www.ncbi.nlm.nih.gov/pubmed/9638070 A study of cattle-to-cattle transmission of Mycobacterium bovis infection. Costello E, Doherty ML, Monaghan ML, Quigley FC, O'Reilly PF.
Veterinary Research Laboratory, Dublin, Ireland. Abstract Twenty steers, positive to the single intradermal comparative tuberculin test (SICTT), were selected from herds with a recent history of Mycobacterium bovis infection. Ten steers, negative to SICTT, were selected from herds with no history of M. bovis infection and served as in-contact animals. The animals were divided into 10 groups, each consisting of two SICTT-positive (reactor) animals and one in-contact animal. Each group was housed in an individual loose-box for a period of 1 year. Five of the groups were fed a restricted diet for part of the experiment. All cattle were slaughtered at the end of the study period and examined at post mortem. Transmission of infection to an in-contact animal occurred in four of the 10 groups. One of the four in-contact animals, which became infected, had a retropharyngeal lymph node tubercle and M. bovis was isolated from lymph nodes without visible lesions from the other three. Two of the infected in-contact animals without visible lesions did not show any detectable cell-mediated immune response. There was no evidence that dietary, restriction had any effect on transmission of disease.
Sally
30 Aug 2010, 6:11 PM
www.ncbi.nlm.nih.gov/pubmed/10985801 Cattle-to-cattle transmission of bovine tuberculosis.www.ncbi.nlm.nih.gov/pubmed/10985801 Menzies FD, Neill SD. Department of Agriculture for Northern Ireland, Veterinary Sciences Division, Belfast, Northern Ireland, UK. fraser.menzies@dardni.gov.uk Comment in: Vet J. 2000 Sep;160(2):85-6. Abstract In developed countries, Mycobacterium bovis infection in cattle is now mostly confined to the respiratory system, which reflects transmission and establishment of infection mainly by this route. A single bacillus transported within a droplet nucleus is probably sufficient to establish infection within the bovine lung. Infected cattle should always be considered as potential sources of infection, since studies have demonstrated that a significant proportion of tuberculous cattle excrete M. bovis. In general, the dynamics of M. bovis transmission are poorly understood and the conditions under which a tuberculous animal becomes an effective disseminator of infection are currently not defined although environmental contamination appears to be a less effective method of disease transmission. Field studies indicate a wide spectrum of transmission rates but generally the spread of M. bovis infection is still considered to be a relatively slow process. Slaughter of diseased cattle detected by tuberculin testing and at meat plant inspection has been shown to be an effective policy for tuberculosis eradication, provided there are no other reservoirs of infection and all involved in the cattle industry are committed to a policy of eradication. Epidemiological approaches, particularly case-control studies, seem to provide the best method for quantifying the relative importance of the various sources of M. bovis transmission to cattle and modelling techniques can be used to assist in the design of cost-effective control measures that may lead to tuberculosis eradication.
Sally
30 Aug 2010, 6:11 PM
www.ncbi.nlm.nih.gov/pubmed/9638070 A study of cattle-to-cattle transmission of Mycobacterium bovis infection. Costello E, Doherty ML, Monaghan ML, Quigley FC, O'Reilly PF.
