What is Bartonella clarridgeiae?

Bartonella clarridgeiae comes from the Bartonella genus and is a gram-negative bacterium. The pathogen was first isolated in the United States . It is a zoonotic pathogen, i.e. a bacterium that can be naturally transmitted between humans and other vertebrates. The Bartonella clarridgeiae pathogen can cause the so-called cat disease. Cat fleas are therefore considered to be the main vectors of Bartonella clarridgeiae.

How was the Bartonella clarridgeiae pathogen isolated?

The Bartonella clarridgeiae pathogen was isolated from blood samples of the infected cats by means of DNA extraction. By means of a nested PCR, the DNA of Bartonella bacteria could be detected . In one human, a serological test proved that the Bartonella clarridgeiae pathogen was causative for the development of cat disease. The bacterium could be identified based on a sequence analysis of PCR-amplified gene fragments .

How is the Bartonella clarridgeiae pathogen transmitted to humans?

A cat infected with the Bartonella clarridgeiae pathogen can transmit the infection to humans through scratches or bites. It is also possible for the cat flea, which acts as a vector, to directly infect the person. However, this is much less common. The transmission of the Bartonella clarridgeiae pathogen from human to human has not yet been observed.

What clinical pictures can an infection with the Bartonella clarridgeiae pathogen lead to in humans?

Bartonella clarridgeiae is suspected of causing some cases of the so-called cat disease (CSD) in humans, which the infected cat can transmit to humans by scratching or biting. In most cases, the cat disease in humans is benign and heals spontaneously. In immunocompromised people, however, the disease can also take a severe course. In this case, antibiotic treatment is necessary . The cat disease is quite rare.

What are the symptoms of cat disease in humans?

Cat disease causes very different symptoms in humans, some of which are quite unspecific:

• transient fever,
• Swelling of the lymph nodes (lymphadenopathy),
• Abscesses in various organs,
• Infection of the inner lining of the heart (endocarditis),
• central nervous symptoms.

 
It is therefore advisable to have the symptoms clarified by a doctor , especially if there is a cat in the household or if one suspects that one has been infected with the cat disease. A Bartonelle clarridgeiae infection in humans can also be asymptomatic in many cases and can also disappear spontaneously without treatment.

How is feline disease diagnosed in humans?

In order to be able to diagnose the cat disease, a blood sample and a blood test are necessary. If the human organism has been in contact with the Bartonella pathogen, it has developed specific antibodies against the bacterium, which can be detected in the blood. Using special procedures, it is now even possible to detect the Bartonella pathogen in blood or tissue samples.

In addition to a blood sample, it is also possible to cultivate the Bartonella pathogen from a blood sample. However, the so-called culture has the disadvantage that the result is only available after several weeks. In some cases, it may also be necessary to take a tissue sample (biopsy) from a swollen lymph node in order to be able to make a reliable diagnosis.

How is the cat disease treated in humans?

In most cases, cat disease does not require any treatment at all , especially as it is often asymptomatic. If symptoms such as fever or pain occur, conventional painkillers such as ibuprofen, but also cooling compresses of the swollen lymph nodes can relieve the symptoms. If the symptoms last longer or the symptoms are very severe, doctors can also prescribe antibiotics to shorten the course of the disease.

What complications can arise from a Bartonella clarridgeiae infection in humans?

In many cases, the cat disease is harmless in humans. Complications only occur if the Bartonella pathogens have infected the heart, lungs or bones and caused inflammation here. Since the Bartonella bacteria also attack the red blood cells, these can be destroyed. If the Bartonella clarridgeiae pathogens have multiplied too much in the blood, the risk of blood poisoning, a so-called sepsis, and anaemia increases. Since sepsis can take on life-threatening proportions , it must be treated immediately by a doctor.

In immunocompromised people, such as HIV patients, the Bartonella pathogens can trigger so-called bacillary angiomatosis. In this case, the bacteria multiply in the smallest blood vessels of the skin, but can also penetrate into the organs. The liver, the spleen and/or the eyes are particularly frequently affected. However, the lymph nodes and the nervous system can also be affected in a special way in immunocompromised people . One sign of the presence of bacillary angiomatosis is the growth of tiny blood vessels. These then appear under the skin as small dark red or purple nodules and appear either singly or in groups. It is possible for them to spread over the entire body and break open in the course of the disease. In this case, bleeding and inflammation occur. Should the small blood vessels at the liver develop , small blood-filled cavities, so-called cysts, can also form in some cases.

How can the cat disease be prevented?

With domestic cats, care should be taken to keep the animal free of fleas . This is especially true if it is a cat that has access to the outdoors. Contact with feral cats should also be avoided. People with immune deficiencies should best stay away from cats altogether to avoid infection.