Rickettsia and Chlamydia
Which one of the following is transmitted by the bite of a hard Ixodes tick?
a. Ehrlichia is an obligate, intracellular parasite that resembles rickettsia. E. chaffeensis has been linked to human ehrlichiosis, although this infection is primarily seen in animals.
b. The majority of patients with this disease report exposure to ticks. It is thought that I. scapularis carries Ehrlichia, although the Lone Star tick, A. americanum, may also transmit the disease.
a. Coxiella is transmitted through the respiratory tract, ingestion of contaminated milk or via skin by handling infected animal placenta.
b. Coxiella may cause chronic endocarditis that is not very responsive to either antimicrobial therapy or valve replacement.
c. B. henselae is transmitted by animal scratches.
d. B. henselae is a fastidious, gram-negative rod that causes bacillary angiomatosis, a disease that forms dermal or subcutaneous nodules. This disease is seen mainly in immunosuppressed individuals and resembles Kaposi’s sarcoma.
e. The role of B. henselae in cat-scratch disease has recently been recognized. Molecular taxonomic studies have indicated that the causative organism is more closely related to Bartonella than to Rochalimaea, hence the name change.