Cat Scratch Fever. Fact or Fiction?

What is Cat Scratch Fever?

Cat scratch fever, also known as cat scratch disease (CSD), is an infection caused by the bacterium Bartonella henselae. The infection is spread primarily through scratches, bites, or exposure to fleas from infected cats. Cat scratch fever gets its name from the fact that people typically become infected after being scratched, bitten, or exposed to fleas from a cat. (1)

The most common symptoms of cat scratch fever include swollen lymph nodes near the scratch or bite site, fever, headache, fatigue, and loss of appetite. A blister or pustule may form at the initial scratch or bite site as well. In rare cases, more serious symptoms can occur such as infection of the liver, spleen, heart, lungs, joints or bones if the infection spreads. (2)

While the symptoms can be unpleasant, cat scratch fever is generally a mild illness that resolves on its own within 2-4 months in individuals with healthy immune systems. However, antibiotics may be prescribed in some cases to help speed recovery. The best way to prevent infection is to thoroughly wash any cat scratches or bites immediately and avoid rough play or activities that might lead to scratches or bites. Treating cats for fleas and regular vet visits can also reduce risk of transmission. (3)

(1) https://my.clevelandclinic.org/health/diseases/23537-cat-scratch-fever

(2) https://www.webmd.com/skin-problems-and-treatments/cat-scratch-fever

(3) https://emedicine.medscape.com/article/214100-overview

Transmission

transmission methods of cat scratch fever

Cat scratch fever, also known as cat scratch disease (CSD), is primarily transmitted to humans through scratches, bites, or exposure to fleas from infected cats, especially kittens. The disease spreads when an infected cat licks a person’s open wound, or bites or scratches a person hard enough to break the surface of the skin. About three to four days after the skin is broken, a mild infection can occur at the site of the scratch or bite 1. CSD is caused by a bacterium called Bartonella henselae that can be carried in a cat’s saliva, blood, and fleas. Kittens are more likely to transmit B. henselae than adult cats. The bacteria cannot be transmitted from person to person.

Symptoms

The most common symptoms of cat scratch fever include redness, swelling, and pain at the site of the scratch or bite. According to the CDC, within 3-14 days after exposure, a small bump or blister may form where the animal scratched or bit the person, followed by swelling of the lymph nodes near the wound as they become infected.1

As the infection spreads, more generalized symptoms can occur including fever, headache, fatigue, and loss of appetite. The fever is often moderate, in the range of 100°F to 104°F. Headaches, joint pain, and fatigue often accompany the fever. Lymph nodes near the original wound become swollen and tender. This lymphadenopathy usually starts 1-3 weeks after the scratch or bite and can last for months. The lymph nodes most often affected are those around the head and neck or in the armpits and groin.

According to Johns Hopkins Medicine, the symptoms usually resolve on their own without treatment after 2-4 months, though the enlarged lymph nodes can persist for up to a year or longer.2 Seeking prompt medical attention can help manage any discomfort and monitor for secondary infections or complications.

Diagnosis

swollen lymph nodes caused by cat scratch fever

To diagnose cat scratch fever, a doctor will start with a physical exam to look for symptoms. They will check for a fever, skin lesions, and swollen lymph nodes near the scratch or bite. Blood tests can also detect antibodies to Bartonella, the bacteria that causes cat scratch fever. A positive antibody test can confirm the diagnosis. In some cases, a biopsy of an enlarged lymph node may be done to test for the presence of the bacteria. The biopsy involves surgically removing part of the lymph node for examination under a microscope.

According to the CDC, diagnosis of cat scratch fever is often made based on symptoms and history of a cat scratch rather than specific lab tests. However, both antibody testing and culture of lymph node biopsy tissue can confirm the diagnosis definitively.

Sources:

https://www.cdc.gov/bartonella/cat-scratch.html

https://www.aafp.org/pubs/afp/issues/2011/0115/p152.html

Treatment

Cat scratch fever usually resolves on its own without treatment within 3-6 weeks. Most people with mild symptoms can manage the disease at home with over-the-counter pain relievers like acetaminophen (Tylenol) or ibuprofen (Advil) to help with fever and body aches. Antihistamines can help relieve itching from the rash.

Antibiotics are only prescribed for people with severe symptoms or complications. The antibiotics azithromycin, rifampin, ciprofloxacin, trimethoprim-sulfamethoxazole, or gentamicin are commonly used. According to the Cleveland Clinic, “Antibiotics will shorten the course of the disease and prevent spread of the infection to other parts of the body.”

Corticosteroids may also be given to reduce inflammation from enlarged lymph nodes.

In rare cases, surgery may be required to drain an abscess or remove infected lymph nodes.

Most people make a full recovery within a few weeks, even without antibiotics. It is important to follow up with a doctor to ensure the infection has fully resolved.

Complications

Although cat scratch fever rarely leads to serious illness, it can cause complications in some cases (Source). People with weakened immune systems, such as those with HIV/AIDS or those taking immunosuppressant medications, are at higher risk of developing complications from cat scratch fever (Source).

person with encephalitis rash

Potential complications include:

  • Inflammation of the brain or spinal cord (neuroretinitis, encephalopathy, transverse myelitis)
  • Damage to the eyes and vision loss
  • Arthritis
  • Glomerulonephritis, a type of kidney disease
  • Hepatitis
  • Endocarditis, an infection of the heart valves
  • Osteomyelitis, an infection of the bones

In rare cases, the bacteria can spread to the brain, liver, eyes, joints, or other areas of the body, leading to more severe neurological problems or damage to major organs (Source). However, most people recover fully within a few months.

Prevention

There are several steps you can take to prevent cat scratch fever:

Avoid rough play with cats. Engaging in rough play like wrestling increases your risk of getting scratched or bitten. Be gentle when petting cats and do not play too aggressively.[1]

washing cat scratch on hand

Promptly clean any cat scratches or bites with soap and water. Thoroughly washing wounds helps remove bacteria and prevent infection. Apply antibiotic ointment after cleaning the area.[2]

Consider testing new kittens for Bartonella infection. Kittens under one year old are more likely to carry the bacteria. Ask your vet to test new kittens so you know if they may pose an infection risk.[1]

Trim cats’ nails regularly to minimize scratch damage. Ask your vet to show you proper nail trimming technique.

Do not allow cats to lick open wounds on humans. Saliva can transmit the bacteria.

Wear gloves when gardening or handling items cats may have scratched. The bacteria can live in the environment.


[1] https://www.cdc.gov/healthypets/diseases/cat-scratch.html
[2] https://my.clevelandclinic.org/health/diseases/23537-cat-scratch-fever

Risk Factors

According to the CDC, there are certain risk factors that make a person more likely to develop cat scratch fever and cat scratch disease (https://www.cdc.gov/bartonella/bartonella-henselae/faq.html):

Owning a kitten under 1 year old is a major risk factor. Kittens are more likely to carry the Bartonella henselae bacteria that causes cat scratch fever. As cats age, they are less likely to carry the bacteria.

People with weakened immune systems, such as those with HIV/AIDS, cancer, or who take immunosuppressant medications, have a higher risk of contracting cat scratch fever and experiencing more severe symptoms.

Veterinarians and animal shelter/rescue workers also have an increased risk of being exposed to cats carrying the bacteria due to their frequent contact with cats and kittens.

Other risk factors include getting scratched or bitten by a stray cat or kitten and having exposure to fleas from an infected cat. Proper flea control on household cats can reduce the risk of transmission.

Prognosis

Cat scratch fever is usually a self-limiting illness that resolves on its own without complications. The vast majority of people will make a full recovery within 2-4 months after the initial infection (Cleveland Clinic).

While cat scratch fever can sometimes cause painful lymph node swelling and flu-like symptoms, fatalities from this disease are extremely rare. Most immunocompetent individuals will clear the infection and recover fully without any long-term effects (Baranowski et al.).

In very rare cases, people with weakened immune systems may experience more severe complications from cat scratch fever, such as infection of the liver, spleen, bones, joints or brain. However, with appropriate antibiotic treatment, even disseminated cat scratch disease is rarely fatal today (Klotz).

So while cat scratch fever can be an unpleasant illness, the prognosis is generally excellent. With rest and time, most people make a full recovery without any lasting effects.

The Bottom Line

Cat scratch fever, also known as cat scratch disease, is generally a mild illness that often resolves on its own. The infection is transmitted through scratches, bites, or exposure to saliva from infected cats, especially kittens. Symptoms like fever, headache, fatigue, and lymph node swelling usually appear 3-14 days after exposure and last 2-4 weeks. While antibiotics are not routinely required, they may be used in severe cases. Complications like encephalitis are rare. The best way to prevent cat scratch fever is to practice good hygiene around cats, avoid scratches and bites, and promptly clean and disinfect any wounds.

Key facts to remember:

  • Cat scratch disease is caused by a bacterial infection, but is generally mild.
  • Symptoms often resolve within a few weeks without treatment.
  • Antibiotics are not usually needed except in severe cases.
  • Serious complications like encephalitis are very rare.
  • Good hygiene and avoiding scratches/bites prevents infection.
  • Promptly clean and disinfect any cat scratches or bites that break the skin.

While cat scratch fever is seldom serious, it’s best to take precautions around cats and see a doctor if symptoms persist or worsen.

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