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A case of Rocky Mountain spotted fever following tick-bite was reported on the Olympic Peninsula in Washington by Semler (9) under circumstances which suggest that the vector was probably the winter tick, Dermacentor albipictus, a species heretofore not under suspicion as a carrier because of its presumed one-host habits. In view of physical findings including rash and history of tick-bite during the previous week, the 35-year-old patient, a regular employee in a plywood mill in Hoquiam, Wash., was hospitalized November 18, 1949, with a tentative diagnosis of Rocky Mountain spotted fever. Chloromycetin therapy was immediately instituted and this probably accounted for subsequent negative complement-fixation findings in accordance with other experience where effective antibiotics have been used early in the course of the disease. This patient was completely afebrile by the third hospital day and his rash had faded by the fourth day. His serum, 4 months later, showed positive Proteus OX19 agglutination in a dilution of 1: 320, which is at least presumptive confirmation of his infection with Rocky Mountain spotted fever. The authors visited the area in August 1950, and failed to obtain any ticks from the vegetation by flagging, but they obtained the following additional facts by interviewing the patient and others concerned: Three days before onset (a short incubation period), the patient took the day off from his work in Hoquiam and assisted his father and others on his father's farm, between Humptulips and Copalis Junction, in skinning and dressing an elk which others had shot the day before in the adjoining wooded section. This was the only place outside of Hoquiam where the patient had been for a considerable time previous to illness. Those present noted that ticks were crawling on the hide of the elk, which was pushed under the table on which the patient did some of the butchering. That evening the patient felt an itching near his navel and on examination found an attached tick which his father pulled loose. The patient recognized it only as a fairly large tick, but the father, on being shown both sexes of D. albipictus and Ixodes pacificus (the two most likely species considering the locality, season, *From the Rocky Mountain Lab3ratory if the National Microbi 1logical Institute, National Institutes of