Makindo Medical Notes

The symptoms of Ehrlichiosis usually develop 1-2 weeks after being bitten by an infected tick. The bite is typically painless, and around half of the people affected may not recall being bitten.

About

• Ehrlichiosis is a serious tick-borne illness that can be fatal if left untreated, even in healthy individuals.
• Immunocompromised patients have a higher case-fatality rate, making timely treatment crucial.

Characteristics

• Symptoms typically appear 1-2 weeks after being bitten by an infected tick.

Source

• Ehrlichiosis is transmitted to humans by the bite of infected ticks.
• Primarily the Amblyomma Americanum (Lone Star tick) and Ixodes scapularis (black-legged tick).

Pathogenicity

• Ehrlichiosis is caused by bacteria from the genus Ehrlichia, which infect white blood cells and disrupt the immune system.

Clinical Symptoms

• Fever, headache, chills, and malaise are common early symptoms.
• Muscle pain, nausea, vomiting, and diarrhoea may also occur.
• Confusion or mental status changes can be a feature in severe cases.
• Conjunctival injection (red eyes) is sometimes observed.
• Rash is more common in children than adults.

Investigations

• Antibody titers: Detectable antibody levels are usually observed 7-10 days after symptom onset.
• PCR testing is helpful in identifying Ehrlichia DNA, although a negative result does not completely rule out the diagnosis.
• Peripheral blood smear: May show morulae (clusters of Ehrlichia bacteria) in the cytoplasm of white blood cells in up to 20% of patients.

Management

• Doxycycline: The first-line treatment for adults and children of all ages and should be started immediately if ehrlichiosis is suspected, even before confirmatory test results.
  • Adults: 100 mg every 12 hours.
  • Children under 45 kg (100 lbs): 2.2 mg/kg body weight, given twice a day.
• Early treatment is critical, as delayed treatment increases the risk of severe complications or death.