The risks posed by the importation of animals vaccinated against foot and mouth disease and products derived from vaccinated animals: a review.

The Terrestrial Animal Health Code of the OIE (World organisation for animal health) (the Terrestrial Code) makes recommendations for international movements of live animals and animal products because of a possible generic risk of foot and mouth disease (FMD) for these different commodities. For instance, international movement of vaccinated live animals or products of such animals is restricted due to the possible masking of clinical disease as a result of vaccination and to the perceived risk of persistently infected animals among vaccinated livestock. In addition, bilateral agreements between exporting and importing countries on the importation of animal products can be based on the 'equivalence' of the animal health conditions in both countries, or on formal or informal risk assessments in accordance with the norms and recommendations of the Terrestrial Code. In this regard, an exporting country may be required to prepare a complete and transparent document describing the animal health situation, including the factors required to assess the risk involved. Furthermore, expert committees of importing countries regularly evaluate and verify these conditions in exporting countries. The level of confidence in the information obtained by the expert committee can then be entered into the risk analysis equation. An important FMD risk reduction factor for the importation of animals and animal products is early recognition of the disease at the source of the commodity by alert stakeholders, such as official and private veterinarians and the chain of the livestock industry. This is true for all countries irrespective of their vaccination status. The risk posed by the importation of vaccinated animals becomes negligible when an adequate protocol--in compliance with the norms and recommendations of the Terrestrial Code--is applied. However, recently, export of live animals from countries that do not practise vaccination has also proven to pose a significant risk and the rules governing such transport may have to be reviewed. Disease surveillance, biosecurity at the farm level, traceability and control of the source cattle and slaughterhouse inspections are the main risk reduction measures for meat and meat products from vaccinated cattle. If these animals are slaughtered and processed under good management practice--in accordance with the norms and recommendations of the Terrestrial Code--these products present a negligible risk for the introduction of FMD. Risk reduction by maturation and deboning is an important procedure, but is probably overemphasised. Mechanical contamination of cattle carcasses with 'carrier virus' from the pharyngeal area during slaughter and processing is very unlikely. Risk assessments showed that the importation of milk products from countries or zones that practise vaccination of dairy herds poses a negligible risk. Risk assessments also demonstrated that the importation of bovine embryos from vaccinated cows--in accordance with the norms and recommendations of the Terrestrial Code--poses a negligible risk. Likewise, the risk from the importation of semen from vaccinated bulls is also negligible when an adequate test protocol is applied in accordance with the Terrestrial Code.

Unapparent foot and mouth disease infection (sub-clinical infections and carriers): implications for control.

Unlike animals which are carriers of foot and mouth disease (FMD), sub-clinically infected animals may be highly contagious. The implications of sub-clinical infections for the control of FMD are serious because such animals are likely to disseminate the disease when in contact with susceptible livestock. Recent dissemination of FMD virus (FMDV) in Europe shows that sub-clinically infected animals render trade in animals or animal products a potential risk for importing countries. This clearly demonstrates that the paradigm 'free of FMD without vaccination' is not synonymous with 'risk-free'. The risk of introduction of subclinical FMD into FMD-free countries may increase significantly, with the occurrence of large susceptible animal populations, changed agricultural practices, expansion of trade in live animals and animal movements, increased trade in animal products and greater mobility of people. Such changes in circumstances require that national and international authorities remain continuously vigilant to determine any altered risk for importation of FMD. A few historical reports and some recent observations in southern Africa indicate the possibility of dissemination of FMD by bovine carriers into herds of susceptible cattle. These reports have greatly influenced FMD trade policies and thus, FMD control and eradication strategies. However, other field evidence does not support this claim and several controlled experiments were unable to show that carriers are able to initiate disease. When millions of cattle were systematically vaccinated with good quality vaccines, FMD disappeared in spite of a large sentinel population in the form of calves and unvaccinated sheep and pigs. A low number of carriers most likely persisted, but they did not hamper the eradication of the disease. Vaccination policies and trade regulation must be based on risk assessments taking these factors into consideration.

[Animal production and animal health and their relationship with veterinary public health in Latin America and the Caribbean]. / La producción y la salud animal y sus interrelaciones con la salud pública veterinaria en América Latina y el Caribe.

The authors analyse the relationships which exist, in terms of programmes, sectors and institutions, between animal health, animal production and veterinary public health on the one hand, and between each of these three sectors and public health in general on the other. The most important common factor is food safety. Undernutrition, which affects some 60 million inhabitants of Latin America and the Caribbean, is still the most important public health problem in this part of the world. While it is known that the major cause of undernutrition is the low gross domestic product and uneven distribution of wealth, increased animal production and productivity would provide the key to an improvement in the situation. The concept of animal health, in its broadest sense, implies optimum animal production in a given region and during a specified period of time. Veterinary public health has functions and objectives which are crucial for food safety: protection and hygiene of foods, and control of the use in animal production of substances toxic to human beings (such as heavy metals, hormones and insecticides). Within the area of transmissible diseases, the authors discuss control measures for zoonoses. Besides the specific subject of interdisciplinary relationships in regard to zoonoses, the authors stress the importance of joint work conducted in the research, development and implementation of laboratory diagnostic activities and the production and quality control of antigens and vaccines. The production of laboratory animals is another sphere of common activity and research, and it cannot be said that such work is specific to any one of the three disciplines. Moreover, the fields of health, animal health and veterinary public health share the same methods and strategies, and reciprocal benefits could be more significant than the objectives of individual programmes. Reference is made to the organisation of state services and their adaptation to administrative de-centralisation, particularly at the local level.

Estratégia continental no combate à febre aftosa / Continental strategy in the fight against foot-and-mouth disease

O presente trabalho expöe sinteticamente o Plano de Açäo do Programa Hemisférico de Erradicaçäo da Febre Aftosa na América do Sul. A pedido dos países, esse Plano foi elaborado pela Organizaçäo Pan-Americana da Saúde (OPAS) e aprovado pelo Comitê Hemisférico de Erradicaçäo da Febre Aftosa (COHEFA)

Aplicación de la técnica inmunoenzimática (ELISA) para el diagnóstico de los virus de la fiebre aftosa y estomatitis vesicular en comparación con la prueba de fijación del complemento

Se ha comparado la técnica inmunoenzimática (ELISA) "sandwich" indirecta con la prueba de fijación del complemento 50 por ciento (FC50) para detectar los serotipos O, A y C del virus de la fiebre aftosa (VFA) y New Jersey (NJ) e Indiana(IND) del virus de la estomatitis vesicular (VEV). Para las cepas O, A, C e IND se usaron antisueros polivalentes como detectores y para las cepas NJ fueron utilizados antisueros monovalentes. La prueba de Elisa mostró ser un procedimiento más satisfactorio para identificar VFA y VEV en muestras de epitelios de animales afectados por enfermedad vesicular.

Caracterización epidemiológica, antigénica, inmunogénica y bioquímica del virus de la fiebre aftosa A-81 Argentina/87

Estudios seroepidemiológicos llevados a cabo en muestras de campo, realizados a fines de 1986 por el Laboratorio de Diagnóstico y Referencia para las Américas en el Centro Panamericano de Fiebre Aftosa (CPFA), mostraron una variación antigénica de virus de la fiebre aftosa tipo A en relación con el usual A24 y aislamientos de campo A-79 en la Argentina.

Seroepidemiologic studies constantly carried out on field samples by the Diagnostic Reference Laboratory for te Americas at the Pan American Foot-and-Mouth Disease Center (PAFMDC) revealed, late in 1986, an antigenic variation of FMDV type A in relation to the usual A24 and A-79 field isolates in Argentina.

Caracterización bioquímica y serológica de diferentes cepas de campo de virus de la fiebre aftosa aisladas en América del Sur

En esta comunicación, se extendieron los estudios al análisis de varias cepas relevantes del virus de la fiebre aftosa, subtipos O, A y C, aisladas en diferentes épocas en el campo y en distintas regiones de América del Sur.

In the present communication studies are axtended to the analysis of several relevant strains of FMDV srotypes O, A and C isolated at different times in the field in different regions of South America.

Respuesta en bovinos a la exposición del virus de la fiebre aftosa un año despues de inmunizados con vacuna con adyuvante oleoso

Treinta vacas, que habían sido vacunadas 3 veces a intrevalos de 6 meses con vacunas antiaftosa con adyuvante oleoso, fueron expuestas 13 meses después de la última vacunación al virus tipo O1 por vía intradermolingual y al contacto con bovinos y cerdos infectados. De acuerdo con los niveles de anticuerpos previos al desafío de virus se esperaba una elevada protección, la que fue confirmada por la prueba de desafío de virus. Sólo uno de los 30 bovinos desarrolló fiebre aftosa generalizada. De los 29 animales sólo 6 tuvieron una lesión en el punto de inoculación. Estas observaciones confirman, en general, que en las encuestas serológicas realizadas en la población bovina a la que pretenecían esos animales, vacunados con vacuna antiaftosa con adyuvante oleoso, los elevados niveles de anticuerpos indican una sólida inmunidad.

[Experimental infection of goats with Brucella ovis. Bacteriological serological and histopathological studies]. / Infección experimental de caprinos machos con Brucella ovis. Estudio bacteriológico, serológico e histopathologico.

The susceptibility of adult male goats to Brucella ovis infection was studied. Fifteen goats and fifteen rams both of ages ranging from 22 to 34 months were inoculated conjunctivally with 10(9) cells of B. ovis strain recently isolated from a case of ram epididymitis. Five goats and five rams were killed 78 days after inoculation and similar groups were killed at two month intervals thereafter. B. ovis was recovered from semen of a male goat, 33 and 61 days after inoculation. The five goats sacrificed 78 days after inoculation contained Brucella in their organs. The semen and the tissues of the two other groups remained culturally negative throughout the observation period. Seven cultures were obtained from the semen of 14 rams used comparatively as inoculated controls. Epididymitis was clinically observed only in one male goat although under six presented macroscopic lesions. Seven rams out of the 15 inoculated showed clinical symptoms of epididymitis. Antibodies detectable by complement fixation and immunodiffusion disappeared 80 days after inoculation in goats, while rams reacted during the 189 days period of observation. It is concluded that the B. ovis infection in male goats is transient and the role that they may play in the epizootiology of the disease is negligible.

El Centro Panamericano de Fiebre Aftosa

En 1951 la Organización de los Estados Americanos, cuando era Secretario General el Dr. Alberto Lleras Camargo, más tarde presidente de Colombia, decidió crear un organismo intergubernamental responsable por la promoción, apoyo y coordinación del combate de la fiebre aftosa en América. La preparación del proyecto se encargó a la Organización Panamericana de la Salud y al Instituto Interamericano de Ciencias Agrícolas. Así nació, hace 25 años, el Centro Panamericano de Fiebre Aftosa, como un Proyecto de Cooperación Técnica (OAS/TA/77/51) de la Organización de los Estados Americanos.

Infección experimental de caprinos machos con Brucella ovis. Estudio bacteriológico, serológico e histopathologico / [Experimental infection of goats with Brucella ovis. Bacteriological serological and histopathological studies]

The susceptibility of adult male goats to Brucella ovis infection was studied. Fifteen goats and fifteen rams both of ages ranging from 22 to 34 months were inoculated conjunctivally with 10(9) cells of B. ovis strain recently isolated from a case of ram epididymitis. Five goats and five rams were killed 78 days after inoculation and similar groups were killed at two month intervals thereafter. B. ovis was recovered from semen of a male goat, 33 and 61 days after inoculation. The five goats sacrificed 78 days after inoculation contained Brucella in their organs. The semen and the tissues of the two other groups remained culturally negative throughout the observation period. Seven cultures were obtained from the semen of 14 rams used comparatively as inoculated controls. Epididymitis was clinically observed only in one male goat although under six presented macroscopic lesions. Seven rams out of the 15 inoculated showed clinical symptoms of epididymitis. Antibodies detectable by complement fixation and immunodiffusion disappeared 80 days after inoculation in goats, while rams reacted during the 189 days period of observation. It is concluded that the B. ovis infection in male goats is transient and the role that they may play in the epizootiology of the disease is negligible.

Infección experimental de caprinos machos con Brucella ovis. Estudio bacteriológico, serológico e histopathologico. / [Experimental infection of goats with Brucella ovis. Bacteriological serological and histopathological studies]

The susceptibility of adult male goats to Brucella ovis infection was studied. Fifteen goats and fifteen rams both of ages ranging from 22 to 34 months were inoculated conjunctivally with 10(9) cells of B. ovis strain recently isolated from a case of ram epididymitis. Five goats and five rams were killed 78 days after inoculation and similar groups were killed at two month intervals thereafter. B. ovis was recovered from semen of a male goat, 33 and 61 days after inoculation. The five goats sacrificed 78 days after inoculation contained Brucella in their organs. The semen and the tissues of the two other groups remained culturally negative throughout the observation period. Seven cultures were obtained from the semen of 14 rams used comparatively as inoculated controls. Epididymitis was clinically observed only in one male goat although under six presented macroscopic lesions. Seven rams out of the 15 inoculated showed clinical symptoms of epididymitis. Antibodies detectable by complement fixation and immunodiffusion disappeared 80 days after inoculation in goats, while rams reacted during the 189 days period of observation. It is concluded that the B. ovis infection in male goats is transient and the role that they may play in the epizootiology of the disease is negligible.