Cat Scratch disease

Cat Scratch disease overview and Definition

The cat scratch disease is caused by the bacteria such as Bartonella Heneselae Bacteria. These diseases develops from the scratches cat


About 80-90% of the cat scratch disease occurs under the age 21.

Structure of Cat Scratch disease

It is a gram negative bacteria which has strong lipopolysaccharide coating in it. It is a rod shaped bacteria.

It is an aerobic bacteria which requires oxygen supply for its survival.

It shows oxidase negative and it does not have flagella for locomotion. It shows twitching mobility.

It has a circular genome. This organism when entered into the host cell, it is not dependent on the glucose metabolism for its survival. The Bartonella bacteria is mainly depended on the amino acid catabolism for its survival.


The clinical hallmark is lymphadenopathy at the site of inoculation. In the immunocompetent host, a granulomatous response ensues. The immunocompromised host may develop a vascular-proliferative response. Affected lymph nodes become enlarged and tender over one to two weeks. Cat scratch disease is a common cause of chronic lymphadenopathy as well, which may spread beyond the site of inoculation. Cat scratch disease can disseminate to the eye, liver, spleen, and central nervous system (CNS).

The bacteria causes changes in the host cytoplasm and also alteres the actin filaments.

This results in aggregation and bacteria is engulfed by host cell membranes and enters the endothelial cells. This structure is called Invasome. These results in elicition of proinflammatory response which also activates the NF-kB, a transcription factor that regulate the innate and adaptive immune response. The formation of an invansome usually takes 24 hours. Once the cell responds to inflammation, it elicits an angiogenic response. Cytokines that promote inflammation such as tumor necrosis factor (TNF-alpha) are released and leads to angiogenesis. This is why patients with bacillary angiomatosis or peliosis hepatitis experience swelling.

Vasoproliferative lesions caused by Bartonella species are usually surrounded by neutrophils. These neutrophils contribute to an inflammatory response which involves endothelial cell activation. Neutrophils then attach to vessel walls and activate CD11/CD18, which are receptors to endothelial molecules such as intracellular adhesion molecule



Routes of Transmission

Cats become infected with Bartonella (the bacteria that cause cat scratch disease) through flea bites or, less commonly, fights with other infected cats or feline blood transfusions.

Sometimes the cat might sick, but most often the cat does not show any symptoms

Clinical signs & symptoms

The following are the symptoms of scratch fever:

A bump or blister at the bite or scratch site

Swollen lymph nodes near the bite or scratch site

Lethargic and fatifueness

Severe headache

A low grade fever which is above 98.6 degree faranheuit

Body aches

Joint pain


Loss of appetite

Weight loss

Sore throat

Rare symptoms of Cat scratch fever might be linked to more or severe version of the disease:



Abdominal pian

Joint pian

Prolonged fever

The duration taken by the blister or bump to develop at the site of the scratch is 3-101 days after the exposure. Other symptoms such as swollen lymph nodes may not occur for several days or weeks.

Lymphadenopathy occurs within one and three weeks.

Conditions that may be mistaken for cat scratch fever include:

Lymphadenitis, an inflammatory disease that results in swollen lymph node

Brucellosis an infection transmitted from livestock to humans that present with flu like symptoms and swollen lymph nodes

Lymphogranuloma venereum a sexually transmitted infection that results in a skin lesion at the site of the infection. The lesion may become a raised bump or blister and it is followed by swollen lymph nodes

Lyme disease, a tick borne infection that has an initial symptoms of bull eye rash before flu like symptoms develop.

Complications of Cat Scratch Disease:

The following constitutes the complications of Cat Scratch fever. This includes


It is a brain disease that occur when the bacteria spreads to the brain. In some cases encephalopathy might result in permanent brain damage or death.


It is the inflammation of the optic nerve and retina. It might result in Blurred vision. The inflammation can occur when the bacteria responsible foe cat scratch fever travels to the eye. Visually usually improves after the infection is gone.


It is the bacterial infection in the bones, which can result in bone damage. In some cases bone damage is severe which might leads to the amputation of the affected bone area in the future.

Parinaud occuloglandular syndrome:

It is an eye infection which is similar to the pink eye. Cat scratch disease might result in eye infection. The bacteria Bartonella enters the eye stream directly and might affects the eye and causes parinaud occuloglandular syndrome

Differential Diagnosis

Gram stain:

It shows gram negative coccobacilli.

Oxidase and Catalase negative

Prolonged incubation is helpful.

It also shows Granuloma formation, stellate abscesses, and lymphocytic infiltrates. A Warthin-Starry silver stain or a Brown-Hopp tissue Gram stain of a lymph node biopsy revealing the small, curved, bacilli can aid in diagnosis

PCR assay:

Amplification of a part of the Bartonella henselae gltA gene encoding for citrate synthase . PCR was performed on pus aspirates, fine needle aspiration specimens or biopsies from affected lymph nodes.

Skin test:

The bacterial DNA is amplified by the PCR techniques and the skin test is performed and the pus is collected.

Microbiologic cultures:

 Whenever sufficient material was available, samples of lymph node tissue or pus were dispersed in PBS pH 7.4, spread onto 2 chocolate agar plates, sealed with shrink seal bands and incubated at 35°C in 5% CO2 for 8–10 weeks. B. henselae was identified by Gram stain, biochemical reactions and PCR. Bacteria and mycobacteria were identified by means of standard bacteriologic methods.


The complete resolution might take atleast 2 months


  • Keep the cat indoors.
  • Avoid rough play with cats and situations in which scratches are likely. Declawing is not recommended to prevent cat scratch disease.
  • Promptly wash any cat scratches or bites with soap and water.
  • Avoid contact with fleas.
  • Treat the cat with a flea control product recommended by your veterinarian.
  • It’s not necessary to test or treat a healthy cat for Bartonella.
  • If you are getting a cat, make sure it’s at least a year old, in good health, and free of fleas. Avoid stray cats and cats with flea infestations.