Specific co-infections


Babesiosis is an infection caused by a malaria-like parasite (Babesia microti and B. duncani are two examples), that infects red blood cells. If ticks are infected with the Lyme bacterium, Borrelia burgdorferi and Babesia, this is a co-infection. Although rare, it’s possible to contract babesiosis from a contaminated blood transfusion.


Babesiosis is often so mild it goes unnoticed, but it can be life-threatening to people with no spleen, the elderly, and people with weak immune systems.

Symptoms of babesiosis are similar to those of Lyme disease, often starting with a high fever and chills. Some symptoms of babesiosis can be very low blood pressure, liver problems, severe hemolytic anemia (a breakdown of red blood cells), and kidney failure.

Common symptoms include

  • Fatigue
  • Headache
  • Drenching sweats
  • Muscle aches
  • Nausea
  • Vomiting


When babesiosis is suspected, a microscopic blood cell examination can determine whether or not the parasite is present, however this method is only reliable in the first two weeks of infection and at certain points in the lifecycle of the parasite.

Currently, commercial tests identify only two species of North American Babesia (Babesia microti and B. duncani), and yet Babesia divergens-like infection has also been seen in North America. In Europe, human infections can be due to other species of Babesia such as B. divergens and B. venatorum.

It may be necessary to run several tests, so a single negative test result does not necessarily rule out infection.


  1. The PCR (polymerase chain reaction) test can be used to detect Babesia DNA in the blood.
  2. There are also some tests that can determine whether antibodies against Babesia are present in the blood.


Babesiosis is usually treated with a combination of two types of anti-parasite drugs:

  1. Atovaquone (Mepron, Malarone)
  2. Erythromycin-type drug (azithromycin, clarithromycin, or telithromycin)

Long-standing infections may require treatment for several months; relapses sometimes occur and should be retreated.

Ehrlichiosis / Anaplasmosis

Ehrlichiosis is caused by various types of Ehrlichia and Anaplasmosis is caused by Anaplasma phagocytophilum.

Ehrlichiosis was formerly called HME, human monocytic ehrlichiosis and Anaplasmosis used to be called HGE, human granulocytic ehrlichiosis.

Some studies suggest that, in endemic areas, as many as 15 – 36% of the human population has been infected, although many people may not be aware that they are infected


The severity of the disease can range from mild to life threatening. Severely ill patients can have low white blood cell count, low platelet count, anemia, elevated liver enzymes, kidney failure and respiratory insufficiency. Older people or people with immune suppression are more likely to require hospitalization.

Common symptoms include:

  • Sudden high fever
  • Fatigue
  • Muscle aches
  • Headache


Diagnosing ehrlichiosis is difficult because currently available tests can identify only two species of the parasite. Ehrlichia parasites multiply inside host cells, forming large mulberry-shaped clusters called “morulae”, which can sometimes be seen in a blood sample, but the infection still can be missed. Diagnosis of Anaplasmosis is usually by PCR of the bacterium in the blood.

Doctors sometimes identify and diagnose ehrlichiosis / anaplasmosis when patients don’t respond well to treatment for Lyme disease.


The treatment of choice for ehrlichiosis / anaplasmosis is doxycycline, with rifampin recommended in case of treatment failure.

Ehrlichia Review Paper (Hotopp et al 2006)


Bartonella are bacteria that live inside cells that can infect humans and a wide range of other animals. Not all Bartonella species cause disease in humans. It is mainly carried by cats and causes cat-scratch disease, endocarditis, and several other serious diseases in humans.

Fleas, body lice and ticks carry Bartonella. Scientists suspect that only ticks can transmit the infection to humans; however, more research is needed to establish the role of ticks in spreading the disease.

Early Symptoms include:

  • Fever
  • Fatigue
  • Headache
  • Poor appetite
  • An unusual looking streaked rash
  • Swollen glands (especially around the head, neck and arms)
  • Lower abdominal pain
  • Enlarged lymph nodes
  • Sore throat


Diagnosing Bartonella infection is difficult. Polymerase Chain Reaction (PCR) tests, standard blood tests and tissue biopsies can be used, although false negatives can be a problem .


Erythromycin and doxycycline have both been used successfully, but experts recommend treating adults with levofloxacin or azithromycin for children under 18.

Bartonella Review Paper (Florin et al 2008)

Other Tick-Borne Diseases

In addition to the above diseases, ticks in different geographic areas may be infected with  the pathogen responsible for one or more of the following: Colorado Tick Fever; Mycoplasmas; Powassan virus; Q Fever; Rocky Mountain Spotted Fever (Rickettsia); Tick-borne Relapsing Fever; Tularemia.


Colorado Tick Fever is caused by a virus transmitted by Rocky Mountain wood ticks.

Symptoms may include:  acute high fever, severe headache, chills, fatigue, and muscle pain.


Mycoplasma species have been identified in ticks. Smaller than bacteria, Mycoplasma invade human cells and disrupt the immune system. Mycoplasma can be treated with antibiotics.

Symptoms may include: fatigue, musculoskeletal symptoms, and cognitive problems.


The Powassan virus causes tick-borne encephalitis (TBE). Ten percent of infected patients die, and survivors may suffer permanent damage.

Symptoms may include: fever, convulsions, headache, disorientation, lethargy, partial coma and paralysis.


Q Fever is caused by Coxiella burnetii, a kind of bacteria carried by cattle, sheep, and goats. Doxycycline is the treatment of choice.

Symptoms may include: high fever, pneumonia, and abnormal liver function.


Rocky Mountain Spotted Fever is caused by bacteria called Rickettsia rickettsii. The disease is treatable with antibiotics (often doxycycline); however, 30% of untreated patients die.

Symptoms may include: high fever, rash, headache, and bleeding problems.


Certain ticks secrete a toxin that causes a progressive paralysis, which is reversed when the tick is removed. In Canada, Dermacentor andersoni (Rocky Mountain wood tick) is most commonly associated with this condition.


Tick-borne Relapsing Fever is caused by the bacterium, Borrelia hermsii, and is carried by the so-called ‘soft ticks’ of the western United States and BC. It is characterized by cycles of high fever; it is treated with antibiotics.


Tularemia, or rabbit fever, is caused by bacteria called Francisella tularensis, and occurs throughout the United States. The most effective treatment is with fluorinated quinolones.

Symptoms may include: skin ulcers, swollen and painful lymph glands, inflamed eyes, sore throat, mouth sores, pneumonia, diarrhea and vomiting.