Cytological studies on heartwater II : Rickettsia ruminantium in the tissues of ticks capable of transmitting the disease

The evidence observed in favour of a causative relationship between Rickettsia ruminantium and the production of heartwater falls under the following headings: (1) The discovery of Rickettsia ruminantium in the tissues of goats, sheep, and cattle suffering from heartwater; the close association between their presence in these three species and the febrile reaction; their disappearance soon after the fever has commenced to decline corresponding to the loss in infectivity of the blood; and their absence in control animals (Part 1 of this Report). (2) The appearance of the same Rickettsia, easily identifiable by their very characteristic morphology and staining reactions in two series of ticks (607 and 614) which had fed upon cases of heartwater and which, before feeding, did not contain them; and their non-appearance in three series of control ticks (604, 605, and 606) from the same parent stock which had fed upon normal animals. (3) The fact that the ticks containing Rickettsia in their alimentary tracts when fed upon susceptible animals, produced in them typical attacks of heartwater, which the control ticks, devoid of Rickettsia, failed to do. (4) The completion of the cycle by the recognition of the same Rickettsia in the tissues of these animals (sheep 8049 and goat 9651) which contracted heartwater as a result of having been bitten by the infective ticks containing Rickettsia.Includes bibliographical referencesThe articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.ab202

Cytological studies on heartwater I : the observation of Rickettsia ruminantium on the tissues of infected animals

A Gram-negative, intracellular, coccus-like micro-organism was found in cases of heartwater in the three species which are susceptible to the disease, namely, goats, sheep, and cattle. The presence of this micro-organism was definitely related to the febrile reaction, and it was absent in controls. It probably occurred throughout the body, but was most easily detected in the renal glomeruli and in the small capillaries of the cerebral cortex. The micro-organism was a typical endothelial parasite, being restricted in distribution to the endothelial cells of the smaller blood-vessels and to portions of them which broke off into the blood stream. It was never observed to cause any injury to the endothelial cells other than mechanical distension through accumulation in large densely packed masses which were characteristically spherical. A typical attribute was the presence of several of these masses with the cytoplasm of a single endothelial cell. In view of the association of this micro-organism with heartwater, which is a disease of ruminants, and thus far the only one in which micro-organisms resembling Rickettsia have been reported, the designation Rickettsia ruminantium is proposed.Includes bibliographical referencesThe articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.ab202

Basic Biological Sciences

Cytomegaloviruses undergo the classical morphologic stages of replication in hedgehog submandibular gland duct cells. A profound cytomegaly is associated with the infection. These features indicate that the hedgehog may be an excellent model in which to study the biology of cytomegalovirus-salivary gland interactions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66837/2/10.1177_00220345830620031501.pd