Ehrlichiosis
A tick-borne bacterial infection with fever and flu-like symptoms
Quick Facts
- Type: Tick-borne bacterial infection
- Spread by: Bites from infected ticks
- Key symptoms: Fever, headache, muscle aches, fatigue
- Treatment: Antibiotics (doxycycline)
Overview
Ehrlichiosis is an illness caused by bacteria of the Ehrlichia group that are spread to people through the bite of an infected tick, most often the lone star tick in parts of the United States. The bacteria infect certain white blood cells, and the illness usually begins within one to two weeks of a tick bite with fever and flu-like symptoms.
Most cases occur during the warmer months when ticks are active and people spend more time outdoors. Ehrlichiosis ranges from a mild, flu-like illness to a serious infection, and it can become severe, particularly in people with weakened immune systems or who are not treated early. The good news is that ehrlichiosis responds well to a specific antibiotic, and prompt treatment based on symptoms and tick exposure usually leads to a full recovery.
Symptoms
Symptoms typically begin about one to two weeks after a bite from an infected tick and often resemble the flu.
- Fever and chills
- Severe headache
- Muscle aches and fatigue
- Nausea, vomiting, or loss of appetite
- Confusion in more severe cases
- A rash in some people (more common in children)
Many people do not remember a tick bite. Warning signs of severe illness include difficulty breathing, bleeding problems, confusion, and very low blood pressure. Because the symptoms are nonspecific, ehrlichiosis is often diagnosed and treated based on the combination of symptoms and possible tick exposure rather than waiting for test results.
Causes
Ehrlichiosis is caused by Ehrlichia bacteria transmitted through tick bites.
- Tick bite: Infected ticks, especially the lone star tick, pass the bacteria to a person while feeding.
- Time attached: A tick generally needs to be attached for a period of time to transmit the bacteria, so prompt removal lowers risk.
- Geography and season: Most cases occur in regions where the carrying ticks are common, during spring and summer.
Ehrlichiosis is not spread from person to person through ordinary contact. Rarely, it can be passed through blood transfusion or organ transplant.
Risk Factors
- Spending time in wooded, grassy, or brushy areas where ticks live
- Outdoor work or recreation such as hiking, camping, and gardening
- Living in or visiting regions where carrying ticks are common
- The warmer months when ticks are most active
- A weakened immune system, which raises the risk of severe illness
Diagnosis
Doctors often diagnose ehrlichiosis based on symptoms and possible tick exposure, starting treatment before tests come back because early therapy is important.
- Clinical assessment: Considering fever and flu-like symptoms in someone with possible tick exposure.
- Blood tests: A low white blood cell or platelet count and abnormal liver tests can support the diagnosis.
- Specific testing: Blood tests can detect the bacteria's genetic material or antibodies, though results may take time and the second of two antibody tests is sometimes needed for confirmation.
Treatment
Ehrlichiosis is treated with antibiotics, and starting them early greatly improves the outcome.
- Doxycycline: This antibiotic is the recommended treatment for adults and children of all ages and usually leads to rapid improvement, often within a day or two.
- Early treatment: Because waiting for test confirmation can delay care, treatment is typically started based on symptoms and exposure.
- Supportive care: Rest, fluids, and fever control help, and severe cases may require hospital treatment.
Most people recover fully with prompt antibiotics. Delayed treatment raises the risk of serious complications such as organ problems and, rarely, death, which is why early therapy is emphasized.
Prevention
- Avoid tick-infested areas and walk in the center of trails
- Use insect repellent and wear long sleeves and pants in tick country
- Treat clothing and gear with permethrin where appropriate
- Check your body, children, and pets for ticks after being outdoors
- Remove attached ticks promptly with fine-tipped tweezers, pulling straight out
- Shower soon after coming indoors to help find and wash off ticks
When to See a Doctor
See a doctor promptly if you develop fever, severe headache, muscle aches, or fatigue within a few weeks of a possible tick bite or time spent in tick country, even if you do not recall a bite. Early antibiotics work best. Seek emergency care for warning signs of severe illness such as confusion, difficulty breathing, unusual bleeding or bruising, severe abdominal pain, or signs of very low blood pressure like fainting, as ehrlichiosis can occasionally become life-threatening.
Frequently Asked Questions
How soon after a tick bite do symptoms of ehrlichiosis appear?
Symptoms usually begin about one to two weeks after a bite from an infected tick. They often start with fever, headache, muscle aches, and fatigue. Many people do not remember being bitten, so any flu-like illness after time in tick country deserves attention.
What antibiotic treats ehrlichiosis?
Doxycycline is the recommended treatment for both adults and children of all ages, and it usually brings rapid improvement. Because delaying treatment increases the risk of serious illness, doctors often start it based on symptoms and tick exposure rather than waiting for test results.
Is ehrlichiosis contagious between people?
No. Ehrlichiosis is spread by tick bites, not through ordinary person-to-person contact. In rare cases it has been transmitted through blood transfusion or organ transplant, but you cannot catch it from someone who has it through everyday contact.
How can I prevent ehrlichiosis?
Avoid tick bites by using insect repellent, wearing long clothing in tick areas, checking yourself, children, and pets for ticks after being outdoors, and removing attached ticks promptly with tweezers. Showering soon after coming inside also helps you find ticks before they attach firmly.
Can ehrlichiosis be dangerous?
Yes, it can become severe, especially if treatment is delayed or in people with weakened immune systems. Serious complications include organ damage, bleeding problems, and breathing difficulty. Seek emergency care for confusion, trouble breathing, unusual bleeding, or fainting, and seek early treatment to prevent these problems.
References
- Centers for Disease Control and Prevention (CDC). Ehrlichiosis.
- Mayo Clinic. Ehrlichiosis and anaplasmosis.
- MedlinePlus, U.S. National Library of Medicine. Ehrlichiosis.
- National Institute of Allergy and Infectious Diseases (NIAID).