++
For further information, see CMDT Part 35–05: Babesiosis
+++
Essentials of Diagnosis
++
History of tick bite or exposure to ticks
Fever, flu-like symptoms, anemia
Intraerythrocytic parasites on Giemsa-stained blood smears
Positive serologic tests
+++
General Considerations
++
An uncommon intraerythrocytic infection caused mainly by Babesia species and transmitted by Ixodes ticks
Most cases in the United States occurs in the coastal northeast, with some cases also in the upper midwest
The incidence of the disease appears to be increasing in some areas
Can be transmitted by blood transfusion, but blood supplies are not screened
A survey of a large set of blood samples from endemic regions of the United States identified ~0.4% as potentially infectious for B microti
++
Serosurveys suggest that asymptomatic infections are common in endemic areas
With B microti infections
Typical flu-like illness develops gradually and is characterized by
Fever
Malaise
Fatigue
Headache
Anorexia
Myalgia
Other findings may include nausea, vomiting, abdominal pain, arthralgia, sore throat, depression, emotional lability, anemia, thrombocytopenia, elevated transaminases, and splenomegaly
B divergens infections
Most cases seen in Europe in patients who have had splenectomy
These infections progress rapidly with
High fever
Severe hemolytic anemia
Jaundice
Hemoglobinuria
Acute kidney injury
Mortality rates are over 40%
++
Identification of the intraerythrocytic parasite on Giemsa-stained blood smears establishes the diagnosis
Repeated smears are often necessary because well under 1% of erythrocytes may be infected, especially early in infection, although parasitemias can exceed 10%
Diagnosis can also be made by PCR, which is more sensitive than blood smear
An indirect immunofluorescent antibody test for B microti is available from the CDC
++
Standard therapy for mild to moderate disease is a 7-day course of atovaquone (750 mg orally every 12 hours) plus azithromycin (600 mg orally once daily), which is equally effective and better tolerated than the alternative regimen, a 7-day course of quinine (650 mg orally three times daily) plus clindamycin (600 mg orally three times daily)
However, there is more experience using quinine plus clindamycin, and this regimen is recommended by some experts for severe disease
+++
Therapeutic Procedures
++
++