Abstract
The last decade has seen the emergence of two new influenza A subtypes and they have become a cause of concern for the global community. These are the highly pathogenic H5N1 influenza A virus (H5N1) and the Pandemic 2009 influenza H1N1 virus. Since 2003 the H5N1 virus has caused widespread disease and death in poultry, mainly in south East Asia and Africa. In humans the number of cases infected with this virus is few but the mortality has been about 60%. Most patients have presented with severe pneumonia and acute respiratory distress syndrome. The second influenza virus, the pandemic H1N1 2009, emerged in Mexico in March this year. This virus acquired the ability for sustained human to human spread and within a few months spread throughout the world and infected over 4 lakh individuals. The symptoms of infection with this virus are similar to seasonal influenza but it currently affecting younger individuals more often. Fortunately the mortality has been low. Both these new influenza viruses are currently circulating and have different clinical and epidemiological characteristics.
Keywords: Influenza A, Pandemic, H1N1
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References
- 1.www.cdc.gov/flu/avian/gen-info/avian-flu-humans.htm. Accessed 20 October 2009
- 2.www.who.int/csr/disease/avian_influenza/country/en. Accessed 20 October 2009
- 3.Update (2007) WHO-confirmed human cases of avian influenza A(H5N1) infection, 25 November 2003–24 November 2006 Wkly Epidemiol Rec 82:41–48
- 4.Oner A.F., Bay A., Arslan S., et al. Avian influenza A (H5N1) infection in eastern Turkey in 2006. N Engl J Med. 2006;355:2179–2185. doi: 10.1056/NEJMoa060601. [DOI] [PubMed] [Google Scholar]
- 5.Dinh P.N., Long H.T., Tien N.T.K., et al. Risk factors for human infection with avian influenza A H5N1, Vietnam, 2004. Emerg Infect Dis. 2006;12:1841–1847. doi: 10.3201/eid1212.060829. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Areechokchai D., Jiraphongsa C., Laosiritaworn Y., Hanshaoworakul W., O’Reilly M. Investigation of avian influenza (H5N1) outbreak in humans — Thailand, 2004. MMWR Morb Mortal Wkly Rep. 2006;55(Suppl.1):3–6. [PubMed] [Google Scholar]
- 7.Sedyaningsih E.R., Isfandari S., Setiawaty V., et al. Epidemiology of cases of H5N1 virus infection in Indonesia, July 2005–June 2006. J Infect Dis. 2007;196:522–527. doi: 10.1086/519692. [DOI] [PubMed] [Google Scholar]
- 8.Ungchusak K., Auewarakul P., Dowell S.F., et al. Probable person-to-person transmission of avian influenza A (H5N1) N Engl J Med. 2005;352:333–340. doi: 10.1056/NEJMoa044021. [DOI] [PubMed] [Google Scholar]
- 9.Beigel J.H., Farrar J., Han A.M., Hayden F.G., Hyer R., Jong M.D., Lochindarat S., Nguyen T.K., Nguyen T.H., Tran T.H., Nicoll A., Touch S., Yuen K.Y. Writing Committee of the World Health Organization (WHO) Consultation on Human Influenza A/H5. N Engl J Med. 2005;353:1374–1385. doi: 10.1056/NEJMra052211. [DOI] [PubMed] [Google Scholar]
- 10.Apisarnthanarak A., Kitphati R., Thongphubeth K., et al. Atypical avian influenza (H5N1) Emerg Infect Dis. 2004;10:1321–1324. doi: 10.3201/eid1007.040415. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.http://www.cdc.gov/ncidod/EID/vol10no7/04-0415.htm. Accessed on 20 October 2009
- 12.Jong M.D., Bach V.C., Phan T.Q., et al. Fatal avian influenza A (H5N1) in a child presenting with diarrhea followed by coma. N Engl J Med. 2005;352:686–691. doi: 10.1056/NEJMoa044307. [DOI] [PubMed] [Google Scholar]
- 13.Chan P.K. Outbreak of avian influenza A (H5N1) virus infection in Hong Kong in 1997. Clin Infect Dis. 2002;2:S58–S64. doi: 10.1086/338820. [DOI] [PubMed] [Google Scholar]
- 14.Yuen K.Y., Chan P.K., Peiris M., et al. Clinical features and rapid viral diagnosis of human disease associated with avian influenza A H5N1 virus. Lancet. 1998;351:467–471. doi: 10.1016/S0140-6736(98)01182-9. [DOI] [PubMed] [Google Scholar]
- 15.Chotpitayasunondh T., Ungchusak K., Hanshaoworakul W., et al. Human disease from influenza A (H5N1) Thailand 2004. Emerg Infect Dis. 2005;11:201–209. doi: 10.3201/eid1102.041061. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Garten R.J., Davis C.T., Russell C.A., et al. Antigenic and genetic characteristics of swine-origin 2009 A (H1N1) influenza viruses circulating in humans. Science. 2009;325:197. doi: 10.1126/science.1176225. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Dawood F.S., Jain S., Finelli L., et al. Emergence of a novel swine-origin influenza A (H1N1) virus in humans. N Engl J Med. 2009;360:2605. doi: 10.1056/NEJMoa0903810. [DOI] [PubMed] [Google Scholar]
- 18.http://www.who.int/mediacentre/news/statements/2009/h1n1_pandemic_phase6_20090611/en/index.html accessed 27 October 2009
- 19.http://www.who.int/csr/don/2009_10_23/en/index.html accessed 27 October 2009
- 20.http://mohfw-h1n1.nic.in/October.html accessed 27 October 2009
- 21.http://www.cdc.gov/h1n1flu/surveillanceqa.htm accessed 27 October 2009
- 22.http://www.cdc.gov/h1n1flu/surveillanceqa.htm accessed 27 October 2009
- 23.http://mohfw-h1n1.nic.in/ accessed 27 October 2009
- 24.http://www.cdc.gov/h1n1flu/surveillanceqa.htm accessed 27 October 2009
- 25.Centers for Disease ControlPrevention Intensive-care patients with severe novel influenza A (H1N1) virus infection — Michigan, June 2009. MMWR Morb Mortal Wkly Rep. 2009;58:749–752. [PubMed] [Google Scholar]
- 26.http://www.who.int/csr/disease/swineflu/assess/disease_swineflu_assess_20090511/en/index.html accessed 27 October 2009
- 27.Centers for Disease ControlPrevention Introduction and transmission of 2009 pandemic influenza A (H1N1) Virus — Kenya, June–July 2009. MMWR Morb Mortal Wkly Rep. 2009;58:1143–1146. [PubMed] [Google Scholar]
- 28.Yang Y, Sugimoto JD, Halloran ME et.al. The transmissibility and control of pandemic influenza A (H1N1) virus. Science. 2009 Sep 10 [Epub ahead of print] [DOI] [PMC free article] [PubMed]
- 29.Jain S, Kamimoto L, Bramley AM et.al. Hospitalized patients with 2009 H1N1 influenza in the United States, April–June 2009. N Engl J Med 2009 Oct 8 [Epub ahead of print] [DOI] [PubMed]
- 30.http://www.cdc.gov/h1n1flu/surveillanceqa.htm accessed 27 October 2009
- 31.Kumar A, Zarychanski R and Pinto R et al. (2009) Critically Ill patients with 2009 influenza A(H1N1) infection in Canada. JAMA. 1496–1498 [DOI] [PubMed]
- 32.The ANZIC Influenza Investigators. Critical care services and 2009 H1N1 influenza in Australia and New Zealand. N Engl J Med 2009 Oct 8 [Epub ahead of print] [DOI] [PubMed]
- 33.http://www.cdc.gov/h1n1flu/identifyingpatients.htm accessed 27 October 2009