Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Aug 8:10:ecurrents.outbreaks.519e170f2740fabd4ccd1642ff533364.
doi: 10.1371/currents.outbreaks.519e170f2740fabd4ccd1642ff533364.

The 2015 Outbreak of Severe Influenza in Kashmir, North India: Emergence of a New Clade of A/H1n1 Influenza Virus

Parvaiz Koul  1 , Varsha Potdar  2 , Hyder Mir  1 , Mandeep Chadha  2
Affiliations

The 2015 Outbreak of Severe Influenza in Kashmir, North India: Emergence of a New Clade of A/H1n1 Influenza Virus

Parvaiz Koul et al. PLoS Curr. .

Abstract

Introduction: Following the initial outbreak of A/H1N1pdm09, periodic resurgences of the virus, with variable morbidity and mortality, have been reported from various parts of India including the temperate Kashmir region of northern India. An outbreak of A/H1N1 was reported in early 2015 across India with a high morbidity and mortality. We studied patients during the outbreak in Kashmir.

Methods: Patients (n=1780, age 1 month to 90 years, median 35 years) presenting with acute respiratory illness to a tertiary care hospital in Srinagar, Kashmir from October 2014 to April 2015 were recruited. After clinical data recording, combined throat and nasal swabs were collected in viral transport medium and tested by real-time RT-PCR for influenza viruses. All influenza A positive samples were further subtyped using primers and probes for A/H1N1pdm09 and A/H3 whereas influenza B samples were further subtyped into B/Yamagata and B/Victoria lineages. Virus isolation, hemagglutination inhibition testing, sequencing and phylogenetic analysis was carried out using standard procedures. Testing for H275Y mutation was done to determine sensitivity to oseltamivir. All patients received symptomatic therapy and influenza positive patients were administered oseltamivir.

Results: Of the 1780 patients, 540 (30%) required hospitalization and 533 tested positive for influenza [influenza A=517(A/H1N1pdm09=437, A/H3N2=78 with co-infection of both in 2 cases); influenza B=16 (B/Yamgata=15)]. About 14% (n=254) had been vaccinated against influenza, having received the NH 2014-15 vaccine, 27 (11.3%) of these testing positive for influenza. Sixteen patients, including 4 pregnant females, died due to multi-organ failure. HA sequencing depicted that 2015 isolates belonged to Clade 6B.1. No H275Y mutation was reported from A/H1N1 positives.

Conclusion: Resurgent outbreak of A/H1N1pdm09, with emergence of clade 6B.1, in 2014-15 resulted in high rate of hospitalizations, morbidity and mortality. Periodic resurgences and appearance of mutants emphasize continued surveillance so as to identify newer mutations with potential for outbreaks and severe outcomes.

Keywords: Influenza; emerging infectious diseases; infectious disease.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Weekwise positivity of influenza cases (October 2014-March 2015)
Figure 2.
Figure 2.
HA phylogenetic analysis of 2015 isolates of A/H1N1pdm09 . The tree consists of 2015 isolates from Pune, Delhi and compared with Srinagar isolates .The asterix and underline isolates are from the fatal severe cases . The 2015-16 vaccine component is shown in red font. Srinagar strains are in blue font. 2015 isolates belong to Clade 6B.1 with clade specific S203T or A203T, and D97N signature mutations
Table 2
Table 2
Details of the HA sequences of the strains over the years.
See this image and copyright information in PMC

References

    1. Chadha MS, Potdar VA, Saha S, Koul PA, Broor S, Dar L, Chawla-Sarkar M, Biswas D, Gunasekaran P, Abraham AM, Shrikhande S, Jain A, Anukumar B, Lal RB, Mishra AC. Dynamics of influenza seasonality at sub-regional levels in India and implications for vaccination timing. PLoS One. 2015 May 4;10(5):e0124122. 10.1371/journal.pone.0124122. - DOI - PMC - PubMed
    1. Koul P, Khan U, Bhat K, Saha S, Broor S, Lal R, Chadha M. Recrudescent Wave of A/H1N1pdm09 Influenza Viruses in Winter 2012-2013 in Kashmir, India. PLoS Curr. 2013 Sep 26;5. PubMed PMID:24818063. 10.1371/currents.outbreaks.f1241c3a2625fc7a81bf25eea81f66e6 - DOI - PMC - PubMed
    1. Koul PA, Mir MA, Bali NK, Chawla-Sarkar M, Sarkar M, Kaushik S, Khan UH, Ahmad F, Garten R, Lal RB, Broor S. Pandemic and seasonal influenza viruses among patients with acute respiratory illness in Kashmir (India). Influenza Other Respir Viruses. 2011 Nov;5(6):e521-7. PubMed PMID:21668665. - PMC - PubMed
    1. Koul PA, Broor S, Saha S, Barnes J, Smith C, Shaw M, Chadha M, Lal RB. Differences in influenza seasonality by latitude, northern India. Emerg Infect Dis. 2014 Oct;20(10):1723-6. PubMed PMID:25279651. - PMC - PubMed
    1. Cousins S. Death toll from swine flu in India exceeds 2500. BMJ. 2015; 351: h4966. doi: 10.1136/bmj.h4966 - PubMed

LinkOut - more resources