Diseases Transmitted by Rats and Mice

Introduction to Rodent-Borne Diseases

The Role of Rats and Mice in Disease Transmission

Direct Transmission Pathways

Rats and mice transmit pathogens to humans through several direct mechanisms that require physical contact or immediate exposure to infectious material.

Bite wounds or scratches inflicted during handling introduce saliva, blood, or tissue directly into the victim’s bloodstream.
Contamination of skin or mucous membranes occurs when individuals touch rodent urine, feces, or secretions and subsequently touch their eyes, nose, or mouth without washing hands.
Inhalation of aerosolized particles is possible when dried rodent droppings or urine are disturbed, releasing infectious droplets that enter the respiratory tract.
Direct ingestion results from consuming food or water contaminated with fresh rodent excreta or from eating rodents themselves.

These pathways facilitate the spread of bacterial agents such as Leptospira spp., viral agents including hantaviruses, and parasites like Bartonella spp. Effective control measures focus on minimizing direct contact, implementing rigorous hygiene protocols, and securing food storage to prevent rodent access.

Indirect Transmission Pathways

Rats and mice serve as reservoirs for a range of pathogenic microorganisms that can reach humans without direct contact. Indirect transmission occurs when contaminated materials act as vectors, allowing disease agents to survive and spread in environments frequented by people.

• Food contamination – rodent droppings, urine, or hair introduced into stored grains, produce, or prepared meals provide a route for bacteria such as Salmonella and viruses like Hepatitis E.
• Water contamination – seepage of urine or feces into water supplies, especially in poorly sealed storage tanks, introduces Leptospira spp. and other water‑borne pathogens.
• Surface contamination – gnawed packaging, furniture, or laboratory equipment become reservoirs for viruses (e.g., Hantavirus) and bacteria, persisting until removed by cleaning.
• Airborne particles – aerosolized droppings or dried urine fragments can be inhaled, delivering hantaviruses and other agents to the respiratory tract.
• Mechanical vectors – ectoparasites (fleas, mites) that feed on rodents acquire pathogens and subsequently bite humans, transmitting plague, murine typhus, or rickettsial diseases.

Effective control relies on eliminating rodent access to food storage, sealing water containers, implementing routine sanitation of surfaces, and applying pest‑management strategies that reduce both rodent populations and their ectoparasites. These measures interrupt indirect pathways, decreasing the risk of rodent‑associated infections.

Major Diseases Transmitted by Rodents

Bacterial Diseases

Leptospirosis («Weil's Disease»)

Leptospirosis, also known as «Weil's Disease», is a zoonotic infection caused by pathogenic spirochetes of the genus Leptospira. The bacteria survive in moist environments and proliferate in the kidneys of numerous mammalian hosts, with rats and mice serving as primary reservoirs. Infected rodents excrete Leptospira in urine, contaminating water, soil, and food sources.

Human exposure occurs through direct contact with contaminated urine or indirectly via skin abrasions, mucous membranes, or ingestion of tainted water. Occupational groups such as agricultural workers, sewage personnel, and veterinarians face heightened risk, while recreational activities in flooded areas increase community exposure.

Typical clinical presentation includes:

Sudden onset of high fever, chills, and severe headache
Myalgia, especially in calf and lumbar muscles
Conjunctival suffusion without purulent discharge
Jaundice, renal dysfunction, and hemorrhagic manifestations in severe cases

Laboratory confirmation relies on:

Microscopic agglutination test (MAT) detecting specific antibodies
Polymerase chain reaction (PCR) identifying Leptospira DNA in blood or urine
Culture of organism from blood, CSF, or urine, though sensitivity is limited

Prompt antimicrobial therapy with doxycycline or intravenous penicillin reduces morbidity and mortality. Severe disease may require supportive measures for renal failure, hepatic dysfunction, and respiratory compromise. Early treatment shortens the febrile period and minimizes organ damage.

Preventive strategies emphasize:

Rodent control through integrated pest management
Provision of clean drinking water and avoidance of contact with potentially contaminated sources
Use of protective clothing and gloves during high‑risk activities
Pre‑exposure chemoprophylaxis with doxycycline for individuals in endemic regions

Awareness of Leptospira transmission dynamics and adherence to control measures significantly lower the incidence of this rodent‑associated illness.

Salmonellosis

Salmonellosis is a bacterial infection caused by Salmonella species, frequently associated with contamination of food, water, and surfaces that have been accessed by rodents. Rats and mice act as reservoirs, shedding the pathogen in feces and urine, which readily contaminates grain, produce, and household utensils.

Transmission occurs through direct contact with rodent droppings, ingestion of contaminated food or water, and inhalation of aerosolized particles generated during cleaning of infested areas. Indirect spread may involve fleas or other arthropods that feed on infected rodents, subsequently contaminating human environments.

Incidence peaks in regions with poor sanitation, dense rodent populations, and limited waste management. Occupational groups such as food handlers, agricultural workers, and pest‑control personnel exhibit elevated exposure. Children and immunocompromised individuals experience higher rates of severe disease.

Typical clinical manifestations include:

Diarrhea, often watery or bloody
Abdominal cramps
Fever ranging from low to high grade
Nausea and vomiting
Dehydration, particularly in pediatric cases

Diagnosis relies on culture of stool, blood, or other sterile specimens, with selective media confirming Salmonella growth. Serotyping identifies specific strains, informing epidemiological tracking and antimicrobial susceptibility testing.

Management emphasizes rehydration, electrolyte replacement, and, when indicated, antimicrobial therapy. Fluoroquinolones, third‑generation cephalosporins, or azithromycin constitute first‑line agents for severe or invasive infections; susceptibility patterns guide final selection.

Preventive strategies focus on rodent control and hygiene:

Seal entry points and eliminate food sources to deter infestation
Employ traps or certified extermination services in high‑risk areas
Implement regular cleaning protocols using disinfectants effective against Salmonella
Store food in rodent‑proof containers and maintain proper waste disposal
Educate personnel on safe handling practices and personal protective equipment

Effective integration of these measures reduces the burden of salmonellosis linked to rodent vectors, safeguarding public health.

Plague («Black Death»)

The plague, historically known as «Black Death», is a severe zoonotic infection caused by the bacterium Yersinia pestis. Primary vectors are fleas that parasitise rodents, especially rats and mice, which serve as reservoirs for the pathogen. Human infection occurs when infected fleas bite, or when aerosolised bacteria are inhaled from contaminated rodent tissues.

Key characteristics of the disease include:

Rapid onset of fever, chills, and painful swelling of lymph nodes (buboes) in the bubonic form.
Development of severe pneumonia and systemic infection (septicemic form) without visible buboes.
Mortality rates ranging from 30 % to 60 % in untreated cases; higher rates observed during historical pandemics.

Transmission dynamics rely on dense rodent populations in urban and rural settings. Flea infestation intensifies during periods of poor sanitation, facilitating spillover to humans. Climate fluctuations influencing rodent reproduction can trigger outbreaks.

Control strategies focus on:

Reducing rodent habitats through waste management and structural maintenance.
Implementing flea control programs using insecticides.
Prompt diagnosis and administration of antibiotics such as streptomycin or doxycycline.
Surveillance of rodent and flea populations to predict risk periods.

The 14th‑century pandemic, attributed to the same pathogen, resulted in the death of an estimated one‑third of Europe’s population, profoundly altering demographic and economic structures. Contemporary public‑health systems maintain vigilance, recognising the plague as a re‑emerging threat in regions where rodent‑borne vectors persist.

Rat-Bite Fever

Rat‑bite fever is a zoonotic infection caused primarily by Streptobacillus moniliformis in North America and Spirillum minus in parts of Asia. Transmission occurs through bites or scratches from infected rodents, as well as through handling of contaminated animal products or ingestion of contaminated food and water.

The disease remains uncommon but is reported among laboratory workers, pet‑store employees, and individuals with frequent contact with rats or mice. Outbreaks are linked to inadequate rodent control and poor personal protective measures.

Typical clinical features appear after an incubation period of 2 to 14 days. Common manifestations include:

Fever and chills
Chills and rigors
Headache
Myalgia
Arthralgia, often affecting large joints
Rash, frequently maculopapular or petechial
Nausea, vomiting, or abdominal pain

Severe cases may progress to septicemia, endocarditis, or meningitis, underscoring the need for prompt recognition.

Diagnosis relies on microbiological confirmation. Blood cultures grown under aerobic conditions frequently isolate S. moniliformis; S. minus requires special media and incubation. Serologic testing and polymerase‑chain‑reaction assays provide supplemental evidence, especially when cultures are negative.

Effective therapy consists of antibiotics. First‑line treatment is intravenous or oral penicillin G for 10‑14 days; alternatives for penicillin‑allergic patients include doxycycline or ceftriaxone. Early administration reduces complications and shortens illness duration.

Prevention centers on rodent management and safe handling practices. Recommended measures comprise:

Regular pest‑control programs to limit rodent populations
Use of gloves, protective clothing, and eye protection when handling rodents
Immediate washing of bites or scratches with soap and water, followed by antiseptic application
Prompt medical evaluation of any wound incurred from a rodent

Awareness of rat‑bite fever and adherence to these control strategies mitigate the risk posed by rodent‑borne pathogens. «Rat‑bite fever exemplifies the direct health threat associated with close contact with commensal rodents».

Viral Diseases

Hantavirus Pulmonary Syndrome («HPS»)

Hantavirus Pulmonary Syndrome (HPS) is a severe acute respiratory disease caused by infection with hantaviruses carried primarily by deer mice (Peromyscus maniculatus) and, in some regions, by other rodent species. Human exposure occurs through inhalation of aerosolized virus particles from rodent urine, droppings, or saliva, typically in enclosed spaces such as cabins, barns, or grain storage facilities.

The clinical course progresses rapidly. Initial symptoms include fever, myalgia, and headache, followed within 3–5 days by non‑cardiogenic pulmonary edema, hypoxemia, and shock. Mortality rates range from 30 % to 40 % despite intensive care. Early recognition and supportive treatment improve outcomes.

Key aspects of diagnosis and management:

Laboratory confirmation through serologic testing (IgM, IgG) or polymerase chain reaction detection of viral RNA.
Immediate hospitalization with oxygen therapy, mechanical ventilation, and careful fluid management.
No specific antiviral therapy approved; clinical care focuses on supportive measures and hemodynamic stabilization.

Prevention relies on rodent control and exposure reduction:

Seal entry points to buildings and store food in rodent‑proof containers.
Conduct thorough cleaning of areas with rodent contamination using wet methods to avoid aerosolization.
Wear protective equipment (gloves, masks) when handling rodent‑infested materials.

Surveillance of rodent populations and public education about risk factors are essential components of public‑health strategies aimed at reducing incidence of this rodent‑associated illness.

Lymphocytic Choriomeningitis Virus («LCMV»)

Lymphocytic Choriomeningitis Virus («LCMV») is an arenavirus maintained primarily in the house mouse (Mus musculus) and, to a lesser extent, in other rodent species. Transmission to humans occurs through direct contact with infected rodent excreta, contaminated bedding, or bites, and occasionally via organ transplantation from asymptomatic donors. The virus can cross the placental barrier, leading to congenital infection with severe fetal outcomes.

Clinical presentation varies with exposure route. Acute infection typically produces a biphasic illness:

Initial flu‑like symptoms: fever, myalgia, headache.
Secondary phase: meningitis or encephalitis, characterized by neck stiffness, photophobia, altered mental status.

Immunocompromised patients may develop persistent viremia, presenting as chronic meningoencephalitis or hepatitis. Diagnosis relies on detection of specific IgM antibodies, polymerase chain reaction (PCR) amplification of viral RNA from blood or cerebrospinal fluid, and virus isolation in cell culture when available.

No approved antiviral therapy exists; management is supportive, focusing on fever control, hydration, and monitoring for neurological complications. Antiviral agents such as ribavirin have shown limited efficacy in experimental settings but lack sufficient clinical evidence.

Prevention strategies focus on rodent control and hygiene:

Exclusion of rodents from residential and laboratory environments.
Use of protective equipment when handling rodents or contaminated materials.
Regular cleaning of animal cages with disinfectants effective against non‑enveloped viruses.
Screening of organ donors for LCMV exposure in high‑risk regions.

Public health surveillance monitors rodent populations for LCMV prevalence, informing risk assessments and guiding community education campaigns.

Parasitic Diseases

Toxoplasmosis

Toxoplasmosis is a protozoan infection caused by Toxoplasma gondii, frequently associated with rodent reservoirs that facilitate transmission to humans and other animals. Rodent populations serve as intermediate hosts, harboring tissue cysts that become infectious when ingested by definitive feline hosts or through accidental consumption of contaminated material.

Key aspects of the disease include:

Transmission pathways: ingestion of undercooked meat containing cysts, accidental ingestion of oocysts from contaminated soil or water, and congenital passage from mother to fetus.
Clinical presentation: asymptomatic seroconversion in most individuals; symptomatic cases may involve lymphadenopathy, fever, myalgia, and, in immunocompromised patients, encephalitis, retinochoroiditis, or severe systemic involvement.
Diagnostic methods: serologic testing for IgG and IgM antibodies, polymerase chain reaction detection of parasite DNA in blood or cerebrospinal fluid, and imaging studies for organ-specific lesions.
Therapeutic regimen: combination therapy with pyrimethamine, sulfadiazine, and folinic acid for acute or severe disease; prophylactic treatment may be indicated for patients with compromised immunity.

Prevention strategies focus on controlling rodent populations, ensuring proper cooking of meat, practicing rigorous hand hygiene after handling soil or cat litter, and screening pregnant women for serologic evidence of infection.

Trichinellosis

Trichinellosis, a parasitic disease caused by nematodes of the genus Trichinella, frequently involves rodents such as rats and mice as reservoir hosts. Infected rodents harbor encysted larvae in skeletal muscle, which become infectious when consumed by carnivorous or omnivorous animals, including humans, through contaminated meat.

Transmission occurs when humans ingest raw or undercooked meat containing viable cysts. Rodent populations, thriving in urban and rural settings, facilitate the spread of Trichinella spp. by contaminating food sources and serving as intermediate hosts for predators and scavengers.

Clinical presentation progresses through two phases:

Intestinal phase (days 1‑2 post‑infection): abdominal pain, diarrhea, nausea.
Muscular phase (weeks 2‑8): fever, facial edema, myalgia, weakness, and eosinophilia.

Diagnosis relies on a combination of methods:

Serological assays detecting specific antibodies (ELISA, Western blot).
Muscle biopsy revealing encysted larvae.
Epidemiological history indicating exposure to rodent‑contaminated food.

Treatment protocols recommend early administration of anthelmintics such as albendazole or mebendazole, supplemented by corticosteroids in severe inflammatory cases. Prompt therapy reduces parasite load and mitigates muscular complications.

Prevention focuses on controlling rodent populations, enforcing proper meat inspection, and ensuring thorough cooking of pork, wild game, and other potential sources. Public health measures include educating consumers about safe food handling and monitoring wildlife reservoirs to interrupt transmission cycles.

Prevention and Control Measures

Rodent Control Strategies

Exclusion Techniques

Exclusion techniques comprise methods that prevent rodents from entering buildings, food‑handling areas, and storage facilities, thereby reducing the risk of rodent‑borne illnesses. Effective implementation relies on physical barriers, environmental control, and systematic maintenance.

Seal all openings larger than ¼ inch with steel wool, cement, or metal flashing.
Install door sweeps and weather‑stripping on exterior doors and service entries.
Fit vent covers with fine mesh that resists gnawing.
Elevate food preparation surfaces and storage units to create a clearance zone beneath.
Remove vegetation, debris, and clutter within a 10‑foot perimeter of structures.
Store waste in sealed containers and schedule frequent removal.
Conduct regular inspections of building envelopes, focusing on utility penetrations, roof eaves, and foundation cracks.
Document findings and repair deficiencies promptly, using durable, rodent‑resistant materials.

Consistent application of these measures limits rodent access, interrupts transmission pathways for pathogens, and supports long‑term public‑health protection.

Sanitation Practices

Effective sanitation reduces the risk of rodent‑borne illnesses by eliminating food sources, shelter, and water that attract rats and mice. Proper waste management, secure food storage, and regular cleaning of premises interrupt the transmission cycle of pathogens carried by these pests.

Key sanitation measures include:

Prompt removal of garbage in sealed containers; containers should be emptied daily and kept away from building entrances.
Storage of dry goods in airtight containers; shelves must be cleared of spills and crumbs.
Maintenance of building integrity; gaps larger than ¼ inch sealed, doors equipped with self‑closing mechanisms.
Elimination of standing water; drainage systems inspected weekly, leaks repaired immediately.
Routine cleaning schedules; floors, countertops, and equipment disinfected with approved agents at least once per shift.

Integration of sanitation with rodent control programs enhances effectiveness. Monitoring logs record waste disposal times, inspection findings, and corrective actions, ensuring compliance with health regulations and facilitating rapid response to infestation indicators. Continuous training of staff on these practices sustains a hygienic environment that limits disease transmission.

Trapping and Baiting

Effective control of rodent populations that serve as vectors for various illnesses requires systematic trapping and baiting. Reducing contact between humans and infected rats or mice directly lowers the incidence of zoonotic infections such as leptospirosis, hantavirus, and plague.

Trapping strategies focus on capture efficiency and humane handling. Common devices include:

Snap traps: rapid kill, suitable for indoor settings.
Live‑catch traps: allow relocation, require frequent checking.
Electronic traps: deliver a lethal shock, minimize odor.
Glue boards: immobilize, best for monitoring rather than eradication.

Placement follows established patterns: along walls, near burrows, in dark corners, and at established runways. Traps must be set at night, checked at least every 12 hours, and disposed of according to local health regulations.

Bait selection targets species‑specific preferences while minimizing risk to non‑target organisms. Effective attractants comprise:

Peanut butter or cheese for omnivorous rats.
Seed mixes or grains for mice.
Commercial rodent baits formulated with anticoagulants for long‑term control.

Bait stations should be tamper‑proof, positioned away from children and pets, and replenished based on consumption rates. Rotation of bait types prevents habituation and maintains trap success.

Integration of trapping, baiting, and environmental management yields the most reliable reduction in rodent‑borne disease transmission. Regular sanitation eliminates food sources, sealing of entry points prevents re‑infestation, and ongoing surveillance tracks population trends to adjust control measures promptly.

Personal Protective Measures

Avoiding Contact with Rodents and Their Droppings

Rodent infestations create direct pathways for pathogens to reach humans. Contact with live rats or mice, as well as exposure to their urine, feces, and nesting material, increases the risk of contracting serious infections such as leptospirosis, hantavirus pulmonary syndrome, and plague. Preventive actions focus on eliminating opportunities for contact and reducing environmental contamination.

Key preventive measures include:

Sealing entry points: install metal flashing, concrete, or steel mesh around gaps in walls, floors, and foundations.
Maintaining cleanliness: store food in airtight containers, promptly clean spills, and dispose of waste in sealed bins.
Controlling moisture: repair leaks, use dehumidifiers, and keep basements dry to discourage nesting.
Using traps responsibly: place snap or electronic traps in concealed locations, inspect and remove captured rodents promptly.
Handling droppings safely: wear disposable gloves and a mask, dampen droppings with a disinfectant solution before removal, and disinfect the affected area with a bleach mixture (1 part bleach to 10 parts water).

Regular inspection of premises, especially in storage areas, attics, and crawl spaces, identifies early signs of activity such as gnaw marks, droppings, or urine stains. Early detection enables swift intervention, limiting exposure to harmful agents and protecting public health.

Hand Hygiene

Rodent‑borne illnesses, such as leptospirosis, hantavirus infection, and salmonellosis, spread primarily through direct contact with contaminated surfaces, food, or water. Hands frequently touch surfaces frequented by rats and mice, creating a direct pathway for pathogens to enter the body.

Effective hand hygiene interrupts this pathway. Proper technique includes:

Wetting hands with clean water.
Applying enough soap to cover all surfaces.
Scrubbing palms, backs of hands, between fingers, and under nails for at least 20 seconds.
Rinsing thoroughly.
Drying with a disposable towel or air dryer.

Critical moments for hand washing encompass:

After handling waste, garbage, or rodent droppings.
Before preparing or consuming food.
After cleaning any area where rodents have been observed.
Following disposal of contaminated materials.

Hand hygiene stations should be positioned near entry points to kitchens, storage rooms, and waste disposal areas. Supplies must include antimicrobial soap, disposable towels, and clear signage reminding personnel of proper procedures.

Regular monitoring, such as periodic visual inspections and microbiological testing of hand‑contact surfaces, ensures compliance and identifies gaps. Documentation of hand‑washing frequency supports risk‑assessment reports and informs corrective actions when deviations occur.

Public Health Interventions

Surveillance and Monitoring

Surveillance of rodent-borne illnesses focuses on detecting pathogen presence in urban and rural environments where rats and mice thrive. Systematic observation enables early identification of infection hotspots, supports risk assessment, and guides preventive measures.

Effective monitoring combines several activities:

Trapping programs that capture representative samples of rodent populations.
Laboratory testing of captured specimens for bacteria, viruses, and parasites known to be carried by these mammals.
Environmental sampling of sewage, food storage areas, and grain facilities to detect contaminating agents.
Geographic information system (GIS) mapping of capture locations and positive test results.
Continuous data entry into centralized databases for real‑time analysis.

Collected data undergo statistical evaluation to determine prevalence trends, seasonal fluctuations, and emerging pathogen strains. Automated alerts trigger notifications to local health authorities when thresholds are exceeded.

Integration of surveillance outputs with public health response plans facilitates targeted rodent control, community education, and vaccination campaigns where applicable. Ongoing evaluation of monitoring protocols ensures adaptability to changing ecological conditions and pathogen evolution.

Education and Awareness Campaigns

Education and awareness campaigns address the public health threat posed by rodent-borne illnesses. Accurate information reduces exposure to pathogens carried by rats and mice and encourages preventive behavior.

Target groups include residents of urban neighborhoods, schoolchildren, food‑service workers, and waste‑management personnel. Tailored messages consider literacy levels, cultural norms, and local risk factors.

Effective campaign components:

Clear description of transmission routes such as contaminated food, water, and surfaces.
Visual guides for identifying signs of infestation and safe removal methods.
Instructions for proper storage of food, waste disposal, and sanitation practices.
Distribution of protective equipment guidelines for occupations with high contact risk.
Contact information for local health authorities and pest‑control services.

Delivery channels combine traditional media (posters, flyers, radio announcements) with digital platforms (social media posts, short videos, interactive quizzes). Community workshops and school presentations reinforce key points through direct engagement.

Monitoring and evaluation rely on pre‑ and post‑campaign surveys, infestation reports, and incidence data of relevant diseases. Adjustments to content and outreach methods follow analysis of these metrics, ensuring continuous improvement of public protection efforts.