INFLUENZA A H1N1, CHILE

Information received on 31/08/2009 from Dr Ternicier Claudio, Jefe División Protección Pecuaria, Servicio Agrícola y Ganadero, Ministerio de Agricultura, Santiago, Chile.

Summary

Report type Follow-up report No. 1
Start date 23/07/2009
Date of first confirmation of the event 20/08/2009
Report date 31/08/2009
Date submitted to OIE 31/08/2009
Date event resolved 23/10/2009
Reason for notification Emerging disease
Morbidity 61.4 %
Mortality 0 %
Zoonotic impact No
Causal agent Influenza A virus
Related reports
Outbreaks There are no new outbreaks in this report

Epidemiology

Source of the outbreak(s) or origin of infection
  • Unknown or inconclusive
Epidemiological comments To date, serological surveillance carried out in 100% of the remaining farms of the same company was negative. Data on mortality and production in these farms are normal. In the rest of the country, the results of the routine surveillance programme for avian influenza in poultry were negative. The samples taken from wild birds near the outbreaks were negative for influenza.
In two breeding turkey flocks, the laying has returned to normal; there are still four flocks which should recover their normal laying rates.
A biosecurity programme has been established in order to contain the infection in the infected flocks and to prevent it on the farms of the company that remain negative. Moreover, a plan to eradicate the virus in the affected farms has been established and it includes sending the birds to slaughter at the end of their production period and once the absence of viral excretion is established on serial samples taken through a rapid test and verifying it by RRT-PCR for the matrix.
Tracing back of the movements of people towards and between farms is ongoing.
During the week before laying began dropping the peak of human cases of influenza A H1N1 was recorded in the area where poultry farms are located (epidemiological week 28).
Regarding the laboratory tests:
– The affected premises have been systematically monitored through serological tests with negative results until 28 July this year.
– On 16 August influenza A was detected by RRT-PCR for the matrix gene, according to the protocol described by Spackman (NVSL/USDA), on samples from tracheal and cloacae swabs, negative for H5 and H7 by RRT-PCR. Subtyping by serology (HI, NI) confirmed the detection of an influenza virus type A H1N1.
– The RNA of this virus of the influenza A H1N1 was sent to the Public Health Institute of Chile (ISP), Ministry of Health, with a positive result for influenza A H1N1, by real-time RRT-PCR, according to CDC protocol. The RRT-PCR for seasonal influenza H1 and H3 was negative.
– The ISP determined the complete genome sequence of the 8 genes (HA, NA, PA, PB, PB2, NP, NS and M) of the H1N1 influenza virus found in turkeys, comparing the similarity percentage with the A/California/4/2009 strain and the H1N1 influenza from Chile: for the HA gene, 99.5% and 100%; for NA, 99.5% and 99.7%; for PB1, 99.8% and 99.9%; for PB2, 99.8% and 99.8%; for PA, 99.7% and 99.9%; for NP, 99.5% and 99.7%; for NS, 99.8% and 99.8%; for M, 99.8% and 99.7%.
The ISP concludes that the influenza virus A (H1N1) from turkeys corresponds to the same viral variant of the virus A (H1N1) 2009 which has been circulating this winter in our country (access number Gene Bank GQ 200279 to GQ 200286).
– The National Veterinary Services Laboratory (NVSL), United States, indicates positive results through real time RT-PCR for novel N1 (SEPRL, Southeast Poultry Research Laboratory, Georgia, USA), for NI (NVSL/WI), for H1 (CDC) and a homology of the HA gene 99.6% similar to CA/14/2009, 99.7% similar to MX/4108/2009 and 100% similar to NY/18/2009. The neuraminidase gene shows a homology of 99.6% to MX/4108/2009, CA/4/2009, AZ/02/2009 and KS/02/2009.

Control measures

Measures applied
  • Quarantine
  • Screening
  • Disinfection of infected premises/establishment(s)
  • Vaccination prohibited
  • No treatment of affected animals
Measures to be applied
  • No other measures

Diagnostic test results

Laboratory name and type

Public Health Institute (National laboratory)

Tests and results
Species Test Test date Result
Birds real-time reverse transcriptase/polymerase chain reaction (RRT-PCR) 20/08/2009 Positive
Birds virus sequencing 28/08/2009 Positive

Laboratory name and type

Quarantine Stations and Laboratories Department, SAG (National laboratory)

Tests and results
Species Test Test date Result
Birds real-time reverse transcriptase/polymerase chain reaction (RRT-PCR) 16/08/2009 Positive

Laboratory name and type

National Veterinary Services Laboratory (NVSL), United States (OIE’s Reference Laboratory)

Tests and results

Species

Test

Test date

Result

Birds

gene sequencing

27/08/2009

Positive

Birds

real-time reverse transcriptase/polymerase chain reaction (RRT-PCR)

27/08/2009

Positive

Future Reporting

The event is continuing. Weekly follow-up reports will be submitted.