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October 2, 1987

Colorado Tick Fever or Ehrlichiosis-Reply

Author Affiliations

Centers for Disease Control Atlanta

Centers for Disease Control Atlanta

JAMA. 1987;258(13):1731-1732. doi:10.1001/jama.1987.03400130045019

In Reply.—  We agree with Dr Ellison that there are clinical similarities between human ehrlichiosis and CTF. Indeed, we recently examined the serum of a Canadian patient suspected of having ehrlichiosis who showed no detectable antibodies to Ehrlichiacanis but who had a rising titer against CTF virus. We regret that the quantity of acute and convalescent serum available from our six patients prevented us from testing our patients' serum against a larger number of antigens.There are, however, a number of differences between CTF and the illness that we described. The geographic distribution is different, Dr Ellison's caveats notwithstanding. The incubation period of CTF is usually three to six days,1 while that of ehrlichiosis appears to be between one and three weeks. None of our patients had a biphasic illness. In six patients we described and in all but one of ten patients we have subsequently identified, fevers