Can ringworm be transmitted from dogs to humans?

Ringworm Transmission from Dogs to Humans

Yes, ringworm can definitely be transmitted from dogs to humans through direct skin contact with infected animals. 1 This zoonotic fungal infection is a significant public health concern when humans interact with animals, including household pets like dogs.

Transmission Mechanism and Causative Organisms

• Ringworm (dermatophytosis) in dogs is most commonly caused by fungal species including:

  • Microsporum canis (accounts for 95.8% of canine ringworm infections) 2
  • Trichophyton mentagrophytes (accounts for 4.2% of canine infections) 2

• Transmission occurs through:

  • Direct skin-to-skin contact with infected dogs 1
  • Contact with contaminated surfaces or objects (fomites) where fungal arthrospores are present 3
  • Environmental exposure in households with infected pets 3

Environmental Contamination Risk

The risk of environmental contamination varies by animal species:

• Dogs appear to cause less environmental contamination than cats:
  • Only 4 out of 9 households with infected dogs showed environmental contamination 3
  • Dogs primarily contaminate surfaces but rarely contaminate the air 3
  • This suggests dogs may present a lower (but still significant) transmission risk compared to cats

Documented Cases of Transmission

Multiple documented cases confirm dog-to-human transmission:

• The National Association of State Public Health Veterinarians (NASPHV) has documented cases of ringworm transmission from animals to humans in various settings 1
• Ringworm is specifically listed among diseases that can be acquired through dog contact 4

Risk Factors for Transmission

• Direct physical contact with infected dogs
• Handling of infected dogs, especially those with visible skin lesions
• Contact with contaminated environments where infected dogs live
• Immunocompromised status of the human (higher risk of infection)
• Young children who may have more physical contact with pets 5

Prevention Measures

To prevent transmission of ringworm from dogs to humans:

• Prompt veterinary treatment for dogs showing signs of skin lesions
• Regular veterinary check-ups for early detection
• Wearing gloves when handling dogs with suspected skin infections
• Thorough handwashing after handling any dogs
• Environmental cleaning and disinfection in households with infected dogs
• Limiting contact between infected dogs and humans until treatment is complete

Clinical Presentation in Humans

Ringworm infection in humans typically presents as:

• Circular, red, itchy patches on the skin
• Raised, scaly borders around the patches
• Hair loss if the scalp is affected
• Skin inflammation and discomfort

Treatment Considerations

• Infected dogs should receive antifungal treatment as prescribed by a veterinarian
• Humans who develop ringworm should seek medical attention for appropriate antifungal therapy
• Environmental decontamination may be necessary to prevent reinfection

Interesting Note

In rare cases, the reverse transmission (human-to-dog) has also been documented. One case report described a dog infected with Trichophyton rubrum that was likely transmitted from the human owner who had tinea pedis (athlete's foot) 6.

Human health risks from dog-transmitted ringworm are generally moderate - the condition is treatable but can cause discomfort and requires medical intervention. Special caution should be exercised with children and immunocompromised individuals who may be more susceptible to infection.