FAO: H5N2 in Taiwan Sheng China

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From FAO Document:
Excerpt:
UNDERSTANDING AVIAN INFLUENZA
2.1. Mutation from LPAI virus to HPAI virus
Excerpt:
An HPAI virus has been generated experimentally by repeat passage of a LPAI virus through chickens by air sac and intracerebral inoculation (Ito et al, 2001) but the exact triggers for this change under natural conditions are not known. In some earlier outbreaks of HPAI, it was evident that the change from a LPAI virus to an HPAI virus followed introduction of LPAI virus to large flocks of commercial poultry. This change apparently occurred within a matter of days in some outbreaks (as was the case of the 2004 Canadian outbreak [Bowes et al, 2004]). On the other hand, in some Central American countries, low pathogenicity H5N2 strains have circulated in poultry for a number of years without developing into highly pathogenic strains. Even in Mexico, where mutation of a LPAI H5N2 virus to an HPAI virus occurred in 1994 and this HPAI virus strain was subsequently eliminated, H5N2 LPAI viruses continue to circulate (Villarreal, 2006) but have not reverted to high pathogenicity.
http://www.fao.org/avianflu/documents/key_ai/key_book_ch2.htm

OIE Report-Highly pathogenic avian influenza,

Highly pathogenic avian influenza, Nepal

Information received on 02/12/2011 from Dr Ram Krishna Khatiwada, Programme Director , Directorate of Animal Health , Ministry of Agriculture and Co-operatives, Kathmandu, Nepal

Summary

Report type	Immediate notification
Start date	10/11/2011
Date of first confirmation of the event	14/11/2011
Report date	02/12/2011
Date submitted to OIE	02/12/2011
Reason for notification	Reoccurrence of a listed disease
Date of previous occurrence	30/10/2010
Manifestation of disease	Clinical disease
Causal agent	Highly pathogenic avian influenza virus
Serotype	H5N1
Nature of diagnosis	Clinical, Laboratory (basic), Laboratory (advanced), Necropsy
This event pertains to	the whole country

New outbreaks

Outbreak 1	Manahara Phat, Madhyapur Thimi Municipality - 16, Bhaktapur, BAGMATI
Date of start of the outbreak	10/11/2011
Outbreak status	Continuing (or date resolved not provided)
Epidemiological unit	Village
Affected animals	Species Susceptible Cases Deaths Destroyed Slaughtered Birds 396 88 88 308 0
Affected Population	Backyard chicken and duck population
Summary of outbreaks	Total outbreaks: 1
Outbreak statistics	Species Apparent morbidity rate Apparent mortality rate Apparent case fatality rate Proportion susceptible animals lost* Birds 22.22% 22.22% 100.00% 100.00% * Removed from the susceptible population through death, destruction and/or slaughter

Epidemiology

Source of the outbreak(s) or origin of infection	Unknown or inconclusive
Epidemiological comments	Stamping out activity was completed on 29 November 2011 and cleaning and disinfection of the infected premises were completed on 30 November 2011. Post-operative surveillance activities are ongoing and no further cases in other areas have been detected so far.

Control measures

Measures applied	Stamping out Quarantine Movement control inside the country Screening Disinfection of infected premises/establishment(s) Dipping / Spraying Vaccination prohibited No treatment of affected animals
Measures to be applied	No other measures

Diagnostic test results

Laboratory name and type	Central Veterinary Laboratory (CVL) (National laboratory)
Tests and results	Species Test Test date Result Birds polymerase chain reaction (PCR) 14/11/2011 Positive Birds rapid tests 14/11/2011 Positive
Laboratory name and type	Veterinary Laboratories Agency (VLA), Weybridge, United Kingdom (OIE’s Reference Laboratory)
Tests and results	Species Test Test date Result Birds reverse transcription - polymerase chain reaction (RT-PCR) 23/11/2011 Positive

Future Reporting http://web.oie.int/wahis/public.php?page=single_report&pop=1&reportid=11347