Learn about Zoonoses: Diseases Transmitted from Cats to Humans!

Learn about Zoonoses: Diseases Transmitted from Cats to Humans!

Living with cats, sharing a bed, and physical contact can be full of happiness and healing.

However, incorrect interactions with cats can lead to disease transmission from them to humans.

Some of these diseases can be life-threatening and require caution. Such diseases transmitted from animals to humans are called "Zoonoses."

To make life with cats happier, it's important to be aware of the diseases, known as zoonoses, that can be transmitted from cats, and their prevention methods.

 

Contents

1. What are Zoonoses
2. Zoonoses Transmissible from Cats
  2-1. Diseases Transmitted through Cat Feces
  2-2. Diseases Transmitted through Cat Skin Diseases
  2-3. Diseases Transmitted by Being Bitten or Scratched by Cats
3. Methods to Prevent Zoonotic Infections
  3-1. Be Careful with Physical Contact 

1. What are Zoonoses

Zoonoses, also known as "animal-borne diseases" or "zoonosis," refer to diseases where pathogens like parasites, bacteria, and viruses are transmitted from animals to humans, causing illness.

Zoonoses can be transmitted from wildlife, livestock, and even pets.

Especially now, with the pet boom, more people are keeping cats and dogs, and the frequency of sleeping together and physical contact has increased.

As a result, cases of zoonotic diseases are also on the rise.

While you may think "my cat is healthy, so there's no worry," some zoonoses can manifest differently in animals and humans.

For example, harmless bacteria in cats can cause serious symptoms once they enter the human body.

 

2. Zoonoses Transmissible from Cats

To avoid zoonotic infections, it's important to know their transmission routes.

This time, we introduce diseases that are easily transmitted from cats in the following three cases:

  • ・Feces
  • ・Skin Diseases
  • ・Being Bitten or Scratched

 

2-1. Diseases Transmitted through Cat Feces

First, let's introduce diseases transmitted through cat feces (poop and urine).

Direct contact with feces, such as during toilet cleaning, is a risk, as is airborne transmission, so caution is needed.

Additionally, transmission can occur through other excretions like nasal discharge, saliva, amniotic fluid, and breast milk.

If anything from the cat's body gets on you, be sure to wash it off.

[1] Toxoplasmosis

Toxoplasma, a type of parasite, is excreted with cat feces, and infection occurs when it enters the human body.

Cats may not show symptoms when infected with Toxoplasma.

In humans, the infection is often asymptomatic, but if pregnant women are infected, it can lead to miscarriage or hydrocephalus in the baby.

However, if a pregnant woman is infected and has antibodies, there is no impact on the baby.

[2] Dipylidium Infection

Dipylidium, another type of parasite, uses fleas as a vector and parasitizes cats.

In small amounts, it causes no symptoms, but in large quantities, diarrhea and bloody stools can occur.

The transmission route from cats to humans often involves fleas attached to cat hair or feces entering the human body.

Though often asymptomatic, symptoms can include diarrhea, abdominal pain, liver swelling, fever, and in rare cases, blindness.

[3] Cat Roundworm

Cat roundworm is a type of parasite.

Cats can become infested by ingesting the larva or through infected mother cats' breast milk.

In small infestations, symptoms might not appear, but in large numbers, diarrhea, constipation, vomiting, and loss of appetite can occur.

In kittens, developmental delays and seizures may happen.

Humans can also get infected if eggs attached to cat feces or hair enter the body.

The roundworm does not grow in the human body but can survive for a while, causing allergic reactions and abnormalities in the eyes and nerves.

[4] Q Fever

Q fever is an infection caused by the microorganism Coxiella burnetii.

It is transmitted through infected animals' feces, breast milk, and amniotic fluid.

In mild cases, symptoms may be mild fever and respiratory symptoms, but in severe cases, pneumonia symptoms and liver dysfunction can occur, leading to death if treatment is delayed.

The incubation period is 2-3 weeks, making it a difficult disease to identify.

[5] Salmonellosis

Known for causing food poisoning, salmonellosis is a disease caused by Salmonella bacteria.

Although it often occurs from raw eggs, it can also be transmitted through cat feces.

Cats infected with salmonellosis rarely show symptoms, but in kittens, diarrhea and vomiting can occur.

In humans, healthy individuals may not exhibit symptoms, but in elderly, children, or those with weakened immune systems, symptoms like diarrhea, fever, and abdominal pain appear after a 12-72 hour incubation period.

In severe cases, extreme dehydration from diarrhea or septicemia can be life-threatening.

[6] Corynebacterium Ulcerans Infection

Corynebacterium ulcerans is a bacterium that commonly resides in animals.

Normally non-toxic, it can mutate to produce toxins and cause infection when lysogenized.

Symptoms in infected cats include cold-like symptoms such as sneezing and nasal discharge, dermatitis, and ulcers on the skin and mucous membranes.

Humans can get infected through contact with infected cats' nasal discharge and saliva.

Symptoms are similar to diphtheria, including throat pain and respiratory symptoms. In severe cases, it can lead to respiratory distress and death.


 

2-2. Diseases Transmitted through Cat Skin Diseases

Next, let's introduce diseases transmitted through cat skin diseases.

Infection can occur even through normal physical contact like petting or holding, so caution is necessary.

Regularly check the cat's skin for abnormalities.

[1] Scabies

Scabies is a skin disease caused by the "Sarcoptes scabiei" mite.

The mite burrows inside the skin, not on the surface, causing intense itching.

Humans can become infected through skin contact with an infected cat, resulting in intense itching similar to that in cats.

Treatment with oral or topical medications usually cures it within a month, but itching and eczema can persist even after the mites are gone.

[2] Fungal Infection (Dermatophytosis)

Fungal infection (dermatophytosis) is a disease caused by fungi (mold) infection.

Fungi live in soil and infect through contact.

Infection causes symptoms like hair loss, dandruff, and dermatitis.

Humans can become infected through contact with infected cat hair or dandruff. Be cautious, as infection can also occur through brushes or blankets used by the cat.

In humans, infection typically results in itchy, red ring-shaped rashes on the arms or face.


 

2-3. Diseases Transmitted by Being Bitten or Scratched by Cats

Finally, let's discuss diseases transmitted by being bitten or scratched by cats.

Even harmless bacteria in cats can cause symptoms when they enter the human body, so be cautious even with healthy pet cats.

[1] Pasteurellosis

Pasteurella is a type of bacteria found in the mouths and claws of most mammals.

Harmless to cats, it can cause symptoms like pain, fever, lymph node pain, and arthritis in humans when they are bitten or scratched.

In severe cases, it can lead to septicemia and osteomyelitis, potentially causing death.

[2] Capnocytophaga Canimorsus Infection

Capnocytophaga canimorsus is a bacterium found in cats' and dogs' mouths.

Humans can get infected through bites or scratches, resulting in symptoms like fever, fatigue, abdominal pain, headache, and nausea.

In severe cases, it can cause septicemia, meningitis, and lead to multi-organ failure and death.

[3] Cat Scratch Disease

Cat scratch disease is an infection with Bartonella henselae as the pathogen.

As the name suggests, it is transmitted to humans through cat scratches or bites.

Symptoms include blisters or swelling at the injury site, fever, headache, and swollen lymph nodes.

Rarely, complications like encephalitis, meningitis, liver abscess, or spleen abscess can occur.

 

※In September 2022, there were reports that the sudden death of the owner of "Japanese Soba Noodles Tsuta," which won a Michelin star, was caused by a cat bite. However, involved parties have denied any factual basis and the causal relationship with the cat.

 

3. Methods to Prevent Zoonotic Infections

What precautions should be taken to prevent disease transmission from cats to humans?

Below are some particularly important preventive measures.


 

3-1. Be Careful with Physical Contact

As mentioned earlier, cats' claws and teeth are breeding grounds for bacteria.

Also, being licked by a cat, especially if it is around fleas or parasites, or kissing a cat can lead to disease transmission.

  •  ・Playing with kittens by letting them bite your hands
  •  ・Over-engaging with a cat to the point it becomes aggressive
  •  ・Kissing cats
  •  ・Letting a cat sleep near your face 
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