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EXPERIMENTAL ANALYSIS OF THE IMPORTANCE OF THE DIFFERENT PHASES IN THE METAMORPHOSIS OF ORNITHODOROS PAPILLIPES IN THE TRANSMISSION OF THE SPIROCHAETES OF TICK-BORNE RELAPSING FEVER,
ARMY BIOLOGICAL LABS FREDERICK MD
Pagination or Media Count:
Larvae, fully or partially engorged on infected pigs, during repeated feeding in the same phase of development, attached themselves on a small scale and did not infect pigs. Considering that larvae which received spirochaetes by the transovarian route caused illness only in rare cases, the role of larvae in the transmission of spirochaetes to susceptible mammals must be considered as insignificant, but they do represent a phase during which the mass infection of ticks by spirochaetes can take place. Nymphs, infected in the previous stage or in the larval phase, infected pigs as a rule. Adult ticks may be infected with spirochaetosis either during the adult phase or by receiving the spirochaetes in one of the previous phases of metamorphosis. Adult ticks which have fed on infected pigs became capable of transmitting the spirochaete in no less than 100 days, and often werent infected at all. The significance of the various phases of development of Ornithodoros papillipes ticks in the infection of humans with tick-borne relapsing fever is unequal. The bites of larvae may cause illness only in exceptional cases. Nymphs, in passing through the several phases of their development, require nourishment more frequently than adults. The feeding of one state I nymph is sufficient for infecting a guinea pig. Author
APPROVED FOR PUBLIC RELEASE