The emergence of the pandemic H1N1 2009 virus and its characteristics Symposium: Grippe - 2009 Académie Royale de Médecine de Belgique, Brussels Keith Hamilton (OIE, Paris) Elizabeth Mumford (WHO, Geneva)

Introduction April 2009 – WHO receives reports of sustained person to person transmission with a new influenza A (H1N1) virus in Mexico and USA Virus currently affecting people in all regions Pandemic alert level 6 Sporadic outbreaks in pigs (1st outbreak reported to OIE 21/04)

Human disease situation

Timeline April 12: an outbreak of influenza-like illness in Veracruz, Mexico reported to WHO April 15–17: notification of clusters of rapidly progressive severe pneumonia in Distrito Federal and San Luis Potosi A case of atypical pneumonia in Oaxaca State promoted enhanced surveillance April 15-17: two cases of the new A (H1N1) virus infection identified in two southern California counties in U.S.A. April 23: new influenza A (H1N1) virus infection confirmed in several patients in Mexico.

Timeline April 26: 38 cases reported from Mexico and the US April 27: Canada and Spain reported confirmed cases April 28: UK, Israel, New Zealand April 27: WHO declared phase 4 April 29: WHO declared phase 5 June 11: WHO declared phase 6 - pandemic

Epidemiology of Pandemic H1N1 2009 virus infection in people Northern hemisphere: An increasing trend in ILI is being reported in many temperate regions ILI level above the seasonal baseline in most regions of USA, a few other countries (France). USA, northern Ireland confirmed with positive H1N1 testing (is early for traditional influenza season). Southern hemisphere: at or below baseline in temperate regions Tropical regions Mixed picture ongoing widespread circulation, some increasing some decreasing trends All countries should stay vigilant and situation in developing countries should be closely watched

Pandemic H1N1 2009 Number of laboratory confirmed cases and deaths as reported to WHO (27 September 2009)

H1N1 infection – findings Most cases in children and young adults Spectrum of disease range from non-febrile, mild upper respiratory tract illness to severe or fatal pneumonia. Occasional gastrointestinal symptoms (diarrhoea, vomiting) Most frequent symptoms: cough, fever, sore throat, malaise and headache WHO – WER – 24 July 2009

Pandemic H1N1 2009 Garten et al. Science (2009); 325:197-201

Occurrence in animals

Reporting in animals Swine influenza is not an OIE listed disease Pandemic H1N1 2009 virus in pigs is reportable to OIE as an ‘emerging disease’ of animals ‘new infection resulting from the evolution or change of an existing pathogenic agent, a known infection spreading to a new geographic area or population, or a previously unrecognized pathogenic agent or disease diagnosed for the first time and which has a significant impact on animal or public health’

SIGNIFICANT SPREAD IN NAIVE POPULATIONS? Criteria for listing a disease INTERNATIONAL SPREAD? Has international spread been proven on 3 or more occasions? OR Are more than 3 countries with populations of susceptible animals free of the disease or facing impending freedom (based on Code provisions, especially Appendix 3.8.1)? OR Do OIE annual reports indicate that at least 3 countries with susceptible populations are reporting absence of the disease? EMERGING? (A newly recognised pathogen or known pathogen behaving differently) Is there apparent zoonotic properties or rapid spread? EXCLUDE NO YES ZOONOTIC POTENTIAL? Has transmission to humans been proven? (with the exception of artificial circumstances) AND Is human infection associated with severe consequences? (death or prolonged illness) SIGNIFICANT SPREAD IN NAIVE POPULATIONS? Does the disease exhibit significant mortality at level of a country or zone? OR Does the disease exhibit significant morbidity at the level of a country or zone? NO INCLUDE YES NO EXCLUDE YES INCLUDE

Reports to OIE 8 reports to OIE of pandemic H1N1 2009 outbreaks in pigs, in Canada (1), Argentina (2), Australia (1), Northern Ireland (3), and Ireland (1) Disease in pigs is mild – like swine influenza 1 report of infection in turkeys in Chile – further studies ongoing

Experimental infections of animals with pandemic H1N1 2009 Pigs infected with human isolates Clinical disease is mild (like SIV infection) Onwards transmission in pigs Pandemic H1N1 2009 virus found only in respiratory tract of pigs Attempts to infect poultry were unsuccessful, with the exception of quail where onwards transmission was not demonstrated

Key messages No information on exact origin of this pandemic virus Animals are not playing a significant role in the epidemiology of the human disease Infections in pigs are to be expected – the situation should be monitored

Key messages Pork and pork products handled in accordance with good hygiene practices are not a food safety risk The name of the virus – Pandemic H1N1 2009 OIE advocates against inappropriate actions such as culling pigs or imposition of trade measures against countries experiencing outbreaks

OFFLU Expanded mandate (May 2009) OIE – FAO network of expertise on animal influenza Initially established in 2005 to address HPAI H5N1 Strengthen links within animal health network and with WHO Expanded mandate (May 2009) In response to pandemic H1N1 2009 To cover all ‘animal influenza’ viruses To address technical issues relating to all animal influenzas, and pandemic H1N1 2009 To collaborate with WHO – GIP and share information to protect both animal and public health

Actions Strong cooperation between human health and animal health sectors Enhanced surveillance for influenzas in animals Biosecurity to protect pigs from human infection Encourage OIE Members to continue to notify outbreaks to OIE Experts to share information quickly through OFFLU Strengthen Veterinary Services globally

k.hamilton@oie.int mumforde@who.int