Marek’s disease: time to review the emerging threat in Indian poultry
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Date
2020
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Abstract
Marek’s disease (MD) is one of the re-emerging diseases in Indian
poultry. MD outbreaks are reported from different parts of the country
in spite of vaccination, causing major economic losses. Flock mortality
of 10–40% have still been observed in vaccinated flocks during outbreaks,
although MD is considered to be well controlled with vaccination.
Almost 100% of the commercial poultry flocks are vaccinated in
the hatchery. Bivalent (HVT+SB1 or HVT+301B/1) or monovalent (HVT)
vaccines are used in India. In spite of intensive vaccination, outbreaks
are still reported from different parts of the world including India. MD
virus (MDV) Indian field isolates from different outbreaks during the
last decade are categorised into virulent (vMDV) and very virulent
(vvMDV) pathotypes, based on different serotype 1 specific gene
sequencing and in vivo pathotyping. The emergence of virulence in
MDV is attributed to compromised bio-security, concurrent immunosuppressive
diseases and vaccination failure. MD outbreaks in vaccinated
Indian poultry flocks cause annual losses of approximately
40 million Indian rupees. Country-wide surveillance and reporting of
MD outbreaks and further characterisation of the Indian field isolate
should be taken as a priority. Reviewing current vaccination strategy
and examining the need for the introduction of more effective vaccines
that give better protection against more virulent strains should
be considered with equal importance along with improved biosecurity
measures, management practices and more effective control
of immunosuppressive diseases.
Description
TNV_WPSJ_2020_(91-99)
Keywords
Veterinary Science