Cornelius B. Philip

Impairment of muscle stretch reflexes in tick paralysis.

Experiments with tick-paralyzed dogs and woodchucks have shown impairment of stretch reflexes in addition to partial paralysis at the neuromuscular junction. Stretch reflexes disappear very early during paralysis, whereas nociceptive reflexes do not appear to be directly affected. The early incoordination and the ascending nature of the paralysis may be related to impairment of stretch reflex pathways.

Elk, Winter Ticks, and Rocky Mountain Spotted Fever : a Query.

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 fathers 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

Rocky Mountain spotted fever: failure of Triatomid bugs to transmit the virus experimentally

1. - The following species of blood-sucking triatomids failed to transmit the virus of Rocky Mountain spotted fever to susceptible guinea pigs by feeding at the following respective time intervals after the infective feeding: Eutriatoma uhleri, 33, 47, 75, and 141 days (one bug); Triatoma protracta, 15 and 37 days (one bug); T. infestans, 8 days (15 bugs); and Rhodnius prolixus, 2 days (1 bug). The last was shown to contain virus. 2. - Mechanical transmission tests by undelayed, interrupted feedings of 3 species, T. protracta and R. prolixus, were also negative. One insect of the former species accepted 2 infective and 2 normal (test) feedings, while 22 bugs of the latter species accepted alternate blood-meals one to 3 times each on infected and normal guinea pigs. 3. - Fecal droplets collected from one R. prolixus 2 days after an infected feeding failed to infect when injected into a susceptible guinea pig, although virus was shown to be present inthe bug by subsequent injection of the viscera into another test animal. 4. - The period of survival of the virus in the bugs was determined by injection of gut contents at various short intervals after infected feedings. T. infestans: Positive once a 24 hours and twice at 48 hours; negative twice at 72, 96, 120 and 192 hours each. Panstrongylus megistus: Positive 3 times at 24 hours, twice at 48 hours, and once at 72 hours; negative once each at 72 and 96 hours; tests doubtful or valueless once at 48 hours, and twice each at 72, 96 and 144 hours. R. prolixus: Positive once each at 24, 48 and 72 hours, and negative at 96 hours. 5. - From these data, involving species of 4 genera of the Triatomidae, it appears unlikely that triatomids can either transmit Rocky Mountain spotted fever by their bites, or retain virulent virus within their bodies for longer than 2 to 4 days.