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The Cat Scratch Disease Bacteria

     Healthy cats can carry five members of the Bartonella bacteria family in their blood: Bartonella henselae, Bartonella clarridgeiae, Bartonella koehlerae, Bartonella elizabethae, and Bartonella weissii, which are transmitted between cats by fleas and ticks. The bacteria can be spread to people via cat scratches and bites, contact with fur, and probably rarely by infected fleas and ticks. Although most infected people do not become ill, Bartonella, transmitted from cats, can cause 22 human diseases.

Incidence of Infection:

     The incidence of Bartonella-infected cats varies in different geographic areas and depends on the average temperature and rainfall (humidity). About 20% of healthy cats in the U.S. are infected carriers. The highest infection rates occur in hot humid climates, which are conditions favorable for fleas and ticks:

Southeast (28%), Hawaii (28%), Coastal California (28%), Pacific Northwest (28%), South Central Plains (22%), Southwest (22%), Northeast and New England (17%), Midwest (9%), Alaska (9%), and Rocky Mountains-Great Plains (9%)

Cat Bartonella Diseases:

     Cat Bartonella possess pili, which are hair-like structures found on the bacteria’s surface. The pili cause Bartonella to stick to, and penetrate, red blood cells and the cells that make up the walls of capillaries. The ability to adhere to the cells of capillary walls leads to the wide and varied tissue specificity observed in cats, dogs, and people. Bartonella induce inflammatory reactions in many tissues throughout the infected animal’s body. These tissues are: oral and respiratory mucosa, ocular tissues, the gastro-intestinal tissues, the skin, and organs such as the liver, spleen and lymph nodes. In fact, since capillaries are found in all tissues, all tissues are susceptible to the inflammatory effects of Bartonella. Inflammatory reactions often occur concurrently in multiple sites such as the oral and respiratory tissues, ocular and oral tissues, or in other combinations. Bartonella cause chronic insidious diseases such as inflammation of the eyes, the gums and oral cavity (a common condition of pet cats), enlarged lymph nodes, fevers, kidney disease, upper respiratory disease, and vague neurological signs in some cats. However, most infected cats are healthy carriers and go unnoticed by their owners. Although numerous microorganisms cause inflammatory diseases, it appears that Bartonella is the cause of about 50% of the following conditions in pet cats.

Bartonella-Induced Inflammatory Diseases of Cats:

Oral Diseases:

Oral inflammatory diseases are the most common Bartonella diseases in cats

Gingivitis- inflammation of the gums

Stomatitis- inflammation of the mouth cavity

Oral Ulcers- ulcers in the mouth cavity

Respiratory Diseases:

Rhinitis- inflammation of the nasal cavity

Sinusitis- inflammation of the sinuses

Ocular Diseases:

Conjunctivitis- inflammation of the conjunctiva

Uveitis- inflammation of the iris

Chorioretinitis- inflammation of the retina and its blood vessels

Blepharitis- inflammation of the eyelids

Keratitis- inflammation of the cornea

Corneal Ulcers- ulcers of the cornea

Intestinal Diseases:

Chronic Diarrhea

Inflammatory bowel disease

Diarrhea (chronic)

vomiting (chronic)

Other Diseases:

Enlarged lymph nodes- lymphadenopathy

Fever of unknown origin

Liver disease- hepatitis

Skin diseases- papules & dermatitis, Dermatitis Granuloma- ear

Heart disease- valvular disease (murmurs) endocarditis

Treatment for Bartonella Diseases:

     Treatment for Bartonella infection in healthy cats and for Bartonella-induced diseases in infected cats is very effective with the appropriate antibiotics that your veterinarian can prescribe.

Human Diseases Caused by Feline Bartonella

     There is an increasing awareness of the human diseases caused by Bartonella transmitted from cats. An article entitled “Cuddle with Care” appeared in Time Magazine in the February 23, 2004 edition, which emphasized the danger to people of infections that can be obtained from their pets. Cat scratch disease (Bartonella diseases) was at the top of the list of diseases discussed. Although most infected people do not become ill, rarely they may become very ill.

Lymphoid System: Cat Scratch Disease, lymphadenopathy

Ocular: Chorioretinitis, Optic nerve neuritis, Uveitis, Disciform keratitis, Conjunctivitis, Parnaud’s oculoglandular syndrome, Orbital abscess

Oral: Gingivitis/periodontitis, Bacillary angiomatosis

Respiratory: Pulmonary granuloma, Pulmonary infiltrates

Heart: Endocarditis, Valvulitis-vegetative

GI Tract: Inflammatory bowel disease, Bacillary Angiomatosis

CNS: Encephalitis, Meningoencephalitis, AIDS encephalopathy

Liver: Bacillary peliosis hepatis, Granulomatous hepatosplenic syndrome

Spleen: Splenic bacillary angiomatosis, Granulomatous hepatosplenic syndrome

Kidney: Necrotizing glomerulonephritis

Skin: Bacillary Angiomatosis, Cutaneous rash- Henoch-Schenlleiin purpura, Cutaneous granuloma annulare

Fever of unknown origin- Febrile bacteremia, Mononucleosis-like syndrome, Chronic fatigue-like syndrome, Co-infection in Lyme Disease.

Kids and Kittens:

     Kittens are more likely than adult cats to transmit Bartonella to people, especially to children. Children often allow kittens to lick their face and to sleep with them. Boys play more roughly than girls with kittens and are more likely to be scratched or bitten and thus are more likely to develop cat scratch disease (CSD) more often than girls.

Cat Scratch Disease:

     Cat scratch disease develops in people a few weeks after transmission of Bartonella from cats. There are 22,000 reported cases every year in humans, and 2,000 hospitalizations. Lymph nodes that drain the injury site become inflamed, enlarged, painful, and may develop an abscess, which may burst and drain. Severe cases may rarely progress to internal organ involvement, neurological complications, and coma. Antibiotics can shorten the clinical course, which usually lasts 6 to 8 weeks if untreated.

“Cat Scratch Disease” is often used to denote all 24 Bartonella diseases in humans.

Bacillary Angiomatosis (BA): BA is a skin condition where Bartonella infection causes red raised nodules, which may be mistaken for a certain skin tumor, Kaposi's sarcoma. BA can also involve major internal organs such as the liver and spleen. This disease occurs most often in immunosuppressed people such as those receiving chemotherapy, organ transplants or infected with HIV.

Neurological Disorders: Encephalopathy, encephalitis, aggression, status epilepticus, convulsions, and coma are some of the rare neurological disorders associated with Bartonella-infections, especially in children. This case was an 11-year-old boy who lived with his parents and 2 kittens. He was admitted to the hospital due to seizures and was unconscious. The EMT found the boy confused, combative and unresponsive to verbal stimuli. He had been well until day of the seizure and there had been no fever, rash or lymphadenopathy. All blood culture specimens were sterile, however he had antibody to Bartonella henselae and was treated for “cat scratch disease” with antibiotics. He made a rapid and complete recovery.

Status epilepticus: Status epilepticus is defined as a repeated seizure or a seizure lasting at least 30 minutes. Six school age children in Virginia with cat scratch disease developed sequelae of status epilepticus after recovering from the classical cat scratch disease syndrome. A review of the hospital database revealed that 4 of 5 previously healthy children, who had developed status epilepticus, were positive for antibody to Bartonella henselae. This report shows that some people who recover from the classical cat scratch disease can develop various serious chronic Bartonella-induced diseases months after recovery from cat scratch disease.

Skin Lesions: Dermatitis, infection of the skin, induced by Bartonella is common in people. The reaction varies from a rash, blotchy red areas, raised red papules, nodules, granulomas, or dry appearing crater-like lesions.

Fever of Unknown Origin: Bartonella-infections may cause persistent high fevers (104-105oF) where the physician is unable to diagnose the cause. The high fevers and flu-like signs may last 7 to 10 days and may recur several times.

Eye Disease: Some Bartonella-infected people develop generalized inflammations in the eye including the outer membranes, iris, retina and optic nerve.

Infectious Mononucleosis-like Syndrome: A syndrome in 6 children, clinically identical to infectious mononucleosis, was recently found to be caused by Bartonella obtained from kittens. An Italian study published in 2000 described the clinical features of Bartonella henselae infections in 20 Italian children (14 males) within a 12-month period. All were positive for antibodies to Bartonella henselae. The mean age was 7 years 4 months with a range from 1 year 1 month to 14 years of age. All children but one had a history of contact with kittens. Clinical manifestations included regional lymph node enlargement in 14 patients, and an infectious mononucleosis-like syndrome in six children. In five patients a severe disorder was first suspected. Fever of unknown origin occurred in 2 children and multiple liver and spleen granulomas occurred in 1 child. Lesions of the bone suggested a bone tumor in one child whereas a marked enlargement of the lymph nodes in the groin suggested Burkitt lymphoma in another. This report ademonstrates the severe nature of Bartonella infections in some people, especially children. Invasive diagnostic procedures may be required before Bartonella infections are considered.

Inflammatory Bowel Disease: There have been reports of Bartonella causing chronic inflammatory bowel disease in people.

Complications of Chronic Lyme Disease: Some people with chronic Lyme disease, that was refractory to therapy, were found to be co-infected with Bartonella derived from cats infested with Bartonella-infected ticks. The signs of disease in these people cleared after treatment for Bartonella infection. This finding is significant since it shows that ticks, as well as fleas, can transmit Bartonella. 

What to Do?

Test: Now cat owners can easily have their cats tested for Bartonella infection. Most infected cats show no sign of illness, yet some cats can carry as many as 1,000 bacteria in each milliliter (one-fifth of a teaspoonful) of blood. The Bartonella blood test requires only a small amount of blood, which can be drawn at the cat's yearly health checkup. The blood sample is then sent to a specialized reference laboratory, The National Veterinary Laboratory, Inc. Franklin Lakes, New Jersey, to perform the test. The test checks for antibody against the bacteria and high amounts of antibody signify infection.

Treatment: If your cat is infected, your veterinarian will prescribe antibiotic therapy and intensive flea control for both your pet and your house. Flea control is very important since fleas can re-infect your cat after therapy. Antibiotic therapy can rid these bacteria from your cat and make it a safe pet once again.

Should Healthy Cats Be Tested?

     We recommend that all healthy pet cats, especially those obtained as strays, from shelters or animal rescue organizations, and those that have had flea infestations, be tested for Bartonella infection. Strays and cats obtained from shelters and humane groups are more likely to have had flea infestations that transmit Bartonella. Kittens are more likely than older cats to transmit the bacteria because of their playful nature and their interactions with people, especially children. Interestingly, boys develop cat scratch disease more often than girls, probably because boys play more roughly, than girls, with kittens and thus are more likely to be scratched or bitten. It is especially important that cats owned by people with young children, people whose cats have had flea infestations at any time, and people who are immunosuppressed by chemotherapy, organ transplants, or HIV infection have their cats tested. At present, the cat scratch disease bacterium, Bartonella, is the most common disease organism transmitted from pet animals to people in the United States.

We recommend that all kittens be tested for Bartonella before their first birthday.

     Now you can stop the spread of Bartonella from cat to cat and cat to human with a simple blood test of your cat. Approximately 20% of healthy cats, living in the United States, are infected carriers of these dangerous Bartonella bacteria.