The prevalence of bovine mastitis has been reduced over the past 25 years due to the implementation of a five-point control plan aimed at reducing exposure, duration and transmission of intramammary infections by bacteria. This has markedly reduced the incidence of bovine mastitis caused by bacteria which show a contagious route of transmission, but has had little effect on the incidence of mastitis due to bacteria which infect the gland from an environmental reservoir. Streptococcus uberis is one such bacterium which is responsible for a significant proportion of clinical mastitis worldwide.The inadequacies of the current methods of mastitis control have led to the search for additional measures, particularly vaccines to prevent intramammary infection by this bacterium. Such an approach requires detailed knowledge of the pathogenesis of intramammary infection. Our understanding of this area has grown in recent years but a lack of information still hampers disease control. Both live vaccines and, recently, crude sub-unit vaccines have shown promise against bovine mastitis due to S. uberis. Vaccines against mastitis must, however, be able to control infection without the participation of a marked inflammatory response. This review provides an overview of the recent advances which have been made in our understanding of host-pathogen interactions which promote infection and disease and highlights areas for strategic research aimed at controlling this bacterial infection. 相似文献
A total of 70 sheep and 330 goats were selected randomly. All the animals were kept under same housing and management conditions.
Serum samples were collected from all the animals and tested for the presence of antibodies against Peste des petits ruminants
(PPR) virus using competitive ELISA (cELISA). All the animals were found negative showing percentage inhibition (PI) values
<50. The animals were vaccinated against PPR with Nig/75/1 strain vaccine of PPR Serum samples were collected from randomly
selected 12 sheep and 30 goats at 10, 30 and 45 days post-vaccination. The samples were subjected to cELISA to determine the
presence of antibodies against PPRV. The samples with PI >50 were considered as sero-positive. The sheep found positive at
10, 30 and 45 days post-vaccination were 1(8.3%), 7(58.3%) and 12(100%) respectively. In case of goats 3(10.0%), 29(96.6%)
and 27(90.0%) animals gave positive results at 10, 30 and 45 days post-vaccination respectively. Mean PI values in sheep at
10, 30 and 45 days post-vaccination were recorded as 37, 65 and 91 respectively, whereas in goats these values were 43, 78
and 86 respectively. 相似文献
Aerosol administrations of RIT 4030 and other available vaccine strains have been carried out in SPF and in conventional chickens. The results indicate that the RIT 4030 and Ulster 2C strains are significantly less reactogenic than the LaSota and the Hitchner B1 strains.The RIT 4030 strain produces an immune response even when administered to chickens with maternal antibodies and induces a better protection to challenge than the Ulster 2C strain.The replication of the RIT 4030 strain in the respiratory tract will be discussed with respect to its attenuation and transmissibility. 相似文献
Chicks and chickens maintained under commercial conditions were vaccinated against Newcastle Disease via drinking water. Prior and after different times of vaccination blood samples were drawn from different numbers of birds and checked for HI antibodies. The modes of distribution of the antibody titers within the random sample were assayed. The following results were obtained:
1. 1. On the basis of the distribution of the serum titers can be concluded whether the antibody level within a flock is increasing or decreasing.
◦ —A right steep asymmetry can be observed up to 20 days post vaccination.
◦ —In the phase of maximal antibody levels an almost symmetric distribution of the titers is present.
◦ —In later times (more than three weeks p. vacc.) the distribution shows a left steep asymmetry (Poisson distribution).
2. 2. A poisson distribution is also observable during the elimination of maternal antibodies of chicks until complete elimination.
3. 3. The mode of distribution of the HI titers in sera of day-old chicks correlates with the mode of distribution of the dams. Therefore, conclusions are possible from the status of the chicks to the dams and reverse.
4. 4. Factors which interfere with the mode of distribution are:
◦ —Two or more peaks after vaccination of chickens. This indicates an uneven immune response within the flock.
◦ —Distributions with several peaks may also occur if flocks are composed of day-old chicks from parent flocks with different levels of antibody titers.
Résumé
Des poulets et des poussins maintenus dans un élevage conventionnel furent vaccinés contre la maladie de Newcastle par un vaccin administré dans l'eau de boisson. Avant et à différents temps après vaccination, des échantillons de sang furent prélevés sur un certain nombre de poussins et les anticorps inhibants de l'hémagglutination furent recherchés. Les modes de la distribution des titres en anticorps pour les échantillons pris au hasard furent recherchés. Les résultats suivants furent obtenus:
1. 1. Sur la base de la distribution des titres sériques, on peut conclure si le taux en anticorps à l'intérieur d'une population a augmenté ou diminué.
◦ —Une courbe asymétrique avec un pic déplacé vers la droite peut être observée 20 jours après la vaccination.
◦ —La phase correspondant au taux maximal en anticorps présente une distribution presque normale.
◦ —Plus tard, (au-delà de 3 semaines après la vaccination), la distribution apparaît asymétrique avec un déplacement vers la gauche (distribution de Poisson).
2. 2. Une distribution de Poisson peut aussi être observée au moment de l'élimination des anticorps d'origine maternelle chez des poussins jusqu'à complète élimination.
3. 3. Le mode de distribution des titres en anticorps inhibant l'hémagglutination dans des sérums de poussins d'un jour correspond au mode de distribution observé chez les mères. Des conclusions peuvent donc être faites à partir de l'état immunologique des poussins vis-à-vis des mères et viceversa.
4. 4. Les facteurs qui peuvent intervenir dans le mode de distribution sont:
◦ —Deux pics ou plus après la vaccination des poussins. Ceci indique qu'il existe une réponse immunitaire inégale dans la population.
◦ —Des distributions avec plusieurs pics peuvent être également observées si les populations sont composées de poussins de un jour provenant de populations parentales ayant des taux différents de titres en anticorps.
The objectives of this study were to determine the characteristics of a dog population, including their accessibility to vaccination and health care, in urban and semiurban areas of Gwagwalada, Abuja, Nigeria. Direct street counts and a house‐to‐house survey of city streets were performed. A total of 451 households were surveyed comprising 43.7% urban and 53.3% semiurban areas. A total of 848 owned dogs were identified, along with 3,115 corresponding humans. With a dog‐to‐human ratio of 1:3.7, the dog population in the study area was estimated as 103,758. A total of 396 dogs were counted on the streets with the greater proportion (74%) in semiurban areas. Most dogs in semiurban areas (77.3%) had no certificate confirming vaccination against rabies, compared to 47.2% in urban areas (p = .004). The majority of dogs in the urban (60.9%) and semiurban (82.0%) were free roaming. In the multivariable model, age, presence of a collar, region, sex, use and having ever visited a veterinarian were significantly associated with rabies vaccination. The majority (125/197, 63.5%) of respondents with higher education were willing to pay more for the healthcare needs of their dogs as opposed to those with a lower level of education (93/251, 37.1%, p = .001). The study revealed a high dog population density, vaccination coverage below WHO recommendation of 70% and generally reduced healthcare‐seeking behaviour among dog owners in Gwagwalada, Abuja, Nigeria. 相似文献