Ticks harbor a variety of infectious pathogens besides Borrelia burgdorferi (Lyme pathogen). Pathogens such as bacteria, viruses, and parasites are commonly found within a tick’s midgut and salivary glands. During a bite, the tick can infect someone with one or more of these pathogens.

Any tick-borne infection other than Lyme disease is usually referred to as a “co-infection.” Co-infections can be acquired with or without Lyme disease in one bite, or through multiple tick bites over time. Polymicrobial infections can lead to an increased severity of certain symptoms, as well as symptoms that persist after proper treatment.

Many of the symptoms of Lyme disease and co-infections overlap. For this reason, they can be challenging to diagnose. Luckily there are some hallmark symptoms for each infection that help us begin the important detective work of identifying and treating each tick-borne disease.

co-infections pathogens lyme bacteria viruses parasites
Mischa Grieder, ND - Naturopathic Doctor

We routinely test for co-infections as part of the normal workup for patients with chronic symptoms.


The FDA estimates 11% of transfusion-related deaths are caused by microbial contaminated blood, with up to 38% of the fatalities linked to Babesia.


Babesiosis: A Malaria-Like Infection

Babesia pathogen lyme disease

While there are over 100 strains of Babesia, not all of them are harmful to people. Here in the US, most cases are caused by Babesia microti or Babesia duncani. The Babesia pathogen is a malaria-like, protozoan parasite known as a “piroplasm.” In simpler terms, Babesia is a parasite that invades red blood cells. There are three ways Babesia can be spread:

  • Through the bite of an infected tick
  • Congenitally from infected mother to baby (pregnancy or delivery)
  • Through blood transfusion from infected donor to recipient

Surprisingly, Babesia turns out to be the most commonly reported transfusion-transmitted parasitic infection in the US. This is counter to everything we have read until recently. Babesia was thought to be a rare disease, found primarily in people who deal with livestock. Now researchers understand it as a worldwide, emerging tick-borne disease, imposing a significant health burden as it increases in prevalence.

In 2019, the FDA published recommendations on reducing the risk of transfusion-transmitted Babesiosis. This was definitely considered a “win” by many, as a mitigation strategy was desperately needed with the high mortality rate. At this time, however, the FDA still does not require testing and only recommends a select number of states test for one strain of Babesia (B. Microti) in donations year round.

More About Co-Infections

Babesia Infection
Individuals with babesiosis present with a broad range of symptoms. While some people are asymptomatic, others experience severe presentations of infection that can at times be fatal. Symptoms usually begin within the first 9 weeks of transmission.

  • Drenching night sweats
  • Vivid dreams
  • Fevers and chills (sometimes spiking fevers)
  • Hemolytic anemia
  • Migraines
  • Shortness of breath (“air hunger”)
  • Dizziness
  • Myalgia
  • Fatigue
  • Depression, anxiety, panic, and/or mood swings
  • Nausea, loss of appetite, and digestive dysfunction
  • Heart palpitations and chest pain
  • Enlarged liver and/or spleen
Bartonella Infection
Symptom pattern and severity will depend on the species of Bartonella, individual immunity, and any additional diseases or infections someone may be fighting. Symptoms range from mild to severe, and usually begin 1 – 3 weeks after exposure.

  • Swollen glands and lymph nodes
  • Papule or pustule at infection site
  • Rashes (may look like “stretch marks”)
  • Fever
  • Headaches
  • Insomnia
  • Pain in soles of the feet
  • Bone pain
  • Muscle twitching
  • Poor appetite
  • Nausea
  • Psychiatric and cognitive impairment
  • Heart palpitations and tachycardia
  • Anemia
  • Vasculitis (inflammation of small blood vessels)
  • Thrombocytopenia (low platelets)
There are a variety of different carriers of Bartonella bacteria that transmit infection to humans. Bartonellosis is passed on by lice, fleas, and sandflies most commonly. Current research has also identified ticks, spiders, mites, and mosquitoes as potential vectors (aka “carriers”). One of the most well-known forms of Bartonellosis is caused by Bartonella henslae, also known as Cat scratch disease. An infected flea transmits the Bartonella henslae bacteria to a cat through a bite or its droppings. The cat then passes the bacteria onto a human being through a scratch.

Of the 45 species of Bartonella identified, Bartonella bacilliformis, Bartonella quintana, and Bartonella henselae are the most common causative agents of human infection. All species are gram negative bacteria that invade red blood cells. Bartonella is able to evade the immune system, partially due to the fact that it hides in red blood cells, among other tactics like biofilm formation, genetic modification, and immune suppression of the host.

Rickettsial Infection

Rickettsial infections result from different types of bacteria of the order Rickettsiales. These zoonotic pathogens cause acute febrile disease in human beings all over the world. Similar to Bartonella bacteria, they are transmitted by infected carriers like ticks, fleas, lice and/or mites. Below we review symptoms of three Rickettsial infections that we see in our clinic: Anaplasma, Ehrlichia, and Rocky Mountain Spotted Fever (RMSF).

Rocky Mountain Spotted Fever falls under the spotted fever group of Rickettsioses, and is the most well known of the group in the United States. It is considered the deadliest tick-borne disease in the Americas by the CDC because it has the potential to be rapidly fatal if not treated within the first 5 days of symptoms. Although some individuals become sick within the first week of infection, RMSF has an incubation period that can last up to 12-14 days.

  • High fever and chills
  • Red, non-itchy rashes
    • Usually develop 2-4 days after fever (but not always)
    • Vary in appearance
  • Severe headache
  • Muscle aches
  • Nausea and vomiting
  • Confusion or other neurological changes

Both Anaplasmosis and Ehrlichiosis present relatively similarly as nonspecific febrile illnesses. The main difference is that individuals with ehrlichia infection have a 30% likelihood of developing a rash (60% likelihood for children) versus individuals with an anaplasma infection who are very unlikely to develop a rash at all (less than 10%).

  • Moderate fever and chills
  • Headache
  • Muscles aches
  • Joint pain
  • Nausea and vomiting
  • Diarrhea
  • Loss of appetite
  • Lymphocytopenia (low white blood cell count)
  • Confusion or other neurological changes