Role of Vaccine in control of Role of Vaccine in control of Avian InfluenzaAvian Influenza

H. K. PradhanHigh Security Animal Disease Laboratory,(A National Referral Facility )Anand Nagar, Bhopal

WORLD SCENARIOWORLD SCENARIO Important AI virus- H5, H7,H9 1997 outbreak -Hong Kong (H5N1) 2003-2006 - 60 countries affected

with H5N1 Countries badly affected: Vietnam, Thailand, Indonesia, China

Russia, Turkey, Romania Human deaths – 141 Indonesia- 46, Vietnam- 42,

Thailand-16, China-14

SITUTATION IN INDIASITUTATION IN INDIA Till Jan, 2006- India was free from HPAI. Since 2003- H9N2 have been detected. First outbreak of H5N1 –February, 2006. States affected- Maharastra, Gujarat and

Madhya Pradesh. Introduced through migratory birds. Heavy mortality in chickens. Culling of 1.14 million birds , destruction

of 1.475 million eggs, 8600 MT feed. Disease controlled.

CONTROL STRATEGIESCONTROL STRATEGIES Stamping out - within 3 Km zone . Vaccination with effective monitoring. Combination of stamping out and

vaccination. Countries effectively controlled AI-

Republic of Korea, India. Countries going for vaccination –

Southern Russia, France, Holland (backyand, sanctuary), China.

TYPES OF VACCINESTYPES OF VACCINES Inactivated Homologous vaccine (field strain) Inactivated heterologus vaccine (same HA,

different NA-DIVA), H5N2, H5N8, H5N9 Recombinant live viral vector vaccines - Fowl

pox, Adeno (HA gene insert). Vaccines developed by reverse genetic

(inactivated). Recombinant H5 HA antigen using prokaryotes

or baculo virus expression system. DNA vaccine (H5 HA); Peptide vaccine.

ADVANTAGES OF VACCINATIONADVANTAGES OF VACCINATION Protect against clinical sign and death. Reduces shedding of virus. Prevents contact transmission. Protects against challenges with high

dose of field virus. Protects against changing virus . Increases resistance to AI infection. Reduces AIV replication. Decreases the risk of human infection.

DISADVANTAGES OF VACCINATIONDISADVANTAGES OF VACCINATION

Fear for mutation.Silent spreading of virusDifficult to differentiate

between vaccinated and infected birds (serological)

ISSUES NEED TO BE RESOLVED ISSUES NEED TO BE RESOLVED BEFORE VACCINATIONBEFORE VACCINATION

Choice of vaccine – homologous, heterologous.

Standardization of manufacturing practices Proper storage, distribution,administration. Adequate serological and virological

studies. Exit strategy to prevent permanent use. Selective vaccination or mass vaccination.

WHAT INDIA SHOULD DOWHAT INDIA SHOULD DO

AI surveillance to continue. Sampling should be adequate and proper. Choice of dianostic methods. If small areas are affected-culling is best. If widespread outbreaks-vaccination to

create immune zone. Vaccination from periphey to central part.

Cont……

WHAT INDIA SHOULD DOWHAT INDIA SHOULD DO

Panic selling should be avoided. Strict biosafety measures. Fear of genetic recombination (H5N1

and H9N2) Grand parent stocks should be protected. Vaccination of backyard poultry is

important.

CHOICE OF VACCINECHOICE OF VACCINE Heterologous inactivated vaccines, Inactivated homolgous vaccine

(H5N1) developed in India. Recombinant fowl pox vaccine (from H5N8, H5N1). Recombinant adeno virus vaccine.

  

Stamping out and vaccination is ideal Thank You