19. Infectious bovine rhinotracheitis (diagnosis, prevention, control, eradication).

Question 1

Diagnosis?

Answer 1

Diagnosis:

• signs (typical cases - respiratory, genital),
• virus isolation (from discharges), detection in tissues (IF, IHC, ELISA, PCR - semen)
• serology (blood, milk after 2 weeks, ELISA, VN)

Question 2

Prevention?

Answer 2

Prevention:

• Treatment with antibiotics against bacteria
• Epizootiology rules (closed population, separation of different age groups)
• Immunization: live and inactivated vaccines, active enzootic - attenuated vaccine
• (mucosal immunity)
• In brood animals inactivated - attenuated may colonize and cause abortion
• Pregnant cow’s immunization 6 and 3 weeks before parturition
• Calf vaccination: age 2-3 months and repeat in 2-3 weeks, repeat every 6 months
• Heifer immunization at fertilization

Question 3

Eradication?

Answer 3

Eradication:

• 1) Replacing: quick, safe, but expensive
• 2) Raising free generation: time-consuming, vaccination of whole herd, seclusion of calves on
• day 3, after colostrum consumption, isolated raising
• 3) Selection: most frequently used strategy
• < 10% seropositivity - removal of positive cattle
• > 10% seropositivity - selection with the help of marker vaccines
• Basic immunization of whole herd with marker vaccine
• Repetition in every 6 months - reduced virus shedding frequency
• and intensity
• oIsolation of calves from the adults,
• vaccinations in every 6 months > heifers
• at parturition are already atleast 4 times vaccinated
• Regular control: repeated, discriminative ELISA
• Maintenance of virus-free status: closed farm, virus-free semen and bull, regular controls