AVIAN INFLUENZA:Zoonosis

Vicente C. Manalo, Jr., DVMMaria Fidelis Manalo, MD,

MSc Epidemiology

Avian Influenza

• A Viral disease of Domestic and Wild Birds characterized by the full range of responses from almost no signs of the disease to very high mortality. The incubation period is also highly variable, and ranges from a few days to a week (3 to 7 days).

Aetiology of Avian Influenza• Influenzavirus A genus of the

Orthomyxoviridae family.• They are enveloped, negative

stranded RNA viruses.• Influenza A viruses can be divided

into 15 Haemagglutinin (H) antigens. 9 Neuraminidase (N) antigens.

• Extreme antigenic variability brought about by genetic reassortment in host cells.

Influenza Viruses

• 2 Pathotypes: HPAI LPAI

Ecology of Avian Influenza Viruses

• The greatest variety of Avian Influenza viruses has been isolated from wild birds, particularly from waterfowls.

• Serve as reservoirs and gene pools• These birds perpetuate only viruses of

low pathogenecity• Natural host of AI viruses to which the

viruses are well adapted.• Waterfowls are resistant to the disease

induced by HPAI viruses.

Ecology of Avian Influenza Viruses

• Domestic Poultry does not appear to be the natural host of these viruses, therefore the degree of adaptation to the host is low and this could possibly explain why documented virus mutation has virtually always occurred in domestic poultry

Highly Pathogenic Avian InfluenzaWorldwide Occurrences

Recent News• Indonesia: Poultry Disease Outbreak

Devastating Regional Sector.• An article in the Jakarta Post on Dec. 18:

• Many poultry farmers forced out of business in the face of the current outbreak of ND. A spokesperson for 1 of the Sleman and Kulonprogo Regency district sector said: Out of 25 members of the neighborhood unit, only 3 still have chickens. The others’ birds are all dead. He added that only 25 % of farmers in his area are still operating. The virus had also spread to other areas of the regency. Some estimates suggest that a number of district have lost up to 80 % of their poultry

South Korea – Latest Developments• The Government is doing its best to support

the industry but public are not buying poultry or eggs despite assurances that this form of AI does not pose a health hazard.

• First confirmed case of bird flu – Dec. 15, 2003: 49 suspected farms• 14 cases confirmed positive for AI

•7 cases are from ducks•1 from broiler breeder •2 from broilers•4 from layers

• 17 cases were negative• The other 18 farms are being tested

Taiwan – Latest Developments

• Taipei (Reuters, Jan 5,2004) Taiwan reported its first case of a highly contagious bird flu Wednesday (Dec. 31,2003), but said six ducks smuggled from mainland China that had tested positive (H5N1) had been destroyed.

Avian InfluenzaDifferential Diagnosis

• Infectious Bronchitis• TRT/APV• Newcastle Disease• Respiratory viruses – Mixed

infections

Avian InfluenzaDiagnosis

1. Clinical Signs2. Virus Isolation and

Characterisation3. Serology4. PCR5. Histopathology and

Immunochemistry

3 Categories of Transmission• Intercontinental • Transport of live poultry, frozen poultry meat and untreated hatching eggs

over long distances. Trade of poultry by-products unheated and egg products and possibly frozen poultry semen. Least importance are free living migrating birds

• International• Trade of commercial poultry including live birds, vehicles, crates,

containers. Also, international exhibitions, shows, bird markets and similar events. Least important are birds which displays seasonal migration pattern.

• Local • Farm personnel, technical crew (debeaker, vaccinators, catchers, etc.).

Also, contaminated poultry manure and waste stuff as well as airborne particle and dust. Significant are live birds in close vicinity to poultry houses

BIOSECURITY

• DEFINITION : all procedures used to prevent the introduction of disease

• OBJECTIVES : - prevent the entry of disease- control the spread of disease

BIOSECURITY IS EVERYONE’S RESPONSIBILITY!

BENEFITS OF BIOSECURITY• HELPS KEEP OUT diseases• REDUCES THE RISK of zoonotic diseases• LIMITS THE SPREAD of diseases• HELPS PROTECT the public health• IMPROVES the overall flock health• CUTS COSTS of disease treatment• REDUCES LOSSES and improves profitability

BETTER BIOSECURITY PROVIDES : Peace of mind, a healthier flock and a more viable

business!

HOW DISEASES SPREAD

• MOVEMENT of people, animals, equipment, vehicles

• CONTACT with neighboring flock• CONTACT with insects, rodents,

stray animals and pets• CONTAMINATED water & feeds• INADEQUATE cleaning and

disinfection

BIOSECURITY INFORMATION

• STRICTLY limit and control access to the farm – fencing w/ a controlled entry point

• KEEP an all-in, all-out flock management• PROVIDE a security or decontamination

area• REQUIRE all persons entering the farm to

sign a visitor’s logbook; vehicle plate numbers must also be recorded

BIOSECURITY INFORMATION• CLEAN & DIRTY areas should be well-defined• THOROUGHLY clean and disinfect all

equipment & vehicles entering AND leaving the farm

• BETTER NOT to borrow equipment or vehicles from other farms

• DON’T USE same vehicles for transporting birds, feeds, equipment or waste products

BIOSECURITY INFORMATION• CLEAN, PROTECTIVE clothing and footwear

must be worn in the farm• HAVE a designated cleaning & disinfecting

area• WHEN DISINFECTING, remove all dirt & solid

matter first – Dirt & manure cannot be disinfected!

• KEEP the farm surroundings clean & tidy• FOOTBATH must be provided in every poultry

house; footbath should be kept clean

BIOSECURITY INFORMATION

• KEEP WILD BIRDS off the poultry houses – bird-proofing

• KEEP other animals, pets or other livestock out of the farm

• PEST & RODENT control program• PROPER DISPOSAL of damaged eggs, dead

birds, litter or manure• REGULARLY clean & disinfect all

equipment & vehicles before and after use

BIOSECURITY INFORMATION

• AFTER EVERY CYCLE, thoroughly clean & disinfect all houses & equipment

• ONCE CLEANED, a farm should be closed & left idle; the longer the down time, the better the results.

IMPLEMENTING A STABLE BIOSECURITY PROGRAM IS INDEED

AN EFFORT WORTH MAKING!

MINIMUM BIOSECURITY STANDARDS

• No Visitors• A sign-in log• Clean clothing and sanitized footwear• Properly maintained foot pans with disinfectant solution• Rodent and insect control • No other animals, esp. wild birds • Vaccination • All in, all out• Sanitize hands

IMPORTANT REMINDERS

• MAKE a flock health plan that includes basic biosecurity measures

• ENSURE that all records are accurate & up-to-date

• ALL poultry personnel should be trained• LOOK OUT for signs of disease – early

detection is key!• REPORT immediately if disease is suspected

BE VIGILANT!

Reminders

• Effective Bird Proofing• Working Pest Control Program

• For Rodents and Fly

• No other animals especially waterfowl• Sign – in Log Book• Power Sprayer at the farm gate• Separate foot wear/Foot Dip• Sanitation/disinfection

Prevention

• Surveillance / Monitoring• Vaccination• Biosecurity

Control• Biosecurity

• Quarantine• Intensify disinfecting measures

• Monitoring/Surveillance• Stamping Out / Depopulation• DIVA Vaccination - only for LPAI

and not for HPAI because it might prolong the shedding of the virus

• Proper Disposal

• Avian Influenza Pictures and Video Clips were taken from

A Color Atlas and Text on Avian Influenza and CD ROM Avian Influenza• Ilaria Capua and Franco Mutinelli• Published by Papi Editore