8 Most Common Diseases Spread By Ticks

According to the Centers For Disease Control And Prevention (CDC), ticks in the U.S carry many known tick borne diseases. Lyme disease and Rocky Mountain Spotted Fever being the best known. Below you will learn about the 8 of the most common diseases.

Lyme Disease

Lyme disease is most frequently reported from the Upper Midwestern and northeastern United States and is spread by the Blacklegged Tick. Some cases are also reported in northern California, Oregon, and Washington. In 2015, 95% of Lyme disease cases were reported from 14 states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, and Wisconsin. The incubation period is between 3-30 days. The symptoms during the early stage of Lyme Disease are Erythema migrans (EM)—red ring-like or homogenous expanding rash; classic rash not present in all cases. Flu-like symptoms—malaise, headache, fever, myalgia, arthralgia and Lymphadenopathy. During the localized (early) stage of illness, Lyme disease may be diagnosed clinically in patients who present with an EM rash. Serologic tests may be insensitive at this stage. During disseminated disease, however, serologic tests should be positive.

Rocky Mountain Spotted Fever (RMSF)

RMSF is most often transmitted by the American dog tick in the Eastern, Central and Western United States; by the Rocky Mountain wood tick in the Rocky Mountain states; and by the brown dog tick in the Southwestern United States, along the U.S.-Mexico border. RMSF can be rapidly fatal if not treated within the first 5 days of symptoms. Before tetracycline antibiotics were available, case fatality rates ranged from 20–80%. Although RMSF cases have been reported throughout most of the contiguous United States, five states (North Carolina, Oklahoma, Arkansas, Tennessee, and Missouri) account for over 60% of RMSF cases. The incubation period is between 3–12 days. The symptoms High fever during the first four days are Severe headache, Malaise, Myalgia, Edema around eyes and on the back of hands, Gastrointestinal symptoms (nausea, vomiting, anorexia). After the initial four have passed the symptoms are Altered mental status, coma, cerebral edema, Respiratory compromise (pulmonary edema, ARDS), Necrosis, requiring amputation and Multiorgan system damage (CNS, renal failure).

Rickettsia Parkeri Rickettsiosis

R. parkeri is closely related to R. rickettsii, the causative agent of Rocky Mountain spotted fever (RMSF). R. parkeri rickettsiosis and RMSF have similar signs and symptoms, including fever, headache, and rash, but also typically include the appearance of an inoculation eschar (seen at right) at the site of tick attachment. Eschar is not common in cases of RMSF. R. parkeri rickettsiosis is transmitted by Gulf Coast ticks in the southeastern and mid-Atlantic states, as well as parts of southern Arizona. The incubation period is between 2–10 days. R. parkeri rickettsiosis is characteristically less severe than RMSF and almost always associated with an inoculation eschar (ulcerated, necrotic lesion) at the site of tick attachment. Several days after an eschar appears, the following can develop: Fever, Headache, Rash (sparse maculopapular or papulovesicular eruptions on the trunk and extremities) and Muscle aches.

Tickborne Relapsing Fever

TBRF occurs most commonly in 14 western states: Arizona, California, Colorado, Idaho, Kansas, Montana, Nevada, New Mexico, Oklahoma, Oregon, Texas, Utah, Washington, and Wyoming. Most cases occur in the summer when people vacation and sleep in rustic cabins. However, TBRF can also occur in the winter months when fires started to warm a cabin activate ticks resting in the walls and woodwork. In Texas, TBRF may be associated with cave exposure. The incubation period is 7 days, followed by recurring febrile episodes that last ~3 days and are separated by afebrile periods of ~7 days. The symptoms include Headache, Myalgia, Chills, Nausea, vomiting, Arthralgia and Facial palsy (rarely).


Naturally occurring tularemia infections have been reported from all states except Hawaii. Ticks that transmit tularemia to humans include the dog tick (Dermacentor variabilis), the wood tick (D. andersoni), and the lone star tick (Amblyomma americanum). Other transmission routes include deer fly bite, inhalation, ingestion, and through skin contact with infected animals. The incubation period is between 3–5 days (range 1–21 days). The symptoms include Fever, chills, Headache, Malaise, fatigue, Anorexia, Myalgia, Chest discomfort, cough, Sore throat, Vomiting, diarrhea and Abdominal pain. (Ulcero) Glandular: Localized lymphadenopathy, Cutaneous ulcer at infection site (not always present). Oculoglandular: Photophobia, Excessive lacrimation, Conjunctivitis, Preauricular, submandibular and cervical lymphadenopathy. Oropharyngeal: Severe throat pain, Exudative pharyngitis or tonsillitis, Cervical, preparotid, and/or retropharyngeal lymphadenopathy. Pneumonic: Non-productive cough, Substernal tightness, Pleuritic chest pain, Hilar adenopathy, infiltrate, or pleural effusion may be present on chest X-ray. Typhoidal: Characterized by any combination of the general symptoms (without localizing symptoms of other syndromes).


Babesiosis is caused by parasites that infect red blood cells. Most U.S. cases are caused by B. microti, which is transmitted by Ixodes scapularis ticks, primarily in the Northeast and Upper Midwest. Babesia parasites also can be transmitted via transfusion, anywhere, at any time of the year. Babesia infection can range from asymptomatic to life threatening. Risk factors for severe babesiosis include asplenia, advanced age, and impaired immune function. Severe cases can be associated with marked thrombocytopenia, disseminated intravascular coagulation, hemodynamic instability, acute respiratory distress, renal failure, hepatic compromise, altered mental status, and death. The incubation period is between 1–9+ weeks. The symptoms include Fever, chills, sweats, Malaise, fatigue, Myalgia, arthralgia, headache, Gastrointestinal symptoms, such as anorexia and nausea (less common: abdominal pain, vomiting), Dark urine. The less common symptoms are: cough, sore throat, emotional lability, depression, photophobia, conjunctival injection, Mild splenomegaly, mild hepatomegaly, or jaundice may occur in some patients.

Colorado Tick Fever

The geographic range of Colorado tick fever virus includes the Western United States, primarily Colorado, Utah, Montana, and Wyoming. Although rare, the virus can also be transmitted from person-to-person via blood transfusion. The incubation period is between 1–14 days. The symptoms are Fever, chills, headache, myalgias, and lethargy
~50% of patients have a biphasic illness with symptoms remitting after 2 to 4 days, but then recurring 1 to 3 days later. Conjunctival injection, pharyngeal erythema and lymphadenopathy may be present. Maculopapular or petechial rash in <20% of patients. Prolonged convalescence characterized by weakness and fatigue is common in adults. Life-threatening complications and death are rare and usually associated with disseminated intravascular coagulation or meningoencephalitis in children.

Heartland and Bourbon Virus Diseases

As of 2017, more than 30 cases of Heartland virus disease have been reported from states in the Midwest and the South. The incubation period for this disease is unknown; most patients report a tick bite in the 2 weeks prior to illness. The symptoms include Fever, Fatigue, Decreased appetite, Headache, Arthralgia, Myalgia, Nausea and Diarrhea.

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