Getting bit by a mosquito is more than just a pesky nuisance. Arthropods like mosquitos and ticks are among the leading carriers of vector-borne diseases. What may seem like a simple bug bite could actually be the start of something more serious.

Vector-borne diseases account for at least 20% of all infectious diseases worldwide and 1 million deaths annually. A vector is a living organism that transmits pathogens from humans to humans or animals to humans. Lyme disease is a well-known vector-borne disease that occurs when an infected tick bites a human and passes along Lyme bacteria.

While Lyme disease from ticks is widely known in our part of the world, there are many vectors besides ticks and many different vector-borne diseases.

The unfortunate truth is that vector-borne diseases are on the rise both worldwide and here in the US. Between 2004 and 2016, the number of vector-borne illnesses in the US tripled, and that trend does not appear to be slowing.

Our current healthcare system is not equipped to handle this emerging crisis. Vector-borne diseases are poorly understood and often difficult for physicians to diagnose. I see many patients come to my clinic with often multiple vector-borne illnesses they have dealt with for years, without any concrete answers to what is going on.

I firmly believe we can do better. Step one is to increase our understanding of vector-borne diseases. Lack of awareness allows these infections to spread without our even knowing. If we want to stop these diseases, we have to know what we are dealing with.

Today I want to look at:

  • Common vectors and the diseases they may carry
  • Highlight Bartonella, its symptoms, diagnosis, and treatment
  • Explore the relationship between Bartonella and MCAS


Understanding Vector-borne Diseases

Vector-borne is just a fancy way of saying “carried by a living organism.” Blood-sucking insects are among the most common vectors. These can include:

  • Mosquitos
  • Ticks
  • Lice
  • Fleas
  • Blackflies
  • Sandflies
  • Mites

When a vector bites an infected host, whether human or animal, it ingests some of the pathogens in the host’s blood. Once infected, the vector can now pass on the pathogen to anyone else it bites.

A large percentage of vector-borne diseases occur in tropical climates. These climates are ideal breeding grounds for many vectors such as mosquitoes, as the warm temperatures favor these cold-blooded arthropods. However, due to warming global temperatures, conditions have become more favorable in other parts of the world for vectors to thrive.

In the US, we currently see an increase in the areas where vectors are likely to be found. Whereas once these diseases were isolated to specific parts of the country or globe, now disease-carrying vectors are found in unexpected places, and the risk of coming in contact with one has increased.

The list of vector-borne diseases is much too long to include here, but I want to highlight a few common ones, and then we’ll narrow in specifically on Bartonella.


  • Powassen
  • West Nile Virus
  • Dengue Fever
  • Zika
  • Chikungunya


  • Borrelia Burgdorferi (Lyme)
  • Other Borrelia species, including tick-borne relapsing fever
  • Rickettsia infections
  • Bartonella
  • Brucella
  • Ehrlichia
  • Anaplasma
  • Tularemia


  • Malaria
  • Babesiosis
  • Theileria
  • Filariasis

All of these infections cause a wide range of symptoms, though many share some common features. A closer look at Bartonella will lay the groundwork for a deeper understanding of these conditions.



Bartonella is a common vector-borne illness I see daily in my practice. It is also very misunderstood.

Bartonella is a category of bacteria that cause infection and disease in humans. What makes Bartonella such a tricky vector-borne disease is its ability to spread through multiple vectors. Unlike Lyme disease, which is transmitted almost exclusively by ticks, Bartonella is transmitted from many sources:

In addition, Bartonella survives in many different hosts, known as reservoirs. A reservoir is simply a community of generally asymptomatic hosts. They maintain the disease’s presence and create the conditions for vectors to become infected and pass the infection along to new hosts who then become sick.

The number of Bartonella reservoirs is growing exponentially due to the bacteria’s high level of adaptability in mammal populations.

Many Bartonella reservoirs exist worldwide.

  • Cats- largest reservoir worldwide
  • Dogs
  • Coyotes
  • Mice
  • Rats
  • Mongoose
  • Raccoons
  • Bats
  • Deer
  • Foxes
  • Squirrels
  • Sheep
  • Humans

In the US, our pets are likely one of the most widespread reservoirs we come in contact with. Cat scratch disease is one classic example of a Bartonella infection by the bacteria Bartonella henselae. If an infected cat bites or scratches someone enough to break the skin, Bartonella bacteria may invade the bloodstream, leading to a serious infection.

As much as we love our pets, they have the potential to perpetuate the cycle of vector-borne disease. Whether by their fleas or other contacts, we have to be aware in our interactions to keep both our pets and ourselves safe.

In the case of cats, there are tests veterinarians can run to determine if they carry Bartonella. It’s worth considering whether having your cat tested can shed light on your risk.


Bartonella Species

There is not just one Bartonella bacteria. Dozens of species of Bartonella exist, and as many as 13 have been implicated in causing infections in humans.

The list of Bartonella species continues to grow. As more strains are identified, I expect the number of illnesses understood to arise from Bartonella will also increase. In my opinion, this is good news, as diagnosing some of the mysterious illnesses patients experience will hopefully become easier with a better understanding of this vector-borne disease.

Until recently, only three species of Bartonella were recognized as disease-causing:

  • Cat scratch disease (CSD, cat scratch fever) = B. henselae
  • Carrion’s disease caused by B. bacilliformus (limited to South America)
  • Trench Fever, caused by B. quintana

However, this is no longer the case. In my practice, I see patients with Bartonella infections from a variety of species that were previously ignored and a variety of different manifestations, even amongst the common Bartonella species.. This is partly due to a lack of understanding of the bacteria’s mechanisms of action but also due to the lack of adequate testing, though thankfully, that is now changing.


Bartonella: A Stealth Infection

The Bartonella bacteria have several sophisticated methods by which they evade a host’s immune system. These stealth tactics are part of what makes these infections so hard to diagnose and treat.

There are two phases to a Bartonella infection.


Dermal Phase

After contact with a Bartonella-carrying vector such as a flea, the bacteria enter the dendritic cells and target endothelial cells (the layer of cells that line blood vessels). The incubation time for a Bartonella infection is often long, upwards of 60 days for some strains. This is likely due to the time it takes for the infection to gain a foothold in the endothelium.

Endothelial cells serve as a sort of “home base” for Bartonella bacteria. Here they can lie in wait for the chance to enter the bloodstream. Even if the bacteria that enter the bloodstream are neutralized by immune cells or an antibiotic, reserve troops in the endothelium are patiently waiting their turn.

This ability to continually repopulate the bloodstream from the safety of the lining of the blood vessels gives Bartonella incredible staying power.


Endovascular Phase

Over time, the bacteria enter the bloodstream and invade erythrocytes (red blood cells), where they disrupt blood flow, decrease energy delivery, decrease Nitric Oxide, and cause vasoconstriction.

To evade the immune system, Bartonella bacteria carry out multiple strategies to both disguise themselves and disrupt a normal immune response. By hiding in plain sight and stimulating inflammation that hinders immune cell function, Bartonella is skilled at avoiding detection and elimination.

Harms A, Dehio C. Intruders below the radar: molecular pathogenesis of Bartonella spp. Clin Microbiol Rev. 2012;25(1):42-78. doi:10.1128/CMR.05009-11

FIG 1: Common infection strategy of the bartonellae. The drawing illustrates the general concept of reservoir host infections with Bartonella. Following transmission by an arthropod vector (a), the bartonellae colonize the primary niche, which probably involves entry into migratory cells (b) and transport to the vascular endothelium (c), where the bacteria persist intracellularly. From the primary niche, the bacteria are seeded into the bloodstream (d), where they invade erythrocytes and reinfect the primary niche. After limited replication inside the red blood cell (e), they persist in the intraerythrocytic niche (f) competent for transmission by a bloodsucking arthropod (g).


Clinical Manifestations

The presence of Bartonella both in the lining of the blood vessels and the red blood cells themselves means it impacts all areas of the body. Every organ system is involved.

Depending on the specific strain of Bartonella present, signs and symptoms vary:


  • Fever, often relapsing
  • Fatigue


  • Chronic eye problems such as blurry vision, redness, and irritation
  • Uveitis
  • Retinitis


  • Joint and muscle aches
  • Joint hypermobility
  • Pain in feet
  • Bone Pain
  • Muscle Twitching


  • Headaches
  • Dizziness/Vertigo
  • Brain fog
  • Numbness/tingling
  • Dysautonomia/POTS
  • Autoimmune encephalopathy/ PANS/PANDAS
  • Tics
  • De-realization
  • Cognitive impairment
  • Depression
  • Anxiety/panic attacks
  • Schizophrenia
  • Obsessive-Compulsive Disorder


  • Swollen lymph nodes
  • Sore throats
  • Autoimmune diseases such as Hashimoto’s, Graves and Type 1 and 2 Diabetes


  • Anemia
  • Low white blood cell count
  • Low platelets


  • Heart issues such as endocarditis or myocarditis
  • Vasculitis (inflammation of the blood vessels)
  • Abnormal changes in weight


  • Liver enlargement (hepatomegaly)
  • Spleen enlargement (splenomegaly)
  • Liver cysts
  • Inflammatory bowel disease/colitis


  • Metabolic disorders
  • Thyroid dysfunction
  • Abnormal changes in weight – weight gain or weight loss

Dermatologic system:

  • Rashes
  • Stretch mark (Striae-like) lesions

This list is by no means exhaustive. While I see some patients with classic Bartonella symptoms, often the bacteria exists alongside other infections or conditions that exacerbate or mask its presentation. This range of side effects can be debilitating for patients, especially when coupled with the inability to find proper diagnosis and treatment.


Bartonella and Mast Cell Activation Syndrome (MCAS)

We can’t talk about vector-borne illnesses without acknowledging mast cell involvement. In my practice, I see the complex interaction between infections and MCAS all the time. Many vector-borne diseases, Bartonella included, may trigger MCAS, in which case treatment must address what is happening in the mast cells in order to eradicate the infection.

Mast cells are one of the body’s first lines of defense. When confronted with a pathogen like Bartonella, the cells release a flood of cytokines and other signaling molecules to rally the immune system and neutralize the threat.

The problem is that mast cells can become sensitized or hijacked. Your mast cells may be overactive in these cases, continually releasing histamine and/or other inflammatory compounds. Due to the chronic nature of Bartonella, the repeated exposure of mast cells to bacteria creates an environment ripe for MCAS.

But, there is hope for treatment in patients with vector-borne illness-induced MCAS. Treatment to stabilize mast cells shows promise as an effective treatment in vector-borne illness. Once the mast cells calm down, the body’s immune system may be able to step up and effectively target the bacteria.


Diagnosis And Treatment

When a patient comes to see me with symptoms suspicious of a vector-borne illness or MCAS, getting a firm diagnosis is critical. Both MCAS and vector-borne illnesses are good at appearing to be something else. And many patients, unfortunately, have been told, wrongly, that it is “all in their head.”

Putting a name to what a patient is experiencing brings a huge amount of relief and sets the stage for their recovery.

When vector-borne illness is suspected, multiple types of testing are usually necessary. The worst test, but the one used most frequently to prove or disprove Bartonella infection is serologic (antibody) testing. However, since Bartonella is known to suppress the immune response and because it’s often hiding from the immune system, many patients don’t mount an immune response with antibodies to Bartonella as would be expected. They may actually only start to make antibodies, and how a positive serologic test, after they have started treatment for Bartonellosis.

Molecular testing with FISH, PCR, and/or Culture is far superior but expensive. It actually shows the presence of the organism, which proves the symptoms are due to the infection with the organism.

  • Bartonella serologic testing: Can be done by commercial labs but is often negative. We only have serologic tests for 2 strains of Bartonella.
  • B. Henselae IgG/IgM
  • B. Quintana IgG/IgM

More extensive testing:

  • Igenex- Serologic testing of 4 Bartonella species (B. henselae, B. quintana, B. elizabethae, B. vinsonii), FISH and PCR are available.
  • Galaxy- includes additional Bartonella species IFA (B.henselae, B. quintana, B. vinsonii berkhoffii B. koehlerae, Culture, and ePCR.
  • T Lab- FISH for B. henselae (plus Biofilm analysis, and Babesia Odocoilei and Borrelia Burgdorferi FISH is also available)

A basic serological test from a commercial lab may rule in a Bartonella infection. However, negative results are not a definitive answer. Remember, there are many strains of Bartonella that can cause disease, and they are not on the radar of many labs.

To find Bartonella, you have to know what you are looking for and be willing to look for the unexpected.

Once an infection is identified, prompt, targeted treatment can begin. Because Bartonella is so good at hiding and persisting even after antibiotics, the most effective treatment is a multi-pronged approach to get at the infection from many angles.

  • If MCAS is confirmed- follow treatment protocols, including initiating mast cell-targeted therapy.
  • Evaluate and address other confounding comorbid conditions such as hormone imbalances, gut health, neurologic issues, mold/mycotoxin illness, EDS/CCI, stress/trauma, etc.
  • Biofilms
  • Homeopathy
  • Herbal protocols
  • Antibiotics/antimicrobials
  • Ozone therapy
  • SOT- Supportive Oligonucleotide Technique
  • Other: Acupuncture, Rife, Frequency Specific Microcurrent, DNRS


Recovery From Bartonella

If not correctly treated, any vector-borne illness can cause poor health and chronic disease. And the growing scope of the problem means we will likely see more of these diseases in the future.

Unfortunately, due to a lack of education and health system constraints, many doctors do not have the necessary skills to identify and eradicate these illnesses.

Our understanding of vector-borne diseases has significantly increased in recent years. But, it can be a full-time job to stay up to date on the best practices and effective treatments. The patients I see have often been down the path of trying to self-diagnose or find a doctor who will listen. I understand how difficult it can be to get the answers you need.

Yet, recovery from Bartonella is possible. Putting patients on the road to healing is the best part of my job and why I do what I do. With sound science and effective treatment, I’ve witnessed, time after time, patients restore their health and recover from vector-borne diseases.

The more we know about these infections, the better equipped we become to halt their destruction and protect our health.

At AIM Center for Personalized Medicine, we use a personalized approach to understanding your symptoms, finding the root of your health issues, and creating an individualized treatment plan to regain your health. Find out more about AIM here.