Ehrlichiosis is an infection of white blood cells that affects various mammals, including mice, cattle, dogs, deer, horses, sheep, goats, and humans. Ehrlichia/Anaplasma are tiny (0.2-2 µm) obligate, intracytoplasmic, gram-negative organisms that resemble Rickettsia; divide by binary fission; and multiply within the cytoplasm of infected white blood cells. Ehrlichiosis is caused by ehrlichia bacteria and is transmitted primarily by the Lone Star tick.
Ehrlichiosis occurs essentially worldwide, and the frequency parallels the distribution of the appropriate tick vectors for the transmission of Ehrlichia bacteria and the mammalian hosts. Most cases of ehrlichiosis in the United States occur in California and Texas and in the southeast and northeast regions of the country, with some cases occurring in the north-central states west of the Great Lakes. Ehrlichiosis is a seasonal disease observed mainly from April to September. In 1999, ehrlichiosis became reportable to the US Centers for Disease Control and Prevention (CDC). Ehrlichia chaffeensis and Ehrlichia ewingii are transmitted by the lonestar tick in the southeastern and southcentral United States. In addition, a third Ehrlichia species provisionally called Ehrlichia muris-like (EML) has been identified in a small number of patients residing in or traveling to Minnesota and Wisconsin; a tick vector for the EML organism has not yet been established.
Ehrlichiosis is a bacterial illness transmitted by ticks that causes flu-like symptoms. The signs and symptoms of ehrlichiosis range from mild body aches to severe fever and usually appear within a week or two of a tick bite. If treated quickly with appropriate antibiotics, ehrlichiosis generally improves within a few days. Tick-borne infections are difficult to diagnose based solely on signs and symptoms because the signs and symptoms, such as fever and muscle aches, are similar to many other common conditions.
Treatment includes the prescription of doxycycline (Doryx, Vibramycin, others). In the case of pregnancy doctor may prescribe the antibiotic rifampin (Rifadin, Rimactane) instead, because doxycycline isn't recommended during pregnancy.