Could Your Cute Kitty Make You Deathly Ill? The Hidden Dangers of Cat Scratches

What is sepsis?

Sepsis is a life-threatening condition that occurs when the body has an extreme response to an infection. It is sometimes referred to as blood poisoning or septicemia. Sepsis happens when chemicals released into the bloodstream to fight an infection trigger inflammation throughout the body instead (Mayo Clinic, 2023).

The main symptoms of sepsis include high heart rate, high or low temperature, rapid breathing, confusion, and extreme pain or discomfort. Sepsis can cause shock, organ failure, and death if not recognized and treated promptly (CDC, 2023).

Sepsis develops when the chemicals the body releases to fight an infection trigger widespread inflammation. This can cause injury to tissues and organs and lead to multi-organ failure. Sepsis progresses quickly and can lead to septic shock, severe low blood pressure that prevents organs from getting enough oxygen and nutrients (Cleveland Clinic, 2023).

What causes sepsis?

Sepsis is most often caused by a bacterial infection that overwhelms the body’s immune system [1]. Bacteria can enter the bloodstream through various routes, including the lungs, urinary tract, skin, and abdomen. Those that more commonly cause sepsis include infections of:

  • Lungs, such as pneumonia
  • Kidneys, such as pyelonephritis
  • Abdomen, such as appendicitis
  • Skin, such as cellulitis

Certain people are at higher risk of developing sepsis, including [2]:

  • Adults 65 or older
  • People with weakened immune systems
  • Infants less than 1 year old
  • People with chronic medical conditions like diabetes, cancer, kidney or liver disease

Can cats transmit infections to humans?

Yes, cats can transmit certain infections and diseases to humans. Cats carry bacteria, parasites, fungi and viruses that can infect humans through close contact. The four main ways cats spread diseases to humans are through their feces, bites and saliva, skin/fur contact, and scratches (, 2022). Some of the more common feline diseases that can be transmitted to humans include:

– Bartonella – Also known as cat scratch disease, this bacterial infection causes swollen lymph nodes. It is spread through scratches, bites, or contact with fleas from an infected cat (, 2022).

– Pasteurella – A bacterial infection that can cause painful wound infections in humans. It is transmitted through bites and scratches from infected cats (, 2021).

– Campylobacter – A bacterial infection that causes diarrhea. It spreads through contact with infected cat feces (, 2022).

– Capnocytophaga canimorsus – A rare bacterial infection that can cause sepsis. It is usually transmitted through cat bites (, 2022).

In addition to good hygiene, preventing infections from cats involves controlling parasites like fleas and ticks, keeping cats indoors, proper handling techniques, and awareness of disease risk factors.

Bartonella Infection

Bartonella bacteria are Gram-negative rod shaped bacteria that can infect both cats and humans. There are over 30 known species and subspecies of Bartonella bacteria, some of which can be transmitted from cats to people. The most notable Bartonella species that causes disease in humans is Bartonella henselae, which can lead to cat scratch disease.

In cats, Bartonella henselae is generally asymptomatic but can cause fever, lymphadenopathy, endocarditis, and neurological symptoms in some cases. According to the CDC, up to 30% of cats carry B. henselae in their blood. The bacteria is transmitted between cats via fleas and cat bites. Cats are the main reservoir for B. henselae in nature.

Cat scratch disease is the most common Bartonella infection in humans, caused by a scratch or bite from an infected cat. Symptoms usually begin 3-14 days after exposure and include enlarged lymph nodes near the injury site, fever, headache, fatigue, and rash. Most cases are self-limiting but antibiotics can be used in severe cases. Other rarer Bartonella species can also be transmitted from cats and cause more systemic illnesses in humans, including endocarditis, bacillary angiomatosis, and bacillary peliosis.


Pasteurella infection

Pasteurella bacteria are common commensals in the mouths and upper respiratory tracts of cats and dogs. The most common pathogenic species is Pasteurella multocida. Pasteurella can cause respiratory infections in cats, but more concerning is its zoonotic potential for humans (Lloret, 2013).

Cats and dogs can transmit Pasteurella to humans through bites, scratches, or just close contact with saliva. In one study, Pasteurella was isolated from 75% of infected cat bite wounds in humans (Arons, 1982). Pasteurella can cause painful wound infections, abscesses, septic arthritis, osteomyelitis, and even sepsis in humans, especially in those who are immunocompromised.

The most common illnesses caused by Pasteurella transmission from cats to humans are:

  • Wound infections
  • Abscesses
  • Cellulitis
  • Arthritis
  • Osteomyelitis
  • Pneumonia
  • Meningitis
  • Sepsis

Therefore, while rare, Pasteurella infection is one mechanism by which cats can potentially cause sepsis in humans (Arons, 1982).

Campylobacter Infection

Campylobacter are bacteria that can cause gastrointestinal illness in humans. The most common species that causes disease is Campylobacter jejuni. Campylobacter bacteria are found in the intestines of many animals, including cats and dogs.

Studies show that up to 80% of cats may carry Campylobacter bacteria at some point, often without showing any symptoms. Campylobacter spreads through the feces of infected animals. Humans can get infected by coming into contact with the feces of an infected animal through various means, such as touching contaminated surfaces or eating contaminated food.

In humans, Campylobacteriosis causes diarrhea, cramping, abdominal pain, and fever within 2 to 5 days after exposure. Usually the infection lasts for about a week and goes away on its own. However, it can occasionally be life-threatening. Post-infectious complications like Guillain-Barre syndrome, reactive arthritis, and irritable bowel syndrome may also occur.

Good hygiene like handwashing is important to prevent the spread of Campylobacter bacteria from cats to humans. Properly cooking meats and avoiding cross-contamination in kitchens also helps prevent infection. Treatment with antibiotics may be required in moderate to severe cases (CDC, 2022; Merck Veterinary Manual, 2022).

Capnocytophaga canimorsus infection

Capnocytophaga canimorsus is a bacterial infection that can be transmitted from dogs and cats to humans through bites, scratches, or close contact. C. canimorsus is a gram-negative rod bacterium that is commonly found in the mouths of dogs and cats (Lloret, 2013).

While C. canimorsus is normally harmless in pets, it can on rare occasions be transmitted to humans and cause severe illness. Transmission occurs through a bite or scratch from a cat, or potentially by a cat licking an open wound on a person. Close contact with cats, especially kittens, is considered a risk factor (CDC, n.d.).

In humans, C. canimorsus can lead to sepsis, meningitis, and other serious complications. The bacteria can enter the bloodstream from a cat bite or scratch, and then multiply rapidly causing sepsis, a life-threatening blood infection. C. canimorsus has been identified as a cause of sepsis in people who were bitten or scratched by a cat (CDC, n.d.).

Those at highest risk include people with weakened immune systems, the elderly, and those who have had their spleen removed. However, even healthy people can develop sepsis from C. canimorsus. Prompt treatment with antibiotics is important for this potentially fatal infection (Lloret, 2013).

Risk factors for sepsis from cats

Some people are at higher risk of developing sepsis from cats. The main risk factors include:

People with weaker immune systems such as the elderly, very young children, and those with chronic diseases are more susceptible to infections that could lead to sepsis. Their immune systems have a harder time fighting off bacteria that cats may transmit.

Not washing hands after touching cats or cleaning litter boxes increases risk. Traces of bacteria can be passed from cats to humans if proper hand hygiene is not followed.

Cat bites and scratches can introduce bacteria deep into the skin and tissue. Bite wounds should be thoroughly cleaned and monitored for signs of infection. Scratches should also be washed and treated with antibiotic ointment.

Having an open wound or sore exposes the body to potential bacteria from cats. Any scratch, cut, or lesion should be properly covered when handling cats.

Being in poor health in general stresses the immune system. Those who are already sick or recoverng from illness should use caution around cats.

These risk factors can be mitigated by practicing good hygiene, promptly treating wounds, and monitoring cat interactions, especially for those most vulnerable to infection.

Preventing sepsis from cats

There are several important steps pet owners can take to help prevent sepsis from developing in cats:

Veterinary care – Regular veterinary checkups and preventative care are essential for monitoring a cat’s health and catching any underlying infections early. Vaccinations, dental cleanings, parasite control and prompt treatment of illnesses can help reduce the risk of sepsis.2

Handwashing – Thoroughly washing hands with soap and water after handling cats, cleaning litter boxes, or contacting any cat fluids can prevent transmission of bacteria. Hand sanitizer can be used if soap is unavailable.

Care with bites and scratches – Cat bites or scratches that break the skin should be thoroughly cleaned with soap and warm water. Seeking medical care promptly for redness, swelling or signs of infection can prevent bacteria from entering the bloodstream. Bite wounds may require antibiotic treatment. Keeping cats’ nails trimmed can reduce potential scratches.1


While cats can transmit bacteria that lead to sepsis, the overall risk remains quite low for most people as long as proper precautions are taken. Cats should receive regular veterinary care, be kept indoors, and have any bites or scratches cleaned immediately. People with weakened immune systems or chronic medical conditions may be at higher risk of developing sepsis from cat-transmitted bacteria. However, prompt treatment with antibiotics can prevent sepsis from taking hold if symptoms arise. Overall, sepsis is a rare outcome from cat contact. With some simple preventive steps, cat owners can continue to enjoy their feline friends safely.

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