Armed Forces Research Institute of Medical Sciences (AFRIMS) Influenza Surveillance Programs in Asia
Title of Contribution: Armed Forces Research Institute of Medical Sciences (AFRIMS) Influenza Surveillance Programs in Asia
Authors: K.S.A. Myint,1 R.G. Jarman, 1 S.K. Shrestha, 1 J. Gaywee, 1 J.M. Velasco, 1 I.K. Yoon, 1 M.M. Fukuda, 1 K. Ungchusak, 2 T. Wongstitwilairoong, 1 C.J. Mason, 1 J.A. Pavlin, 1 R.V. Gibbons1
Affiliation: 1Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand; 2Ministry of Public Health, Bangkok, Thailand
Abstract: The next major influenza pandemic could occur any time with potentially devastating consequences to the human population. New influenza strains frequently emerge in Asia. Thus, comprehensive influenza surveillance is critical especially in this region for the purposes of vaccine component determination as well as early detection of an influenza virus strain with pandemic potential.
The Armed Forces Research Institute of Medical Sciences (AFRIMS) has established influenza sentinel sites in South and Southeast Asia. In Thailand, two field sites in Sangkhlaburi and Kamphaeng Phet provide respiratory virus samples from the Thai-Burmese border and from a region that has previously been the site of probable human-to-human avian influenza virus transmission. The Royal Thai Army has established a network of respiratory disease surveillance sites at 6 border area hospitals. Field sites outside of Thailand, in Kathmandu, Nepal and Manila and Cebu, Philippines, are also active participants in respiratory virus surveillance.
At each site, patients who present with a history of fever and cough or sore throat are consented and enrolled. Respiratory samples are tested with a rapid test for influenza A and B on-site. In Kamphaeng Phet, Cebu and Kathmandu, the field site tests the samples using realtime PCR for influenza A (H1, H3, H5) and B, the other sites send aliquots to AFRIMS for testing. Some positive samples undergo virus isolation, characterization and sequencing in the US at the US Air Force School of Aerospace Medicine laboratory or the Centers for Disease Control and Prevention (WHO Collaborating Center for Surveillance, Epidemiology and Control of Influenza). In addition, AFRIMS can identify other respiratory pathogens by MassTag PCR which amplifies genetic material utilizing domain-specific primers tagged with a unique mass to allow spectrometric analysis and detection of up to 30 respiratory pathogens.
Since surveillance began in 2005, AFRIMS sites have collected 2,783 samples with 46.5% positive for influenza A or B by PCR. Evaluation of influenza rapid tests compared to PCR differed by site but had overall 60% sensitivity and 97% specificity. The results of phylogenetic analyses have assisted with global vaccine selection. In Nepal in 2004, strains from an outbreak of influenza A (H3N2) demonstrated drift from the previous influenza A vaccine strain, influencing the selection of the 2005/06 vaccine strain (A/California/7/2004) to contain an H3N2 strain with the same 4 amino acid substitutions found in the Nepalese isolates. In 2005, the isolated B/Victoria-lineage strains in Nepal were clearly divergent from the 2005/06 northern hemisphere vaccine strain (B/Yamagata) and only semi-reactive with the last B/Victoria-lineage vaccine strain. The confirmed major antigenic strain, B/Hawaii/33/2004 helped influence WHO influenza vaccine strain selection for the 2006/07 season. In 2008, an oseltamivir resistant H1N1 strain was isolated from Kamphaeng Phet, Thailand, the only Thai H1N1 virus resistant to oseltamivir. This unique finding of O-resistance was provided to the Thai Ministry of Public Health and WHO.
