While Lyme disease is the most common tick-borne infection in Delaware, there are other tick-associated diseases to be aware of in case you suffer a tick bite.

This page lists the most common tick-associated infections found in Delaware, with information about which ticks in Delaware can cause which health issues, and with links to the website of the Centers for Disease Control and Prevention for more information.

Health care providers may conduct diagnostic testing to determine if you have been infected with a tick-borne pathogen. Alternatively, they may choose to diagnose based on your symptoms and exposure (e.g., taking into consideration the time of year, geographic location, and if you had a known tick bite), without testing.

Most tick-associated illnesses can be easily treated, however, a delay in diagnosis or treatment can lead to more severe illness that is more difficult to treat.

Lyme Disease (Borreliosis)

Lyme disease is the most common tick-borne infection in Delaware and in North America.  In 2024, there were 344 confirmed cases of Lyme disease in Delaware.

The causative agent is Borrelia burgdorferi bacteria. It is carried by the blacklegged or deer tick (Ixodes scapularis).

Clinical signs and symptoms may include fever, aches, fatigue, and a distinctive rash (pictured). More serious symptoms can result from delayed or inadequate treatment.

Learn more about lyme disease from the Delaware Division of Public Health.

Ehrlichiosis

Ehrlichiosis is caused by infection with bacteria in the genus Ehrlichia. In 2024, there were 26 reported cases of ehrlichiosis in Delaware.

The main vector of Ehrlichia bacteria in Delaware is the lone star tick (Amblyomma americanum).

Clinical signs and symptoms may include fever, aches, gastrointestinal upset, and a rash.

Anaplasmosis

Anaplasmosis is caused by infection with Anaplasma phagocytophilum bacteria. In 2024, there were 5 reported cases of anaplasmosis in Delaware.

These bacteria are transmitted by the bite of a blacklegged/deer tick (Ixodes scapularis).

Clinical signs and symptoms may include fever, aches, and gastrointestinal upset.

Babesiosis

Babesiosis is caused by infection with Babesia microti. Unlike the tick-borne pathogens above, this pathogen is not bacterial, but a protozoan parasite (similar to the causative agent of malaria). In 2024, there were 6 confirmed cases of babesiosis in Delaware.

These parasites are carried by the blacklegged/deer tick, (Ixodes scapularis).

Clinical signs and symptoms may include fever, aches, nausea, and fatigue.

Spotted Fever Group Rickettsioses

Bacteria in the genus Rickettsia cause Rocky Mountain spotted fever, Tidewater spotted fever, and closely related illnesses. In 2024, there was 1 reported case of spotted fever rickettsiosis in Delaware.

American dog ticks (Dermacentor variabilis) transmit Rickettsia rickettsii, the agent of Rocky Mountain spotted fever.

Gulf Coast ticks (Amblyomma maculatum) transmit Rickettsia parkeri, the agent of Tidewater spotted fever.

Clinical signs and symptoms include fever, aches, gastrointestinal upset, and a rash.

Alpha-Gal Syndrome (Mammalian meat allergy)

Unlike the other diseases on this list, alpha-gal syndrome or mammalian meat allergy is not caused by a pathogen or an infectious agent.

It is a condition that begins with the bite of a tick, which triggers an immune reaction to subsequent ingestion of mammalian meat (e.g., beef, pork, lamb, venison) and related products (e.g., dairy, gelatin). In 2024, there were 119 reported cases of alpha-gal syndrome in Delaware.

The lone star tick (Amblyomma americanum) is the main species associated with alpha-gal syndrome in the United States, but it is possible that other tick species are involved. 

Not everyone who is bitten by a lone star tick will develop this allergy.

Signs and symptoms of alpha-gal syndrome may include rash, hives, itchiness gastrointestinal upset, joint pain and dizziness. Reactions may be delayed and typically occur two to eight hours after ingesting mammalian meat products.

It is important that alpha-gal syndrome patients avoid future tick bites, as additional tick bites can lead to increased reactivity to mammalian meat products. And avoiding tick bites can lead to reduced reactivity to these products over time.

Tularemia

Tularemia is caused by infection with Francisella tularensis bacteria. There have been no reported cases of tularemia in Delaware in recent years.

The main vectors of tularemia in Delaware are the American dog tick (Dermacentor variabilis) and the lone star tick (Amblyomma americanum).

Clinical signs and symptoms include fever, skin ulcers, and swelling of lymph glands.

Powassan Virus (Deer tick virus)

Powassan virus is a virus transmitted by blacklegged/deer ticks (Ixodes scapularis) and groundhog ticks (Ixodes cookei). The virus can be transmitted from the tick to the patient in as little as 15 minutes of attachment. There have been no reported cases of Powassan virus in Delaware to date.

Signs and symptoms of Powassan virus can include fever, headaches, confusion, and seizures. There is no specific treatment for Powassan virus. 

Tick-borne Relapsing Fever

Tick-borne relapsing fever is caused by infection with Borrelia miyamotoi bacteria. 

These bacteria are transmitted by the bite of a blacklegged/deer tick (Ixodes scapularis). 

Signs and symptoms of tick-borne relapsing fever can include headache, fever, fatigue, nausea, muscle and joint aches. 

Related Topics:  dfw, disease, fish and wildlife, Health and Safety, lyme, tick