What Causes A Bartonella Infection?

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In this blog, we will look at the causes of Bartonella. You will learn:

  • What Bartonella is and how it compares to Lyme Disease
  • What causes Bartonella 

Do you know what Bartonella is? Do you know what causes Bartonella? If you want to know more about this growing threat and how to best optimize your health, then this blog is for you. Please read on for answers!  

** Please note: If you want the longer, more detailed summary version of this article, then please click here **

What is Bartonella?

Bartonella is a bacterium that causes the disease Bartonellosis. 

It can infect humans and animals including cats and dogs, and cause Bartonellosis. In recent years, Bartonella infections are reported to be on the rise (Álvarez-Fernández A, 2018). 

What we call the Bartonella bacteria is actually approx. 16 different bacterial species (Columbia Univ., 2022). Three species are thought to be responsible for the majority of Bartonella illness (de Almeida Lins K, 2019)

  • Bartonella bacilliformis
  • Bartonella quintana
  • Bartonella henselae 

Bartonella bacteria can cause many health issues. It is sometimes asymptomatic and causes no symptoms. On the other extreme, it can be potentially fatal (de Almeida Lins K, 2019). We discuss specific Bartonella symptoms in our blog here.

Which Different Diseases does the Bartonella Bacteria Cause? 

Bartonella can potentially cause three different diseases in humans: 

Cat scratch disease (CSD): Cat scratch disease is the most well-known disease caused by the Bartonella henselae species of Bartonella bacteria. Often, healthy people don’t develop any symptoms. People with a mild infection usually get better without any treatment. Although rare, CSD can cause people to have serious complications. 

Carrion’s disease: Carrion’s disease is an infection caused by the Bartonella bacilliformis species. In its acute phase, it can be serious and life-threating, especially for weaker immunity populations like children. It is currently largely limited to Peru, Ecuador and Colombia (de Almeida Lins K, 2019).

Trench fever: Trench fever or quintana fever is a recurring 5-day fever caused by the Bartonella quintana species. The episodes of fever typically become less severe over time. The mortality rate of trench fever is low (ECDPC, 2022). It is currently common among the homeless, alcoholics and AIDS patients

Despite the fact that Bartonellosis has increased in recent years, doctors often don’t consider Bartonella infection in their differential diagnoses. This leaves many Bartonella cases undiagnosed (de Almeida Lins K, 2019). Not getting a diagnosis, or getting a misdiagnosis, can result in chronic, painful symptoms for the patient.

We cover Bartonella symptoms and testing in our blogs here and here. 

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What Causes Bartonella?

The main way Bartonella bacteria are spread to humans is via insects and animals. Fleas, body lice, sand flies, ticks or contact with other infected animals spreads the bacteria. Transmission through animal scratches to humans spreads the infection. 

Bartonella bacteria can also be transmitted through blood transfusion (de Almeida Lins K, 2019). A study conducted in Brazil found that contact with ticks is associated with a Bartonella infection in blood donors (de Almeida Lins K, 2019).

Bartonella henselae is the most common form of Bartonellosis in the US. It is by transmitted by a vector, primarily fleas and by animal bites, scratches or needles (CDC, 2020).

The main creatures that spread the different Bartonella bacteria are:

Cats: Cats sometimes get fleas. These fleas can carry the Bartonella henselae bacteria and pass it onto cats. When cats scratch themselves, the bacteria can get under their claws. If the cat scratches a human, then it is transmitted to the person through a cat scratch. 

Ticks: The CDC maintains that there is no evidence that ticks spread Bartonella infection to people, despite studies proving this is true (Columbia Univ., 2022). It is widely known that ticks transmit the bacteria that cause Lyme Disease. However, it was only in 2008 that a medical journal published details about tick transmission of Bartonella (de Almeida Lins K, 2019).

Other Insects: Sand flies, lice, mosquitoes and even spider bites can transmit and spread Bartonella to people (de Almeida Lins K, 2019).

Other small animals commonly kept as pets can be carriers, including guinea pigs, rabbits and dogs (de Almeida Lins K, 2019).

Bats: Bartonella has been identified in bats (Stuckey MJ, 2017). The species of Bartonella bacteria varies by species of bat. 

Considering the multiple carriers that can spread Bartonella bacteria, the broad range of symptoms and the potential complications associated with Bartonella, it should be considered more frequently by doctors when they are assessing difficult to diagnose idiopathic conditions (de Almeida Lins K, 2019).

Is Bartonella the Same as Lyme Disease?

Bartonella is a co-infection of Lyme Disease. A Lyme Disease co-infection is when a person is simultaneously infected with Lyme Disease and one or more of the other vector-borne diseases. Co-infections may actually be more common than a single infection. A co-infection may explain why some people with Lyme remain chronically ill, even after being treated for Lyme Disease. 

While Bartonella is a co-infection of Lyme Disease, it is also its own disease. It is possible to have Bartonella without having Lyme Disease. 

In our clinic, we are Lyme-literate doctors. We are experts at identifying root causes, diagnosing conditions like chronic Lyme Disease and Lyme co-infections. We help people to address the root causes of illness and improve their health. We treat Lyme co-infections and chronic Lyme symptoms, with both natural and pharmaceutical approaches, depending on the individual case. 


  • Bartonella is a bacterium that causes Bartonellosis
  • 3 of 16 Bartonella species cause the majority of infections
  • Bartonella infections can cause 3 different diseases in humans: Cat Scratch Disease, Carrion’s Disease, and Trench Fever
  • Bartonella can be spread by fleas, body lice, sand flies, ticks, or contact with infected animals through scratches
  • When infected with both Lyme Disease and Bartonella, Bartonella is known as a Lyme Disease co-infection, though it can also occur independently from Lyme Disease.

** Please stay tuned for our next Blog!  **

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Dr. Miles has spoken for the following organizations:

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