NELAD: What Are Co-Infections?

One of the reasons that diagnosing Lyme and tick borne/vector borne diseases is very difficult, is the common presence of co-infections and “associated diseases”. Because co-infections involve more than one pathogen infecting the same individual, diagnostic tests must try to target all possible pathogens, in order to give an accurate diagnosis, and to assist with individualizing the most effective treatment options.

The term “Lyme disease co-infection” typically describes when a patient is infected with Lyme disease, along with one or more of the other tick-borne/vector borne diseases that are commonly transmitted by ticks and other bugs that spread Lyme (Borrelia burgdorferi). Lyme disease co-infections seem to be more common than single infections. 

Co-infections are medically significant well beyond tick-borne diseases. For example, a common co-infection of HIV is Hepatitis. 

There is often a misunderstanding when people hear “Lyme Disease co-infections.” They assume that Lyme has to be present to be infected with any of the co-infections. This is not true. In fact, a more accurate description would be “tick-borne disease” co-infections. Therefore, it is possible to be infected with any one or more of the pathogens ticks carry. You could be infected with Babesia, for example, without getting Lyme, or contract TBRF( Tick Borne Relapsing Fever) Borrelia and Babesia, without Lyme.

Studies indicate that tick-borne disease co-infections are more common than single infections.In a 2017 survey, LymeDisease.org profiled 3,000 chronic Lyme disease patients and found that over half of them reported laboratory-confirmed co-infections, and 30% of those surveyed, reported two or more co-infections.

It is very common for a single tick to be carrying several different pathogen species. The LymeDisease.org cited above reports that a study in France found that every tick sampled carried at least one other microorganismthat can affect transmission of disease, and 45% were carrying up to five different pathogens. With ticks able to carry so many pathogens, it’s no surprise that co-infections might be “the rule” and not the exception. 

According to Lymedisease.org, the most common Lyme disease co-infections are reported in the following order from most to least common:

1. Babesia: A parasite spread by ticks that causes a disease similar to malaria

2. Bartonella: The bacteria that causes Cat Scratch Disease (also called cat scratch fever)

3. Ehrlichia: A group of at least three sub-species that cause disease (Ehrlichiosis) in the U.S.

4. Rickettsia rickettsii: The bacteria that causes Rocky Mountain Spotted Fever, the deadliest tick-borne disease in the world

5. Anaplasma: A bacteria causing Anaplasmosis, with a sub-species in the U.S. and another in China

It is also possible to be co-infected with the potentially fatal Powassan virus. Finally, while more data is needed, it should be noted that there is one species of Borrelia that causes Tick-Borne Relapsing Fever – Borrelia miyamotoi – that is spread by blacklegged ticks, the same ticks that spread Lyme disease. As such, doctors who suspect a patient may be infected with Lyme disease should also consider testing for Tick-Borne Relapsing Fever.

The presence of co-infectionsand associated diseases can significantly complicate the diagnostic and treatment process. Each co-infection needs to be tested for, diagnosed, and treated on its own. If you are diagnosed with, and treated for Lyme disease, but have a co-infection or multiple co-infections that were not detected because your doctor did not test for them, the Lyme treatment will not resolve the other infections. It is not uncommon for patients to undergo treatment for one tick-borne disease, only to have persistent symptoms related to a co-infection that was never diagnosed. 

When testing for Lyme disease, it is crucial that physicians consider and test for possible co-infections. Untreated or undertreated tick-borne diseases can take a major toll on one’s health and finances, and in some cases – for example, with Rocky Mountain Spotted Fever or Powassan Virus –can be deadly. Additionally, because pathogens can interact with each other within the human they’ve infected, there is evidence that co-infections can cause more severe symptoms and longer recovery periods.

While this information focuses on the most common tick that carries Borrelia burgdorferi, the black-legged tick, it is important to keep in mind that there are many species of ticks and they all carry pathogens that cause disease.

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