Effective animal health disease surveillance using a network-enabled approach.

There are many benefits that derive from real-time knowledge of the health status of the national livestock population. Effective animal disease surveillance is a requirement for countries that trade in live animals and their products in order to comply with the World Organization for Animal Health (OIE) guidelines. Rapid identification of introduced and emerging disease allows rapid response and mitigation of the economic consequences. Connections between animal and human disease caused by a common pathogen can be recognized and control measures implemented, thereby protecting public health and maintaining public confidence in the food supply. Production-limiting diseases can be monitored, and control programmes be evaluated with benefits accruing from decreased economic losses associated with disease as well as reducing the welfare concerns associated with diseased animals. Establishing a surveillance programme across a wide area with diverse ecosystems and political administrations as Canada is a complex challenge. When funding became available from a government programme to enable early detection of a bio-terrorist attack on livestock, the Canadian Animal Health Surveillance Network (CAHSN) became officially established. An existing web-based information platform that supports intelligence exchange, surveillance and response for public health issues in Canada was adapted to link the network animal health laboratories. A minimum data set was developed that facilitated sharing of results between participating laboratories and jurisdictions as the first step in creating the capacity for national disease trend analysis. In each of the network laboratories, similar quality assurance and bio-containment systems have been funded and supported, and diagnostic staff have been trained and certified on a suite of diagnostic tests for foreign animal diseases. This ensures that national standards are maintained throughout all of the diagnostic laboratories. This paper describes the genesis of CAHSN, its current capability and governance, and potential for future development.

Risk management of the transmissible spongiform encephalopathies in North America.

As North American Free Trade Agreement partners, Canada, the United States of America (USA) and Mexico apply independent but harmonised transmissible spongiform encephalopathy (TSE) risk management strategies in observance of Office International des Epizooties guidelines. The divergence between bovine spongiform encephalopathy (BSE) risk management approaches in North American and Europe reflects comparatively reduced external and internal BSE risks in North America. The external quarantine and internal surveillance measures adopted for BSE respond to several iterations of national risk assessments initiated in the early 1990s and revised as recently as 2002. Feed bans applied since 1997 to preclude establishment of BSE also bear the potential to limit intra-species and inter-species exposure to scrapie, chronic wasting disease (CWD) and transmissible mink encephalopathy (TME). Surveillance continues for the four TSEs through collaborative efforts of national and sub-national veterinary infrastructures and accompanying laboratory networks. Mexico has never identified the presence of any TSE. The last diagnosed case of TME in North America dates back to 1985. Since the only recognised appearance in Canada through an import from Great Britain in 1993, BSE has not been detected in North America. Scrapie and CWD remain at generally low prevalence in Canada and the USA. Independent but harmonised eradication programmes target elimination of the latter two diseases.

Titers to Leptospira species in horses in Alberta.

Sera from horses in Alberta, submitted to Agriculture and Agri-Food Canada for routine testing for equine infectious anemia from January 1987 to June 1989, were tested for antibody against 13 serovars of pathogenic Leptospira spp., using the microscopic agglutination test. The purpose of the study was to investigate the prevalence of serum titers to those serovars in horses in Alberta, and to analyze the associated risk factors. Descriptive statistics were compiled and logistic regressions were computed. Titers to L. interrogans serovars icterohaemorrhagiae, bratislava, copenhageni, and autumnalis were common (94.6%, 56.6%, 46.5%, and 43.5%, respectively). The prevalence of titers to other serovars ranged from 0.8% to 27.2%. Age was almost always significantly associated with the presence of titers. In general, the chances of being seropositive rose by approximately 10% with each year of life. Horses managed individually (eg, track horses) were approximately half as likely to be seropositive as were horses managed in groups (eg, rodeo horses).

Ovine Haemophilus somnus: experimental intracisternal infection and antigenic comparison with bovine Haemophilus somnus.

Experimental infection was produced by two of four isolates of ovine Haemophilus somnus given by intracisternal inoculation into two to three-month-old lambs. Isolate 2041 (originally obtained from a septicemic lamb in Alberta) caused lethal infection in eight of nine lambs, isolate 67p from the prepuce of a normal lamb produced less acute disease in four of nine lambs, and the other two isolates (93p and 1190) caused no detectable disease. Significant lesions were limited to the brain and spinal cord. Purulent meningitis was characteristic but vasculitis or septicemia were not detected, perhaps due to the route of inoculation. Since a difference in virulence was noted among strains, we analyzed surface proteins thought to be virulence factors of bovine H. somnus. Protein profiles of bovine and ovine H. somnus done by sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed similar patterns for virulent bovine isolates and ovine septicemic isolates. Preputial isolates showed a lower molecular mass major outer membrane protein than septicemic isolates. Antigenic analysis revealed that outer membrane proteins p270, p78, p76, p40, and p39 were detected in both ovine and bovine isolates except for 1190, which was probably not a true H. somnus isolate. Thus the preputial and septicemic isolates of ovine H. somnus were similar to bovine H. somnus in pathogenicity and in surface antigens.

CRITTER: A database for managing research animals.

We describe CRITTER, a computer database program for managing research animals. We designed it especially for institutions which operate health surveillance plans, such as specific pathogen-free schemes. Because CRITTER can be used to record any type of test result in any species of animal, it can be customized to suit each institution and its management protocol. In addition to maintaining a current inventory of each individual animal and its location, the program retains historical information on those that have been removed from the colony. Output summaries are generated by selecting from a menu of standard reports or by designing a custom query. Although CRITTER has been designed for individual research establishments, it could be modified for use in area health surveillance programs. CRITTER operates on IBM compatible computers using a menu-driven, runtime version of Paradox.

Isolation of border disease virus from twin lambs in Alberta.

We describe herein a field case of border disease (BD) in twin lambs. Both lambs were unthrifty, stunted, and one exhibited nervous signs characteristic of BD, with tremors of the head, neck, hind legs, and pelvis. Hairiness of the coat and excessive pigmentation, often seen in lambs with BD, were not observed. A noncytopathic virus, which showed cross-reactivity with bovine viral diarrhea (BVD) virus antiserum and BVD virus monoclonal antibodies, was isolated repeatedly from leukocytes from one lamb and from tissues of the other. Although the source of the virus is unknown, our results suggest that the dam of the affected twins had been infected during pregnancy. We used the BD virus isolated to inoculate pregnant ewes and experimentally reproduce the disease in a newborn lamb. Our findings indicate that leukocytes, rather than serum, should be utilized for BD virus isolation. Further, it is recommended that BD virus, rather than BVD virus, be used in serum neutralization tests when screening sheep for antibody titers.

Epidemiology of Haemophilus somnus in young rams.

The prevalence of Haemophilus somnus in the prepuce of young rams was examined. Of 473 rams entering Record of Performance (ROP) stations at 50 days of age, 43 (9.1%) were positive. Average daily gain was not affected by Haemophilus status, but was influenced by breed of ram. Suffolks were predicted to gain 0.515 kg daily compared to 0.427 kg for a group combining all other breeds. Using logistic regression to identify risk factors for individual H. somnus infection, rams in 1989 were 0.382 times as likely to be infected as rams in 1988, and Suffolks were 0.314 times as likely to be infected as the other breeds group, but these factors were not significant at the flock level. Of 80 eligible flocks of origin, 22 (27.5%) were classified as infected with H. somnus, based on rams submitted to the ROP station. Infected flocks contributed 133 rams, 43 (32.3%) of which were positive. There was no association between H. somnus status and lambing percent of the percent of abortions and stillbirths, but there was a statistically significant association with the percent of ewes which failed to lamb. In the model developed, 6% of the bred ewes in noninfected flocks failed to lamb, compared to a rate of 12% in infected flocks. These results suggest H. somnus may influence ewe fertility earlier, rather than later in gestation. Purchasing replacement animals and having cattle on the farm were risk factors for Haemophilus infection in the flock. Where replacements had been purchased within the previous year, the risk of flock infection rose 8.5 times, and on farms having cattle as well as sheep, the risk rose 13.2 times.(ABSTRACT TRUNCATED AT 250 WORDS)