the causative agent of Chagas disease.

Animals: As the largest group of mammals, rodents are characterized by two continuously growing incisors, which they use to gnaw upon food items. Rodents include rats, mice, squirrels, hamsters, prairie dogs, porcupines, and their relatives. Although many mice and rat species have a short lifespan of around 9 months to 2 years, they reproduce extremely rapidly, becoming sexually mature as early as 4-5 weeks of age with a gestation of only 21 days. When food is adequate and warm habitat exists, rodents can reproduce year-round, allowing for many offspring from one pair of house mice.Rodents are a common reservoir for ticks and fleas, and rodents can also play a role in disease transmission to other animals. Rodents can be impacted and suffer from many of the same diseases as humans or can be asymptomatic carriers of disease.Rodents are opportunists and can adapt to live in human buildings and on human food. Rodents that live in human structures and in higher densities carry more pathogens than do rodents in natural habitats with more biodiversity. In addition, rodents residing in human structures create a risk of pathogen transmission. Therefore, it is important to keep rodents from being attracted to human dwellings and entering buildings.

Environment: Rodents are important parts of the ecosystem. They are a source of food for many species. For example, the survival of the endangered black-footed ferret is dependent upon the availability of their prey, healthy prairie dog populations. Rodents eat insects, recycle nutrients in the soil to promote plant growth, and disperse seeds. In a healthy ecosystem, predators and competition with other species of rodents keep rodent populations and their associated diseases in check. However, when habitats and ecosystems are disturbed or predators and other species are excluded, such as with human development, rodent communities and behavior can change. When these changes occur, rodent problems in an environment can occur.

PREVENTION

• Avoid contact with rodents, their droppings, urine, saliva, and nesting materials.
• Properly store and dispose of food and trash.
• Employees, including those who live in housing:
  • Report information about rodents inside buildings to park maintenance staff or a supervisor immediately.
  • Exclude rodents from areas in which people live, work, and eat. Seal any gap greater than one-quarter of an inch. Keep vegetation at least 18 inches from buildings. Additional guidance is available in the NPS Rodent Exclusion Manual.
  • Utilize snap traps to both remove and monitor rodents.
  • Take precautions when cleaning up after rodent infestations or opening/cleaning buildings that have been closed for a period of time. Instructions for cleaning a light infestation are available in resources. Heavy infestations should be handled by a specialist and require the use of a respirator and enrollment in a respiratory protection program. Because it can be difficult to differentiate between light and heavy rodent infestations, consult the Office of Public Health and your safety officer for additional direction.
  • Utilize the resources provided below to educate employees and the public on the risk of rodents and how to reduce exposure.

RESPONSE

• If you become ill following a potential exposure, contact your healthcare provider and let them know of your concern.
• Please report any exposures or confirmed illnesses to the NPS Office of Public Health (e-mail us) as directed in the “Disease Reporting” guidance below.
• Report concerns about sick or dead wildlife (including rodents) to the park resource manager and the Wildlife Health Branch (e-mail us).

(Last updated: 5/10/2023)

NPS RESOURCES:

• NPS Hantavirus Fact Sheet and Clean/Trapping Instructions (combined)
• NPS IPM Indoor Rodent Management for NPS Properties (restricted access)
• NPS Rodent Exclusion Manual (2014)
• NPS Rodent Exclusion Video (2017) (restricted access)
• NPS Proper Use and Placement of Snap Traps
• NPS Integrated Pest Management: Rodent Management (restricted access)
• NPS Pest and Invasive Species Management: Hantavirus (restricted access)

OTHER RESOURCES:

• CDC “How to Control Wild Rodent Infestations” webpage

NPS-SPECIFIC PUBLICATIONS:

• Danforth ME, Messenger S, Buttke D, et al. Long-Term Rodent Surveillance after Outbreak of Hantavirus Infection, Yosemite National Park, California, USA, 2012. Emerg Infect Dis. 2020;26(3):560-567. doi:10.3201/eid2603.191307
• Pesapane R, Enge B, Roy A, et al. A Tale of Two Valleys: Disparity in Sin Nombre Virus Antibody Reactivity Between Neighboring Mojave Desert Communities. Vector Borne Zoonotic Dis. 2019;19(4):290-294. doi:10.1089/vbz.2018.2341
• Burns JE, Metzger ME, Messenger S, et al. Novel Focus of Sin Nombre Virus in Peromyscus eremicus Mice, Death Valley National Park, California, USA. Emerg Infect Dis. 2018;24(6):1112-1115. doi:10.3201/eid2406.180089
• Wilken JA, Jackson R, Materna BL, et al. Assessing prevention measures and Sin Nombre hantavirus seroprevalence among workers at Yosemite National Park. Am J Ind Med. 2015;58(6):658-667. doi:10.1002/ajim.22445
• Núñez JJ, Fritz CL, Knust B, et al. Hantavirus infections among overnight visitors to Yosemite National Park, California, USA, 2012. Emerg Infect Dis. 2014;20(3):386-393. doi:10.3201/eid2003.131581
• Hartline J, Mierek C, Knutson T, Kang C. Hantavirus infection in North America: a clinical review. Am J Emerg Med. 2013;31(6):978-982. doi:10.1016/j.ajem.2013.02.001
• Outbreak news. Hantavirus pulmonary syndrome, Yosemite National Park, United States of America. Wkly Epidemiol Rec. 2012;87(37):345-346.
• Hantavirus pulmonary syndrome in visitors to a national park--Yosemite Valley, California, 2012. MMWR Morb Mortal Wkly Rep. 2012;61(46):952.
• Zeitz PS, Graber JM, Voorhees RA, et al. Assessment of occupational risk for hantavirus infection in Arizona and New Mexico. J Occup Environ Med. 1997;39(5):463-467. doi:10.1097/00043764-199705000-00013
• Glass GE, Johnson JS, Hodenbach GA, et al. Experimental evaluation of rodent exclusion methods to reduce hantavirus transmission to humans in rural housing. Am J Trop Med Hyg. 1997;56(4):359-364. doi:10.4269/ajtmh.1997.56.359

Disease Reporting

Visitors: Please email us to report any disease or health concern you believe may be related to your visit. You should also contact your healthcare provider who will report any confirmed and reportable disease on your behalf to the local or state health department.

Concessioners & Partners: Please email us to report illnesses as defined in NPS guidance and policy and in the Concessions contract.

Employees & Volunteers: NPS staff should report all employee and volunteer incidents as defined in NPS guidance and policy by contacting your NPS Public Health Consultant (restricted access), or you can email us. All work-related exposures and illnesses must also be reported in the Safety Management Information System (SMIS) (restricted access). All known disease exposures should be reported in SMIS as well.