Tick-Borne Illnesses Causing Gastrointestinal Symptoms

Clinical Presentation

The Centers for Disease Control and Prevention (CDC) reports that Ehrlichia chaffeensis infection (human monocytic ehrlichiosis) commonly presents with gastrointestinal manifestations including nausea (57%), vomiting (47%), and diarrhea (25%) 1
Abdominal pain, vomiting, and diarrhea are more common in children with ehrlichiosis than in adults 1
Symptoms of tick-borne diseases typically appear a median of 9 days (range: 5-14 days) after the bite of an infected tick 1
The CDC recommends considering geographic location, season, and presence of other symptoms when evaluating a patient with diarrhea following a tick bite 2

The primary vector for E. chaffeensis is the lone star tick (Amblyomma americanum) 2
Anaplasma phagocytophilum infection (human granulocytic anaplasmosis) can also cause gastrointestinal symptoms, though less frequently than ehrlichiosis 3
Patients with anaplasmosis typically seek medical care 4-8 days after fever onset 4
The primary vectors for anaplasmosis are Ixodes scapularis (blacklegged tick) in the northeastern and Midwestern United States and Ixodes pacificus (western blacklegged tick) along the West Coast 2

Tick-borne rickettsial diseases typically begin with fever, headache, malaise, and myalgia 4
Gastrointestinal symptoms may be prominent early in the course of illness, especially in ehrlichiosis 1
Early empiric therapy with doxycycline is the best way to prevent progression and reduce morbidity and mortality in tick-borne rickettsial diseases 1
Laboratory findings in the first week of illness may include leukopenia (low white blood cell count) 3, thrombocytopenia (low platelet count) 1, and elevated hepatic transaminase levels 3

Increased severity of ehrlichiosis has been associated with advanced age (≥60 years) 2 and immunosuppression 3
The case-fatality rate for E. chaffeensis ehrlichiosis is approximately 3% 3