Cat scratch disease

Cat scratch disease

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Being in contact with a cat is, without knowing it, exposing yourself to a risk of scratching which can lead to a bacterial disease which is fortunately not serious in the majority of cases. What are the causes and symptoms? Are there any complications and what is the treatment for humans and animals? The answers of Dr. Barbara Dufour, veterinarian.

Definition of Cat Scratch Disease

Cat scratch disease is a mild but fairly common bacterial disease contracted by humans following a cat scratch or bite. The scratch is often more contagious than the bite. Cat scratch disease is a zoonosis, meaning it is transmitted from animals to humans.

Around 40% of European cats carry Bartonella henselae at some point in their lives.

How do you get bartonellosis?

Infection with Bartonella Henselae bacteria

Under the claws of some cats and in their mouths is the bacteria Bartonella Henselae. This bacteria gets there through a complex cycle linked to cat fleas. The cat is contaminated by the bites and excrement of fleas carrying the bacteria (recovered from another infected cat). Flea droppings are therefore found on its coat. It then infects its claws (by scratching) and its mouth (by licking). The infected flea can jump onto another healthy cat and contaminate it in turn either by biting it or by depositing its droppings on its coat. And the cycle continues.

If the infected cat begins to bite or scratch a human on an area of ​​skin, it will contaminate the person with the bacteria contained under its claws or in its mouth.

“An adult cat is usually infected for 2 to 3 weeks maximum,” explains Barbara Dufour, veterinarian and Emeritus Professor of infectious diseases and epidemiology at the Alfort national veterinary school. “This then considerably limits the possibility of new fleas becoming infected. In young cats it is different because they can have more persistent infections (lasting several months), we are talking about bacteremia. They are the ones who are most at risk of transmitting the disease to healthy fleas (during their blood meal) but also to humans because young cats scratch and bite more often than adults, particularly during play. .

What are the symptoms of cat scratch disease?

In cats there are no real symptoms. Its immune system will allow it to get rid of the bacteria fairly quickly (more slowly in young cats).

In humans, cat scratches can cause lymphadenitis, i.e. an increase in volume of the lymph nodes near the injury (regional lymphadenopathy). “For example, if you are scratched on the hand by an infected cat, it is the axillary lymph nodes that swell. specifies the specialist. “The phenomenon and symptoms last a few days, without fever. This infection is mild and can go completely unnoticed. Most of the time, we don’t even know that we have had an infection.”

Other symptoms of the disease:

  • Fatigue ;
  • Fever ;
  • Headache ;
  • Loss of appetite ;
  • Stomach ache ;
  • Conjunctivitis;
  • Muscle or joint pain.

Is cat scratch disease serious?

Complications are very rare. Children are more affected than adults by the infection because they tend to play more with young cats. “At the beginning in children, we notice certain signs such as a small vesico-pustule, skin rashes like a primary insect bite, at the site of the scratch. describes veterinarian Barbara Dufour. “It heals on its own in a few days. Then after 15 days, persistent lymphodenopathy appears (nodes but without fever). This pathology is benign and appears as the manifestation of a significant local immune reaction. The phenomenon lasts 3 weeks and then in the majority of cases it regresses spontaneously and we no longer talk about it.”

But sometimes in severely immunocompromised individuals, particularly people infected with HIV, suffering from cancer, chronic illness or an autoimmune disease, cat’s scratch disease can lead to more serious illnesses within 2 or 3 weeks. serious asangiomatose bacillaire which corresponds to a vascular proliferation resembling a tumor and which induces papular and purple skin lesions. Lesions can also appear on the liver or spleen. We then talk about peliosis hepatis. Peliosis and bacillary angiomatosis are serious but very rare diseases.

How is the diagnosis made in humans?

Regarding diagnosis in humans, it is not necessary to identify benign disease by performing a serological test. “In Europe, it is estimated that there are thousands of cases per year, but they go completely unnoticed medically.”notes the veterinarian.

My cat scratched me. What to do ?

On the other hand, after any scratch in a person suffering from immunosuppression (weak immune system), it is advisable to consult a doctor quickly so that the latter can decide whether or not to put them on preventive antibiotic therapy. There are currently no vaccines against cat scratch disease.

What antibiotic treatment to treat my cat scratch injury?

The disease does not require treatment with antibiotics in children and adults, except in immunocompromised people who will receive appropriate antibiotic treatment in consultation with their doctor.

Domestic cats will not be treated either since this infection is inapparent and disappears spontaneously.

After a cat bite (even if the injury is not significant), you must immediately wash the wound thoroughly with soapy water and then disinfect.

How to avoid it?

Prevention is very simple since you just need to remove the fleas from your cat.

“The cat most at risk is the small kitten that we find in a litter of domestic cats in the countryside and which has crossed paths with other animals,” evokes the veterinarian. “If you treat it for fleas, there is no longer any risk for humans even if the kitten remains infected with the bacteria for a few weeks or months.”

There are several types of treatments to rid your cat of fleas: sprays, pipettes to apply to the skin, tablets or even collars. The choice depends on the preferred method of administration and the desired effectiveness. Treatment alone is not enough; it is also important to treat the cat’s environment in order to eliminate flea larvae.

“Cat scratch disease should not hide another disease”, would like to express Barbara Dufour. “In particular the pasteurellose, less known but more common and more disabling than cat scratch disease. It is caused by a bite from cats or dogs which naturally harbor bacteria called pasteurella in their oral cavity. Within a few hours, even a seemingly benign scratch can become extremely painful and swell abnormally. There is no point in opening the wound, antibiotic therapy will also cure it in a few hours.” In this case, you must therefore consult a doctor quickly.