Lyme Disease is the most common vector-borne illness in the United States.  However, ticks also carry many other bacterial, protozoal, viral and parasitic infections that can be transmitted through the same tick bite.  These co-infections “can complicate the treatment and management of the primary infection and lead to a longer-lasting, more devastating illness,” according to Dr. Daniel Cameron, President of ILADS.  Co-infections may be difficult to diagnose because many of the co-infection symptoms are often attributed to Lyme Disease.  Dr. Joseph Burrascano Jr., board member of the International Lyme and Associated Diseases Society (ILADS) stresses that the “diagnoses of tick-born co-infections remains a clinical one,”  based on signs and symptoms and a history of exposure to blacklegged ticks.

Babesiosis:  caused by a parasite that infects the red blood cells.  The organism can be transmitted through a tick bite or contaminated blood transfusion.  Symptoms are often flu-like and include high fever, irregular fevers, chills, sweats, lethargy, headaches, nausea, body aches and fatigue.  The disease may also cause a specific type of anemia, called hemolytic anemia, since the parasites infect and destroy red blood cells.

Bartonella:  caused by a bacteria carried by fleas, body lice and ticks.  Early symptoms usually include fever, fatigue, headaches,  swollen glands, enlarged lymph nodes and sore throat.  Some patients may present with a streak-mark rash, which has the appearance of stretch marks.  Other key symptoms may include insomnia, seizures, encephalitis, gastritis, lower abdominal pain, and sore soles of the feet.

Ehrlichiosis:  caused by a parasite that infects and kills white blood cells.  Many patients experience flu-like symptoms such as fatigue, fevers, headaches and muscle aches.  More severe symptoms may include vomiting, confusion, anemia, decreased white blood cells, seizures, encephalopathy, meningitis, elevated liver enzymes and even death.

Anaplasmosis:  caused by a bacterial infection and shares the same symptoms as Ehrlichiosis.

STARI (southern tick-associated rash illness):  a Lyme-like disease believed to be transmitted by the Lone Star tick.  However, the causative agent has not been clearly identified and there is no commercial test available.  Symptoms may include a rash (similar to those seen in Lyme Disease), fevers, headaches, stiff neck, joint pain and fatigue.

Powassan Virus:  caused by a flavi virus.  Common symptoms include fever, headache, nausea, vomiting, stiff neck, sleepiness and weakness.  More severe symptoms may include confusion, seizures, memory loss, encephalitis and long-term neurologic problems.

Tularemia:  caused by a bacterial infection.  Symptoms may include headaches , chills,  skin ulcers, swollen lymph nodes, inflamed eyes, sore throat, mouth sores, pneumonia, diarrhea and vomiting.

Other tick-borne co-infections include Colorado Tick Fever, Tick-borne Relapsing Fever, Q Fever, Rocky Mountain Spotted Fever and Tick Paralysis.  This list is not all-inclusive as new tick-borne diseases continue to be discovered.