What is Bartonellosis?
Bartonella is a type of bacteria that often causes infections in animals and can be passed on to humans. Across the globe, almost 20 different Bartonella species have been identified. Three of these species – Bartonella henselae, Bartonella quintana, and Bartonella bacilliformis – are commonly associated with human infections.
Trench fever, often referred to as five-day fever, first appeared in European soldiers. This disease only affects humans and is spread by body lice.
Oroya fever was first identified in 1870 in Peru, during the construction of a railway line from Lima to Oroya. A serious outbreak of this fever led to thousands of worker deaths, and the disease was named after the place it first appeared. Some survivors of this outbreak developed verruga peruana, which are skin sores that turn into ulcers. This disease is typically found in the mountainous areas of Peru, Columbia, and Ecuador. In 1885, a Peruvian medical student named Daniel Carrion injected himself with a sample from a verruga sore and died from Oroya fever. This is why Oroya fever is also known as Carrion disease.
What Causes Bartonellosis?
Cat scratch disease, which is caused by Bartonella henselae, is the most common infection caused by the Bartonella species of bacteria. Other Bartonella bacteria can cause different types of illnesses. For example, Bartonella bacilliformis causes Oroya fever and verruga peruana, while Bartonella quintana is known to cause trench fever.
Carrion’s disease, on the other hand, comes from B. angiomatosis. This disease can cause fever, extreme tiredness due to the destruction of red blood cells, enlargement of the spleen and liver, bleeding into the lymph nodes, and harm to blood vessels. Without treatment, Carrion’s disease could be fatal in 40% of cases.
Risk Factors and Frequency for Bartonellosis
The global incidence of cat-scratch disease is 6.4 cases per 100,000 adults and 9.4 cases per 100,000 children between 5-9 years of age. The highest incidence is seen in the southeastern United States, peaking in January, late summer, and fall. In terms of trench fever, there have been epidemic and occasional outbursts reported since the early 20th century in various countries, with the largest reported during world war 1 and world war 2.
Trench fever is most common in the homeless population owing to their increased exposure to the pathogen. Infections caused by Bartonella bacilliformis, on the other hand, are endemic in Peru, Columbia, and Ecuador. However, these infections have also sporadically occurred in Chile, Guatemala, and Bolivia.
Signs and Symptoms of Bartonellosis
Cat scratch disease is a condition that often starts with skin symptoms at the location where the bacteria entered the body. Within a week to ten days, there might be skin changes like blisters, redness, or small raised areas. The lymph nodes near this area may start to swell. Some people might also experience symptoms like fever, tiredness, or swelling of various organs, but these are rare.
After the lymph nodes, the eye is the next most commonly affected organ. However, the changes to the eye might not cause symptoms, so they might not be noticeable. One particular eye problem related to cat scratch disease is neuroretinitis, an issue with the optic nerve that can cause a collection of fluid in the back of the eye. This happens in about 1-2% of cases.
Another symptom is known as Parinaud oculo-glandular syndrome. It causes swelling of the lymph nodes in front of the ear, under the jaw, and in the neck, along with infection of the conjunctiva, eyelids, and nearby skin. This happens in about 2-8% of people with cat scratch disease.
The disease can also cause various neurological symptoms such as encephalopathy, a condition that affects the brain; transverse myelitis, inflammation of the spinal cord; radiculitis, inflammation of the nerve root; and cerebellar ataxia, a loss of muscle control in the arms and legs.
- Changes on the skin where bacteria entered
- Swollen lymph nodes
- Rare symptoms: Fever, tiredness, swelling of organs
- Potential eye-related issue: Neuroretinitis
- Potential symptoms: Parinaud oculo-glandular syndrome
- Possible neurological symptoms: Encephalopathy, transverse myelitis, radiculitis, cerebellar ataxia
Severe cases of the disease can cause endocarditis, an infection of the heart’s inner lining, typically due to two specific types of Bartonella bacteria. Furthermore, people with weakened immune systems, such as those living with HIV or those who have had organ transplants, are at risk of severe, widespread disease. This can be life-threatening if left untreated.
In patients with AIDS, a condition called bacillary angiomatosis may occur. This includes skin lesions, lumps under the skin, and bone lesions. It’s sometimes confused with other conditions like Kaposi’s sarcoma or hemangiomas. The bacteria can also affect the bone marrow, liver, spleen, or lymph nodes.
Bartonella bacteria can cause a condition called Peliosis Hepatis, which is marked by excessive blood vessel growth in the liver, leading to blood-filled cavities. This was previously linked to tuberculosis and the use of certain drugs, showing up in HIV patients and organ transplant recipients.
Trench fever, caused by a specific type of Bartonella, can lead to symptoms such as fatigue, fever, headache, bone pain, and an enlarged spleen. Fever patterns vary and can either be a one-time episode or persist for several days.
Bartonella bacilliformis infection has an acute phase (Oroya fever) characterized by fever, fatigue, headache, and a chronic phase (Verruga Peruana) characterized by skin lesions that appear about 2-8 weeks after the acute phase.
People with chronic Bartonella infection may experience symptoms such as recurring low-grade fever, vision problems, bone pain, most prominent in the shins, and foot pain upon waking up in the morning. Other symptoms may include anemia, poor balance, decreased cognition, memory impairment, insomnia, and restlessness.
Testing for Bartonellosis
There are certain classic criteria for the diagnosis of Cat Scratch Disease (CSD). It typically involves close contact with cats or a scratch or bite from a cat. It’s usually associated with a specific histology, which means the tissues affected by the disease have a particular appearance under a microscope. Finally, a diagnosis also relies on serology, which is testing of the blood for antibodies against the bacteria causing CSD, B. henselae.
Determining whether someone has CSD usually involves more than one type of test, as no single test can be entirely reliable on its own. Some common tests used to detect Bartonella, the bacteria causing CSD, are serological testing, culture, histopathology, and PCR DNA detection. While each has its benefits, there are challenges, as the bacteria may not be continuously present in the blood (bacteremia).
There are direct and indirect methods of detecting CSD. The direct methods include growing the bacteria in a lab or culture, using scientific techniques to find proteins or genetic material from the bacteria, or using specialist stains to see the bacteria. Indirect methods usually involve looking for the body’s immune response to the bacteria, like finding antibodies.
While culturing the bacteria can definitively diagnose CSD, it is a slow, expensive process, and growing the Bartonella bacteria itself can be challenging. Therefore, this method is usually not recommended. Instead, serology is often the best initial test.
Serological tests, antibody tests, have variable accuracy. It can fail to detect early-stage disease, but it has a high positive predictive value, meaning if the test result is positive, the probability of having the disease is very high. However, the accuracy of the test can vary. Furthermore, these tests not only detect a current infection but also past infections.
Examination of infected tissues can also be useful. This involves looking for changes in the tissue and staining the bacteria for easier visualization. However, newer techniques like PCR on lymph nodes or other bodily material offer high specificity and faster identification but may lack sensitivity.
Treatment Options for Bartonellosis
The treatment of cat scratch disease depends on how severe the symptoms are. For those with mild symptoms like swollen lymph nodes and fever, doctors usually don’t prescribe antibiotics because the condition tends to get better on its own.
However, research has found that a single course of antibiotics can significantly shorten the duration of symptoms. The antibiotics commonly used include azithromycin, ciprofloxacin, gentamicin, trimethoprim-sulfamethoxazole, and rifampin.
Patients with severe lymph node swelling are usually given azithromycin to take orally: an initial dose of 500 mg, followed by 250 mg each day for the next four days.
For retinitis (an inflammation of the retina), the recommended treatment is 100 mg of doxycycline taken orally twice a day for 4 to 6 weeks, alongside 300 mg of rifampin orally twice a day for the same duration.
Trench fever or chronic bacteremia with B. quintana is typically treated with 200 mg of oral doxycycline once daily for 4 weeks, in addition to 3 mg/kg of intravenous gentamicin for 2 weeks.
Bacillary angiomatosis and Peliosis Hepatis are treated with 500 mg of oral erythromycin four times a day for 3 to 4 months.
If a culture test confirms Bartonella endocarditis, the recommended treatment is 100 mg of oral doxycycline for 6 weeks and 3 mg/kg/day of intravenous gentamicin for 14 days.
For neuroretinitis and involvement of the central nervous system, a combination of 100 mg of oral doxycycline twice a day and 300 mg of rifampin twice a day is recommended.
While there haven’t been any controlled trials comparing not treating the condition with antibiotic treatment, retrospective case series have consistently shown that antibiotics speed up visual recovery and improve visual outcomes. The use of corticosteroids in cat scratch disease with eye involvement has had mixed results.
For the management of Oroya fever, ciprofloxacin is the first choice of treatment, with chloramphenicol and ceftriaxone being effective alternatives. Verruga peruana is primarily managed with azithromycin, with rifampin, ciprofloxacin, and chloramphenicol as other preferred treatment options.
What else can Bartonellosis be?
These are some medical conditions that may not be part of the everyday jargon, but are nonetheless significant:
- Atypical mycobacterial diseases: these are infections caused by a type of bacteria different from the usual ones we know.
- Coccidioidomycosis and Valley Fever: both are lung infections caused by a type of fungus found in soil.
- Leishmaniosis: a disease spread by the bite of a sandfly that can affect the skin, and sometimes internal organs.
- Lyme disease: an infection that is transmitted through the bite of infected ticks.
- Lymphogranuloma venereum (LGV): a sexually transmitted infection caused by specific strains of bacteria.
- Nocardiosis: a rare infection caused by soil-borne bacteria that can manifest in the lungs, brain, or skin.
- Sarcoidosis: a disease that causes tiny collections of inflammatory cells in different parts of your body, most commonly the lungs and lymph nodes.
- Sporotrichosis: a skin infection usually acquired by getting the fungus, found in soil and plants, into a scrape or cut in the skin.
- Syphilis: a sexually transmitted bacterial infection that can cause long-term complications if not treated correctly.
- Toxoplasmosis: an infection caused by a parasite, usually acquired by consuming undercooked contaminated meat or contact with infected cat feces.
Preventing Bartonellosis
Preventing infections caused by Bartonella, like cat scratch disease and trench fever, can be achieved through simple everyday actions. If you want to prevent cat scratch disease, it’s important to take good care of your cats. This includes avoiding scratches, keeping them inside as much as you can, treating them regularly for fleas, and always washing your hands after you play with them. These steps can help you avoid contracting the disease.
As for trench fever, you can prevent it by avoiding contact with human lice and immediately treating any lice infestations that you might find.
Carrion’s disease, another Bartonella-related infection, can be kept at bay by wearing long-sleeved clothes and using insect repellent to avoid bites from sandflies.
