Progress of Spirochaete Infection in the Developmental Stages of the Host Tick, Ornithodoros Hermsi, Wheeler

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  • Pacific Institute of Tropical Medicine within the Hooper Foundation for Medical Research, University of California, San Francisco, California
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From the above series of experiments it has been demonstrated: (1) That hereditary transmission of spirochaetes of California relapsing fever was effected through a small percentage 0.29 per cent of the progeny of infective female ticks; (2) that from 35 per cent to 48 per cent of non-infective ticks when allowed to feed as larvae on infected laboratory white mice were able to acquire the spirochaetes and transmit them to normal animals in some one or all of the subsequent developmental stages; (3) that clean larval ticks produced by a female tick taken at Lake Tahoe were able to acquire the relapsing fever spirochaetes from a white mouse previously infected through the bite of an infected tick taken at Big Bear Lake, some 400 miles distant, and were able to transmit these spirochaetes to clean white mice.