Experimental Transmission of Tularemia by the Tropical Rat Mite 1

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Abstract
Summary 1. Quantitative methods of study were used in an attempt to observe the changes which took place within infected mites (Bdellonyssus bacoti) after prolonged periods of starvation and after feeding on various types of hosts. 2. The tropical rat mite was shown capable of retaining an infection of Bact. tularense from the protonymph stage throughout the subsequent stages of a single generation. In certain instances this mite transmitted the infection to the next generation. 3. The infection was also retained after several feedings on recovered mice without reduction of the number of infectious organisms. 4. Even after prolonged periods of fasting, no significant decrease in the number of organisms per mite was noted. 5. The tropical rat mite was unable to produce an infection in normal mice by biting. Infection resulted when the mites were crushed orally by the mice. 6. The LD50 titration indicated no loss of virulence in the Sm strain of Bacterium tularense upon mite passage, nor was any increase in virulence noted.