• Dr. Nicole Vumbaco | DVM

Bartonella and Mast Cell Activation Syndrome (MCAS):

Updated: Oct 27

Many patients with Bartonellosis and other Vector-Borne Disease suffer from a multitude of syndromes and disorders. Mast Cell Activation Syndrome or MCAS is one of the most complicated. It is sometimes the limiting factor in one's ability to treat for infection.


In short, MCAS is a type of mast cell activation disorder during which a specific immune cell (the mast cells) inappropriately and excessively, release pro-inflammatory chemical mediators, like histamine. Outwardly, this appears similar to an allergic reaction or allergy. Internally, the chronic inflammation leads to disorders of our connective tissue, small vessels, nervous tissue and immune system. Irritable Bowel Syndrome, Chronic Fatigue Syndrome and Fibromyalgia are just a few of the diseases involving mast cell dysfunction.


MCAS is a newer diagnosis, attaining it's name a little over a decade ago. The first case reports were published in 2007. An important distinction between other Mast Cell Disorders and Mast Cell Activation Syndrome is that patients typically have a normal number of mast cells circulating in their body. The problem isn't too many mast cells, the problem is they are too active. The severity of MCAS can incrementally escalate, which occur secondary to one or many triggers. Researchers are working hard to further define the syndrome but there has been vast implications. It is best to start with explaining what a mast cell is and what it does before we dive in to understanding this syndrome.


What are Mast Cells?

Mast cells were discovered in the late 1800's. They are a type of white blood cell and an integral part of the immune response. Mast cells have powerful granules within them that can release certain defensive chemical mediators in response to a potential threat. Mast Cells play an important role in protecting neurons from pathogens (this is called the neuroimmune system) and is our 1st line of defense to any invading infectious disease process.

Mast cells play a key role in the body's inflammatory response. When activated, they selectively release mediators through the process of degranulation (a process where the granules within a Mast Cell release it's defensive contents). These cells carry an arsenal of mediators (>200 are presently known). This includes pro-inflammatory cytokines, chemokines, growth factors, vasodilatory chemicals, heparin, superoxide dismutase, histamine, serotonin, tryptase, chymase, and proteoglycans. All of which are awaiting activation and have a specific indication for immune defense. [Im