Tick-borne Fever Research Articles

Preservation of the infectious agent of tick-borne fever in the frozen state

Preservation of the infectious agent of tick-borne fever in the frozen state

Electron microscopy of tick-borne fever agent in bovine and ovine phagocytizing leukocytes.

Tuomi, Jaakko (University of Helsinki, Helsinki, Finland), and C.-H. von Bonsdorff. Electron microscopy of tick-borne fever agent in bovine and ovine phagocytizing leukocytes. J. Bacteriol. 92:1478-1492. 1966.-Two strains of tick-borne fever agent, one more virulent to cattle and the other more virulent to sheep, were studied in thin sections of leukocyte concentrates of an affected calf and sheep, respectively. The calf was partially immune from previous infections. To obtain leukocyte concentrate, erythrocytes were lysed by ammonium chloride solution. Glutaraldehyde fixation and osmium tetroxide postfixation were used. Agent particles were detected in neutrophil and eosinophil granulocytes (occasionally also in monocytes) inside cytoplasmic vacuoles. The preparation from the sheep revealed that the tick-borne fever agent has a life cycle; it appeared as large particles, intermediate forms, and small particles. In the preparation from the calf, only large particles were observed, probably as a result of partial immunity. Large particles had a cell wall, plasma membrane, cytoplasm with ribosome-like granules, and nucleoid. They were often elongated, bearing closer resemblance to rickettsiae than to psittacosis-lymphogranuloma-trachoma (PLT) agents. The arrangement of large particles in vacuoles was variable and provided an explanation for the different forms of light microscopic tick-borne fever bodies. The intermediate forms and small particles resembled those of PLT organisms. Release of particles occurred by rupture of inclusions. In the calf also extrusion of whole inclusions was observed. This phenomenon was thought to reflect increased resistance of the cells. The large particle was considered to be the usual infective form of the agent. A middle-ground position of the agent between the genus Rickettsia and the PLT group is suggested.

Pathology of Domestic Animals

Volume II covers the systemic and special pathology of the alimentary, urinary, and nervous system and the liver, peritoneum, mesentery, muscle, eye, ear, skin, and appendages. Certain diseases which resisted the authors' systemic classification (including African horsesickness, hog cholera, toxoplasmosis, and tickborne fever) are covered in the appendix. The rather unusual method of presentation of the material will elicit varying responses, and the over-all effectiveness of the arrangement cannot be judged until the book has been used extensively by workers in a variety of activities. Both volumes are sure to be received favorably by research workers and teachers—if not because of the unusual arrangement, then in spite of it, for this is indeed a notable production. The important subject of neoplasia seems to suffer somewhat from the organ-system method of presentation. This may be justified, however, by the strong emphasis on the diseases of organs and systems which has been achieved.

Adaptation of the Infectious Agent of Tickborne Fever To Guinea-Pigs And Mice

Adaptation of the Infectious Agent of Tickborne Fever To Guinea-Pigs And Mice

Further experiments on the effect of tick borne fever infection on the susceptibility of lambs to staphylococci

Further experiments on the effect of tick borne fever infection on the susceptibility of lambs to staphylococci

The Effect of Tick-Borne Fever on the Resistance of Lambs to Staphylococci

The Effect of Tick-Borne Fever on the Resistance of Lambs to Staphylococci

Tick-borne fever as a cause of abortion in sheep.

Tick-borne fever as a cause of abortion in sheep.

Tick-borne fever as a cause of abortion in sheep.

Tick-borne fever as a cause of abortion in sheep.

The Recognition of Tick-Borne Fever as a Disease of Cattle

The Recognition of Tick-Borne Fever as a Disease of Cattle

Dr. W. S. Gordon

IN the obituary notices in this issue reference is made to the work of the late Major G. W. Dunkin, who was director for the past five years of the Compton Field Station of the Agricultural Research Council. Dr. W. S. Gordon, senior bacteriologist, Animal Diseases Research Association, Moredun Institute, Gilmerton, Edinburgh, has been appointed to succeed Major Dunkin. A graduate of the Glasgow Veterinary College in 1923, Dr. Gordon was on the staff of the Wellcome Physiological Research Laboratories, Beckenham, for some years and took up the Scottish appointment in 1930. At Beckenham he was associated with Prof. Dalling, and other workers in those laboratories, in the production of biological products, and particularly in investigations of anaerobic infections in sheep. In Scotland he has led a team of workers in investigating and dealing with certain sheep diseases, notably louping-ill, tick-borne fever, braxy and lamb dysentery.

Studies in Tick-borne Fever of Sheep

(1) Female Ixodes ricinus ticks which feed on a sheep infected with tick-borne fever are not capable of transmitting the infective agent to their progeny. Only the nymphs and females, therefore, can be infective to sheep. In the case of an infective female, the infection may have been acquired, (a) in the immediately preceding stage, or (b) in the larval stage, the infective agent remaining in the tissues of the tick during the nymphal engorgement and subsequent moult. This appears to occur irrespective of whether the host on which the nymph feeds is a susceptible or an insusceptible. animal.(2) Ticks which have acquired infection are infective as soon after moulting to the next stage as they are able to attach to hosts. Unfed ticks were not found to be infective after a period of about 14 months.(3) Infection is transmitted to the sheep in the course of the 2nd day after attachment of infective nymphs.(4) The disease may be transmitted to sheep by inoculation of emulsions of infective ticks, if these have been allowed to commence engorgement. The use of saline for such emulsions appears to be inadvisable.

Studies in Tick-borne Fever of Sheep. I. Transmission by the Tick, Ixodes ricinus, with a Description of the Disease Produced

1. The causal agent of tick-borne fever is transmitted by the adult female and the nymphal stage of the tick Ixodes ricinus. Two female ticks are sufficient to produce infection in a sheep. The larval stage does not appear to be infective. In a limited number of experiments the disease has not been produced in sheep by the inoculation of emulsions of presumably infective ticks.2. The disease as produced by tick infestation is characterised by a period of incubation which varies from 3 to 13 days, after which there is a sharp rise in temperature; a “plateau” type of febrile reaction follows which lasts from 6 to 22 days, the temperature gradually subsiding to normal. Affected animals usually recover. Mortality as a direct result of infection is rare, but there is evidence to suggest that tick-borne fever may predispose affected animals to death from secondary causes.3. The blood of a sheep which has reacted to the disease remains infective for some time after the subsidence of the thermal reaction.4. The goat is susceptible to tick-borne fever.5. The economic importance of tick-borne fever is discussed.

American Mountain Tick-Fever—Semiography and Nosology

Excerpt The tick borne fever of the mountainous areas of western North America has on several occasions since 1850 been the subject of brief remarks and of other publications of a more comprehensiv...