Ehrlichiosis

Reportable by Laboratories and Providers

About this Reportable Disease

Infectious agent:  Ehrlichia chaffeensis, Ehrlichia ewingii, Ehrlichia muris-like

Description of illness: Symptoms include fever, headache, chills, malaise, muscle pain, gastrointestinal symptoms (nausea, vomiting, diarrhea, anorexia), confusion, conjunctival injection, rash (more commonly reported among children).  Few people will develop all symptoms and the number and combination of symptoms varies greatly from person to person. Similar symptoms are seen with anaplasmosis but they occur in different regions of the U.S. with ehrlichiosis most frequently reported from the southeastern and south-central U.S., from the eastern seaboard extending westward to Texas. The areas from which 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. Three states (Oklahoma, Missouri, Arkansas) account for 35% of all reported E. chaffeensis infections. Since 2009, >70 cases of ehrlichiosis caused by Ehrlichia muris eauclarensis, have been identifed in patients in the upper Midwest. The tick responsible for transmitting this new subspecies is suspected to be Ixodes scapularis and the clinical presentation is generally similar to those associated with infections caused by E. chaffeensis and E. ewingii. No deaths have been reported.

Interactive Disease Data


Laboratory Reporting for this Disease

Reporting requirements apply to all laboratories located within Tennessee, as well as laboratories outside of Tennessee that test residents of Tennessee, including laboratories located within healthcare facilities. Healthcare providers and laboratories in the same healthcare facility both have a duty to report. The type of organisms and analytes laboratories must report to TDH for 2026 are indicated, and there are several ways laboratories can report results to TDH.

 

Information about this Reportable Disease for Healthcare Providers

Clinical Summary

  • Ehrlichiosis is a tick-borne bacterial illness (most commonly caused by Ehrlichia chaffeensis and E. ewingii) that typically begins within 1–2 weeks after an infected tick bite (tick bites can be painless and often not noticed). Illness ranges from a nonspecific febrile syndrome to severe, life-threatening disease.
  • Common clinical features include fever, headache, malaise, myalgias, and sometimes nausea/vomiting or rash. Severe disease can include complications such as respiratory failure, meningoencephalitis, renal failure, shock, and can be fatal, especially in older adults, immunocompromised patients, or when treatment is delayed.
  • Diagnosis is based on compatible illness plus tick exposure risk, with testing guided by timing. CDC notes PCR on whole blood is most sensitive in the first week of illness (before or early in antibiotics), while serology (IFA IgG) is confirmed by paired acute and convalescent samples (a single early titer can be negative). Do not delay treatment while awaiting results.
  • Treatment is doxycycline for adults and children of all ages; CDC recommends treating suspected ehrlichiosis for at least 5–7 days and until 72 hours after fever resolves with clinical improvement. In Tennessee, ehrlichiosis is a reportable condition, supporting surveillance and public health response.

Healthcare Provider Reporting

Healthcare reporting requirements apply to all providers located within Tennessee, as well as providers whose patients reside in Tennessee.

Providers must report cases of all diseases and conditions listed through one of these methods:

• Mail or fax a completed PH-1600 form to your local health department or fax to the state health office at (615) 741-3857

• Send automatically via electronic case reporting (eCR). See this TDH webpage for more information on eCR, register at the Trader Partner Registration website, or contact MU.Health@tn.gov for assistance.

• Submit online via NBS. NBS is TDH's reportable disease system. To request an NBS account for reporting Complete this user survey to request an NBS account for reporting. 

• Blood lead levels can be sent via fax ( (615) 741-3857), entered online, or reported using the instructions at this link. 

Information about this Reportable Disease for the Public

What It Is

Ehrlichiosis is the general name for a group of tick-borne diseases caused by bacteria. People most commonly get sick after being bitten by an infected tick, including the Lone Star tick and blacklegged tick species.

Signs and Symptoms

Symptoms usually begin within 1–2 weeks after a tick bite. Common symptoms include fever, chills, headache, muscle aches, nausea, and sometimes a rash. Delaying treatment can increase the risk of severe illness.

How It Spreads

Ehrlichiosis spreads through the bite of an infected tick. It is not spread through casual person-to-person contact like coughing or sharing food.

Diagnosis and Treatment

Healthcare providers diagnose ehrlichiosis based on symptoms and exposure history, and lab testing can help confirm the diagnosis. CDC emphasizes that treatment should not be delayed while waiting for test results. The recommended treatment for suspected ehrlichiosis in adults and children of all ages is doxycycline, and early treatment helps prevent severe illness.

Prevention

Prevent tick bites by using EPA-registered insect repellent, wearing long sleeves and pants when possible, checking for ticks after being outdoors, and removing ticks promptly. These steps are especially important in warmer months and in wooded or brushy areas.

This Page Last Updated: March 25, 2026 at 8:53 PM