Field evaluation of the protective efficacy of Mycobacterium bovis BCG vaccine against bovine tuberculosis.
The protective efficacy of Mycobacterium bovis BCG (1 x 10(6) single dose) was evaluated under field conditions. A total of 140 male Holstein Friesian calves, one to two week-old were selected. Two groups of 70 each were formed, one group was vaccinated and the other was injected with a placebo during their second week of age and followed until 12 months of age. The study considered a positive case of tuberculosis to be an animal that had a positive reaction to the three following tests in a row: tuberculin, IFNgamma PPD-B and IFNgamma ESAT6-CFP10 during the 12 months of exposure. The results showed a 59.4% efficacy (IC95%: 47.64-71.16). The non-vaccinated calves were 2.4 times more at risk of becoming infected (IC95%: 1.07-5.68) compared to vaccinated animals. As a complementary test a PCR test was performed using nasal exudates in some animals from both groups using a Mycobacterium complex detection kit. All the positive PCR reactions (5/44) were found in the non-vaccinated animals. These findings suggest that the use of the BCG vaccine, even though it is not capable of protecting 100%, does prevent TB vaccinated animals from excreting bacilli in their nasal secretions at their first year of age.
Lopez-Valencia
G
G
Laboratorio de Tuberculosis y Brucelosis, Instituto de Investigaciones en Ciencias Veterinarias, Universidad Autónoma de Baja California, Colonia Independencia, Mexicali, 21290 Baja California, Mexico. glopez_mx@yahoo.com
Renteria-Evangelista
T
T
Williams
J de Jesús
Jde J
Licea-Navarro
A
A
Mora-Valle
A De la
Ade L
Medina-Basulto
G
G
D000367:Age Factors; D000818:Animals; D001500:BCG Vaccine / Q000627:therapeutic use*; D002417:Cattle / Q000276:immunology / Q000382:microbiology; D007371:Interferon-gamma / Q000097:blood; D008297:Male; D009163:Mycobacterium bovis / Q000276:immunology; D009297:Nasal Mucosa / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000662:veterinary; D014374:Tuberculin Test / Q000662:veterinary; D014380:Tuberculosis, Bovine / Q000276:immunology / Q000517:prevention & control*
D001500:BCG Vaccine; D007371:Interferon-gamma