Questions réglementaires liées à l’autorisation temporaire de vacciner les animaux en situation d’urgence : l’exemple de la fièvre catarrhale du mouton en Europe

in Revue Scientifique et Technique (International Office of Epizootics) (2007), 26(2), 395-413

A marketing authorisation for a veterinary vaccine is granted after the quality, safety and efficacy of the product have been assessed in accordance with legal standards. The assessment includes complete ... [more ▼]

A marketing authorisation for a veterinary vaccine is granted after the quality, safety and efficacy of the product have been assessed in accordance with legal standards. The assessment includes complete characterisation and identification of seed material and ingredients, laboratory and host animal safety and efficacy studies, stability studies, and post-licensing monitoring of field performance. This assessment may not be possible during the emergence of a new animal disease, but several mechanisms exist to allow for the availability of products in an emergency animal health situation, e.g. autogenous biologics, conditional licences, experimental and emergency use authorisations, the importation of products in use elsewhere in the world and pre-approved vaccine banks. Using the emergence of bluetongue in northern Europe as an example, the regulatory issues regarding the temporary authorisation of animal vaccination are described. Several conditions must be fulfilled before a temporary authorisation can be granted, e.g. inactivated vaccines should be used in order to exclude reversion to virulence and reassortment between vaccine viruses and/or field strains of the bluetongue virus; decision-making must be supported by scientific evidence and risk analysis; there must be a complete census of the susceptible animals that were vaccinated; vaccination protocols must be adhered to and there must be a scheme allowing for registration, delivery and follow-up of vaccination, and monitoring, analysis and, possibly, adjustment of field use of the vaccination. This temporary authorisation must be replaced by a full authorisation as quickly as possible. [less ▲]

Effects of Inhalation of Dust and Endotoxin on Respiratory Tracts of Pigs

in American Journal of Veterinary Research (1999), 60(9), 1055-1060

OBJECTIVE: To assess the effects of inhalation of feed flour dust and dustborne endotoxin on respiratory tracts of pigs. ANIMALS: 29 healthy Belgian Landrace pigs. PROCEDURE: Pigs housed in an ... [more ▼]

OBJECTIVE: To assess the effects of inhalation of feed flour dust and dustborne endotoxin on respiratory tracts of pigs. ANIMALS: 29 healthy Belgian Landrace pigs. PROCEDURE: Pigs housed in an environmental chamber were exposed for 6 days to feed flour dust (1 to 15 mg/m3) and dustborne endotoxins (50 to 2,500 ng/m3). Effects were evaluated by measuring albumin concentration, lactate dehydrogenase (LDH) activity, cell composition of nasal lavage (NL) and bronchoalveolar lavage (BAL) fluids and blood, and percentages of CD4+ and CD8+ T lymphocytes in blood and lavage fluids. Dustborne endotoxin was obtained by mixing endotoxins from Escherichia coli (serotype O127:B8) with feed flour before spraying the flour in the environmental chamber. RESULTS: Exposure did not affect cell composition of NL fluid or blood. Total cell counts of BAL fluids were increased in all groups exposed to dust. Macrophage counts were increased in pigs exposed to inhalable dust concentrations as low as 4.4 mg/m3, and lymphocyte counts were increased in groups exposed to high dust concentrations. Percentages of CD4+ and CD8+ T lymphocytes in blood and lavage fluids were unchanged. In all dust-exposed groups, albumin content of BAL fluid was increased, whereas LDH activity was unaffected. Macrophage and lymphocyte infiltration and edema in the bronchi were identified by light microscopy. Effects attributable to E. coli endotoxin exposure were not identified. CONCLUSIONS: Inhalation of feed flour dust did not affect nasal mucosa but did induce bronchial airway inflammation. Dustborne endotoxins did not have effects attributable to endotoxin alone. [less ▲]

A Morphometric and Functional Study of the Toxicity of Atmospheric Ammonia in the Extrathoracic Airways in Pigs

in Veterinary Research Communications (1996), 20(4), 381-399

The effects of atmospheric ammonia (NH3) on the nasal and tracheal mucosa of pigs were investigated by morphometric and functional methods. Pigs were exposed to four concentrations of NH3 [5 (control), 25 ... [more ▼]

The effects of atmospheric ammonia (NH3) on the nasal and tracheal mucosa of pigs were investigated by morphometric and functional methods. Pigs were exposed to four concentrations of NH3 [5 (control), 25, 50 and 100 ppm] for 6 days in a specially designed air-pollutant exposure chamber. Samples were taken from the turbinates and the trachea, and the respiratory mucosa was examined by light and scanning electron microscopy. Dose-response curves to carbachol and isoproterenol were constructed using isolated strips of tracheal smooth muscle, with or without epithelium. In pigs exposed to ammonia, considerable mucosal injuries were observed in the turbinates but not in the trachea. The number of neutrophils in the epithelial layer and in the lamina propria, and epithelial hyperplasia were closely and significantly correlated with the concentrations of ammonia (r = 0.894, p < 0.001; r = 0.727, P < 0.001; and r = 0.818, p < 0.001, respectively). Except for the lamina propria, all these changes were significant (p < 0.05) at ammonia concentrations as low as 25 ppm. The percentage of the surface of the turbinate mucosa that was ciliated tended to decrease with increasing ammonia concentration (r = 0.439, p < 0.082). Ammonia induced smooth-muscle hyperresponsiveness to carbachol with a close linear correlation between individual values of the carbachol-induced maximal effect and the NH3 concentrations (r = 0.526, p < 0.003). While mechanical destruction of the epithelium induced an increase in Emax in the control group, no difference was observed between the intact and denuded strips from animals exposed to ammonia. The response to isoproterenol was not influenced by ammonia. It was concluded that quantitative histological analysis of the inflammatory infiltration and epithelial hyperplasia in the turbinates is a useful tool for quantifying the effects of atmospheric pollutants in pigs; a 6-day exposure to ammonia induces nasal irritation and functional disturbances of the tracheal smooth-muscle contractions at concentrations as low as 25 ppm [less ▲]

Effects of Atmospheric Ammonia on Pulmonary Hemodynamics and Vascular Permeability in Pigs: Interaction with Endotoxins

in Toxicology and Applied Pharmacology (1994), 125(1), 17-26

The influence of atmospheric ammonia on the somatic growth, the plasma cortisol and ammonia concentrations, and cell blood counts was investigated in pigs exposed to four concentrations (0, 25, 50, and ... [more ▼]

The influence of atmospheric ammonia on the somatic growth, the plasma cortisol and ammonia concentrations, and cell blood counts was investigated in pigs exposed to four concentrations (0, 25, 50, and 100 ppm) for 6 days in a specifically designed air-pollutants exposure chamber. The effects of this gas on pulmonary vascular hemodynamics and permeability and on the endotoxin-induced vascular response were also assessed using an isolated perfused lung preparation. The total pulmonary blood flow resistance (Rt) was partitioned into four components: arterial (Ra), pre-(Ra′) and post-(Rv′) capillary and venous (Rv). The capillary filtration coefficient (Kf,c) was evaluated by using a gravimetric technique. None of the concentrations of ammonia significantly modified the plasma cortisol and ammonia concentrations or the differential leukocyte percentages and total white blood cell count, suggesting an absence of stress related to ammonia. In exposed animals, lethargy and a concentration-related depression of the somatic growth were observed. The equation of the regression line plotted relating the mean values of the changes in body weight gain recorded over the exposure period expressed as percentages of the initial body weight (y) and ammonia concentrations (x) was: y = 3.204 − 0.177x + 0.001x2(r = 0.99; p≤0.013). Endotoxin infused in the perfusion liquid of lungs from unexposed animals for 180 min induced a significant 208% increase in Rt (p < 0.001) which can be ascribed to a 338 and 180% increase in Ra′ and Rv′, respectively. Endotoxin infusion also induced a 62% (p ≤ 0.001) increase in the Kf,c. Exposure of pigs to ammonia at any concentration did not modify the baseline values of any hemodynamic or permeability parameters. However, the hemodynamic response to endotoxins in lungs from pigs exposed to 100 ppm was significantly altered. The increase in Rt, Ra′, and Rv′ observed in unexposed pigs was completely abolished as shown by the limited changes in Rt (+34.9%). An intermediate reaction (+131.7%) was obtained in pigs exposed to 50 ppm. This inhibiting effect of ammonia was closely correlated with gas concentration by a linear regression (r = 0.99; p ≤ 0.037). The changes in the Kf,c recorded in the control group were not modified by exposure to ammonia. It was concluded that exposure of pigs to aerial ammonia concentrations from 0 to 100 ppm for 6 days has no direct effect on the pulmonary microvascular hemodynamics and permeability and induces no stress response. A marked depressive effect on the somatic growth is observed at concentrations greater than 25 ppm. Concentrations greater than 50 ppm can modulate the pulmonary vascular response to endotoxins [less ▲]

Microclimat et composition de l'air dans une enceinte fermée destinée à l'étude de la toxicité des polluants atmosphériques chez le porcelet

in Veterinary Research (1993), 24(6), 503-514

An experimental model representing the pollution background in a pigpen was constructed in order to study the toxicology of pig respiratory air pollutants. Temperature, relative humidity, air-flow rate ... [more ▼]

An experimental model representing the pollution background in a pigpen was constructed in order to study the toxicology of pig respiratory air pollutants. Temperature, relative humidity, air-flow rate, total dust, total viable particles, endotoxins in respirable dust (< 5 microns) and ammonia were measured in a 1.9 m3 environmental chamber designed for piglets. The activity of 1 piglet was recorded on video. Temperature and relative humidity were respectively 23.9 +/- 1.3 degrees C and 70.5 +/- 8.3% (mean +/- SD). Air flow rate was 10 m3/h. Dust, viable particles, endotoxin and ammonia concentrations were respectively 7 +/- 2 particles/ml, 3.4 x 10(4) +/- 2.9 x 10(4) BCFP (bacterial colony-forming particles)/m3, 4.8 +/- 1.5 ng/m3 and 6 +/- 0.8 ppm (mean +/- SD). All these parameters were comparable to the lowest values recorded in pigpens [less ▲]

Comparaison of dust concentrations in pig buildings and in an environmental inhalation chamber

in Proceedings of the 12th Congress of the International Pig Veterinary Society (1992)

Impact de la pollution atmosphérique sur le système respiratoire. I : l’ammoniac

in Annales de Médecine Vétérinaire (1991), 135