Calcutta strain. Originally isolated from a patient in 1943.
Following from Zarafonetis, C.J.D. 1945. The Susceptibility of the rodents, Gerbillus pyramidum and Gerbillus gerbillus, to experimental tsutsugamushi infection (scrub typhus). Proceedings of the Society for Experimental Biology and Medicine 59 (2): 113-116
“Major M. T. Parker, R.A.M.C., obtained this strain from the blood of a patient in his 12th day of disease. Washed
blood clot material was inoculated intraocularly into a rabbit which showed iritis on the 11th day. One of the third passage rabbits was received in Cairo on January 7, 1944.”