Ehrlichiosis and Anaplasmosis

Clinical features of ehrlichiosis and anaplasmosis are similar. Although some infections are asymptomatic, most cause abrupt onset of an influenza-like illness with nonspecific symptoms such as fever, chills, myalgias, weakness, nausea, vomiting, cough. headache, and malaise, usually beginning about 12 days after the tick bite.

Rash is uncommon in anaplasmosis. Some patients infected with E. chaffeensis develop a maculopapular or petechial rash on the trunk and extremities.

Ehrlichiosis and anaplasmosis may result in disseminated intravascular coagulation Disseminated Intravascular Coagulation (DIC) Disseminated intravascular coagulation (DIC) involves abnormal, excessive generation of thrombin and fibrin in the circulating blood. During the process, increased platelet aggregation and coagulation... read more , multiorgan failure, seizures, and coma.

Both infections appear to be more severe and have a higher mortality rate in patients with compromised immunity caused by immunosuppressants (eg, corticosteroids, cancer chemotherapy, long-term treatment with immunosuppressants after organ transplantation), HIV infection, or splenectomy.

Diagnostic serologic tests are available for ehrlichiosis and anaplasmosis, but PCR of blood is more sensitive and specific and can result in an early diagnosis because serologic tests require comparison of serial titers. Cytoplasmic inclusions in monocytes (ehrlichiosis) or in neutrophils (anaplasmosis) may be detected, but cytoplasmic inclusions are more commonly seen in anaplasmosis.

Blood and liver tests may detect hematologic and hepatic abnormalities, such as leukopenia, thrombocytopenia, and elevated aminotransferase levels.

Treatment of ehrlichiosis and anaplasmosis is best started before laboratory results return. When treatment is started early, patients generally respond rapidly and well. A delay in treatment may lead to serious complications, including viral and fungal superinfections and death in 2 to 5%.

Primary treatment is doxycycline 200 mg orally once followed by 100 mg twice a day in adults until the patient improves and has been afebrile for 24 to 48 hours but is continued for at least 7 days.

Although some tetracyclines can cause tooth staining in children < 8 years of age, the Centers for Disease Control and Prevention (CDC) and American Academy of Pediatrics Committee on Infectious Diseases advise that a course of doxycycline 2.2 mg/kg orally or IV twice a day is warranted (1 Treatment references Ehrlichiosis and anaplasmosis are caused by rickettsial-like bacteria. Ehrlichiosis is caused mainly by Ehrlichia chaffeensis; anaplasmosis is caused by Anaplasma phagocytophilum... read more ). Research indicates that short courses of doxycycline (5 to 10 days, as used for rickettsial disease) can be used in children without causing tooth staining or weakening of tooth enamel (2 Treatment references Ehrlichiosis and anaplasmosis are caused by rickettsial-like bacteria. Ehrlichiosis is caused mainly by Ehrlichia chaffeensis; anaplasmosis is caused by Anaplasma phagocytophilum... read more ).

Chloramphenicol is not effective.

Some patients continue to experience headache, weakness, and malaise for weeks after adequate treatment.

No vaccine is available to prevent ehrlichiosis or anaplasmosis. Measures can be taken to prevent tick bites. (See also Centers for Disease Control and Prevention: Preventing tick bites.)

Preventing tick access to skin includes

DEET should be used cautiously in very young children because toxic reactions have been reported. Permethrin on clothing effectively kills ticks. Frequent searches for ticks, particularly in hairy areas and on children, are essential in endemic areas.

Engorged ticks should be removed with care and not crushed between the fingers because crushing the tick may result in disease transmission. The tick’s body should not be grasped or squeezed. Gradual traction on the head with a small forceps dislodges the tick. The point of attachment should be swabbed with alcohol. Petroleum jelly, lit matches, and other irritants are not effective ways to remove ticks and should not be used.

No practical means are available to rid entire areas of ticks, but tick populations may be reduced in endemic areas by controlling small-animal populations.

The following are some English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.