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SWINE FLU

SWINE FLU. Dr. Asad Ramlawi D.G PHC & PH Palestine. Communicable Disease Surveillance, Forecasting and Response, CSR/EMRO). Influenza Virus. H1-H16. N1-N9. Types of Influenza Virus. Three types: A, B, C

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SWINE FLU

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  1. SWINE FLU Dr. Asad Ramlawi D.G PHC & PH Palestine

  2. Communicable Disease Surveillance, Forecasting and Response, CSR/EMRO) Influenza Virus H1-H16 N1-N9

  3. Types of Influenza Virus • Three types: A, B, C • Influenza Type A can infect: People, birds, pigs, horses, seals, whales and others • Classified into subtypes • Influenza Type B: Human virus • Not classified according to Subtype • Cause human epidemics but not pandemics • Influenza Type C cause mild illness in humans • Not classified according to subtype • Do not cause epidemics or pandemics

  4. Influenza Virus: Types A and B

  5. Influenza A Virus Subtyping • Influenza A subtypes are determined by two surface glycoproteins: • Hemagglutinin (HA) • Neuraminidase (NA) • 16 HA’s and 9 NA’s

  6. Species Infected by Influenza A, HA and NA Subtypes N1 H1 N2 H2 N3 H3 N4 H4 H5 N5 H6 N6 H7 N7 H8 N8 H9 N9 H10 H11 H12 H13 H14 H15,16

  7. Influenza: Epidemiologic Success • The long-term epidemiologic success of influenza viruses is primarily due to antigenic variation that takes place in the two surface glycoproteins of the virus: HA and NA. • Antigenic variation renders an individual susceptible to new strains despite previous infection by influenza viruses or previous vaccination.

  8. Influenza Epidemiologic Success: Antigenic Drift • Point mutations in the hemagglutinin gene cause minor antigenic changes to HA. • Continuous process • Immunity against one strain may be limited • These genetic changes often encode amino acid changes in the surface proteins and consequently in their antigenic properties. • Antigenic drift produces new virus strains that may not be recognized by antibodies to earlier influenza strains

  9. Influenza Epidemiologic Success: Antigenic Drift • Antigenic drift is one of the main reasons why people can get the flu more than one time (Seasonal epidemics) and why the vaccine formulation has to be evaluated and modified every year. • One or two of the three virus strains included in the annual influenza vaccine are updated: • 6-8 months process • Targeted at high-risk (inactivated)

  10. Influenza Epidemiologic Success: Antigenic Drift • Global surveillance of influenza viruses has shown that antigenic variation and the consequent epidemiologic behavior of influenza A viruses follows a relatively uniform pattern. • Each successive antigenic variant replaces its predecessor such that the co-circulation of distinct antigenic variants of a given subtype occurs for relatively short periods. • During the past decade, new epidemic variants of influenza often are first detected in China before they spread to other locations.

  11. Influenza Epidemiologic Success: Antigenic Shift • Gives rise to new influenza virus that can infect humans and has (new HA subtype ± NA) through: • Genetic reassortment (human and animal viruses) • Direct animal (poultry) to human transmission • As most people have little or no protection against the new virus: • Spread easily from person to person • Pandemic (worldwide spread) may occur

  12. Influenza A Viruses in Swine • Influenza viruses reported in swine: • H1N1 (swine classic) • H1N1 (avian and human like) • H3N2 (avian and human like)

  13. Recent Transmissions of Swine Influenza in Humans • 1998 at present: • Triple reassortant (human, avian and swine genes) • 2005-2009: 12 human cases in USA Avian N Am PB2 Seasonal H3N2 PB1 Avian N Am PA Classic swine N Am HA Classic swine N Am NP Classic swine N Am NA M Classic swine N Am Classic swine N Am NS Triple Reassortant Swine

  14. Recent Transmissions of Swine Influenza in Humans • Novel Swine Origin Influenza A H1N1 • First reported: • California, April 15, 2009 • May 16: 36 countries • 8,451 cases • 72 deaths (0.85 %) Avian N Am PB2 Seasonal H3N2 PB1 Avian N Am PA Classic swine N Am HA Classic swine N Am NP Eurasian swine NA M Eurasian swine Classic swine N Am NS

  15. Recent Transmissions of Swine Influenza in Humans Novel Swine Origin Influenza A H1N1 (2009) Triple Reassortant Swine Avian N Am PB2 Avian N Am PB2 Seasonal H3N2 PB1 Seasonal H3N2 PB1 Avian N Am PA Avian N Am PA Classic swine N Am HA Classic swine N Am HA Classic swine N Am NP Classic swine N Am NP Eurasian swine NA Classic swine N Am NA M Eurasian swine M Classic swine N Am Classic swine N Am NS Classic swine N Am NS

  16. Novel Influenza A (H1N1) • CDC developed a real time RT-PCR specific for novel influenza (H1N1) Avian N Am PB2 Seasonal H3N2 PB1 Avian N Am PA Classic swine N Am HA Classic swine N Am NP Eurasian swine NA M Eurasian swine Classic swine N Am NS

  17. Novel influenza A (H1N1) Diagnostic Flowchart Specimen: swabs in VTM Preserve remnant at -70C (if not available, then -20C) Nucleic Acid Extraction: 140 ul specimen Negative: Univ. Flu A Stop: Non-Flu A virus PCR Universal Flu A Positive: Univ. Flu A (continue with SwH1N1 primers) Univ. Flu A = Pos Sw Flu A = Neg Sw H1 = Neg RP = Pos STOP: Flu A virus PCR set up: Univ Flu A Sw Flu A SW H1 RP Seasonal Flu Subtype specimen Univ. Flu A = Pos Sw Flu A = Pos Sw H1 = Pos Univ. Flu A = Pos Sw Flu A = Neg Sw H1 = Pos Univ. Flu A = Pos Sw Flu A = Pos Sw H1 = Neg Sw H1N1 Repeat reaction from extraction Contact NAMRU-3 or CDC

  18. Novel Influenza A (H1N1) Surveillance Activities • Objectives: • Detect and confirm cases of novel influenza A (H1N1) infections • Establish the extent of international spread • Assist in the early severity assessment of the disease.

  19. 2009 Swine Influenza Testing: Testing Algorithm Specimen meets criteria for rRT-PCR Swine Flu Panel testing Perform rRT-PCR Swine Flu Panel Inf A (+) Universal SW InfA (+) Novel SW H1 (+) Inf A (+) Universal SW InfA (-) Novel SW H1 (-) Inf A (-) Universal SW InfA (-) Novel SW H1 (-) Inf A (+) Universal SW InfA (+) Novel SW H1 (-) Inf A (+) Universal SW InfA (-) Novel SW H1 (+) Inf A (-) U. SW InfA (+) N. SW H1 (+) Or Inf A (-) U. SW InfA (-) N. SW H1 (+) Or Inf A (-) U. SW InfA (+) N. SW H1 (-) Other Results Report Results To CDC per normal surveillance protocol and send specimens to CDC according to current guidance. Flu A positive specimens negative for human H1, H3, B , and swine H1 should be reported to CDC immediately for priority testing. Subtype specimens using rRT-PCR Flu Panel IVD test or other approved methods (as resources permit and the prevalence of other circulating strains dictates) Report results To CDC per normal surveillance protocol Repeat results from the extraction step in house, report results to CDC per normal surveillance protocol, and send specimens to CDC according to current guidance Repeat results from the extraction step in house, report results to CDC per normal surveillance protocol, and send specimens to CDC according to current guidance Report results to CDC per normal surveillance protocol Repeat results from the extraction step in house, report results to CDC per normal surveillance protocol * This algorithm assumes a positive RP result

  20. Avian Virus Communicable Disease Surveillance, Forecasting and Response, CSR/EMRO) Human virus Avian Virus Migratory birds Reassortment (in Animals and Humans) Reassortment in humans Reassortment in Swine Human Pandemic Strain

  21. Communicable Disease Surveillance, Forecasting and Response, CSR/EMRO) Prerequisites for pandemic influenza A new influenza virus emerges to which the general population has little/no immunity The new virus must be able to replicate in humans and cause disease The new virus must be efficiently transmitted from one human to another

  22. Communicable Disease Surveillance, Forecasting and Response, CSR/EMRO) Phases of pandemic influenza

  23. WHO Pandemic Phases c c

  24. Way Forwards:Transparency • The media are not your enemies • Need for a positive relationship • Give early, regular, accurate and consistent information • Get messages to the public (avoid confusion and panic) • Let the world know what you are doing Early Accurate Regular Consistent Media The Public Government Health Workers

  25. What is Swine Flu • Swine influenza virus (referred to as SIV) refers to influenza cases that are caused by Orthomyxovirus endemic to pig populations. SIV strains isolated to date have been classified either as Influenza(virus C or one of the various subtypes of the genus Influenza virus A)

  26. Different Strains circulate Periodically • In the United States the H1N1 subtype was exclusively prevalent among swine populations before 1998; however, since late August 1998, H3N2 subtypes have been isolated from pigs. As of 2004, H3N2 virus isolates in US swine and turkey stocks were triple reassortants, containing genes from human (HA, NA, and PB1), swine (NS, NP, and M), and avian (PB2 and PA) lineages.

  27. Swine Influenza (Flu) • Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza that regularly cause outbreaks of influenza among pigs. Swine flu viruses do not normally infect humans, however, human infections with swine flu do occur, and cases of human-to-human spread of swine flu viruses has been documented.

  28. Swine Flu-Present Status • From December 2005 through February 2009, a total of 12 human infections with swine influenza were reported from 10 states in the United States. Since March 2009, a number of confirmed human cases of a new strain of swine influenza A (H1N1) virus infection in the U.S. and internationally have been identified. An investigation into these cases is ongoing.

  29. Swine Flu 2009 • In late March and early April 2009, cases of human infection with swine influenza A (H1N1) viruses were first reported in Southern California and near San Antonio, Texas. Other U.S. states have reported cases of swine flu infection in humans and cases have been reported internationally as well.

  30. Update - Status Swine Flu • The United States Government has reported seven confirmed human cases of Swine Influenza A/H1N1 in the USA (five in California and two in Texas) and nine suspect cases. All seven confirmed cases had mild Influenza-Like Illness (ILI), with only one requiring brief hospitalization. No deaths have been reported.

  31. Swine Flu in Mexico • In the Federal District of Mexico, surveillance began picking up cases of ILI starting 18 March. The number of cases has risen steadily through April and as of 23 April there are now more than 854 cases of pneumonia from the capital. Of those, 59 have died. In San Luis Potosi, in central Mexico, 24 cases of ILI, with three deaths, have been reported.

  32. Swine Flu and Virus • 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, but most outbreaks occur during the late fall and winter months similar to outbreaks in humans. The classical swine flu virus (an influenza type A H1N1 virus) was first isolated from a pig in 1930.

  33. Cause by Reassortment of different strains • 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 genes) and new viruses that are a mix of swine, human and/or avian influenza viruses can emerge

  34. Swine Flu differs from Human Flu • The H1N1 swine flu viruses are antigenically very different from human H1N1 viruses and, therefore, vaccines for human seasonal flu would not provide protection from H1N1 swine flu viruses

  35. Out breaks among Pigs • Outbreaks among pigs normally occur in colder weather months (late fall and winter) and sometimes with the introduction of new pigs into susceptible herds. Studies have shown that the swine flu H1N1 is common throughout pig populations worldwide, with 25 percent of animals showing antibody evidence of infection.

  36. Present Swine Flu strains • 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.

  37. How man is exposed • Most commonly, these cases occur in persons with direct exposure to pigs (e.g. children near pigs at a fair or workers in the swine industry). In addition, there have been documented cases of one person spreading swine flu to others.

  38. How Swine Flu presents inHumans • The symptoms of swine flu in people are expected to be similar to the symptoms of regular human seasonal influenza and include fever, lethargy, lack of appetite and coughing. Some people with swine flu also have reported runny nose, sore throat, nausea, vomiting and diarrhea

  39. Is the eating Pork infects ? • No. Swine influenza viruses are not transmitted by food. You can not get swine influenza from eating pork or pork products. Eating properly handled and cooked pork and pork products is safe. Cooking pork to an internal temperature of 160°F kills the swine flu virus as it does other bacteria and viruses

  40. Close proximity with PIGS spread the Infections • Influenza viruses can be directly transmitted from pigs to people and from people to pigs. Human infection with flu viruses from pigs are most likely to occur when people are in close proximity to infected pigs, such as in pig barns and livestock exhibits housing pigs at fairs. Human-to-human transmission of swine flu can also occur.

  41. How Swine flu spread among Pigs • Swine flu viruses are thought to be spread mostly through close contact among pigs and possibly from contaminated objects moving between infected and uninfected pigs. Herds with continuous swine flu infections and herds that are vaccinated against swine flu may have sporadic disease, or may show only mild or no symptoms of infection.

  42. Seek emergency medical care.IF -in Children • In children emergency warning signs that need urgent medical attention include: • Fast breathing or trouble breathing Bluish skin color.Not drinking enough fluids • Not waking up or not interacting • Being so irritable that the child does not want to be held • Flu-like symptoms improve but then return with fever and worse cough • Fever with a rash

  43. Adults Need attention if Present with • Difficulty breathing or shortness of breath • Pain or pressure in the chest or abdomen • Sudden dizziness • Confusion • Severe or persistent vomiting

  44. Diagnosis • To diagnose swine influenza A infection, a respiratory specimen would generally need to be collected within the first 4 to 5 days of illness (when an infected person is most likely to be shedding virus). However, some persons, especially children, may shed virus for 10 days or longer. Identification as a swine flu influenza A virus

  45. CDC helps in Diagnosis • Requires sending the specimen to CDC for laboratory testing as many laboratories in Developing world do not have facilities

  46. Drugs which are effective in Swine Flu • There are four different antiviral drugs that are licensed for use in the US for the treatment of influenza: Amantidine, rimantadine, oseltamivir and zanamivir. While most swine influenza viruses have been susceptible to all four drugs

  47. Drugs proved resistant at Present • Most recent swine influenza viruses isolated from humans are resistant to Amantidine and Rimantadine

  48. CDC recommends at Present • CDC recommends the use of oseltamivir or zanamivir for the treatment and/or prevention of infection with swine influenza viruses

  49. Treatment of serious cases Oseltamivir • Reduce significantly the risk of pneumonia( leading case of death for pandemic & seasonal influenza , • Reduce the need for hospitalization

  50. Cont,,, • If Oseltamivir is unavailable or can’t be used , zanamavir may be given. • This recommendation applies to all patient groups( pregnant women, young children, and infants). • Pregnant women & patients with underlying medical conditions recommended to receive AVT as soon as possible after symptom onset.

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