An epizootic of bovine tuberculosis in Georgia.

A tuberculous beef animal was detected Aug 29, 1973, by a veterinary medical officer in a Georgia slaughter establishment. Animal identification and traceback eventually led to a purebred beef herd in Decatur County, Georgia. Investigation and tuberculin testing of 23,000 cattle in 350 herds revealed 11 Mycobacterium bovis-infected beef herds and resulted in the complete depopulation of 5 herds. The epizootic was confined to Georgia and was eradicated by April, 1975.     

An epizootic of bovine cysticercosis.

In March, 1973, a large feedlot near Phoenix, AZ, reported an increased incidence of bovine cysticercosis. Approximately 10% of cattle sent to slaughter from January to April, 1973, were infected with the cysticercus stage of Taenia saginata. One employee who worked at the feed mill and loaded hay in the fields was also found to be infected with T saginata. Recommendations for control of similar epizootics included educating employees about mode of transmission and improved personal hygiene, the inauguration of a surveillance program that included examination of employees prior to employment and periodically thereafter, maintenance of animal source and destination records, restriction of unauthorized personnel to critical areas, and periodic microbiologic assay of water supply.     

Current status of bovine haemoparasitic diseases in Martinique (French West Indies)]

A serological survey using indirect immunofluorescence (IFAT) for bovine babesiosis (Babesia bovis and B. bigemina) and card test for anaplasmosis, indicates that these haemoparasites are widespread in Martinique. The high prevalences (62% for B. bovis, 52% for B. bigemina and 43% for Anaplasma marginale) lead to the hypothesis of an unstable epizootic situation for these three haemoparasitic diseases. However, the number of smears examined was too low to evaluate their clinical incidence. Both the American and Cuban card tests gave similar results in the detection of antibodies to A. marginale. Theileria mutans is described for the first time in Martinique. Trypanosomosis (Trypanosoma vivax) has disappeared from Martinique, on clinical and serological evidence.     

Radiography for the diagnosis of spirocercosis in apparently healthy dogs, St. Kitts, West Indies

Fifty apparently healthy island dogs presenting to the Ross University School of Veterinary Medicine (RUSVM), St. Kitts, West Indies for neutering were used in this prospective study. Twelve of the dogs (24%) were diagnosed with spirocercosis based on a positive fecal analysis and characteristic lesions seen during esophagoscopy. Routine thoracic survey radiographs revealed changes previously reported with spirocercosis in 10/12 (sensitivity = 83%) infected dogs, but in none of the uninfected dogs (38/38; specificity = 100%). The most common radiographic changes were an increased fluid density within the caudal dorsal thorax on the lateral view and a widening and/or bulging of the caudal mediastinum on the dorsoventral view. After oral administration of barium sulfate, barium retention or a tortuous esophagus was visible in all infected dogs (12/12; sensitivity 100%) and in one uninfected dog (1/38; specificity 97%). The results show spirocercosis is common on St. Kitts and that radiographs are as dependable as fecal analysis and/or endoscopy in diagnosing the condition.     

Studies on the pathogenesis of epizootic bovine abortion

Ornithodoros coriaceus Koch ticks were fed on 37 pregnant cows. The fetuses were obtained from the cows at 23 to 126 days after maternal tick exposure. Characteristic lesions of epizootic bovine abortion were observed only in those fetuses recovered 100 days more or after maternal tick exposure. Fetuses collected between 50 and 100 days showed mild-to-moderate lymphoid and mononuclear cell hyperplasia. Reaction in fetuses studied less than 50 days after maternal tick exposure were mild. Lesions could not be seen in 2 of the youngest fetuses. Increases in serum immunoglobulin concentrations were present only in those fetuses examined 80 days or more after their dams had been exposed to ticks. The specificity of the immunoglobulins could not be determined. Sera from 12 fetuses tested failed to fix complement in tests for group-specific chlamydial antibodies. A wide variety of microbiological cultivation attempts were made to recover the causative agent of epizootic bovine abortion from these fetuses; however, no agent was recovered regularly, and chlamydial organisms were not recovered from any. The significance of 2 recovered agents, apparently viral, is still to be determined. Fetal tissues, both frozen and fresh, collected from fetuses of dams exposed to a feeding of ticks were capable of reproducing the disease after inoculation into pregnant cows or directly into fetuses.     

Congenital spirochetosis in calves: association with epizootic bovine abortion

Congenital spirochetosis was encountered as a newly recognized infection of cattle. The spirochete was seen in blood of fetuses with lesions of epizootic bovine abortion. A spirochete with morphologic features similar to those found in the fetuses was detected in Ornithodoros coriaceus ticks. Ticks collected from rangelands were allowed to feed on cows that then produced epizootic bovine abortion-affected fetuses, and the fetuses had spirochetosis. Inapparent spirochetosis also was found in fetuses in clinically normal cattle sent to slaughter. Only a few lesions were seen in abattoir-collected fetuses. Fetal spirochetosis was common in the bovine population studied, and it appeared that infection may be limited only by the availability of the tick vector.     

Integrating banana and ruminant production in the French West Indies

Using a mechanistic model, we compared five alternative farming systems with the purpose of transforming monoculture (MON) banana farms into mixed farming systems (MFS) with ruminants feeding banana by-products (leaves, pseudostems and nonmarketable fruits) and forage from the fallow land. The paper presents the main structure of the model (land surface changes, available biomass for animals, stocking rates, productive or reproductive indicators), and impact assessment (change in farm productivity) is discussed. Five MFS with typical local ruminant production systems were used to compare MON to the strategies using forage from fallow and/or integrating Creole cattle (CC), Creole goats (CG) or Martinik sheep (MS) into banana farming. One hectare MON shifted into an MFS allows a stocking rate of 1,184, 285, and 418 kg of live weight per hectare for CC, CG and MS, respectively. Banana by-products seem to be better valorized by the CC scenario. However, parameters such as length of the cycle, local prices for cattle, goat and sheep meat, work time and farmer's skills in ruminant management may have been taken into account by the farmer when choosing the ruminant species to rear.     

An experimental intratonsilar infection model for bovine tuberculosis in African buffaloes, Syncerus caffer

An infection model for Mycobacterium bovis in African buffaloes, Syncerus caffer, was developed, using the intratonsilar route of inoculation. Two groups of 11 buffaloes each, aged approximately 18 months, were infected with either 3.2 x 10(2) cfu (low dose) or 3 x 10(4) cfu (high dose) of M. bovis strain isolated from a buffalo. A control group of six buffaloes received saline via the same route. The infection status was monitored in vivo using the comparative intradermal tuberculin test, and in vitro by the modified interferon-gamma assay. All buffaloes were euthanazed 22 weeks post infection and lesion development was assessed by macroscopic examination, culture and histopathology. It was found that the high dose caused macroscopic lesions in nine out of 11 buffaloes. Mycobacterium bovis was isolated from all buffaloes in the high-dose group and from six out of 11 in the low-dose group.     

An epizootic of leptospirosis in California sea lions

Between May and December 1984, an epizootic of leptospirosis in California sea lions (Zalophus californianus) occurred along the west coast of the United States from Monterey County, Calif, northward to Seattle, Wash. Clinical signs observed were severe depression, excessive thirst, and tucked-up posturing, with associated leukocytosis and increased globulin, BUN, and creatinine values. Effective antibiotic therapy consisted of tetracycline (22 mg/kg of body weight every 8 hours, orally) or potassium penicillin G (44,000 U/kg every 12 hours, orally or IM) for 10 to 14 days. Sixty-six sea lions were treated successfully and released. Necropsies of animals that died indicated marked kidney swelling, darkened reniculi, and poorly differentiated cortices and medullae, thick, black bile in gallbladders, thick, pale yellow pericardial fluid, and friable hemorrhagic mesentery. Primary histologic lesions were tubular nephritis and glomerulonephritis. Darkfield microscopy of kidney macerates and/or urine, and results of the microscopic agglutination test, using Leptospira serovar pomona-killed antigen led to a presumptive diagnosis of leptospirosis. Bacteriologic isolation and identification is ongoing. The epizootic primarily affected juvenile or subadult male California sea lions migrating northward from breeding rookeries of southern California's Channel Islands.     

Histochemical and immunohistochemical evidence of a bacterium associated with lesions of epizootic bovine abortion.

Epizootic bovine abortion (EBA), a tick-transmitted disease of pregnant cattle grazing foothill pastures, is a major cause of reproductive failure in California and adjacent states. Affected fetuses develop a chronic disease, resulting in late-term abortion or premature calving. Despite investigations spanning 50 years, to the authors' knowledge, the etiologic agent of EBA has not yet been isolated from affected fetuses or the tick vector. The diagnosis of EBA is based on gross and microscopic lesions. Recently, documentation that the etiologic agent is susceptible to antibiotics and identification of a unique 16S deltaproteobacterial rDNA gene sequence in 90% of thymus tissues from aborted fetuses have supported the role of a bacterial infection as the cause of EBA. To determine whether bacteria could be detected in the tissues, histochemical staining and immunohistochemical procedures were used on formalin-fixed, paraffin-embedded tissues. Use of a modified Steiner silver stain revealed small numbers of intracytoplasmic bacterial rods in 37 of 42 thymic samples from EBA-affected fetuses. Improved detection was achieved by use of immunohistochemical staining with serum from EBA-affected fetuses that resulted in detection of numerous bacterial rods in the cytoplasm of histiocytic cells in the thymus from all 42 EBA-affected fetuses. Immunohistochemical examination of additional tissues from 21 field and experimental EBA cases revealed positively stained intracytoplasmic bacterial rods in many organs with inflammatory lesions. Use of the modified Steiner stain and immunohistochemical staining of tissues from negative-control fetuses failed to reveal organisms. To the authors' knowledge, this is the first report to document morphologic evidence of a bacterium associated with the lesions of EBA.     

Lymphocyte blastogenesis and cellular cytotoxicity in a congenital infection of bovine fetuses related to epizootic bovine abortion

The disease referred to as epizootic bovine abortion (EBA) was experimentally induced in bovine fetuses. Dark-field microscopy was used to detect congenital infection with an unclassified spirochaete-like organism. Some of the fetuses collected at abattoirs were also found to be naturally infected with a morphologically similar microorganism. Blood counts and organ weights were correlated with the presence of the microorganism. Lymphocyte blastogenesis increased, the result of in vivo stimulation among the infected fetuses. Phytomitogens (phytohaemagglutinin, concanavalin A and lipopolysaccharide) also stimulated greater responses in infected fetuses when compared to results in normal fetuses. Cellular cytotoxicity was examined by the single cell assay and results indicated that there were fewer cytotoxic lymphocytes among the diseased fetuses. The infected abattoir-collected specimens were obtained from clinically normal adult cattle, and the immunological changes in these fetuses were closely characterised with those of the EBA diseased fetuses. These naturally infected fetuses showed signs of a mild infectious disease.     

ELISA tests for antibodies in experimental bovine tuberculosis.

It was shown that 10(4) cfu of a field isolate of Mycobacterium bovis caused illness in five experimentally infected calves; one of these died. One of three contact calves also became clinically infected. Considerable variation in the humoral response of the affected animals was demonstrated by ELISAs using purified protein derivative (PPD) and phosphatide antigens. The inoculation of antigens used in the comparative tuberculin skin test significantly enhanced the level of PPD antibodies in the affected animals whereas that of the apparently non-infected contact animals remained unchanged.