International standards: the World Organisation for Animal Health Terrestrial Animal Health Code.

This paper provides a description of the international standards contained in the TerrestrialAnimal Health Code of the World Organisation for Animal Health (OIE) that relate to the prevention and control of vector-borne diseases. It identifies the rights and obligations of OIE Member Countries regarding the notification of animal disease occurrences, as well as the recommendations to be followed for a safe and efficient international trade of animals and their products.

International standards in mitigating trade risks.

This paper describes the role of the World Organisation for Animal Health (OIE), as a science-based and democratic standard-setting organisation that provides guidance on preventing the spread of animal diseases, including zoonoses, in international trade. The World Trade Organization is identified as the international institution with the legal power to encourage adherence to international standards and mediate trade disputes. The importance of assuring good governance and the credibility of national Veterinary Services through a process of official certification is identified as an essential component in the safety of trade. Private-public partnerships and the evolution of responsibilities are also identified as essential for the implementation of health guarantees such as compartmentalisation. The rapid emergence of private standards is described as a potential complement to the implementation of sanitary standards, as long as they are applied globally and in support of the OIE standards. Ultimately, the biggest challenge is for the international community to create the incentives and generate the political will for fair trade and for the universal recognition and application of the established international sanitary standards.

Animal welfare and international trade.

Globalisation is becoming a force that is revolutionising international trade, particularly that of animals and animal products. There is increasing interest in animal welfare worldwide, and as part of its 2001-2005 Strategic Plan the World Organisation for Animal Health (OIE) identified the development of international standards on animal welfare as a priority. The OIE's scientific approach to standard-setting provides the foundation for the development, and acceptance by all OIE Member Countries, of these animal welfare guidelines. The paper discusses how these guidelines on animal welfare can be implemented, both within the provisions of World Trade Organization (WTO) agreements and within the framework of voluntary codes of conduct. Even if animal welfare guidelines are not covered by any WTO agreements in the future, bi- and multilateral agreements, voluntary corporate codes, and transparent labelling of products should result in a progressive acceptance of OIE guidelines. Ultimately, consumer demands and demonstrable gains in animal production will result in an incremental evolution in animal welfare consciousness and adherence to international standards.

Approaches to resolving trade disputes.

The authors discuss the various approaches to resolving trade disputes available to Member Countries of the OIE (World organisation for animal health). The paper first describes the rights and obligations of Member Countries in setting health measures for the importation of animals and animal products, according to the provisions of the World Trade Organization (WTO) Agreement on the Application of Sanitary and Phytosanitary Measures (the SPS Agreement). The authors indicate how OIE standards may be used to set import measures and introduce issues such as equivalence and the use of provisional measures, which are both areas of potential conflict. The authors then describe the options available for resolving disputes--bilateral discussions, mediation through the OIE, the use of the WTO SPS Committee and the formal WTO dispute settlement process, discussing the advantages and disadvantages of each.

Protecting health, facilitating trade, or both?

The General Agreement on Tariffs and Trade (GATT) has existed and dealt with trade issues since 1947. However, to take on the question of to what extent can we set fair and science-based rules allowing countries to have the sovereign right to set measures for protecting public, animal and plant health and food safety, while not creating unjustified barriers to trade was the challenge of the Uruguay Round negotiators. The outcome of this seven-year exercise was the SPS Agreement discussed here. A number of key issues are addressed: transparency including notification, special and differential treatment for developing countries, harmonization, equivalence, regionalization, risk analysis, and other matters. Early warning and exposure of these issues has encouraged countries to resolve their problems quickly. Some of the issues that should be taken into consideration during this next round are the following: biotechnology, aquaculture, consumer concerns, animal welfare, the environment, organic foods, morality in trade, compliance with the WTO, compensation, and the precautionary principle. Compliance with the decision of the WTO is an area of grave concern, especially if developed and powerful countries continue to threaten the survival of the WTO system through lengthy and costly legal interpretations and appeals of dispute settlements without serious efforts by all parties to find win-win solutions. In spite of these problems, over all we must recognize the significant gains in trade thanks to the SPS Agreement. The most flagrant trade violations have been eliminated as a result of improved transparency in the process. Consumers are in general better off, since they have greater diversity and increased safety in what they can buy.

The relationship between the World Trade Organisation and the Office International des Epizooties.

The provisions of the World Trade Organisation Agreement on the Application of Sanitary and Phytosanitary Measures are designed to extend the liberalisation of trade, without increasing the risk to public, animal or plant health. The international standards set by the Office International des Epizooties (OIE) will be used as a benchmark by World Trade Organisation panels and committees when evaluating national sanitary-based regulations. For a significant liberalisation of trade to be achieved, Member Countries are faced with a dual mandate: a) each country must put these concepts into practice when making import/export decisions; and b) each country must make the commitment to support the OIE in its efforts to develop and review sanitary standards. Of equal importance to the application of standards is the cultural change that trade and regulatory communities must undergo. The author examines the role of Member Countries and the OIE in the implementation of this important agreement.

Restriction endonuclease analysis as a taxonomic tool in the study of pig isolates belonging to the Australis serogroup of Leptospira interrogans.

Restriction endonuclease analysis was performed on DNAs from the type strains of the Australis serogroup of Leptospira interrogans by using 20 restriction enzymes, and the electrophoretic patterns obtained were compared with patterns obtained from 162 Australis serogroup isolates from pigs. It proved to be a quick and reliable method for typing such strains. All of the pig isolates were identified as either serovar bratislava or muenchen. It also showed differences at the subserovar level which may be important in (i) understanding the epidemiology of the Australis serogroup, (ii) the development of suitable vaccines, and (iii) pathogenesis and pathogenicity studies. Two genotypes (B2b and M2) accounted for 92% of isolates from aborted or stillborn piglets, while a third genotype (B2a) was the only one recovered from the brains of piglets with meningitis.

Effect of vaccination with a pentavalent leptospiral vaccine on Leptospira interrogans serovar hardjo type hardjo-bovis infection of pregnant cattle.

Effectiveness of a pentavalent leptospiral vaccine to protect cattle from infection and reproductive problems caused by Leptospira interrogans serovar hardjo type hardjo-bovis was evaluated. Seven cows were vaccinated once and 8 cows were vaccinated twice with a USDA-licensed pentavalent leptospiral vaccine. Five cows were maintained as nonvaccinated controls. Cows were bred 1 to 2 months after the last vaccination. During the 4th to 6th month of gestation, all cows were challenge exposed on 4 occasions by conjunctival instillation of 10(8) serovar hardjo type hardjo-bovis organisms and on 3 occasions by conjunctival instillation of urine from a cow shedding hardjo-bovis. All control cows and 13 of 15 vaccinated cows became infected and shed leptospires in the urine. Leptospires were detected in fewer urine samples collected from vaccinated cows, compared with those collected from control cows. Four stillborn calves and 3 weak calves were born to control and vaccinated cows. Leptospires were detected in the kidneys of 11 apparently healthy calves born to vaccinated and control cows. Agglutinating antibodies were not detected in the precolostral serum of these calves.

The distribution of ferritin, lactoferrin and transferrin in granulomatous lymphadenitis of bovine paratuberculosis.

Immunohistochemical examination of iron-binding proteins was carried out in the formalin-fixed mesenteric lymph nodes of normal cattle and of cattle with paratuberculosis. Ferritin (FT) and lactoferrin (LF) were found in the granulomas in ileal lymph nodes from six infected cattle. A weak reaction for transferrin (TF) was found in granulomas of a lymph node from one of the infected cattle. FT was found in the macrophages in the medullary sinuses of normal and infected nodes; however, the reaction in infected nodes was generally stronger than that in normal ones. LF in the macrophages was found in only two infected nodes. Neutrophils in both normal and infected cattle always reacted strongly for LF. The TF was always found in the blood vessels and intracellular space. These results suggest that: (1) FT and LF may be important in vivo sources of iron for Mycobacterium paratuberculosis, since their own iron-binding compounds are considered to acquire iron from FT and LF in vitro; (2) the increase in FT and LF in the granulomas may be related to inflammatory hyposideraemia associated with paratuberculosis and (3) epithelioid and giant cells may have a different iron metabolism, from normal macrophages.

Restriction endonuclease analysis of Leptospira interrogans serovar hardjo isolates from cattle.

The genomes of 253 strains of Leptospira interrogans serovar hardjo were examined by restriction endonuclease analysis of their DNA. The strains had been isolated from cattle at an abattoir (190), milk of agalactic cows (seven) and from aborted bovine fetuses (56). Two distinct genome types, Hardjoprajitno and Hardjobovis, were detected. The majority (91 per cent) of isolates from abattoir cattle were of the Hardjobovis type while most (76 per cent) of the isolates from clinical/pathological material were similar to Hardjoprajitno.

Role of M cells and macrophages in the entrance of Mycobacterium paratuberculosis into domes of ileal Peyer's patches in calves.

Ligated ileal loops of calves were inoculated with live and heat-killed Mycobacterium paratuberculosis and were examined by light and electron microscopy. At 5 hours after inoculation, acid-fast bacilli were in subepithelial macrophages, but not in M cells covering domes. At 20 hours, more than 50 acid-fast bacilli per cross section were in subepithelial macrophages in domes. Both living and heat-killed bacilli passed into domes. Addition of anti-M. paratuberculosis bovine serum to the inoculum enhanced entry of bacteria into domes. By electron microscopy, intact bacilli with electron-transparent zones (peribacillary spaces) were in the supranuclear cytoplasm of M cells at 20 hours. M cells also contained vacuoles, including electron-dense material interpreted as degraded bacilli. Subepithelial and intraepithelial macrophages contained bacilli and degraded bacterial material in phagosomes. These results suggest that calf ileal M cells take up bacilli, and that subepithelial and intraepithelial macrophages secondarily accept bacilli or bacterial debris which are expelled from M cells.

Genetic and antigenic differences of serologically indistinguishable leptospires of serovar hardjo.

Pathogenic leptospires of serovar hardjo isolated from North American cattle were compared genetically and antigenically to reference strain hardjoprajitno of the Sejroe serogroup. Guanine-plus-cytosine (G+C) contents were determined for the genomes, and microscopic agglutination, Western blotting (immunoblotting), and immunoprecipitation were used to characterize antigenic relatedness. Major differences were demonstrated between the isolates and the reference strain. The G+C content of the reference strain was calculated to be approximately 34 +/- 1%, and those of the isolates were calculated at 39 +/- 1%. Antigenic differences between the isolates and the reference strain were identified by using rabbit immune serum raised against a hardjo isolate exhaustively adsorbed with hardjoprajitno whole and sonicated cells. Western blot analysis and immunoprecipitation using this adsorbed serum revealed antigens apparently unique for the hardjo isolates. Microscopic agglutination with the adsorbed rabbit serum did not agglutinate hardjoprajitno when diluted 1:2 but agglutinated bovine isolates to a 1:32 dilution. Bovine antiserum raised against the isolates was also used to identify antigens by immunoprecipitation.

Isolation and analysis of restriction endonuclease digestive patterns of chromosomal DNA from Mycobacterium paratuberculosis and other Mycobacterium species.

A relatively rapid and efficient method for the extraction of chromosomal DNA from Mycobacterium paratuberculosis and other mycobacteria was developed. Approximately 25 to 50 micrograms of DNA could be extracted from 100 mg (wet weight) of cells, which was sufficient to perform several restriction endonuclease analyses from a single preparation. The DNA from five Mycobacterium species, including four strains of M. paratuberculosis and four strains of M. avium, was analyzed by this method. Digestion with the restriction endonucleases BstEII and PstI yielded the most definitive restriction patterns. For some strains, the restriction endonuclease analysis results were in agreement with the current identification of these organisms. The two strains of M. avium serotype 2 had identical fragment patterns. Similarly, the two strains of M. avium complex serotype 6 had identical fragment patterns. The three mycobactin-dependent M. paratuberculosis strains were very similar, whereas the mycobactin-independent M. paratuberculosis strain was more similar to the M. avium serotype 2 strains. Although many more cultures would need to be evaluated to determine correct groupings, the results of this study demonstrated the potential of restriction enzyme analysis for the differentiation of slowly growing mycobacteria.

Survey of selected diseases in wild swine in Texas.

Tissue, fecal, and serum specimens and swabs of nasal turbinates and tracheas were collected from 100 wild swine (Sus scrofa) from 10 populations in Texas and, along with 24 additional serum specimens, were evaluated for selected swine diseases. Swine positive for pseudorabies were detected in 7 populations. Brucella suis biovar 1 was isolated from 4 swine from 2 populations, but positive serologic results may indicate a more widespread distribution of the organism. All populations contained swine that were positive for leptospirosis. Trichinella spiralis was not found in the swine evaluated.

Isolation of leptospires from the genital tracts of Iowa cows.

Leptospira interrogans serovar hardjo was recovered from 5 of 11 nonpregnant cows chosen at random from an Iowa slaughterhouse. Isolations were made from the kidney in each instance, the genital tract of 3 cows: uterus from 1 cow, oviduct of another, and oviduct and uterus of a 3rd cow.

Isolation of Leptospira interrogans serovar bratislava from sows in Iowa.

Leptospira interrogans serovar bratislava was recovered from 2 of 10 sows examined from an Iowa slaughterhouse. Isolations were made from the kidney and genital tract of each sow. Serovar bratislava is not included in vaccines because it has not been previously isolated in the United States.

DNA homology studies of leptospires of serogroups Sejroe and Pomona from cattle and swine.

Hybridization studies of chromosomal DNA from leptospiral strains representing Leptospira interrogans, serogroups Sejroe and Pomona from cattle and swine were performed to determine the degree of homology among their DNA sequences. Chromosomal DNA isolated from leptospires of the Sejroe and Pomona serogroups was radiolabeled and used to probe DNA isolated from other strains in these serogroups. Serovars hardjo (hardjoprajitno), hardjo (hardjo-bovis), balcanica (1627 Burgas), pomona (pomona), and kennewicki (LT-1026) were probed to determine the degree of homology among their chromosomes. Serovars pomona and kennewicki were homologous to each other. They also had a high degree of homology with hardjo (hardjoprajitno) and, to a lesser extent, with hardjo (hardjo-bovis) strains. However, hardjoprajitno and hardjo-bovis had little homology to each other. Serovar balcanica had a high degree of homology with hardjo-bovis isolates, but little homology with hardjoprajitno. Although serologically indistinguishable, the reference strain hardjoprajitno was genetically dissimilar to hardjo-bovis strains isolated from North American cattle.

Isolation of leptospires from the genital tract and kidneys of aborted sows.

Twenty sows were examined as part of an investigation into the relative importance of the genital and urinary tracts as sites of leptospiral persistence in pigs. The sows had previously either aborted leptospire-infected fetuses or aborted on farms where leptospire infection had been demonstrated in other litters. Leptospires belonging to the Australis serogroup were recovered from the upper genital tract of all the sows. In contrast, leptospires were only recovered from 75 per cent of their kidneys. Isolates from 10 of the sows were identified to serovar level: six were serovar muenchen and four were bratislava. Persistence was observed in renal and genital tissues for up to 147 days after abortion.