Pulmonary tuberculosis in free-living lechwe antelope in Zambia

Summary The Kafue lechwe population of Zambia numbers90,000 and is divided by the River Kafue into two virtually segregated populations. The south bank population is known to be infected with tuberculosis but the north bank is thought to be free. One hundred and twenty-five south bank lechwe were cropped at random and lesions of tuberculosis were found in45 (36%). Isolates from lung lesions were typed asMycobacterium tuberculosis var.bovis. Twenty-five of27 pneumonia cases appeared active and on the assumption that these would die within12 months the annual mortality due to tuberculosis was estimated as around8,000. The disease in lechwe and the neighbouring cattle population is discussed.

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Sumario La poblacion Kafue lechwe de Zambia alcanza a 90,000 y esta dividida por el rio Kafue en dos poblaciones virtualmente segregadas. La poblacion del banco sur es conocida estar infectada con tuberculosis pero el banco norte es sabido estar libre. Se tomaron ciento veinticinco antilopes lechwe al azar del banco sur y se encontraron lesiones de tuberculosis en 45 (36%). Los aislamientos de las lesiones pulmonares fueron tipificadas comoMycobacterium tuberculosis var.bovis. Veinticinco de los veintisiete casos de neumonia parecian activos y asumiendo que estos morrrian en 12 meses, la mortalidad anual debido a tuberculosis fue estimada en aprox. 8,000. Se discute la enfermedad en lechwe y en la poblacion de ganado de los alrededores.

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Résumé La population de cobes de la Kafue lechwe en Zambie compte 90 000 têtes et est divisée par cette rivière de la Kafue en 2 populations virtuellement isolées. La population de la rive sud est connue pour être infectée de tuberculose, mais celle de la rive nord passe pour indemne. Cent vingt cinq cobes lechwe de la rive sud ont été sacrifiés au hasard et quarante cinq (36 p. 100) d'entre eux présentaient des lésions de tuberculose. Les cultures isolées des lésions pulmonaires ont été typées commeMycobacterium tuberculosis var. bovis. Sur 27 cas de pneumonie, 25 sont apparus comme actifs, et sur la supposition que ces animaux seraient morts dans les 12 mois, la mortalité annuelle due à la tuberculose a été estimée à 8 000. Ceci pose le problème des rapports entre la maladie des cobes et celle du bétail voisin.

     

Peripartal changes in serum alkaline phosphatase activity and lactate dehydrogenase activity in dairy cows.

Peripartal serum alkaline phosphatase activity and lactate dehydrogenase activity were measured in 30 dairy cows in order to examine the association between retained fetal membranes and enzyme activity. Daily blood samples were obtained from pregnant cows, starting 15 days before the expected day of calving until eight days after parturition. Sera from 15 cows which retained fetal membranes longer than 24 hours and 15 cows which shed fetal membranes within six hours after parturition were analyzed for alkaline phosphatase and lactate dehydrogenase enzyme activities. Mean alkaline phosphatase enzyme activities ranged from 15.93 to 32.6 U/L in retained and nonretained placenta cows. There was a trend towards higher serum alkaline phosphatase activities in retained placenta cows but the differences were not significant among the groups (P greater than 0.05). Mean lactate dehydrogenase activities ranged from 307.2 to 438.86 U/L in nonretained and retained placenta cows. Lactate dehydrogenase enzyme activities in nonretained and retained placenta cows were similar (P greater than 0.05). The alkaline phosphatase and lactate dehydrogenase enzyme activities peaked at the time of parturition in both groups. However, the differences in alkaline phosphatase and lactate dehydrogenase activities on different days within non-retained and retained placenta cows were significant (P less than 0.05). Results indicate that prepartal changes in alkaline phosphatase and lactate dehydrogenase enzyme activities are not predictive of placental retention postpartum.     

Lesions in the small intestine of newborn pigs inoculated with porcine, feline, and canine coronaviruses

The infectivity and pathogenicity to newborn pigs of antigenically related coronaviruses from pigs (transmissible gastroenteritis virus; TGEV), cats (feline infectious peritonitis virus; FIPV), and dogs (canine gastroenteritis virus; CGEV) were studied by light, scanning electron, and immunofluorescence microscopy. Hysterectomy-derived, 12-hour-old pigs were orally given tissue culture or frozen preparations of 6 coronavirus strains (3 porcine, 2 feline, and 1 canine). The pigs were killed at regular intervals between 24 and 144 hours after exposure. Virulent TGEV and virulent FIPV produced necrosis of villous epithelium, resulting in villous atrophy in the jejunum and the ileum. Similar, but less extensive and severe lesions, were produced by the 4 other viruses. Coronaviral antigens were identified by immunofluorescence in villous epithelial cells of pigs that had been inoculated with virulent TGEV, attenuated TGEV, virulent FIPV, and tissue culture-adapted FIPV. In contrast, coronaviral antigens were not induced by the small plaque variant TGEV and virulent CGEV in the villous epithelium, but rather in cells of the lamina propria and crypt epithelium.     

Should they stay,or should they go? Relative future risk of bovine tuberculosis for interferon-gamma test-positive cattle left on farms

Bovine tuberculosis (bTB), caused by Mycobacterium bovis, is a serious infectious disease that remains an ongoing concern for cattle farming worldwide. Tuberculin skin-tests are often used to identify infected animals (reactors) during test-and-cull programs, however, due to relatively poor sensitivity, additional tests can be implemented in parallel. For example, in Northern Ireland interferon-gamma (IFN-g) testing is used in high-risk herds. However, skin-test negative animals which are positive to the IFN-g test are not required by law to be slaughtered – therefore the final choice for these animals’ fate is left with the owner. During this study we investigated whether these animals represented a greater risk of becoming a skin reactor, relative to IFN-g test negative animals from the same herds. Our study population included 1107 IFN-g positive animals from 239 herds. A Cox-proportional hazard model indicated that animals which tested IFN-g positive were 2.31 times (95% CI: 1.92-2.79; P < 0.001) more likely to become a reactor compared with IFN-g negative animals. Animals from dairy herds, and from herds in the south-east, were of higher risk than animals from beef herds and other regions, respectively. Our findings suggest that IFN-g positive animals represent a higher risk of failing a skin-test in the future, indicating the value of IFN-g testing for identifying early-stage infected animals. These IFN-g positive animals are not under any disease restriction, and may move freely (trade), which may put recipient herds at increased risk. Our findings provide important evidence for stakeholders engaged in bTB eradication programs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-015-0242-8) contains supplementary material, which is available to authorized users.