Animal Health
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Item Connective tissue reactions in acute fatal East Coast Fever (Theileria Parva) of cattle(The Journal of Infectious Diseases, 1960) Barnett, S. F.; The Department of Microbiology, The University of Chicago, Chicago 37, Illinois; The East African Veterinary Research Organization, Muguga, KenyaA study was made of the lymph nodes, spleen, myeloid tissue, liver, kidney and blood during the acute fatal course of infections with Theileria parva ( East Coast fever of Africa) in cattle. Temperature readings were also made. Normal tissues formed a base line for comparison. In addition to biopsies, 6 normal cattle and 19 cattle, infected from several days to 21 days, were killed and suitable tissues and blood and tissue smears were made. Especial attention was directed toward the histological findings after the marked onset of fever which occurred from 1.0 to 13 days after infection. Fever, once started, persisted until death. Parasites were only rarely found in lymphocytes during the first 2 days of enlargement of the local node but, thereafter, they increased rapidly until 600 to 900 parasites per 1000 lymphocytes were found at the time of death (after 8 to 11 days of fever). I n the local lymph node adjacent to the site of the infection (the ear via infected ticks) during the early part of enlargement and continuing through the 4th day, lymphocytes and reticular cells mobilized and many dividing forms were seen. These activities began to be augmented by degenerative changes on the 4th to the 6th day and were eventually overshadowed by regressive, degenerating and pathological changes involving depletion of the lymphocytes, disruption and destruction of the lymphocytopoietic centers, a progressive toxicosis of cells associated with cellular destruction especially of the lymphocytes and granulocytes, and terminally a total destruction of heterophils. The local nodes in the final stages of most infections consisted of a uniformly eosinophilic reticular fibrinous material in which normal blood vessels stood out with great clarity. In a few animals, which lived several days longer than the majority, some slight tendency toward recovery was evidenced by the transformation of reticular cells into lymphocytes and by some lymphocyte proliferation. As compared to the local lymph node, these processes were not as intense and were initiated later in other lymph nodes and in the spleen. Extensive changes in the myeloid tissue involved in succession a transient development and proliferation of all cell types, a prolonged period of cell destruction, the arrest of maturation of all cells and the disappearance of the heterophils. Finally, abnormal cells predominated. The liver and kidney as such were not particularly affected except that a regenerative attempt to produce lymphocytes in the kidney destroyed much functional renal tissue in advanced stages of the disease. The above changes were reflected by the blood in that an initial leucocytosis (in about 30% of the animals) gave way to a leucopenia. The white cell count fellprecipitously or gradually about 4 days after the onset of fever to a low level in 2 or more days. An animal rarely survived long after the count reached 1000 cells per cmm. Occasionally, there was a terminal leucocytosis
