Scientists recognize more than a dozen tick borne diseases in the United States and new ones are still being discovered.

introduction to co-infections

One tick may carry more than one disease, so sometimes people get more than one co-infection from the bite of a single tick. The symptoms of these co-infections are often non-specific - such as fever and headache - which makes diagnosis difficult. An the treatments may be different. Doxycycline, for example, works for Lyme Disease and Ehrlichiosis, but is not effective for Babesiosis. 

Experienced doctors may be able to distinguish each of the tick-borne co-infections and order appropriate tests and treatment. Sometimes they start to suspect a co-infection when the patient doesn't respond well to treatment and it becomes obvious that something else is causing the symptoms. Co-infections generally result in more severe illness, more symptoms, and a longer recovery. 

Ticks in different geographic areas may be infected with one or more of the following: Colorado tick fever virus; Mycoplasmas; Powassan encephalitis virus; Q Fever; Rocky Mountain spotted fever (Rickettsia); tickborne relapsing fever Borrelia; Tularemia (bacteria); Babesiosis; Bartonella. The Tick Chart tells where these diseases are found.

It is certain that we have not yet identified all the diseases that ticks carry and transmit. Coinfections complicate diagnosis and treatment and make recovery even more difficult. Doctors may suspect coinfections in patients who do not respond satisfactorily to antibiotics prescribed for Lyme disease.

There are other possible explanations for treatment failures. People with chronic tickborne infections often have a weakened immune response. This allows other opportunistic infections to flourish, such as HHV-6, CMV, and EBV. These diseases are not necessarily carried by ticks but are widespread in the environment. PCR rather than antibody tests should be used to diagnose these infections. Some people may also have exposure to toxic metals. Specialists should evaluate these cases.