Highly pathogenic avian influenza H5N6, Laos (OIE, May 7 2014): No New Outbreak, New Reassortant Isolated

[Giuseppe]

[Source: OIE, full page: (LINK). Edited.]


Highly pathogenic avian influenza H5N6, Laos


Information received on 07/05/2014 from Dr Khambounheuang Bounkhouang , Directeur G?n?ral, D?partement de l'Elevage et des P?ches , Minist?re de l'Agriculture et des For?ts , Vientiane capital, Laos

• Summary
  • Report type Follow-up report No. 1 (Final report)
  • Date of start of the event 13/03/2014
  • Date of pre-confirmation of the event 18/03/2014
  • Report date 07/05/2014
  • Date submitted to OIE 07/05/2014
  • Date event resolved 31/03/2014
  • Reason for notification Reoccurrence of a listed disease
  • Date of previous occurrence 12/2008
  • Manifestation of disease Clinical disease
  • Causal agent Highly pathogenic avian influenza virus
  • Serotype H5N6
  • Nature of diagnosis Laboratory (advanced)
  • This event pertains to a defined zone within the country
  • Related reports
    • Immediate notification (31/03/2014)
    • Follow-up report No. 1 (07/05/2014)
• Outbreaks
  • There are no new outbreaks in this report
• Epidemiology
  • Source of the outbreak(s) or origin of infection
    • Introduction of new live animals
• Epidemiological comments
  • Samples from this outbreak have now been tested at the Australian Animal Health Laboratory.
  • Sequencing analysis of original samples (post-mortem tissues) from both chickens and ducks shows that these are H5N6 highly pathogenic avian influenza viruses, with the highly pathogenic HA cleavage site sequence motif, PLRERRRKR*GLF.
  • Phylogenetic analysis of the HA gene sequence indicates that the HA is derived from the Asian H5N1 clade 2.3.4 HA lineage; however, they clustered with ?variant? (reassortant) clade 2.3.4 H5 HPAI viruses from China of various NA subtypes.
  • Follow-up sequencing of virus isolates from these samples confirms these findings.
  • Full genome sequencing has been completed.
• Control measures
  • Measures applied
    • Quarantine
    • Movement control inside the country
    • Screening
    • Disinfection of infected premises/establishment(s)
    • Modified stamping out
    • Vaccination prohibited
    • No treatment of affected animals
  • Measures to be applied
    • No other measures
• Future Reporting
  • The event is resolved. No more reports will be submitted.

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[Giuseppe]

Re: Highly pathogenic avian influenza H5N6, Laos (OIE, May 7 2014): No New Outbreak, New Reassortant Isolated

[Source: ProMedMail.org, full page: (LINK). Edited.]


Published Date: 2014-05-09 10:02:31 / Subject: PRO/AH/EDR> Avian influenza (61): Laos, HPAI H5N6, poultry, OIE, RFI / Archive Number: 20140509.2461275

AVIAN INFLUENZA (61): LAOS, HPAI H5N6, POULTRY, OIE, REQUEST FOR INFORMATION

A ProMED-mail post http://www.promedmail.org / ProMED-mail is a program of the International Society for Infectious Diseases http://www.isid.org

Date: Thu 8 May 2014 / Source: OIE, WAHID (World Animal Health Information Database), weekly disease information 2014; 27(19) http://www.oie.int/wahis_2/public/wahid.php/Reviewreport/Review?page_refer=MapFullEventReport&reportid=15217


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Communicated by: ProMED-mail promed@promedmail.org


[According to the immediate notification from Laos dated 31 Mar 2014, the outbreak statistics were the following:

Species / Susceptible / Cases / Deaths / Destroyed / Slaughtered
Birds / 5142 / 457 / 457 / 543 / 0

The affected population was described as, "affected birds, newly introduced into the village one week before the outbreak."

The "start" of the outbreak was given as 13 Apr 2014, "pre-confirmation" on 18 Apr 2014, when the Laos Laboratory performed the real-time PCR test, preliminarily concluding that the virus was HPAI H5N1.

Out of the 5142 susceptible birds on the farm, reportedly 457 died, 543 were destroyed, none reported as slaughtered. This means that 4152 contact birds on the farms have been kept alive.

Two questions arise:

1. What were the considerations to declare the event as "resolved"? Has surveillance been applied, regionally?
2. What was the origin of the introduced affected birds, reportedly causing the outbreak? Were they introduced from another location within Laos or was their introduction inter-boundary? In case the latter is the case, where from? Authorised or otherwise?

The designation of the isolate, by the Australian reference laboratory, as a highly pathogenic H5N6 strain is rather unique.

LPAI H5N6 strains have been recorded in wild birds (particularly mallards) in several continents in the past; H5N6 virus has been used as a poultry vaccine strain to produce DIVA ("differentiating infected from vaccinated animals") vaccines against HPAI H5N1.

Recently, an LPAI H5N6 virus was reported to cause (subclinical) infection in poultry and a fatal human case in Sichuan, central China (see ProMED-mail post 20140505.2451125 and OIE report at http://tinyurl.com/m6zfvoe ).

It would be interesting to check if the Chinese isolate was laboratory confirmed for its pathogenicity for chickens, and to investigate the genetic relationship between the H5N6 strains from China and Laos.

It would also be interesting to note if a poultry vaccine, including AI H5N6 vaccine strain, has been applied in Laos.

Re Laos' OIE reporting history, please refer to Mod.CRD commentary in ProMED-mail post 20140401.2371131. - Mod.AS A HealthMap/ProMED-mail map can be accessed at: http://healthmap.org/promed/p/146.]

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