Causative & risk factors
The causative agent is the Ehrlichia chaffeensis bacteria and the transmitting agent is the Lone Star tick.
Ehrlichiosis is caused when ticks infected with the Ehrlichia chaffeensis bacteria feed on or bite a human.
Other modes of transmission include a direct transmission from mother to fetus or receiving a blood transfusion from an infected person.
Clinical presentation
Once an individual is infected with the Ehrlichia chaffeensis bacteria, the symptoms of ehrlichiosis appear within a week or two. The patient develops a mild fever with chills, headache and myalgia. Non-specific symptoms such as nausea, vomiting, cough, joint pains and diarrhea may be present.
Most children and a few adults infected with ehrlichiosis develop a rash. It is a non itchy, flattened or slightly raised rash.
Ehrlichiosis in its severe form can produce bleeding disorders and difficulty in breathing. If untreated, it can even lead to death of the patient.
Investigations
There is no specific test to diagnose ehrlichiosis. Several blood tests are performed to look for any abnormal values. These include a complete blood count, liver function tests, polymerase chain reaction (PCR) test and an ‘indirect fluorescent antibody test’.
Treatment
Treatment consists of a course of antibiotics for a week or ten days. Persistent cases may need treatment for a longer duration.
Statistics
The estimated mortality rate of patients with ehrlichiosis is about 1.8%.
