Introduction
Cat fungus refers to various fungi that can infect cats and potentially spread to humans. One of the most common is Sporothrix schenckii, which lives in soil and plants and can enter a cat’s body through scratches or other wounds (Journal of Advanced Veterinary Research). This fungus is estimated to infect about 3% of cats globally. Other fungal pathogens like Cryptococcus, Aspergillus, and Blastomyces can also infect cats under certain conditions.
These cat fungi do have zoonotic potential, meaning they can transmit from cats to humans in some cases. This typically requires direct contact with a cat’s infected wounds or breathing in fungal spores. Immunocompromised individuals are at highest risk. According to studies, approximately 10-20% of people exposed to Sporothrix from an infected cat will develop sporotrichosis fungal infections. So while cat fungus can spread to humans, the overall risk is relatively low for healthy individuals.
Types of Fungal Infections in Cats
Some of the most common fungal infections seen in cats include:
Ringworm
Ringworm is a highly contagious fungal skin infection in cats caused by Microsporum canis. It often causes circular lesions on the skin, head, paws, and ears. Ringworm is transmittable to humans and other animals (Source).
Candidiasis
Candidiasis is a yeast infection caused by Candida albicans that can affect the mouth, skin, respiratory tract, and other areas in cats. It often occurs secondary to other illnesses that suppress the immune system (Source).
Aspergillosis
Aspergillosis is caused by the mold Aspergillus and often affects a cat’s respiratory tract and sinuses. It can spread to other organs. Aspergillosis may be challenging to treat (Source).
Cryptococcosis
Cryptococcosis is an infection caused by the fungus Cryptococcus neoformans that often affects a cat’s respiratory tract and central nervous system. It can be spread through inhalation and is potentially fatal if untreated (Source).
Transmission of Cat Fungus to Humans
Cat fungus can be transmitted to humans through direct contact, inhalation of spores, and contaminated environments. According to the CDC, the fungus Sporothrix brasiliensis spreads via bites and scratches from infected cats as well as contact with their lesions. Droplet exposure when an infected cat sneezes or coughs near a person can also lead to transmission. Additionally, humans can inhale fungal spores that have been aerosolized from contaminated soil, plants, and environments where infected cats have been present.
The highest risk of transmission occurs with direct contact with exudate from skin lesions on infected cats. Care should be taken when handling cats that display skin lesions, respiratory illness, or other signs of fungal infection. Wearing gloves and masks when cleaning areas contaminated by an infected cat can lower risk. Promptly treating fungal infections in cats and disinfecting environments where infected cats have been present are also important to prevent spread to humans.
Symptoms in Humans
The most common symptom of sporotrichosis infection in humans is a rash on the skin where the fungus entered the body. The rash typically starts as a small bump that later develops into an open sore or ulcer. Over time, the sore may spread into lymph nodes and cause them to become enlarged and tender.
Respiratory issues can occur if the fungal spores are inhaled. This can lead to pneumonia or other lung infections as the fungus spreads in the respiratory tract. Symptoms may include a cough, shortness of breath, chest pain, and fever.
Some patients experience flu-like symptoms such as fever, chills, fatigue, muscle or joint aches, and headaches. This reflects the body’s inflammatory response as it tries to fight off the infection.
In rare cases, the infection can spread to internal organs and bones if left untreated. This can cause additional symptoms depending on the parts of the body affected.
The symptoms may start relatively mild but can worsen over time as the infection spreads. Seeking prompt medical treatment is important, especially for those with weakened immune systems who are at greater risk of complications.
Treatment in Humans
Treatment of sporotrichosis fungal infection in humans often involves the use of antifungal medications. According to the CDC, the oral antifungal itraconazole is typically used to treat sporotrichosis. Other antifungal medications that may be prescribed include posaconazole, terbinafine, and saturated solution of potassium iodide (SSKI) (CDC).
For localized cutaneous sporotrichosis infections, topical antifungal creams may be effective. These are usually applied directly to the infected skin lesions. Common topical antifungal creams contain medications like ketoconazole, terbinafine, or naftifine (Cornell Feline Health Center).
In addition to medications, it is important to thoroughly clean the environment to prevent reinfection or spreading the fungus to others. This includes disinfecting areas where infected cats spent time and properly cleaning or disposing of contaminated items (CDC).
Prevention
There are several ways to help prevent the transmission of fungal infections from cats to humans:
Grooming and bathing cats regularly with antifungal shampoos can help reduce fungal growth on their skin and fur. Products like miconazole and chlorhexidine shampoos can be used every 1-2 weeks if fungal infections are present. Be sure to follow all label instructions carefully. Fungal Infections in Cats – Types, Causes & Treatments
Disinfecting environments frequented by cats can kill fungal spores that may be shed. Use disinfectants effective against fungi like bleach solutions or quaternary ammonium compounds. Clean any surfaces the cat contacts regularly.
Washing hands with soap and water after handling cats, their bedding, and litter boxes is important to prevent transfer of fungi to humans. Hand sanitizers are less effective against fungi.
Diagnosis
Diagnosing cat fungus in humans typically begins with a physical exam. The doctor will look for skin lesions, nodules, and other signs of infection. Skin scrapings may be taken from lesions and examined under a microscope for evidence of fungal elements. Fungal cultures can also be done by collecting samples from skin, nails, or discharge from lesions. The sample is cultured in a laboratory to allow any fungus present to grow for identification. Blood tests look for antibodies and antigens related to specific fungal infections like sporotrichosis. Molecular tests like polymerase chain reaction (PCR) can detect fungal DNA and help identify particular fungal species. Imaging like X-rays, CT scans, or MRI may be used if internal organs are affected. While many fungal infections have similar symptoms, identifying the particular fungus involved is important for selecting the most effective treatment.
Vulnerable Groups
Certain groups of people are more vulnerable to contracting fungal infections from cats and experiencing severe symptoms. These high-risk groups include:
Young Children
Young children have underdeveloped immune systems, making them more prone to infections. Their frequent contact with pets also increases exposure. According to the CDC, the majority of human Sporothrix brasiliensis infections in Brazil have occurred in children.
Elderly
Older adults tend to have weakened immune systems due to age and other health conditions. This impairs their ability to fight off fungal infections contracted from infected cats. The mortality rate for elderly patients with cat-associated fungal diseases is higher compared to younger individuals.
Immunocompromised
People with compromised immune systems, such as those with HIV/AIDS, cancer, or who take immunosuppressant medications, are at great risk. Their impaired immunity makes it difficult to fend off fungal infections. For example, cryptococcosis fungal infections from cats often occur in immunocompromised patients.
Outlook and Prognosis
Cat fungus infections in humans are generally treatable with proper medications prescribed by a doctor. The CDC reports that most cases of sporotrichosis respond well to antifungal therapy, especially when treatment is started early. With appropriate treatment, the prognosis is often good.
However, the outlook can vary depending on the type and severity of infection. Disseminated sporotrichosis, for example, can be more difficult to treat and may require prolonged therapy over several months. Relapse is also possible if the antifungal treatment is stopped too soon.
It’s important to follow up regularly with a doctor during treatment to monitor progress. Persistent symptoms or lack of improvement may indicate a need to change medications or continue treatment for a longer duration. Consulting an infectious disease specialist can help determine the optimal treatment regimen.
With prompt diagnosis and compliant adherence to prescribed antifungal medications, most cases of sporotrichosis transmitted from cats to humans can achieve a full recovery. However, ignoring symptoms or delaying treatment raises the risks of complications. Contact a doctor right away if cat fungus exposure is suspected.
Conclusion
In summary, fungal infections transmitted from cats to humans can cause a range of symptoms depending on the type of fungus. Sporotrichosis is the most common fungal infection spread from cats and causes skin lesions that can spread. Toxoplasmosis is another concerning disease that can lead to flu-like symptoms or serious complications if a person has a weakened immune system. Proper prevention methods like washing hands after handling cats, avoiding scratches and bites, and keeping cats indoor can reduce transmission risks. Quick diagnosis and treatment with antifungal medications leads to better outcomes. While fungal diseases from cats rarely cause fatalities in healthy humans, vulnerable populations should take extra precautions. Overall, being aware of the risks and taking preventative steps allows cat owners to enjoy their pets while minimizing the chances of developing a fungal infection.
