Are you Linda C Canas?

Claim your profile

Publications (13)50.76 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Armed Forces Health Surveillance Center's Division of Global Emerging Infections Surveillance and Response System (AFHSC-GEIS) supports and oversees surveillance for emerging infectious diseases, including respiratory diseases, of importance to the U.S. Department of Defense (DoD). AFHSC-GEIS accomplishes this mission by providing funding and oversight to a global network of partners for respiratory disease surveillance. This report details the system's surveillance activities during 2009, with a focus on efforts in responding to the novel H1N1 Influenza A (A/H1N1) pandemic and contributions to global public health. Active surveillance networks established by AFHSC-GEIS partners resulted in the initial detection of novel A/H1N1 influenza in the U.S. and several other countries, and viruses isolated from these activities were used as seed strains for the 2009 pandemic influenza vaccine. Partners also provided diagnostic laboratory training and capacity building to host nations to assist with the novel A/H1N1 pandemic global response, adapted a Food and Drug Administration-approved assay for use on a ruggedized polymerase chain reaction platform for diagnosing novel A/H1N1 in remote settings, and provided estimates of seasonal vaccine effectiveness against novel A/H1N1 illness. Regular reporting of the system's worldwide surveillance findings to the global public health community enabled leaders to make informed decisions on disease mitigation measures and controls for the 2009 A/H1N1 influenza pandemic. AFHSC-GEIS's support of a global network contributes to DoD's force health protection, while supporting global public health.
    BMC Public Health 01/2011; 11 Suppl 2:S6. · 2.08 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Clinicians frequently use influenza rapid antigen tests for diagnostic testing. We tested nasal wash samples from 1 April to 7 June 2009 from 1538 patients using the QuickVue Influenza A+B (Quidel) rapid influenza antigen test and compared the results with real-time reverse transcription polymerase chain reaction (rRT-PCR) assay (gold standard). The prevalence of 2009 pandemic influenza A (pH1N1) was 1.98%, seasonal influenza type A .87%, and seasonal influenza type B 2.07%. The sensitivity and specificity of the rapid test for pH1N1 was 20% (95% CI, 8-39) and 99% (95% CI, 98-99), for seasonal influenza type A 15% (95% CI, 2-45) and 99% (95% CI, 98-99), and for influenza type B was 31% (95% CI, 9-61) and 99% (95% CI, 98-99.7). Rapid influenza antigen tests were of limited use at a time when the prevalence of pH1N1 and seasonal influenza in the United States was low. Clinicians should instead rely on clinical impression and laboratory diagnosis by rRT-PCR.
    Clinical Infectious Diseases 01/2011; 52 Suppl 1:S116-22. · 9.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Department of Defense (DoD) Global Laboratory-Based Influenza Surveillance Program was initiated in 1997 to formally consolidate and expand existing influenza surveillance programs within the DoD and in areas where DoD was working. Substantial changes in 2008 provided an opportunity to review the operation of the surveillance program as it existed during seven complete influenza seasons (1998-2005); the review was conducted in 2008. A unique aspect of the DoD program was the global reach for specimen collection and the ability to rapidly ship, process, and evaluate specimens from 27 countries. The resulting epidemiologic data combined with the culture results from >46,000 patients provided information that was shared with similar national and international programs, such as those of the CDC. Likewise, selected influenza isolates were molecularly characterized and shared with the CDC to be compared with other surveillance programs. Timeliness of the samples contributed to the information available for annual influenza vaccine selection.
    American journal of preventive medicine 10/2009; 37(3):235-41. · 4.24 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Influenza viruses type A (H3N2 and H1N1 subtypes) and B are the most prevalently circulating human influenza viruses. However, an increase in several confirmed cases of high pathogenic H5N1 in humans has raised concerns of a potential pandemic underscoring the need for rapid, point of contact detection. In this report, we describe development and evaluation of 'type,' i.e., influenza virus A and B, and 'subtype,' i.e., H1, H3, and H5, specific, single-step/reaction vessel format, real-time RT-PCR assays using total RNA from archived reference strains, shell-vial cultured and uncultured primary (throat swab/nasal wash) clinical samples. The type A and B specific assays detected all 16 influenza type A viruses and both currently circulating influenza B lineages (Yamagata and Victoria), respectively. 'Type' and 'subtype' specific assays utilize one common set of thermocycling conditions, are specific and highly sensitive (detection threshold of approximately 100 target template molecules). All clinical specimens and samples were evaluated using both the unconventional portable Ruggedized Advanced Pathogen Identification Device (RAPID) and standard laboratory bench LightCycler instruments. These potentially field-deployable assays could offer significant utility for rapid, point of care screening needs arising from a pandemic influenza outbreak.
    Influenza and Other Respiratory Viruses 08/2007; 1(4):167-75. · 1.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Currently circulating influenza B viruses can be divided into two antigenically and genetically distinct lineages referred to by their respective prototype strains, B/Yamagata/16/88 and B/Victoria/2/87, based on amino acid differences in the hemagglutinin surface glycoprotein. During May and July 2005, clinical specimens from two early season influenza B outbreaks in Arizona and southeastern Nepal were subjected to antigenic (hemagglutinin inhibition) and nucleotide sequence analysis of hemagglutinin (HA1), neuraminidase (NA), and NB genes. All isolates exhibited little reactivity with the B/Shanghai/361/2002 (B/Yamagata-like) vaccine strain and significantly reduced reactivity with the previous 2003/04 B/Hong Kong/330/2001 (B/Victoria-like) vaccine strain. The majority of isolates were antigenically similar to B/Hawaii/33/2004, a B/Victoria-like reference strain. Sequence analysis indicated that 33 of 34 isolates contained B/Victoria-like HA and B/Yamagata-like NA and NB proteins. Thus, these outbreak isolates are both antigenically and genetically distinct from the current Northern Hemisphere vaccine virus strain as well as the previous 2003-04 B/Hong Kong/330/2001 (B/Victoria lineage) vaccine virus strain but are genetically similar to B/Malaysia/2506/2004, the vaccine strain proposed for the coming seasons in the Northern and Southern Hemispheres. Since these influenza B outbreaks occurred in two very distant geographical locations, these viruses may continue to circulate during the 2006 season, underscoring the importance of rapid molecular monitoring of HA, NA and NB for drift and reassortment.
    Archives of Virology 10/2006; 151(9):1863-74. · 2.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Identification of genetic variations of influenza viruses is essential for epidemic and pandemic outbreak surveillance and determination of vaccine strain selection. In this study, we combined a random amplification strategy with high-density resequencing microarray technology to demonstrate simultaneous detection and sequence-based typing of 25 geographically distributed human influenza virus strains collected in 2004 and 2005. In addition to identification, this method provided primary sequence information, which suggested that distinct lineages of influenza viruses co-circulated during the 2004-2005 season, and simultaneously identified and typed all component strains of the trivalent FluMist intranasal vaccine. The results demonstrate a novel, timely, and unbiased method for the molecular epidemiologic surveillance of influenza viruses.
    Emerging infectious diseases 05/2006; 12(4):638-46. · 5.99 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In July 2004, an outbreak of influenza A (H3N2) was detected at 3 Bhutanese refugee camps in southeastern Nepal. Hemagglutination inhibition showed that approximately 40% of the viruses from this outbreak were antigenically distinct from the A/Wyoming/3/03 vaccine strain. Four amino acid differences were observed in most of the 26 isolates compared with the A/Wyoming/3/2003 vaccine strain. All 4 substitutions are located within or adjacent to known antibody-binding sites. Several isolates showed a lysine-to-asparagine substitution at position 145 (K145N) in the hemagglutinin molecule, which may be noteworthy since position 145 is located within a glycosylation site and adjacent to an antibody-binding site. H3N2 viruses continue to drift from the vaccine strain and may remain as the dominant strains during the 2005-2006 influenza season. Thus, the 2005-2006 Northern Hemisphere vaccine strain was changed to A/California/7/2004, a virus with all 4 amino acid substitutions observed in these Nepalese isolates.
    Emerging infectious diseases 09/2005; 11(8):1186-91. · 5.99 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Influenza is a viral respiratory pathogen responsible for frequent seasonal epidemics. There are currently three major human influenza viruses in global circulation, H1N1, H3N2 and B. A one-step multiplex reverse transcription (RT)-polymerase chain reaction (PCR) assay targeting the HA1 segment of the human hemagglutinin gene was developed as a rapid surveillance method. A researcher-blind study was performed using 112 randomly selected, culture-positive clinical samples collected through the Department of Defense (Global Emerging Infectious Surveillance (DOD-GEIS) influenza network during the 2000-2001 influenza season. Three subtype specific primer sets capable of producing PCR products with base-pair lengths of 585, 402 and 290 corresponding to influenza H1, H3, and B subtypes, respectively, were utilized together in a one step, one tube, reaction. Multiplex primers were able to simultaneously type, and subtype 100% (112/112) of positive cultures. The results confirm that this assay is a highly sensitive and timely surveillance tool for rapid detection and simultaneous subtyping of clinical influenza specimens isolated worldwide.
    Journal of Clinical Virology 01/2003; 25(3):345-50. · 3.29 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Department of Defense (DoD) Global Influenza Surveillance Program was initiated in 1997 to monitor and prevent influenza outbreaks attributable to newly emerging strains. This tri-service program is managed from Brooks Air Force Base, Texas and is largely funded by the DoD Global Emerging Infections Surveillance and Response System. Throat swabs were collected from individuals presenting with a fever and either a cough or sore throat, or evidence of acute non-bacterial pneumonia. These specimens were sent to the Epidemiology Surveillance Division (AFIERA/SDE) for viral isolation and identification. During the 2001-2002 influenza season, AFIERA/SDE processed 3049 specimens from 63 installations worldwide. Influenza A activity peaked in Week 4 (20-26 Jan 02) when nearly 36 percent of total specimens were positive for influenza viruses. Influenza B peaked in Week 13 (24-30 Mar 02). Compared to last season when influenza B predominated throughout the season, influenza B first appeared mid-season and accounted for only 10 percent of all influenza viruses identified by the DoD program. All of the 58 H3N2 and 16 H1H1 influenza A viruses that were sequenced were similar to the 2001-2002 vaccine strains.
    05/2002;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: From February through May of 1999, 13 cases of Influenza A virus (FLUAV), type H1N1 were reported at a Department of Defense influenza surveillance sentinel site in Lima, Peru. Genetic and antigenic analysis by hemagglutination inhibition and direct nucleotide sequencing of the HA1 region of the hemagglutinin gene were performed on two isolates, A/Peru/1641/99 and A/Peru/1798/99. Both isolates were distinct from the Bayern/7/95-like viruses circulating in the Americas and closely related to a Beijing/262/95-like variant, A/New Caledonia/20/99. With the exception of travel-related cases, the detection of these isolates represents the first appearance of New Caledonia/20/99-like viruses in the Americas. Since the characterization of these Peru isolates, a number of New Caledonia/20/99-like viruses have been reported worldwide. For the 2000/01 and 2001/02 influenza seasons, the World Health Organization (WHO) has recommended the inclusion of A/New Caledonia/20/99 as the H1N1 vaccine component for both the southern and northern hemispheres.
    Emerging infectious diseases 05/2002; 8(4):408-12. · 5.99 Impact Factor
  • Journal of Clinical Virology 01/2002; 25(3). · 3.29 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Military global influenza surveillance began in 1976 as an Air Force program. In 1997, the Department of Defense (DoD) Global Emerging Infections Surveillance and Response System expanded the program to include all services. Also included were local residents in areas where DoD overseas research activities operated. This new, worldwide DoD surveillance infrastructure provides valuable information and can respond quickly to outbreaks. This was demonstrated during the current influenza season when a suspected outbreak was reported in Panama. In less than 3 weeks, specimens were collected, transported, and cultured, and isolates were subtyped and sent to the Centers for Disease Control and Prevention for further studies. This influenza surveillance initiative combines viral isolation, antigenic characterization, and molecular sequencing with clinical and public health management of information. The information obtained is shared with the Centers for Disease Control and Prevention and the World Health Organization and has contributed to important decisions in influenza vaccine composition.
    Military medicine 08/2000; 165(7 Suppl 2):52-6. · 0.77 Impact Factor
  • Source
    Emerging infectious diseases 01/1998; 4(1):128-30. · 5.99 Impact Factor