The pathology of Rift Valley fever. I. Lesions occurring in natural cases in new-born lambs

A widespread epizootic of Rift Valley fever occurred in the Republic of South Africa and South West Africa during 1974-75. This is a report on the gross pathology of 34 new-born lambs and the histopathology of 93 new-born lambs that died during this outbreak. The liver was affected in every case and showed the most pronounced lesions. The organ was grossly enlarged in most cases, with scattered greyish-white necrotic foci 1-2 mm in diameter and haemorrhages of varying size throughout. Haemorrhages were also frequently seen in the mucosa of the abomasum. The massive diffuse necrosis of hepatocytes (pannecrosis) associated with well-demarcated foci of primary coagulative necrosis, present in 100% of the cases examined, was characteristic of the histopathology of the new-born lamb. Bile thrombi were noticed in the livers of 31% of the lambs and intranuclear inclusions in 49% of the cases. The diagnostic significance of the microscopic liver lesions is discussed. Focal necrosis and haemorrhages were frequently seen in the adrenal cortex while generalized destruction of lymphocytes in the lymph nodes and spleen occurred in many of the animals. In addition, the following hitherto undescribed or previously not well-documented lesions are recorded: (i) mineralization of single or groups of necrotic hepatocytes in 62% of the livers: (ii) pyknosis and karyorrhexis of the cellular elements in the glomeruli and a hyalinized appearance of many of these affected glomeruli; and (iii) necrosis of the tips of the villi in the small intestine in some of the animals.The 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

The pathology of Rift Valley fever. II. Lesions occurring in field cases in adult cattle, calves and aborted foetuses

Since the original description of Rift Valley fever in sheep, cattle and man in the Rift Valley in Kenya in 1931, very little has been published on the disease in cattle. This report deals with the macroscopic and microscopic pathology of field cases of Rift Valley fever in 22 adult cattle, 8 calves and 8 aborted foetuses. The microscopic liver lesions in 13 adult cattle were characterized by marked centri- and midzonal eosinophilic necrosis, involving almost ⅔ of the lobules, and accompanied by sparsely distributed primary foci of necrosis. In 3 animals, however, the hepatic lesions were more focal in nature, while a massive hepatic necrosis was evident in 6 others. In calves, the lesions in the liver ranged from cases showing numerous haphazardly scattered primary foci of necrosis to cases where the latter were accompanied by eosinophilic necrosis of the remaining hepatocytes in the lobules. Vascular lesions, thrombosis and sinusoidal fibrin deposits were sometimes seen in the livers of both calves and adult cattle. Although the aborted foetuses were in a fairly advanced state of autolysis, it was still possible to make a diagnosis of Rift Valley fever from the characteristic lesions which were similar to those reported for new-born lambs. Other noteworthy lesions in adult cattle and calves included pyknosis and karyorrhexis of lymphocytes in the spleen and lymph nodes, widespread serosal and visceral haemorrhages which were sometimes accompanied by copious free blood in the gastrointestinal tract, and a nephrosis.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Photosensitivity in South Africa. IV. Pathological changes in the liver in ovine photosensitivity caused by the plant Asaemia axillaris (Thunb.) Harv. Ex Jackson

Hepatic lesions in 4 field cases of ovine hepatogenous photosensitization caused by the plant, Asaemia axillaris (Thunb.) Harv. Ex Jackson, are described. The liver was usually swollen, friable and yellowish-brown, with distinct lobulation. Microscopically, the lesions ranged from peripheral coagulative necrosis in 1 animal to others with scattered single cell or small foci of necrosis as well as hepatocellular degeneration and unrest, ductular proliferation, portal fibroplasia and cholestasis. The liver lesions are compared with those of previously reported experimental cases of A. axillaris poisoning in sheep. The significance of zonal necrosis and factors that may have a bearing on their production in different hepatotoxic plant poisonings in sheep and cattle in South Africa are discussed.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Subcutaneous and pulmonary emphysema as complications of bovine ephemeral fever

Subcutaneous and pulmonary emphysema was observed in some cattle on farms on which outbreaks of bovine ephemeral fever (BEF) occurred. BEF virus was isolated in baby hamsters from one of the cases and cattle were injected with blood from this animal. Although the experimental animals developed typical BEF symptoms, no signs of emphysema could be detected by clinical and pathological examinations. The histopathological changes in the skeletal muscle and synovial membranes of the natural case resembled those of BEF described by Basson, Pienaar & Van der Westhuizen (1970). The lumina of the terminal and respiratory bronchioles in the lungs were obliterated by cellular debris and the muscular portion of some of these bronchioles was necrotic. The possible pathogenesis of pulmonary emphysema is discussed.This article has 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

Sequential development of the liver lesions in new-born lambs infected with Rift Valley fever virus. I. Macroscopic and microscopic pathology

Ten new-born lambs were necropsied at various intervals after artificial infection with Rift Valley fever virus for the study of the sequential development of the hepatic lesions. During the late stage of the disease, the livers were slightly to moderately swollen and mottled yellow, orange-brown and red. Greyish-white foci, approximately 0,25-0,5mm in diameter, were also scattered throughout the parenchyma. Microscopically, the liver lesions progressed from sparsely distributed acidophilic bodies and hepatocytes, revealing acidophilic degeneration and necrosis 6-12h post-inoculation, to small randomly scattered primary foci of necrosis 12-24h after infection. At 30-36h, these primary foci were larger and more circumscribed. In addition, numerous acidophilic bodies and necrotic hepatocytes were dispersed throughout the markedly degenerated parenchyma. The terminal stage of the disease (48-53h after inoculation), was characterized by massive hepatic necrosis in which primary foci of necrosis could still be recognized as dense aggregates of cytoplasmic and nuclear debris.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Clinical and pathological studies in adult sheep and goats experimentally infected with Wesselsbron disease virus

The clinical symptoms and pathology in 33 adult sheep and 31 adult goats experimentally infected with Wesselsbron disease virus are described. There was moderate to severe hyperthermia in most animals, but no other clinical signs of disease or deaths were recorded. Eleven sheep and 6 goats were sacrificed for pathological studies at various stages during the febrile response. The macroscopic and microscopic lesions in these cases are described. Microscopic studies revealed that the liver was consistently affected and showed small foci of necrosis. These were sparsely distributed and associated with a marked localized Kupffer cell response ("retothelial nodules"). In addition, acidophilic bodies and small groups of necrotic hepatocytes were evident in some lobules. Apart from the hepatic lesions, mild to moderate pyknosis and karyorrhexis of lymphocytes were seen in the spleen and lymph nodes. This report also compares the microscopic lesions in the livers of adult sheep and goats with those of new-born lambs for Wesselsbron disease as well as with those reported for Rift Valley fever in adult sheep.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Wesselsbron disease : virological and serological studies in experimentally infected sheep and goats

Adult sheep and goats and new-born lambs and kids were experimentally infected with a Wesselsbron disease virus. The viraemia in lambs commenced approximately 27 h after infection and lasted on the average for 50 h. A febrile reaction, which was mostly biphasic, commenced several hours after the viraemia and outlasted it by 50 h. The viraemia in adult animals began about 50 h after infection and lasted for 30 h. The fever usually commenced several hours after the viraemia and, as in 3 cases out of 4 in lambs, it outlasted the viraemia by at least 30 h. The virus could be reisolated in mice from every tissue examined in lambs,although it has previously been shown that pathological lesions are restricted to the liver and lymphatic tissues.The 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

Studies on Parafilaria bovicola Tubangui, 1934. Ill. Pathological changes in infested calves

More lesions were found in the carcass of an animal that has been naturally infested with Parafilaria bovicola than in one artificially infested with a single subcutaneous injection of infective larvae of this species. This may be because natural infestations are either more frequent or more successful. Similarities in the distribution of lesions in naturally and experimentally infested animals suggest that certain predilection sites may be used by the intermediate fly hosts. Subcutaneous areas infiltrated with eosinophils are more conspicuous during the first 20 days after infestation and during the patent phase of the life cycle of P. bovicola. Yellowish discolorations caused by oedema are usually present in all lesions. When these are combined with eosinophil infiltrations, the lesions become yellowish-green. After the appearance of bleeding spots the green colour of lesions is dominated by the appearance of a brown pigment (haemosiderin) in numerous macrophages. The histopathological changes in the dermis, subcutis and superficial muscles bordering the affected areas are described.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

The pathology of an inherited lysosomal storage disorder of calves

The clinical symptoms, gross and histopathological, as well as the ultrastructural appearance of a condition in cross-bred Aberdeen Angus calves resembling the inherited lysosomal storage disease, α-mannosidosis, are reported. The neurones and perithelial cells in the brain and the reticuloendothelial cells in the lymph nodes and spleen were extensively vacuolated. The vacuoles were filled with a sparse, flocculated to granular material within which membranous structures were frequently seen. No specific substance could be identified within the vacuoles, either histochemically or ultrastructurally. Besides the vacuolation, cystic tubular structures were seen in the kidneys. The lining epithelial cells of the thyroid follicles were vacuolated while some of the follicles contained no colloid.The 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

Seroprevalence of Rift Valley fever and lumpy skin disease in African buffalo (Syncerus caffer) in the Kruger National Park and Hluhluwe-iMfolozi Park, South Africa

Rift Valley fever and lumpy skin disease are transboundary viral diseases endemic in Africa and some parts of the Middle East, but with increasing potential for global emergence. Wild ruminants, such as the African buffalo (Syncerus caffer), are thought to play a role in the epidemiology of these diseases. This study sought to expand the understanding of the role of buffalo in the maintenance of Rift Valley fever virus (RVFV) and lumpy skin disease virus (LSDV) by determining seroprevalence to these viruses during an inter-epidemic period. Buffaloes from the Kruger National Park (n = 138) and Hluhluwe-iMfolozi Park (n = 110) in South Africa were sampled and tested for immunoglobulin G (IgG) and neutralising antibodies against LSDV and RVFV using an indirect enzyme-linked immunosorbent assay (I-ELISA) and the serum neutralisation test (SNT). The I-ELISA for LSDV and RVFV detected IgG antibodies in 70 of 248 (28.2%) and 15 of 248 (6.1%) buffaloes, respectively. Using the SNT, LSDV and RVFV neutralising antibodies were found in 5 of 66 (7.6%) and 12 of 57 (21.1%), respectively, of samples tested. The RVFV I-ELISA and SNT results correlated well with previously reported results. Of the 12 SNT RVFV-positive sera, three (25.0%) had very high SNT titres of 1:640. Neutralising antibody titres of more than 1:80 were found in 80.0% of the positive sera tested. The LSDV SNT results did not correlate with results obtained by the I-ELISA and neutralising antibody titres detected were low, with the highest (1:20) recorded in only two buffaloes, whilst 11 buffaloes (4.4%) had evidence of co-infection with both viruses. Results obtained in this study complement other reports suggesting a role for buffaloes in the epidemiology of these diseases during inter-epidemic periods