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Research Health Avian Influenza Avian influenza - AISER update 5
Research Health Avian Influenza Avian influenza - AISER update 5 | Avian influenza - AISER update 5 |
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| Written by Ramaz Mitaishvili | |
| Saturday, 01 September 2007 | |
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31 August 2007 No cases of human infection detected in Abkhazia (breakaway province of Georgia)
Based on the amended criteria, the Ministry of Health of Viet Nam confirms the following 5 additional cases of human infection with H5N1 avian influenza, including 4 deaths, in the country. The table of cumulative number of confirmed human cases has been amended accordingly. But possibility of outbreak is high. WHO has introduced an External Quality Assessment Project (see description of EQA project) for national reference laboratories for the detection of subtype influenza A viruses by polymerase chain reaction (PCR) testing and has now amended the criteria for accepting confirmed cases of A(H5) infection (see amended WHO criteria). WHO External Quality Assessment Project for the Detection of Subtype Influenza A Viruses by PCR Since 1952, the National Influenza Centres (NICs)i have been the backbone of the WHO Global Influenza Surveillance Network (GISN) and the WHO Global Influenza Programme (GIP). They collect specimens, conduct preliminary analysis and send representative isolates to WHO Collaborating Centres to support the annual recommendation of influenza vaccine composition for the next season. The tests employed are mainly virus isolation and hemagglutination inhibition test. The on-going presence of the A(H5N1) strain of avian influenza since early 2004, has increased the need for PCR (polymerase chain reaction) as part of the diagnosis process in order to improve the accuracy and efficiency of testing. PCR has become the principal laboratory test for the detection of H5 infections in both humans and animals. As the avian influenza A(H5N1) situation evolves it has become increasingly important to detect H5 infections efficiently and reliably, in order to facilitate outbreak response and influenza pandemic preparedness. Although many NICs are now utilizing PCR for the detection of influenza viruses, there is, however, no globally coordinated external quality assessment programme that monitors the quality and comparability of the performance of these laboratories. The WHO External Quality Assessment (EQA) Project has now been established to improve the global laboratory capacity for influenza diagnosis, both seasonal and avian. It aims specifically to monitor the quality and standards of performance of NICs around the world in the detection of subtype influenza A viruses using PCR as well as to promote good laboratory practice. The EQA Project is being conducted jointly by the WHO Global Influenza Programme, based at WHO Headquarters and the WHO H5 Reference Laboratory and National Influenza Centre in the Virology Division, Centre for Health Protection of the Department of Health, Hong Kong, Special Administrative Region, China, with the support from the WHO Collaborating Centres on influenza, other WHO H5 Reference Laboratories and WHO Regional Offices. Outlines of the EQA Project Objectives: • To build and strengthen influenza laboratory diagnostic capacity of using PCR for the detection of subtype influenza A viruses including A(H5); and • To promote good laboratory practice. Participants: All NICs and other national influenza laboratories in countries without NICs. Process: • The Project requires testing twice a year a panel of simulated RNA specimens including H1, H3 and H5, accompanied with a Good Laboratory Practice questionnaire. Testing results are required to be reported back within a defined time frame. • WHO analyses the results received from participants and produces a full report on the performance of each participating laboratory. All NICs have been informed of the EQA Project and its process and have been invited to participate. For further information about the EQA Project, please contact the WHO Global Influenza Programme email: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it i NICs are influenza laboratories designated by national authorities and recognized by WHO being as a member of the WHO Global Influenza Surveillance Network under the Terms of Reference published at: http://www.who.int/csr/disease/influenza/TORNICs.pdf WHO criteria for accepting positive PCRi test results of H5 infection in humans from national reference laboratoriesii Amendment ● 30 August 2007 Laboratory testing is the only way to confirm that infection with H5 influenza viruses has occurred and is critical for both national H5N1 surveillance activities as well as optimal clinical care in this current period when H5N1 infections remain sporadic. WHO has published recommended laboratory tests to use for confirming influenza A(H5) infectioniii and guidance on the interpretation of test resultsiv. Among these tests, polymerase chain reaction (PCR) is the most common approach used by most laboratories to confirm H5 infection. However, testing for H5 influenza virus infections is not done routinely by many laboratories. Among laboratories that do test for H5, the levels of experience and diagnostic capacities can vary. This document provides the necessary criteria by which WHO will accept country reported H5 positive PCR test results as "confirmed". All countries are urged to share with WHO all H5 positive specimens/virus isolates from humans so that analyses of pandemic risk, development of H5 vaccines, development and updating of diagnostic protocols and reagents, monitoring of antiviral susceptibility patterns and other important risk assessment and response activities can proceed. WHO will accept H5 positive PCR test results from national reference laboratories as follows: 1. Results are accepted from a national reference laboratory that is also a WHO H5 Reference Laboratoryv. 2. Results are accepted from other national reference laboratories (a) that have participated in the WHO External Quality Assessment (EQA) Projectvi for the detection of subtype influenza A viruses by polymerase chain reaction (PCR) testing, and that have achieved excellent results with the use of the most recent test panel provided by the EQA Project, demonstrated by the correct detection of all H5 viruses and the absence of any false H5 positive results; and (b) that also have had, in the period since 2004, direct experience in testing for human H5 influenza virus infections and that have made at least 3 positive H5 diagnoses, of which all have been confirmed by WHO H5 Reference Laboratories. 3. Countries that do not yet have a national reference laboratory, or whose national reference laboratory is neither a WHO H5 Reference Laboratory nor able to fulfill the complete criteria listed under 2., must have its positive H5 test results confirmed through referral of samples for re-testing at a) a WHO H5 Reference Laboratory; or b) a national reference laboratory from which H5 testing results are accepted by WHO. 4. In exceptional situations WHO may decide that there is need for follow up investigation of the results received from a laboratory that fulfills criteria 1. to 3. above. In such situations, e.g. if there is a sudden increase in positive H5 test results that does not appear to reflect the epidemiologic situation in the country, staff from WHO Headquarters, relevant Regional Offices or Country Offices will work with the national reference laboratory to further review the situation. All countries are encouraged to participate routinely in the WHO EQA Project to accumulate and maintain H5 testing proficiency skills. WHO will periodically review these criteria and may change them in the future as indicated. i Positive H5 results using laboratory tests other than PCR will be reviewed and accepted on a case-by-case basis only. ii National reference laboratories here refers to National Influenza Centers and other laboratories designated by government for influenza diagnosis iii http://www.who.int/csr/disease/avian_influenza/guidelines/labtests/en/index.html iv http://www.who.int/csr/disease/avian_influenza/guidelines/case_definition2006_08_29/en/index.html v http://www.who.int/csr/disease/avian_influenza/guidelines/referencelabs/en/ vi http://www.who.int/csr/disease/avian_influenza/guidelines/eqa_project/en/index.html |
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