• Dr. Nicole Vumbaco | DVM

Understanding Bartonellosis

Updated: Oct 27

Bartonella are a group of stealth, slow-growing, intracellular bacteria. Over 38 species have been identified. Bartonella is best known for causing Cat Scratch Disease. This is usually self-limiting or resolves with short-course antibiotics. However, some of these infections progress into something more serious causing systemic illness known as Bartonellosis.


Recent research shows that bartonella can cause a wide range of chronic symptoms (involving muscles, joints, connective tissue, bone marrow, nervous system, liver, spleen, eyes, skin, psychological status, and the entire vascular system). In this form, it is classified as a Small Vessel Inflammatory Disease and can lead to an Undifferentiated Connective Tissue Disorder with preference for endothelial tissue and collagen, respectively.


This bacteria is a slow-growing, aerobic, nonmotile, pleomorphic, non-spore forming, hemotropic, facultative, intracellular coccobacillus. Stephen Harrod Buhner explains it well. Basically this means "they are choosy in what they eat, like oxygen, take 24 hours to reproduce, have variations in their size and shape, don't form spores, love blood, usually exist inside other cells but do not have to (facultative) and are intermediate in shape, roundish (cocco) and elongated (bacillus)"


Bartonella has many pathogenic strategies. While the pathogenesis still remains poorly understood, recent research has confirmed some of their highly evolved host interactions. One of those strategies involves using our host cytokine pathways for it’s own benefit. Cytokines are responsible for signaling inflammation. Through a series of interactions bartonella intentionally induces an inflammatory response releasing substances like Interleukin-8 (IL-8). This cytokine is one of the major substances necessary for mounting inflammation, an environment bartonella thrives in. This can lead to endothelial proliferation (reproduction of endothelia cells), inhibition of our host cells to undergo apoptosis (decreases the body's controlled process to eliminate questionable cells), stimulation of endothelial migration (new capillary or blood source formation) and increased epidermal growth factor (stimulates cell growth). Not only does it exploit our natural host interactions to cause inflammation and cellular recruitment, but it also uses existing inflammation in our body to seed new infections.


The collateral of chronic inflammation is tissue injury. Bartonella’s ability to manipulate host inflammation is one of the ways it targets our connective tissue’s extracellular matrix and collagen. This contributes to the development of bursitis, tendinosis, meniscal instability, joint pain, hypermobility, migraines, bone pain and neuropathy in patients suffering from this infection.


When Bartonella gains access to the human circulatory system, it can colonize secondary infections in locations distant and remote from the primary site of exposure (ie away from the location of the initial cat bite, cat scratch, flea bite, tick bite etc). It targets and infects a multitude of cells in the body. This includes CD34+, fibroblasts, monocytes, macrophages, red blood cells, microglial cells, dendritic cells and endothelial cells . The significance of this lays within their cellular function:

  1. CD34+: These are also known as 'Hematopoietic Progenitor Cells or HPC's'. This cell is capable of producing multiple cell lines in our body, forming our red blood cells, white blood cells, platelets, lymphocytes

  2. Fibroblasts: These cells create the extracellular matri