دکتر بهروز نقیلی استاد بیماریهای عفونی مرکس تحقیقات بیماریهای عفونی و گرمسیری پاییس 88
FLU.. How often can you escape?
Three viral types are distinguished by their matrix and nucleoproteins Type Host Clinical Importance Pattern of Occurrence Subtypes A Humans, birds, horses, other mammals Moderate to severe disease Sporadic, epidemics, pandemics Yes H1-H16 N1-N9 B Humans Moderate to severe disease Sporadic, epidemics No 2 lineages co-circulate C Humans and swine Mild disease Sporadic, localized outbreaks No Influenza A is further classified according to its H and N subtypes, e.g. A/H3N2, A/H1N1 H = hemagglutinin; N = neuraminidase. Bridges et al. 2008.
Antigenic drift can lead to more severe and earlier outbreaks of disease A/Sydney/5/97(H3N2)-like drift variant Europe and United States Severe outbreaks of influenza 1,2 A/Fujian(H3N2)-like drift variant Europe Medium-high incidence of influenza like illness (19 of 21 countries) 3 1997 1998 1999 2000 2001 2002 2003 2004 Year 2005 2006 2007 2008 A/Sydney/5/97(H3N2)-like drift variant South Africa Major epidemic 4 1. Aymard et al. 1999; 2. Klimov et al. 1999; 3. Paget et al. 2005; 4. Besselaar et al. 1999. 5 INFLUENZA THE DISEASE
Pandemic Phases Interpandemic phase "Animal influenza outbreaks" Low risk for humans 1 High risk for humans 2 Pandemic Alert "New influenza subtype in humans" No or only inefficient h2h transmission Evidence for increased h2h transmission Significant increase in h2h transmission Pandemic 6 3 4 5
Local & Systemic symptoms what are the local symptoms of ILI? what are the systemic symptoms of ILI and what causes them? what are the complications of influenza? for which risk-groups is influenza vaccination indicated?
systemic symptoms of ILI The influenza viruses do not cause these systemic symptoms themselves, because they are restricted to the respiratory tract and do not (usually) circulate through the entire body The interferons, produced by the body to fight viral replication, are circulating in the blood throughout the body and cause the systemic symptoms
Influenza is a highly infectious disease Transmitted primarily by respiratory droplets 1 Infects people of all ages Children are significant transmitters 1,2 Seasonal influenza epidemics may vary in their severity 1
Influenza virus infects cells of the tracheobronchial epithelium Virus transmitted by respiratory droplets 1,2 Attaches to respiratory epithelium and multiplies within cells 1,3 Destroys ciliated cells lining the airways 3 Recovery of respiratory epithelium may take up to 1 month 1 1. Bridges et al. 2008; 2. CDC 2008; 3. Dolin 2005. 15 INFLUENZA THE DISEASE
Transmission and Evolution The H1N1 virus is transmitted easily from person to person when speaking, by sneezing or coughing and can be confused with other severe Influenza illnesses caused by different viruses. The general incubation period is 1-4 days, with an average of 2 days. Adults may be contagious from one day prior to the commencement of symptoms to up to 7 days after becoming sick.
Children may be contagious for a period of up to 14 days after the appearance of symptoms.
Swine Flu What is Swine Influenza? Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza virus that regularly causes outbreaks of influenza in pigs. Swine flu viruses cause high levels of illness and low death rates in pigs. Swine influenza viruses may circulate among swine throughout the year, mostly during the late fall and winter similar to humans. The classical swine flu virus (an influenza type A H1N1 virus) was first isolated from a pig in 1930.
How many swine flu viruses are there? Like all influenza viruses, swine flu viruses change constantly. Pigs can be infected by avian influenza and human influenza viruses as well as swine influenza viruses. When influenza viruses from different species infect pigs, the viruses can reassort (i.e. swap gen) Over the years, different variations of swine flu viruses have emerged. At this time, there are four main influenza type A virus subtypes that have been isolated in pigs: H1N1, H1N2, H3N2, and H3N1. However, most of the recently isolated influenza viruses from pigs have been H1N1 viruses.
Subtypes of influenza A hemagglutinin (H) and neuraminidase (N) 1.3 Host range of influenza viruses Hemagglutinin (H) Neuraminidase (N) Subtype Predominant hosts Subtype Predominant hosts H1 human, pig, birds N1 human, pig, birds H2 human, pig, birds N2 human, pig, birds H3 human, pig, horse, birds N3 birds H4 birds N4 birds H5 birds N5 birds H6 birds N6 birds H7 horse, birds N7 horse, birds H8 birds N8 horse, birds H9 birds N9 birds H10 birds H11 birds H12 birds H13 birds H14 birds H15 birds H16 birds
Clinical Criteria for suspicion of Influenza A (H1N1) Fever higher than 38oC Rhinorrhea Cough Sore throat Other possible symptoms: headache, dyspnoea, myalgia, joint pain, nausea, vomiting and diarrhoea.
Suspected case: Include the clinical criteria and at least one epidemiologic criterion.
Epidemiologic Criteria Any person who resides in or has travelled in the last seven (7) days from a locality where there has been one or more confirmed cases of H1N1 Influenza; Any person who has been in close contact to in the last seven (7) days with a person who is a confirmed case of H1N1 Influenza infection.
Probable case: Include the clinical criteria, at least one epidemiologic criterion and a positive test for Influenza A that is unsubtypable by real-time PCR
Confirmed case: There is a confirmed laboratory test. real-time RT-PCR viral culture
Most of the identified persons who have contracted the H1N1 Influenza show improvement in one to two weeks. Some cases evolve with clinical deterioration, involving lower respiratory tract infections (pneumonias), with severe and occasionally fatal outcomes, which have occurred more frequently in persons who have underlying chronic diseases, are pregnant or immunosuppressed
Protection Is there a way to protect ourselves and our beloved people..?