Tick-Borne Diseases

September 14, 2005
W. B. Wadlington, MD

The rash of tick tularemia is seen here on the arm of a 5-year-old boy. He also had a tick bite on his back that became necrotic and ulcerated. Within 2 weeks of his having been bitten, axillary lymph nodes developed.

The rash of tick tularemia is seen here on the arm of a 5-year-old boy (A). He also had a tick bite on his back that became necrotic and ulcerated. Within 2 weeks of his having been bitten, axillary lymph nodes developed.

The diagnosis of ulceroglandular tularemia was confirmed by blood agglutination titer of 1:4,000. (Agglutination titer greater than 1:80 is diagnostic, although often the titer is not elevated during the first week.) The patient was treated with streptomycin and responded well; the prognosis for tularemia is usually good.

Ulceroglandular tularemia is the most common form of tick tularemia. All forms provoke fever, chills, headache, and myalgia to varying degrees.

Rickettsia rickettsii is also transmitted to humans by a tick bite. The boy in photograph B had been camping a short time before a fever and the classic rash of Rocky Mountain spotted fever developed.

The erythematous macular rash first appears on wrists and ankles and spreads to the trunk. Note the puffy appearance resulting from vasculitis.