The incidence of tickborne infections in the United States has risen significantly within the past decade. Due to this increase, it is becoming more important that public health officials and scientists improve their understanding of pathogenesis, design improved diagnostics, and develop preventive vaccines for tickborne illnesses.

Tickborne diseases are becoming a serious problem in this country as people increasingly build homes in formerly uninhabited wilderness areas where ticks and their animal hosts live. Tickborne diseases can be caused by viruses, bacteria, or parasites. Most people become infected through tick bites during the spring and summer months.

BLACKLEGGED TICKIxodes scapularis
WHERE FOUND Widely distributed across the eastern United States.
TRANSMITSBorrelia burgdorferi and B. mayonii (which cause Lyme disease), Anaplasma phagocytophilum (anaplasmosis), B. miyamotoi disease (a form of relapsing fever), Ehrlichia muris eauclairensis (ehrlichiosis), Babesia microti (babesiosis), and Powassan virus (Powassan virus disease).
COMMENTS The greatest risk of being bitten exists in the spring, summer, and fall in the Northeast, Upper Midwest and mid-Atlantic. However, adult ticks may be out searching for a host any time winter temperatures are above freezing. All life stages bite humans, but nymphs and adult females are most commonly found on people.

LONE STAR TICKAmblyomma americanum
WHERE FOUND Widely distributed in the eastern United States, but more common in the South.
TRANSMITSEhrlichia chaffeensis and E. ewingii (which cause human ehrlichiosis), Francisella tularensis (tularemia), Heartland virus (Heartland virus disease), Bourbon virus (Bourbon virus disease), and Southern tick-associated rash illness (STARI).
COMMENTS The greatest risk of being bitten exists in early spring through late fall. A very aggressive tick that bites humans. The adult female is distinguished by a white dot or “lone star” on her back. The nymph and adult females most frequently bite humans. Growing evidence suggests that alpha-gal syndrome (AGS) may be triggered by the bite of lone star ticks; however, other tick species have not been ruled out.

AMERICAN DOG TICKDermacentor variabilis, D. similis
WHERE FOUND D. variabilis is widely distributed east of the Rocky Mountains. Newly described D. similis is found west of the Rocky Mountains. More research is needed to understand the role of these species in disease transmission.
TRANSMITSFrancisella tularensis (tularemia) and Rickettsia rickettsii (Rocky Mountain spotted fever).
COMMENTS The greatest risk of being bitten occurs during spring and summer. Adult females are most likely to bite humans.

BROWN DOG TICKRhipicephalus sanguineus
WHERE FOUND Worldwide.
TRANSMITSRickettsia rickettsii (Rocky Mountain spotted fever). Primary vector for R. rickettsii transmission in the southwestern United States and along the U.S.-Mexico border.
COMMENTS Dogs are the primary host for the brown dog tick in each of its life stages, but the tick may also bite humans or other mammals.

GROUNDHOG TICKIxodes cookei
WHERE FOUND Throughout the eastern half of the United States.
TRANSMITS Powassan virus (Powassan virus disease).
COMMENTS Also called woodchuck ticks. All life stages feed on a variety of warm-blooded animals, including groundhogs, skunks, squirrels, raccoons, foxes, weasels, and occasionally people and domestic animals. Photo courtesy of Steve Jacobs, PSU Entomology

GULF COAST TICKAmblyomma maculatum
WHERE FOUND Distributed primarily in the southeastern United States, with focal populations in the northeastern, midwestern, and southeastern United States.
TRANSMITSR. parkeri (R. parkeri rickettsiosis), a form of spotted fever.
COMMENTS Larvae and nymphs feed on birds and small rodents, while adult ticks feed on deer and other wildlife. Adult ticks have been associated with transmission of R. parkeri to humans.

ROCKY MOUNTAIN WOOD TICKDermacentor andersoni
WHERE FOUND Rocky Mountain states.
TRANSMITSRickettsia rickettsii (Rocky Mountain spotted fever), Colorado tick fever virus (Colorado tick fever), and Francisella tularensis (tularemia).
COMMENTS Adult ticks feed primarily on large mammals. Larvae and nymphs feed on small rodents. Adult ticks are primarily associated with pathogen transmission to humans.

SOFT TICKOrnithodoros spp.
WHERE FOUND Throughout the western half of the United States, including Texas.
TRANSMITSBorrelia hermsii, B. turicatae (tick-borne relapsing fever [TBRF]).
COMMENTS Humans typically come into contact with soft ticks in rustic cabins. The ticks emerge at night and feed briefly while people are sleeping. Most people are unaware that they have been bitten. In Texas, TBRF may be associated with cave exposure.
O. hermsi tick, before and after feeding. Photo taken by Gary Hettrick RML, NIAID.

WESTERN BLACKLEGGED TICKIxodes pacificus
WHERE FOUND In the Pacific Coast states.
TRANSMITSAnaplasma phagocytophilum (anaplasmosis), B. burgdorferi (Lyme disease), and very likely B. miyamotoi (Borrelia miyamotoi disease, a form of relapsing fever).
COMMENTS Larvae and nymphs often feed on lizards, birds, and rodents, and adults more commonly feed on deer. Although all life stages bite humans, nymphs and adult females are more often reported on humans.

Ticks That Commonly Bite Humans

When warm weather arrives, you might get the urge to walk barefoot through the grass. But before you stroll through your lawn or head out on a hiking trail, you’ll want to protect yourself and your loved ones from ticks that often lurk in tall grass, thick brush, and wooded areas. Many ticks carry disease, so do what you can to keep ticks from taking a bite out of you.

Tick-borne diseases are found in many areas across the country, and they’re on the rise. The diseases are often clustered in specific regions. Rocky Mountain spotted fever, for instance, occurs mainly in the mid-Atlantic and southern states.

Lyme disease is the most common tick-borne illness. It’s found mainly in the Northeast and upper Midwest. Each year, more than 30,000 cases are reported in the United States, and many more likely go unreported. The U.S. Centers for Disease Control and Prevention (CDC) estimates that as many as 300,000 Americans get Lyme disease each year.

Ticks are tiny 8-legged creatures that can be hard to see. Deer ticks—which can carry Borrelia burgdorferi, the bacterium that causes Lyme disease—are especially small. The young “nymphs” are only the size of poppy seeds. Adult deer ticks aren’t much larger—about the size of a sesame seed. If an infected deer tick chooses you for its next blood meal, that bite can transmit Lyme disease or another infection to you.

“Ticks can be so tiny that most people who get Lyme disease don’t recall a tick bite,” says Dr. Adriana Marques, a Lyme disease expert at NIH. But if you have symptoms of the disease, she says, “the earlier you get treated, the better.”

Tick-borne diseases tend to share certain symptoms. Symptoms can include fever, headache, muscle or joint pain, and extreme fatigue. People with Lyme disease usually get an expanding red rash that sometimes resembles a bull’s-eye. “The rash is usually tender, not painful or itchy, so people may not realize they’re sick,” says Marques.

If left untreated, the infection can spread and cause rashes in other parts of the body. Some people may develop nerve problems, arthritis, or other disorders. But even if Lyme disease isn’t caught until later stages, most people fully recover after treatment with antibiotics .

Of course, the best way to avoid Lyme and other tick-borne diseases is to prevent tick bites in the first place. Most bites from disease-causing ticks occur in the spring and summer months, when ticks are most active and when people are spending more time outside.

Help keep ticks off your skin by wearing long sleeves, long pants, and long socks. You can also ward off ticks by using an insect repellant that contains at least 20% DEET (for the skin) or permethrin (for clothes). To avoid ticks, walk in the center of trails and steer clear of tall vegetation.

If you’ve been in an area where ticks are common, bathe or shower as soon as possible, and wash or tumble your clothes in a dryer on high heat. Check your body carefully for ticks. They dig and burrow into the skin before they bite and feed. Removing ticks right away can help prevent disease. If you develop a rash or fever after removing a tick, see your doctor.

So watch out for ticks! Make a habit of tick prevention as you venture into the great outdoors.

To Remove a Tick

Promptly remove ticks to reduce the risk of tick-borne diseases.

• Use fine-tipped tweezers.
• Grab the tick close to the skin and gently pull upward to remove the entire tick.
• Don’t use home remedies like petroleum jelly, nail polish, or a lit match to try to detach ticks.
• After removing the tick, clean the bite area and wash your hands thoroughly.
• If you develop a fever, severe headaches, or a rash within weeks of removing the tick, see a doctor.

Researchers found that some people’s repeated, severe allergic reactions stemmed from a red meat allergy linked to a specific type of tick bite.

Doctors analyzed 70 patients who had repeated episodes of a severe allergic reaction, called anaphylaxis, from unknown causes. Anaphylaxis can cause a host of problems, such as trouble breathing and passing out. It requires immediate medical attention to prevent severe consequences, even death.

The researchers found that six of the patients had an allergy to a sugar molecule called alpha-gal, which is found in red meats. Most food allergy symptoms develop within a half hour. People with the alpha-gal allergy showed symptoms between three to six hours after eating meat.

Previous studies have linked lone star tick bites to this unusual food allergy. The patients with the alpha-gal allergy lived in the central and southern United States, where lone star ticks thrive. All six confirmed that they had been bitten by ticks in the past.

“Alpha-gal allergy appears to be yet another reason to protect oneself from tick bites,” says Dr. Anthony S. Fauci, director of NIH’s National Institute of Allergy and Infectious Diseases (NIAID).

Agent

Anaplasma phagocytophilum

Anaplasmosis was formerly known as Human Granulocytic Ehrlichiosis (HGE).

Severe and life-threatening illness is less common with anaplasmosis compared to other rickettsial diseases, such as Rocky Mountain spotted fever (RMSF) or E. chaffeensis ehrlichiosis. While the case-fatality rate among patients who seek care for the illness is 1%, predictors of a more severe course include advanced age, immunosuppression, comorbid medical conditions, and delay in diagnosis and treatment.

Where Found

Anaplasmosis is most frequently reported from the Upper Midwest and northeastern United States in areas that correspond with the known geographic distribution of Lyme disease and other Ixodes scapularis-transmitted diseases. Due to the common vector, co-infection with A. phagocytophilum and B. burgdorferi, Babesia microti, or Powassan virus is possible; illness may be marked by a more severe course or incomplete response to treatment.

A. phagocytophilum is typically transmitted by the bite of an infected tick but may also be associated with blood product transfusions or organ transplant.

Incubation Period

5–14 days

Signs and Symptoms

• Fever, chills, rigors
• Severe headache
• Malaise
• Myalgia
• Gastrointestinal symptoms (nausea, vomiting, diarrhea, anorexia)
• Rash (10%)

The Signs and Symptoms list presents symptoms commonly seen with anaplasmosis. However, it is important to note that few people will develop all symptoms and the number and combination of symptoms varies greatly from person to person.

General Laboratory Findings

Typically observed during the first week of clinical disease:

• Mild anemia
• Thrombocytopenia
• Leukopenia (characterized by relative and absolute lymphopenia and a left shift)
• Mild to moderate elevations in hepatic transaminases

Visualization of morulae in the cytoplasm of granulocytes during examination of blood smears is highly suggestive of a diagnosis; however, blood smear examination is insensitive and should never be relied upon solely to rule anaplasmosis in or out.

LABORATORY DIAGNOSIS

• Detection of DNA by PCR of whole blood. This method is most sensitive during the first week of illness; sensitivity may decrease after administration of tetracycline-class antibiotics.
• Demonstration of a four-fold rise in IgG-specific antibody titer by indirect immunofluorescence antibody (IFA) assay in paired serum samples. The first sample should be taken within the first 2 weeks of illness and the second should be taken 2 to 4 weeks later.
• Immunohistochemical (IHC) staining of organism from skin, tissue, or bone marrow biopsies.

NOTE: Antibody titers are frequently negative in the first 7–10 days of illness. Acute antibody results cannot independently be relied upon for confirmation.

NOTE: IgM antibodies are less specific than IgG antibodies and are more likely to generate false positives. IgM results alone should not be used for laboratory diagnosis.

Treatment

Anaplasmosis, ehrlichiosis, and spotted fever group rickettsioses are treated with doxycycline. Clinical suspicion of any of these diseases is sufficient to begin treatment. Delay in treatment may result in severe illness and even death. These regimens may need to be adjusted depending on a person’s age, medical history, underlying health conditions, pregnancy status, or allergies. Consult an infectious disease specialist in cases of pregnancy or life-threatening allergy to doxycycline.

NOTE: Use doxycycline as first-line treatment for suspected anaplasmosis in patients of all ages. The use of doxycycline to treat suspected anaplasmosis in children is recommended by both the CDC and the American Academy of Pediatrics Committee on Infectious Diseases. Use of antibiotics other than doxycycline increases the risk of patient death. At the recommended dose and duration needed to treat anaplasmosis, no evidence has been shown to cause staining of permanent teeth, even when multiple courses are given before the age of eight.

Agent

Babesia microti and other Babesia species

Babesiosis is a disease caused by parasites that infect red blood cells. Most U.S. cases are caused by B. microti, which is transmitted mainly by Ixodes scapularis ticks, primarily in the Northeast and Upper Midwest and sporadically on the West Coast. Babesia parasites can also be transmitted via blood transfusion, perinatally, and via organ transplantation, anywhere, at any time of year. In 2019, the FDA licensed tests for the detection of Babesia species to utilize for screening of donors and recommended year-round regional testing for blood donations in areas endemic for babesiosis. Babesia infection can range from asymptomatic to life-threatening. Risk factors for severe babesiosis include asplenia, advanced age (age >50), and impaired immune function.

Where Found

Babesiosis is most frequently reported from the Northeastern and Upper Midwestern United States in areas where microti is endemic; cases peak during spring and summer months. Sporadic cases of infection caused by novel Babesia agents have been detected in other U.S. regions, including the West Coast. Cases of babesiosis linked to B. divergens-like organisms have occurred in the Midwest region, Arkansas, Kentucky, Pennsylvania and Washington State. Cases linked to B. duncani have occurred on the West Coast of the United States. Transfusion-associated cases of babesiosis can occur anywhere in the country, at any time of year.

Incubation Period

1-4 weeks following tick bite; 1-9 weeks after contaminated blood transfusion (up to 24 weeks)

Signs and Symptoms

Not all infected persons are symptomatic or febrile (an estimated 25% of infected adults and 50% of children are asymptomatic). The clinical manifestations, if any, usually develop within several weeks after exposure, but may develop or recur months later (for example, in the context of surgical splenectomy).

• Fever, chills, sweats
• Malaise, fatigue
• Myalgia, arthralgia, headache
• Gastrointestinal symptoms, such as anorexia and nausea (less common: abdominal pain, vomiting)
• Dark urine
• Less common: dry cough, sore throat, photophobia, conjunctival injection
• Mild splenomegaly, mild hepatomegaly, or jaundice may occur in some patients
• 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.

General Laboratory Findings

Findings consistent with hemolysis include:

• Hemolytic anemia with decreased haptoglobin, elevated lactate dehydrogenase (LDH) values, and reticulocytosis
• Thrombocytopenia
• Elevated creatinine and blood urea nitrogen (BUN) values
• Mildly elevated hepatic transaminase values
• Proteinuria

Laboratory Diagnosis

• Identification of intraerythrocytic Babesia parasites by light-microscopic examination of a peripheral blood smear; or
• Positive Babesia (or B. microti) polymerase chain reaction (PCR) analysis; or
• Demonstration of a Babesia-specific antibody titer by indirect fluorescent antibody (IFA) testing for total immunoglobulin (Ig) or IgG

NOTE: If the diagnosis of babesiosis is being considered, manual (nonautomated) review of blood smears should be requested explicitly. In symptomatic patients with acute infection, Babesia parasites typically can be detected by blood-smear examination by experienced technicians, although multiple smears may need to be examined. It can be difficult to distinguish between Babesia and malaria parasites and even between parasites and artifacts (such as stain or platelet debris). Consider having a reference laboratory confirm the diagnosis, and if applicable, perform serologic or molecular testing to get a species-level identification.

NOTE: Antibody detection by serologic testing can provide supportive evidence for the diagnosis but does not reliably distinguish between active and prior infection.

Treatment

Treatment decisions and regimens should consider the patient’s age, clinical status, immunocompetence, splenic function, comorbidities, pregnancy status, other medications, and allergies. Expert consultation is recommended for persons who have or are at risk for severe or relapsing infection or who are at either extreme of age (e.g., >50 years of age or neonates).

The typical regimens for adults are provided in the table below. Note that some patients diagnosed with babesiosis may have concurrent Lyme disease, or anaplasmosis or may be infected with other pathogens transmitted by Ixodes scapularisin a region. For pediatric dosing and non- microti treatment recommendations please reference the Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA): 2020 Guideline on Diagnosis and Management of Babesiosis.

* The duration of therapy may be greater than 10 days for patients that are immunocompromised; highly immunocompromised patients may benefit from 6+ weeks.
** In immunocompromised adults, consider azithromycin doses of 500-1000 mg daily.
*** Patients with high-grade parasitemia (>10%), severe hemolytic anemia, or severe pulmonary, renal, or hepatic compromise may benefit from exchange transfusion. Expert consultation is strongly advised.
****Patients who fail to improve while on therapy with the preferred regimen or who are unable to take the preferred regimen should be treated with clindamycin and quinine.

NOTE: Most persons without clinical manifestations of infection do not require treatment unless parasites are seen on thin blood smear for >30 days.

Agent

Colorado tick fever virus

Where Found

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.

Incubation Period

1–14 days

Signs and Symptoms

• 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.

General Laboratory Findings

• Leukopenia
• Moderate thrombocytopenia

Laboratory Diagnosis

Preliminary diagnosis of Colorado tick fever (CTF) is based on signs and symptoms, places and dates of travel, activities, and history of potential tick exposure. Acute samples should be tested by reverse-transcriptase polymerase chain reaction (RT-PCR) to detect viral RNA as antibody production is delayed until 14–21 days after onset of symptoms.

Note: CSF, cerebrospinal fluid; CNS, central nervous system

*If possible, acute and convalescent samples, collected at least 2 weeks apart, with the convalescent sample collected at least 3 weeks after symptom onset, should be obtained to look for seroconversion or a 4-fold rise in antibody titers typically using a plaque reduction neutralization test (PRNT).

Note: CTF testing is available at some commercial and state health department laboratories and at CDC. Contact your state or local health department for assistance with diagnostic testing. CTF cases are reportable to local public health authorities in certain states.

Treatment

No specific antiviral treatment is available. Patients with suspected CTF should receive supportive care as appropriate. Patients with confirmed CTF should defer blood and bone marrow donation for at least 6 months after recovery.

Agents

Ehrlichia chaffeensis, Ehrlichia ewingii, Ehrlichia muris eauclairensis

E. chaffeensis can cause fatal illness, whereas no deaths have been reported for E. ewingii or E. muris euclairensis ehrlichiosis.

Incidence of E. chaffeensis enhrlichiosis generally increases with age, however, case-fatality rates are highest among children aged 10 years and adults aged ≥70 years.

Where Found

Ehrlichiosis is most frequently reported from the southeastern and south-central United States, from the East Coast extending westward to Texas. The areas from which most cases are reported correspond with the known geographic distribution of the lone star tick (Amblyomma americanum), which is associated with transmission of both E. chaffeensis and E. ewingii. In 2019, four states (Missouri, Arkansas, North Carolina, and New York) accounted for nearly half of all reported cases of E. chaffeensis ehrlichiosis. Since 2009, >115 cases of ehrlichiosis caused by E. muris eauclairensis have been identified in patients in the Upper Midwest. The tick responsible for transmitting this new subspecies of Ehrlichia is Ixodes scapularis, and the clinical presentation is generally similar to those associated with infections caused by E. chaffeensis and E. ewingii.

Incubation Period

5–14 days

Signs and Symptoms

• Fever, chills
• Headache
• Malaise
• Muscle pain
• Gastrointestinal symptoms (nausea, vomiting, diarrhea, anorexia)
• Altered mental status
• Rash (more commonly reported among children)

The Signs and Symptoms list presents symptoms commonly seen with ehrlichiosis. However, it is important to note that few people will develop all symptoms, and the number and combination of symptoms varies greatly from person to person.

General Laboratory Findings

Typically observed during the first week of clinical disease:

• Thrombocytopenia
• Leukopenia (absolute)
• Anemia (generally occurs later in illness than thrombocytopenia or leukopenia)
• Mild to moderate elevations in hepatic transaminases

During the acute stage of illness, morulae can be detected in about 20% of patients. E. chaffeensis most commonly infects monocytes, whereas E. ewingii more commonly infects granulocytes. The target cell of E. muris eauclairensis has not yet been identified. Visualization of morulae during examination of blood smears is highly suggestive of a diagnosis; however, blood smear examination is insensitive and should never be relied upon solely to rule ehrlichiosis in or out.

Laboratory Diagnosis

• Detection of DNA by PCR of whole blood. This method is most sensitive during the first week of illness and sensitivity can decrease after administration of tetracycline-class antibiotics.
• Demonstration of a four-fold rise in IgG-specific antibody titer by indirect immunofluorescence antibody (IFA) assay in paired serum samples. The first sample should be taken within the first 2 weeks of illness, and the second should be taken 2 to 4 weeks later.
• Immunohistochemical (IHC) staining of organism from skin, tissue, or bone marrow biopsies.

NOTE: Antibody titers are frequently negative in the first 7–10 days of illness. Acute antibody results cannot independently be relied upon for confirmation.

NOTE: IgM antibodies are less specific than IgG antibodies and are more likely to generate false positives. IgM results alone should not be used for laboratory diagnosis.

Treatment

Anaplasmosis, ehrlichiosis, and spotted fever group rickettsioses are treated with doxycycline. Clinical suspicion of any of these diseases is sufficient to begin treatment. Delay in treatment may result in severe illness and death. These regimens may need to be adjusted depending on a person’s age, medical history, underlying health conditions, pregnancy status, or allergies. Consult an infectious disease specialist in cases of pregnancy or life-threatening allergy to doxycycline.

NOTE: Use doxycycline as first-line treatment for suspected ehrlichiosis in patients of all ages. The use of doxycycline to treat suspected ehrlichiosis in children is recommended by both the CDC and the American Academy of Pediatrics Committee on Infectious Diseases. Use of antibiotics other than doxycycline increases the risk of patient death. At the recommended dose and duration needed to treat ehrlichiosis, no evidence has been shown to cause staining of permanent teeth, even when multiple courses are given before the age of eight.

Agent

Borrelia miyamotoi

Where Found

Occurs in the upper midwestern, northeastern, and mid-Atlantic states, where it is transmitted by Ixodes scapularis ticks, and in Pacific coastal states, where it is transmitted by I. pacificus ticks. Unlike Lyme disease, which most commonly occurs in June and July, hard tick relapsing fever occurs most commonly in July and August.

Incubation Period

3 days to 6 weeks, exact range unknown

Signs And Symptoms

Infection with B. miyamotoi most frequently presents as a self-resolving acute febrile illness, but the spectrum of illness varies from subclinical to severe. Severe manifestations (e.g., meningoencephalitis) appear to be more common in people with immunocompromising conditions. Symptoms may include:

• Fever
• Chills
• Relapsing fever (10-40% of cases)
• Fatigue
• Arthralgia/myalgia

General Laboratory Findings

• Leukopenia
• Thrombocytopenia
• Elevated hepatic transaminases
• Proteinuria

Laboratory Diagnosis

Diagnosis relies on signs and symptoms coupled with:

1. Polymerase chain reaction (PCR) assays that detect B. miyamotoi DNA in blood or cerebrospinal fluid; or
2. Serologic assays

Notably, serologic tests are most often negative during the acute presentation and are therefore of limited utility in diagnosis, though paired acute and convalescent tests can confirm a recent infection. Some serologic and PCR tests can cross-react with other Borrelia species, making travel and tick exposure history important to distinguish between these entities.

Treatment

There are no randomized controlled trials that evaluate treatment regimens, but in published case series, patients were successfully treated with antimicrobial regimens effective for Lyme disease. A 2-week course of doxycycline or amoxicillin is appropriate for outpatient treatment of most patients, including young children. For persons with severe illness requiring hospitalization (e.g., meningoencephalitis), IV antibiotics such as ceftriaxone are appropriate initial therapy. When treating patients with immunocompromising conditions for suspected B. miyamotoi infection, consultation with an infectious disease specialist is advised.

B. miyamotoi symptoms typically improve within 24-72 hours following administration of appropriate antibiotics. The Jarisch-Herxheimer reaction has been described in a minority of treated patients.

Agent

Heartland virus

Where Found

As of 2017, more than 50 cases of Heartland virus disease have been reported from states in the Midwest and the South.

Incubation Period

Specific ranges are unknown; most patients report a tick bite in the 2 weeks prior to illness.

Signs and Symptoms

• Fever
• Fatigue
• Decreased appetite
• Headache
• Arthralgia
• Myalgia
• Nausea
• Diarrhea

General Laboratory Findings

• Leukopenia
• Thrombocytopenia
• Mild to moderate elevation of hepatic transaminases

Bourbon Virus Disease

As of 2017, a limited number of Bourbon virus disease cases have been identified in the Midwest and southern United States. Some people who have been infected later died. Scientists continue to investigate possible symptoms caused by this new virus. Symptoms of people diagnosed with Bourbon virus disease included fever, tiredness, rash, headache, body aches, nausea, and vomiting. General laboratory findings included leukopenia and thrombocytopenia.

Laboratory Diagnosis

Molecular and serologic testing for Heartland virus infection can be performed at CDC. There are no commercially available tests for Heartland virus infection in the United States. Please contact your state health department if you have a patient with an acute illness that may be compatible with Heartland virus disease.

Treatment

Treatment of Heartland virus disease is supportive. Many patients diagnosed with the disease have required hospitalization. With supportive care, most people have fully recovered; however, a few older individuals with medical comorbidities have died.

Agents

Borrelia burgdorferi, B. mayonii

Where Found

Lyme disease is most frequently reported from the upper midwestern, northeastern, and mid-Atlantic states where it is spread by Ixodes scapularis ticks. Some cases are also reported from northern California, Oregon, and Washington, where it is spread by Ixodes pacificus ticks. High-incidence states include Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, Washington D.C., West Virginia, and Wisconsin. While these states account for the majority of cases,  the geographic area of risk is expanding to include neighboring states.

Incubation Period

3-30 days

Signs and Symptoms

Early Localized (3 to 30 days after a tick bite):

• Erythema migrans (EM)— Red annular or homogeneous rash at the site of tick bite; expands gradually over several days to >5 cm in diameter; central clearing may develop as the rash expands, resulting in a “target” or “bull’s-eye” appearance; may feel warm to the touch but rarely itchy or painful. EM occurs in 70-80% of infected persons. The classic rash is not present in all cases; see examples on the following pages.
• Fever, chills, malaise, fatigue, headache, myalgia, arthralgia
• Lymphadenopathy

Disseminated (days to months after a tick bite):

Untreated or unnoticed early Lyme disease will progress to disseminated disease for about 60% of patients, with diverse clinical manifestations. Most manifestations will appear in the first few weeks to months of infection, though rheumatologic manifestations may be particularly delayed.

Dermatologic manifestations

• Multiple EM rashes, distant from site of tick bite

Neurologic manifestations

• Cranial neuritis, most commonly Bell’s palsy (facial paralysis, can be bilateral)
• Lymphocytic meningitis
• Painful radiculoneuritis involving one or multiple dermatomes
• Painful peripheral motor and sensory neuropathy (mononeuritis multiplex)
• Intracranial hypertension (rare)

Cardiac manifestations

• Lyme carditis resulting in conduction abnormalities (e.g., atrioventricular node block; myopericarditis)
• Rarely, can be fatal

Rheumatologic manifestations

• Oligoarticular arthritis: transient, migratory arthritis and effusion in one or multiple joints, often large joints; may cause Baker’s cyst
• Migratory pain in tendons, bursae, muscle, and bones

LYME DISEASE OR STARI?

An erythema migrans-like rash has also been described in humans following bites of the lone star tick. This condition has been named Southern Tick-Associated Rash Illness (STARI). Although the rash may be accompanied by systemic symptoms, disseminated or severe disease has not been reported. Because the cause of STARI is unknown, diagnostic blood tests are not available. It is not known whether antibiotic treatment is necessary or beneficial for patients with STARI. Nevertheless, because STARI resembles early Lyme disease, physicians often treat patients with the same antibiotics recommended for Lyme disease.

Lone star ticks can be found from central Texas and Oklahoma eastward across the southern states and along the Atlantic Coast as far north as Maine.

General Laboratory Findings for Lyme Disease

• Elevated erythrocyte sedimentation rate
• Mildly elevated hepatic transaminases
• Microscopic hematuria or proteinuria

Laboratory Diagnosis

1. For patients who present with an EM rash after being in an area where Lyme disease is common, Lyme disease should be diagnosed clinically (without diagnostic testing), as serologic tests may be negative during the first few weeks of infection before antibodies have developed.
2. Serologic tests are highly sensitive in patients with disseminated Lyme disease, and diagnosis relies on signs and symptoms supported by results of testing.
3. Two-step serologic testing is recommended using validated first- and second-tier tests according to a standard or modified two-test algorithm. IgM Western immunoblot results should only be considered if signs and symptoms have been present for less than 30 days.

Notes on Serologic Tests for Lyme Disease

• For details, refer to the APHL guide for interpretation of serologic test results [PDF – 17 pages].
• While not necessary, acute and convalescent serologies may be useful for diagnosis in some cases, such as for patients with suspected re-infection.
• Serologic tests cannot be used to measure treatment response.
• Other conditions, including some tickborne infections and autoimmune diseases, can result in false positive test results.

NOTE: Coinfection with Babesia microti or Anaplasma phagocytophilum should be considered in patients who present with initial symptoms that are more severe than are commonly observed with Lyme disease alone, especially in those who have high-grade fever for more than 48 hours despite appropriate antibiotic therapy or who have unexplained leukopenia, thrombocytopenia, or anemia. Coinfection should also be considered in patients whose erythema migrans skin lesion has resolved but who have persistent systemic symptoms.

Treatment of Erythema Migrans Rash

People treated with appropriate antibiotics in the early stages of Lyme disease usually recover rapidly and completely. Early diagnosis and proper antibiotic treatment of Lyme disease can help prevent late Lyme disease. Treatment regimens listed in the following table are for the erythema migrans rash, the most common manifestation of early Lyme disease. These regimens may need to be adjusted depending on a person’s age, medical history, underlying health conditions, pregnancy status, or allergies. Consult an infectious disease specialist regarding individual patient treatment decisions. For treating other manifestations, see www.cdc.gov/Lyme/treatment.

*When different durations of antibiotics are shown to be effective for the treatment of Lyme disease, the shorter duration is preferred to minimize adverse effects, including infectious diarrhea and antimicrobial resistance.

NOTE: For people intolerant of amoxicillin, doxycycline, and cefuroxime, the macrolide azithromycin may be used, although it is less effective. People treated with azithromycin should be closely monitored to ensure that symptoms resolve.

Agent

Powassan virus

Where Found

Most cases have occurred primarily in northeastern states and the Great Lakes region. Less frequently, cases have been identified in Mid-Atlantic States.

Incubation Period

1–4 weeks

Signs and Symptoms

• Fever, headache, vomiting, and generalized weakness
• Usually progresses to meningoencephalitis. May include meningeal signs, altered mental status, seizures, aphasia, paresis, movement disorders, or cranial nerve palsies.

General Laboratory Findings

CSF findings include lymphocytic pleocytosis (neutrophils can predominate early), normal or mildly elevated protein, and normal glucose.

Laboratory Diagnosis

• Primarily through testing available at CDC and selected state health departments; limited commercial testing.
• Measurement of virus-specific IgM antibodies in serum or CSF. Cross-reaction with other flaviviruses (e.g., West Nile, dengue, or St. Louis encephalitis viruses) can occur; plaque reduction neutralization tests should be performed to confirm the diagnosis.
• RT-PCR may detect viral RNA in acute CSF specimens or tissues, but this method should not be used to rule out the diagnosis, as antibodies are often present at the onset of neuroinvasive signs and symptoms. RT-PCR might be more appropriate for very acute samples or samples obtained from patients who are immunocompromised.

Treatment

No specific antiviral treatment for Powassan virus disease is available. Patients with suspected Powassan virus disease should receive supportive care as appropriate.

Agent

Rickettsia parkeri

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.

Where Found

R. parkeri rickettsiosis is transmitted by Gulf Coast ticks found primarily in the southeastern United States, with focal populations in the northeastern, midwestern, and southwestern United States.

Incubation Period

2–10 days

Signs and Symptoms

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)
• Muscle aches

NOTE: R. parkeri rickettsiosis can be difficult to distinguish from RMSF and other spotted fevers, especially during early stages of these diseases. Eschars are uncommonly identified in persons with RMSF.

General Laboratory Findings

• Mildly elevated hepatic transaminases
• Mild leukopenia
• Mild thrombocytopenia, less common

Laboratory Diagnosis

• Detection of rickettsial DNA by PCR in eschar swab, whole blood, or skin biopsy.
• Demonstration of a four-fold rise in IgG-specific antibody titer by indirect immunofluorescence antibody (IFA) assay in paired serum samples. The first sample should be taken within the first 2 weeks of illness and the second should be taken 2 to 4 weeks later.

NOTE: Species-level testing for R. parkeri is not commercially available. RMSF antibody tests are available commercially and often cross-react.

NOTE: IgM antibodies are less specific than IgG antibodies and are more likely to generate false positives. IgM results alone should not be used for laboratory diagnosis.

NOTE: Acute antibody results cannot independently be relied upon for confirmation.

Treatment

See Rocky Mountain spotted fever treatment.

Agent

Rickettsia rickettsii

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%.

Where Found

Since 2010, cases of RMSF are reported as spotted fever rickettsiosis along with other spotted fevers like Rickettsia parkeri rickettsiosis in national surveillance. RMSF has become increasingly common in certain areas of Arizona over the last several years; between 2002-2021 more than 500 cases and 28 fatalities occurred.

Incubation Period

3–12 days

Rash

• Typically appears 2–5 days after onset of symptoms; approximately 10% of RMSF patients never develop a rash.
• Decision to treat should not be based on presence of rash.

Early Rash

• Maculopapular: Small, flat, pink, non-itchy spots (macules) initially appear on the wrists, forearms, and ankles then spread to the trunk and sometimes palms and soles.

Late Rash

• Petechial: Red to purple spots (petechiae) are usually not seen until day 6 or later after onset of symptoms.
• Petechial rash is considered a sign of progression to severe disease. Every attempt should be made to begin treatment before petechiae develop.

Signs and Symptoms

Early (1–4 Days)

• High fever
• Severe headache
• Malaise
• Myalgia
• Edema around eyes and on the back of hands
• Gastrointestinal symptoms (nausea, vomiting, anorexia)

Late (5 Days and Beyond)

• Altered mental status, coma, cerebral edema
• Respiratory compromise (pulmonary edema, ARDS)
• Necrosis, requiring amputation
• Multiorgan system damage (CNS, renal failure)

General Laboratory Findings

• Thrombocytopenia
• Elevated hepatic transaminases
• Hyponatremia

NOTE: Laboratory values are often within normal limits in early illness.

Laboratory Diagnosis

• Demonstration of a four-fold rise in IgG-specific antibody titer by indirect immunofluorescence antibody (IFA) assay in paired serum samples. The first sample should be taken within the first 2 weeks of illness and the second should be taken 2 to 4 weeks later.
• Detection of DNA in a skin biopsy specimen of a rash lesion by PCR assay or in an acute phase whole blood specimen. Additionally, new pan-Rickettsia and R. rickettsii-specific PCR assays are available at some local and state health departments.
• Immunohistochemical (IHC) staining of organism from skin or tissue biopsy specimen.

NOTE: Antibody titers are frequently negative in the first 7–10 days of illness. Acute antibody results cannot be independently relied upon for confirmation

NOTE: IgM antibodies are less specific than IgG antibodies and are more likely to generate false positives. IgM results alone should not be used for laboratory diagnosis.

Treatment

Anaplasmosis, ehrlichiosis, and spotted fever group rickettsioses are treated with doxycycline. Clinical suspicion of any of these diseases is sufficient to begin treatment. Delay in treatment may result in severe illness and even death. These regimens may need to be adjusted depending on a person’s age, medical history, underlying health conditions, pregnancy status, or allergies. Consult an infectious disease specialist in cases of pregnancy or life-threatening allergy to doxycycline.

NOTE: Use doxycycline as the first-line treatment for suspected RMSF in patients of all ages. The use of doxycycline to treat suspected RMSF in children is recommended by both the CDC and the American Academy of Pediatrics Committee on Infectious Diseases. Use of antibiotics other than doxycycline increases the risk of patient death. At the recommended dose and duration needed to treat RMSF, no evidence has been shown to cause staining of permanent teeth, even when multiple courses are given before the age of eight.

Agent

Borrelia hermsii, B. turicatae

Where Found

In the United States, TBRF usually occurs in mountainous areas of Western states, where it is associated with exposure to soft ticks in rustic cabins (B. hermsii), and in Texas, where it is most often associated with exposure to soft ticks in caves (B. turicatae).

Incubation Period

Approximately 7 days (range 4-21), with recurrent febrile episodes that last around 3 days and are separated by afebrile periods of approximately 7 days.

Signs and Symptoms

TBRF most commonly presents with fever, headache, and myalgias. As with other borrelioses, neurologic involvement is possible, including meningoencephalitis, cranial neuritis and ocular manifestations. Acute respiratory distress syndrome is a rare complication.

• High fever with relapses
• Chills/rigors
• Sweats
• Headache
• Myalgia/arthralgia
• Dizziness
• Nausea/vomiting
• Facial palsy (rarely)

Note: TBRF can be transmitted transplacentally and has been associated with pregnancy complications including spontaneous abortion, premature birth, and neonatal death.

General Laboratory Findings

• Leukocytosis
• Thrombocytopenia
• Mild hyperbilirubinemia
• Elevated erythrocyte sedimentation rate
• Slightly prolonged prothrombin time (PT) and partial thromboplastin time (PTT)

Laboratory Diagnosis

Tests may include the following:

• Visualization of spirochetes by microscopy of peripheral blood obtained during a febrile episode prior to treatment.
• Molecular testing, such as PCR. Molecular tests should be performed as early as possible, ideally prior to treatment or soon after. PCR testing is more sensitive than microscopy.
• Serologic testing by immunofluorescence assay (IFA), enzyme immunoassay (EIA), or immunoblot.

NOTE: Serologic tests and some commercially available PCR tests cross-react with other Borrelia species, including B. burgdorferi, the cause of Lyme disease.

Treatment

Treatment data for patients with TBRF are limited. Consider the following regimens for nonpregnant patients who do not have neurologic complications. In pregnant individuals or when neurologic involvement is present, initial parenteral therapy with a beta-lactam is advised; treatment should be continued for 10-14 days with close monitoring given the potential for severe complications.

NOTE: When initiating antibiotic therapy, all patients should be observed during the first 4 hours of treatment for a Jarisch-Herxheimer reaction.

Agent

Francisella tularensis

Tularemia is caused by the highly infectious F. tularensis bacteria. It is spread through exposure to infected arthropods (including deer flies and several species of ticks), contact with infected carcasses or animals (such as rabbits, hares, and rodents), contaminated food or water, or inhalation of aerosols (such as by mowing over an infected rabbit carcass).

Where Found

Tularemia has been reported in all states except Hawaii, but it is most common in the south-central United States, the Great Plains region, and parts of Massachusetts.

Incubation Period

3–5 days (range 1–21 days)

Signs and Symptoms

The clinical presentation of tularemia depends on many factors, including the route of inoculation and subtype of F. tularensis. Tularemia can be serious or fatal without adequate treatment. Unusual and severe clinical manifestations have been described in patients with immunocompromising conditions.

• Fever, chills
• Headache
• Malaise, fatigue
• Anorexia
• Myalgia
• Chest discomfort, cough
• Sore throat
• Vomiting, diarrhea
• Abdominal pain

(Ulcero) Glandular

• Localized lymphadenopathy
• Cutaneous ulcer at infection site (not always present)

Oculoglandular

• Photophobia
• Vision impairment/loss
• Conjunctivitis
• Regional lymphadenopathy

Oropharyngeal

• Severe throat pain
• Exudative pharyngitis or tonsillitis
• Regional 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 the localizing symptoms of other syndromes
• May have infiltrates in chest radiograph in the absence of respiratory symptoms

General Laboratory Findings

• Hyponatremia
• Leukocytosis
• Thrombocytopenia
• Elevated hepatic transaminases
• Elevated creatine kinase
• Elevated erythrocyte sedimentation rate
• Myoglobinuria
• Sterile pyuria

Laboratory Diagnosis

Isolation of F. tularensis in culture is optimal for diagnosis but can be challenging due to the slow-growing, fastidious nature of the organism. Appropriate specimens for culture include swabs or scrapings of ulcers, lymph node aspirates or biopsies, pharyngeal swabs, or respiratory specimens (e.g., pleural fluid), depending on the form of illness. Blood cultures are often negative.

Seroconversion from negative to positive IgM and/or IgG can also confirm the diagnosis when tularemia is suspected. Ideally, these are performed as paired acute and convalescent specimens, the latter collected 2-3 weeks after initial illness.

When available, other tests can be useful, including:

• Direct immunofluorescence assay (DFA)
• Immunohistochemical staining
• PCR assay

Clinicians who suspect tularemia should alert the laboratory to the possible need for special safety procedures to minimize risk of laboratory transmission.

Treatment

These regimens may need to be adjusted depending on a person’s age, medical history, underlying health conditions, pregnancy status, or allergies. Consult an infectious disease specialist regarding individual patient treatment decisions.

* Not a U.S. FDA-approved use but has been used successfully to treat patients with tularemia.
** Once-daily dosing could be considered in consultation with a pediatric infectious disease specialist and a pharmacist

NOTE: Gentamicin is preferred for treatment of severe tularemia. Dose should be adjusted for renal insufficiency.

NOTE: For tularemic meningitis, combination therapy should be considered in consultation with an infectious disease specialist.

See Tularemia For Clinicians for detailed treatment information.

Tularemia prophylaxis is recommended in cases of laboratory exposure to infectious materials.

• Doxycycline (100 mg orally twice daily for 14 days) is generally recommended for prophylaxis in adults.
• Ciprofloxacin (500 mg orally twice daily) is not FDA-approved for prophylaxis of tularemia but has demonstrated efficacy in various studies and may be an alternative for patients unable to take doxycycline.

African Tick Bite Fever (ATBF)

Agent

Rickettsia africae

African tick bite fever (ATBF) is the most commonly diagnosed rickettsial disease among returning international travelers. ATBF is transmitted by Amblyomma hebraeum and A. variegatum ticks. Travel-associated cases of ATBF often occur in clusters with exposure during activities such as safari tours, game hunting, and bush hiking.

Where Found

Sub-Saharan Africa, Caribbean (French West Indies), and Oceania

Incubation Period

Typically 5–7 days but may be as long as 10 days

Signs and Symptoms

ATBF is typically a mild-to-moderate disease; no known deaths are attributable to infection with R. africae. ATBF is almost always associated with an inoculation eschar (see R. parkeri rickettsiosis) at the site of tick attachment. Multiple eschars are described in approximately 20–50% of patients with ATBF. Several days after eschar(s) appear, the following can develop:

• Fever
• Headache
• Myalgia
• Regional lymphadenopathy
• Rash (generalized with maculopapular or vesicular eruptions)

General Laboratory Findings

• Similar to other Rickettsia, see R. parkeri rickettsiosis.

Laboratory Diagnosis

Confirmation of the diagnosis is based on laboratory testing, but antibiotic treatment should not be delayed pending laboratory confirmation.

• ATBF can be confirmed using IFA or detection of Rickettsial DNA by PCR of eschar swab, skin biopsy, or whole blood. See R.parkeri rickettsiosis.
• ATBF can be confirmed by comparing acute and convalescent (taken 4–6 weeks following illness onset) samples for evidence of seroconversion in IgG antibodies.

Treatment

See RMSF treatment.

Lyme Disease (Europe and Asia)

Agents

Borrelia afzelii, B. garinii, B. burgdorferi sensu stricto, and B. bavariensis (previously considered a variant of B. garinii)

Outside North America, Borrelia spp. that cause Lyme disease are transmitted through the bite of infected Ixodes ricinus and I. persulcatus ticks.

Where Found

In Europe, Lyme disease is endemic from southern Scandinavia into the northern Mediterranean countries of Italy, Spain, Portugal, and Greece and east from the British Isles into central Russia. Incidence is highest in Central and Eastern European countries. In Asia, infected ticks occur from western Russia through Mongolia, northeastern China, and Japan; however, human infection appears to be uncommon in some of these areas.

Incubation Period

3–30 days

Signs and Symptoms

Outside of North America, most infections are caused by B. afzelii, B. garinii, B. burgdorferi sensu stricto, and B. bavariensis (previously considered a variant of B. garinii), with each causing somewhat different clinical manifestations.

As in the United States, the erythema migrans (EM) rash is the most common early manifestation; later neurologic, cardiac, and rheumatologic disease may occur. In European Lyme disease, the EM rash may spread more slowly and is less commonly accompanied by systemic symptoms. Atrophic skin lesions (acrodermatitis chronica atrophicans) are a frequent late manifestation of infection with B. afzelii. In Lyme disease caused by B. garinii, some individuals may develop Bannwarth syndrome, a severe neuroborreliosis characterized by radiculopathy, neuropathy, and lymphocytic meningitis.

Laboratory Confirmation

Antibodies to Borrelia species that cause Lyme disease outside the United States may not be reliably detected by all tests used in the United States. Providers who suspect internationally-acquired Lyme disease should use diagnostic tests that have been validated for these species.

Treatment

See Lyme disease treatment.

References

Steere AC, Strle F, Wormser GP, et al. Lyme borreliosis. Nat Rev Dis Primers. 2016;2:16090.

Stone BL, Tourand Y, Brissette CA. Brave new worlds: The expanding universe of Lyme disease. Vector Borne Zoonotic Dis. 2017;17(9):619-629.

Vandekerckhove O, De Buck E, Van Wijngaerden E. Lyme disease in Western Europe: an emerging problem? A systematic review. Acta Clin Belg. 2021;76(3):244-252.

Tickborne Encephalitis (TBE)

Agent

Tick-borne encephalitis virus

TBE is transmitted through the bite of infected Ixodes ricinus and I. persulcatus ticks.

Where Found

Endemic in focal areas of Europe and Asia, extending from western and northern Europe through to northern and eastern Asia. The highest disease incidence has been reported from the Baltic states, Slovenia, and Czech Republic. Asian countries with reported cases or virus activity include China, Japan, Kazakhstan, Kyrgyzstan, Mongolia, and South Korea. TBE may also be acquired by ingestion of unpasteurized dairy products from infected goats, sheep, or cows.

Incubation Period

8 days (range, 4–28 days)

Signs and Symptoms

TBE disease often presents with mild illness but can cause neuroinvasive disease (i.e., aseptic meningitis, encephalitis). The course of illness can be monophasic or biphasic. If biphasic, the two phases are:

• First phase: nonspecific febrile illness with headache, myalgia, and fatigue. Usually lasts for several days and may be followed by an afebrile and relatively asymptomatic period.
• Second phase: central nervous system involvement. Findings depend on the specific presentation but might include meningeal signs, altered mental status, cognitive dysfunction, ataxia, rigidity, seizures, tremors, cranial nerve palsies, and limb paresis.

Laboratory Confirmation

During the first phase of the illness, TBE virus or viral RNA can sometimes be detected in serum samples by virus isolation or RT-PCR. However, by the time neurologic symptoms are recognized, the virus or viral RNA is usually undetectable. Therefore, virus isolation and RT-PCR should not be used to rule out a diagnosis of TBE. Clinicians should contact their state or local health department or CDC’s Division of Vector-Borne Diseases (970-221-6400) for assistance with diagnostic testing.

Treatment

There is no specific antiviral treatment for TBE; therapy consists of supportive care and management of complications.

Prevention

Inactivated TBE vaccine (manufactured as TICOVAC) is licensed and available in the United States. This vaccine is approved for use in people aged 1 years and older and is administered as a three-dose series.

TBE vaccine is recommended for persons who are moving or traveling to a TBE-endemic area and will have extensive exposure to ticks based on their planned outdoor activities and itinerary. In addition, TBE vaccine may be considered for persons traveling or moving to a TBE-endemic area who might engage in outdoor activities in areas ticks are likely to be found.

Additional Travel-Associated Tickborne Infections

Tick Bite Prevention

1. Know where to expect ticks. Ticks live in grassy, brushy, or wooded areas, or on animals. Spending time outside walking your dog, camping, gardening, or hunting could bring you in close contact with ticks. Many people get ticks in their own yard or neighborhood. Soft ticks that spread tickborne relapsing fever (TBRF) most often live in caves and rodent-infested rustic cabins.
2. Use Environmental Protection Agency (EPA)-registered insect repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone. Treat clothing and gear, such as boots, pants, socks and tents with products containing 0.5% permethrin.
3. Treat dogs and cats for ticks as recommended by a veterinarian.
4. Check for ticks daily, especially under the arms, in and around the ears, inside the belly button, behind the knees, between the legs, around the waist, and on the hairline and scalp.
5. Shower soon after being outdoors.

Tick Removal

1. Use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible. The key is to remove the tick as soon as possible. Avoid using nail polish, petroleum jelly, or heat to make the tick detach from the skin.
2. Pull upward with steady, even pressure. Don’t twist or jerk the tick; this can cause the mouth-parts to break off and remain in the skin.  If you are unable to remove the mouth parts easily, leave them alone and let the skin heal.
3. After removing the tick, thoroughly clean the bite area and your hands with rubbing alcohol, an iodine scrub, or soap and water.

In areas that are highly endemic for Lyme disease, a single prophylactic dose of doxycycline (200 mg for adults or 4.4 mg/kg for children of any age weighing less than 45 kg) may be used to reduce the risk of acquiring Lyme disease after a high-risk tick bite.

Benefits of prophylaxis may outweigh risks when all of the following circumstances are present:

1. Where the tick bite occurred, are ticks likely to be infected with Borrelia burgdorferi?

2. Was the tick removed within the last 72 hours?

3. Was the tick’s body engorged with blood (not flat)?

4. Was the tick an Ixodes (blacklegged) tick?

5. Is doxycycline safe for the patient? Considerations include allergy to doxycycline, pregnancy, and lactation.

Antibiotic treatment following a tick bite is not recommended as a means to prevent anaplasmosis, babesiosis, ehrlichiosis, Rocky Mountain spotted fever, or other rickettsial diseases. Instead, persons who experience a tick bite should be alert for symptoms suggestive of tickborne illness and consult a physician if fever, rash, or other symptoms of concern develop.