What is Bartonella Bacteria?
There are several different species of Bartonella bacteria, which are small intracellular parasites that cause the illness bartonellosis. They infect red blood cells, macrophages (a type of white blood cell), and endothelial cells.
The bacteria are carried by various vectors and can also be transmitted through animal bites and scratches. There is strong evidence that Ixodes ticks can carry and transmit Bartonella bacteria, in addition to Borrelia, Babesia and Anaplasma organisms.
Bartonellosis is a group of infectious diseases, including cat scratch disease (Bartonella henselae), Carrion’s disease (Bartonella bacilliformis), and trench fever (Bartonella quintana). Approximately 20,000 cases of cat scratch disease are reported in the United States every year.
What Are the Symptoms of Bartonella Bacteria Infection?
All forms of bartonellosis can cause fever. Other symptoms of cat scratch disease include tender and enlarged lymph nodes developing one to three weeks after exposure, and a papule or pustule at the site of the scratch. Eye infections, severe muscle pain, and swelling of the brain (encephalitis) may also occur in some patients.
Carrion’s disease has two phases. The first phase is called Oroya fever. In addition to fever, it’s characterized by headache, muscle aches, and abdominal pain. Severe anemia can also occur. During the later phase, verruga peruana (Peruvian warts) growths form under the skin. These then develop into red or purple vascular sores that may bleed.
Trench fever leads to headache, rashes, and bone pain, usually in the shins, neck, and back. It was first observed among military populations during World War I.
Immunocompromised patients can experience some complications of bartonellosis. The infection bacillary angiomatosis (caused by Bartonella henselae and Bartonella quintana) results in skin, bone, and organ lesions. Bacillary peliosis (caused by Bartonella henselae) is associated with sores in the liver and spleen.
Bartonella bacteria can also infect the heart valves, leading to subacute endocarditis in patients with pre-existing heart conditions. Some signs of subacute bacterial endocarditis are fever, malaise, and excessive sweating.
How Is Bartonellosis Diagnosed?
The diagnosis of bartonellosis requires laboratory testing, because clinical signs and symptoms are often non-specific. There are serological tests available for Bartonella infections, the most popular of which are immunofluorescence assays (IFA) for IgM and IgG antibodies. However, false negative results are very common.
Western blot tests and polymerase chain reaction (PCR) are generally considered to be more accurate. Cultures of Bartonella bacteria grown in the laboratory tend to be insensitive and grow too slowly.
A more modern and highly effective diagnostic technique is the ELISpot, offered by Infectolab. It’s a blood test that can detect the presence of two important molecules, in order to get a clearer picture about the infection. The two molecules are IFN-gamma (or type II interferon) and IL-2 (interleukin-2). They are produced by T-cells, which are a type of white blood cell and an essential component of your immune system.
If a patient has recovered and the infection has cleared up, only IL-2 producing T-cells are found in the blood sample. The purpose of these cells is to identify the Bartonella bacteria if they encounter them in the future, and to provide defense against them. If the ELISpot test detects both IL-2 and IFN-gamma molecules, that means that the patient’s immune system is still fighting an active infection.
How Is Bartonellosis Treated?
There’s not a single, specific treatment approved by the Food and Drug Administration (FDA), the Centers for Disease Control (CDC), or the Infectious Diseases Society of America (IDSA). In otherwise healthy patients, cat scratch disease normally resolves without treatment within two to four months. The aim of any therapy is to relieve symptoms and support natural immune function. Your doctor may suggest taking some fever-reducing medication and painkillers. Applying local heat to tender lymph nodes can also be helpful.
Patients with weakened immune systems and those experiencing severe symptoms or complications may need antibiotic treatment. Azithromycin has been shown to decrease lymph node swelling caused by cat scratch disease more rapidly compared to no treatment. Carrion’s disease, trench fever, Oroya fever, verruga peruana, and endocarditis due to Bartonella infection are much more serious illnesses that always require antibiotic therapy.
Is There a Connection Between Bartonella and Lyme Disease?
Lyme disease is a tick-borne infection caused by the bacterium Borrelia burgdorferi. Its classic sign is a red “bull’s-eye” rash, which is present in 70–80% of those diagnosed with the illness. Although the initial symptoms of Lyme are mild in patients with robust immune systems, the infection may spread throughout the body if left untreated. Months or years later, it can lead to serious neurological, cognitive, and heart problems.
Ticks that carry Borrelia burgdorferi may also be infected with Bartonella bacteria. Therefore, bartonellosis is a potential co-infection of Lyme disease. The symptoms of both conditions may mimic the flu and other viral illnesses, which can make the co-infection difficult to diagnose.