The Role of Co-infections

Ticks can harbor multiple infectious organisms, which can be transmitted through the same tick bite. While Lyme disease is the most common vector-borne illness in the country, other diseases are increasingly being reported.

Co-infections can be challenging to diagnose

Co-infections can be challenging to diagnose

Co-infections can be challenging to diagnose, as clinical features often overlap with many of the other tick-borne diseases, including Lyme disease. However, the importance of identifying and treating polymicrobial infections is critical in getting a patient well.

Practitioners should consider co-infections in the diagnosis when a patient’s symptoms are severe, persistent, and resistant to antibiotic therapy. Physicians have found that co-infections typically exacerbate Lyme disease symptoms.

Several of the most common tick-borne infections are described below. The list is not all-inclusive, as new diseases continue to be discovered.


There are over 100 known species of Babesia.

There are over 100 known species of Babesia.

There are over 100 known species of Babesia, a parasite, but only a few warrant concern for humans. Most cases involve Babesia microti and Babesia duncani. The severity of Babesiosis infections can vary.

Some individuals can present with flu-like symptoms, which include irregular fevers, chills, sweats, lethargy, headaches, nausea, body aches and fatigue. The disease can cause a specific type of anemia, called hemolytic anemia, since the parasites infect and destroy red blood cells.

The organism can be transmitted by tick bites or through contaminated blood transfusions. Babesiosis is treated with a combination of anti-malaria medications and antibiotics. The disease can be life-threatening to patients with weakened immune systems and the elderly.


Ehrlichiosis is a tick-borne bacterial infection that kills white blood cells. The infection is caused primarily by Ehrlichia chaffeenis. Several other species have been shown to cause infections in humans, as well.

While some patients are asymptomatic, others experience flu-like symptoms, such as fatigue, fevers, headaches, and muscle aches. If left untreated, Ehrlichiosis can become severe and require hospitalization.


Anaplasmosis is caused by the bacterium Anaplasma phagocytophilum. Clinical presentations are similar to Ehrlichiosis but the causative agents are different. Symptoms can be non-specific, but typical symptoms include headaches, fever, chills, malaise and muscle aches.

Anaplasmosis was previously known as Human Granulocytic Ehrlichiosis, or HGE. The disease can be difficult to distinguish from Ehrlichiosis, Lyme disease, and other tick-borne illnesses.


Bartonella bacteria can cause several diseases in humans.

Bartonella bacteria can cause several diseases in humans.

The Bartonella bacteria can cause several diseases in humans. Studies have focused primarily on “cat scratch fever,” caused by Bartonella henselae. This disease is transmitted through a flea bite or cat scratch/bite. However, various Bartonella species have been found in ticks. Species have been identified in Black-legged ticks in northern New Jersey and in Western Black-legged ticks in California.

Several studies found that symptoms were more severe in patients who were infected with both Borrelia burdorferi and Bartonella henselae. Some patients present with a streak-mark rash. The underlying cause of the rash needs further study. Early symptoms usually include: fever, fatigue, headaches, and swollen glands.

Southern Tick-Associated Rash Illness (STARI)

Southern tick-associated rash illness (STARI) is an emerging tick-borne illness related to Lyme disease and was identified in the southeastern and south-central United States. It is sometimes referred to as the Masters disease. STARI is believed to be transmitted by the Lone Star tick. The causative agent has not been clearly identified, and there are no commercial tests available.

The hallmark sign of STARI is an EM-like rash, similar to that seen in Lyme disease. Individuals may also experience fevers, headaches, stiff neck, joint pain and fatigue. The long-term consequences of the illness are unknown.

Other tick-borne diseases include: Rocky Mountain Spotted Fever, Colorado Tick Fever, Powassan Virus, Borrelia miyamotoi and Rickettsiosis.

What Is Lyme Disease?

What Is Lyme Disease?

Lyme disease is a bacterial infection typically transmitted through the bite of an infected tick. It is one of the fastest growing infectious diseases in the country, and the steadily increasing number of cases has led many in the medical/scientific community and legislative arena to deem the disease a “public health crisis” and “epidemic”. learn more →

Lyme Disease Signs and Symptoms

Signs and Symptoms

Lyme disease has been associated with numerous neurologic, rheumatologic and psychiatric manifestations. However, the full range of symptoms needed to recognize the disease may not be apparent to a physician during a routine examination. learn more →

About Ticks

About Ticks

Ticks are tiny parasites that feed on the blood of their hosts (humans and animals) in order to survive and advance to the next life cycle stage. Most ticks have four stages: egg, larva, nymph and adult. The larva and nymph need a blood meal to move to the next stage. Ticks are extremely small, with the nymph the size of a pinhead. learn more →