Human ehrlichiosis history and symptoms
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
The early clinical presentations of ehrlichiosis may resemble nonspecific signs and symptoms of various other infectious and non-infectious diseases. It is unclear if all persons infected with ehrlichiae become ill. It is possible that many infected persons develop an illness so mild they do not seek medical attention or perhaps have no symptoms at all.
History and Symptoms
Patients with ehrlichiosis generally visit a physician in their first week of illness, following an incubation period of about 5-10 days after the tick bite. Initial symptoms generally include fever, headache, malaise, and myalgia. Other signs and symptoms may include nausea, vomiting, diarrhea, cough, joint pains, confusion, and occasionally rash. In contrast to Rocky Mountain spotted fever, rash is relatively uncommon in adult patients with HME, and is rarely reported with HGE. However, rash has been described in approximately 60% of pediatric patients infected with E. chaffeensis.
Laboratory findings indicative of ehrlichiosis include leukopenia, thrombocytopenia, and elevated liver enzymes. See Laboratory Detection for more information on laboratory confirmation of ehrlichiosis.
Ehrlichiosis can be a severe illness, especially if untreated, and as many as half of all patients require hospitalization. Severe manifestations of the disease may include prolonged fever, renal failure, disseminated intravascular coagulopathy, meningoencephalitis, adult respiratory distress syndrome, seizures, or coma. It is estimated that 2%-3% of patients may die from the infection. Preliminary evidence suggests that E. chaffeensis infection may become more severe than other ehrlichial infections.
The severity of ehrlichiosis may be related in part to the immune status of the patient. Persons with compromised immunity caused by immunosuppresive therapies (e.g., cortiocosteroids or cancer chemotherapy), HIV infection, or splenectomy appear to develop more severe disease, and case-fatality ratios for these individuals are characteristically higher than case-fatality ratios reported for the general population.