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Avian influenza
- 1. Avian Influenza Hossam Ghoneim, MD Cairo University
- 2. OverviewOverview • Organism • Epidemiology • Transmission • Clinical Signs • Diagnosis and Treatment • Prevention and Control • Economic impact • Actions to take
- 3. The Organism
- 4. Influenza VirusInfluenza Virus • Family Orthomyxoviridae • Three main types − Type A § Multiple species − Type B § Humans − Type C § Humans and swine
- 5. • 2 major antigenic glycoproteins: − Haemagglutinin (HA) (H1-16) − Neuraminidase (NA) (N1-9) • Antigenic Drift − Change of genetic material due to lack of proof-reading during replication − Responsible for annual epidemic • Antigenic Shift − reassortment and merging of genetic materials from different influenza strains − ànovel viral subtype, most human lack immunity − Responsible for pandemics Single-strand RNA with 8 gene segment Haemagglutinin Neuraminidase The Influenza Virion Influenza VirusInfluenza Virus
- 6. Influenza AInfluenza A • Multiple species − Humans − Avian Influenza • Most virulent group • Classification by surface antigens into subtypes − Hemagglutinin (H or HA) − Neuraminidase (N or NA)
- 7. H5N1 is of particular concernH5N1 is of particular concern • Mutates rapidly • Acquire genes from flu strains in other species • Highly pathogenic in humans • Birds, if surviving the infection, excrete the virus for 10 days, orally and in feces
- 8. Influenza BInfluenza B • Mostly humans • Common • Less severe than A • Epidemics occur less often than A • Human seasonal vaccine − Two strains of type A − One strain of type B
- 9. Influenza CInfluenza C • Humans and swine • Different pattern of surface proteins • Rare − Mild to no symptoms • By age 15, most have antibodies
- 10. Human InfluenzaHuman Influenza Ÿ Subtypes: A(H1 - H3), B Ÿ Droplet transmission Ÿ Typical Incubation period: 2–4 days, with an average of 2 days Ÿ Symptoms: Ÿ Fever, headache, myalgia, running nose, cough, sore throat. Usually subside in 2 – 7 days
- 11. Avian InfluenzaAvian Influenza • Pathogenicity based on genetic features and/or severity of disease in poultry − Low pathogenic AI (LPAI) § H1 to H15 subtypes − Highly pathogenic AI (HPAI) § Some H5 or H7 subtypes § LPAI H5 or H7 subtypes can mutate into HPAI
- 12. Epidemiology
- 13. Geographic DistributionGeographic Distribution • Worldwide distribution • Reservoir − Free flying aquatic birds: Ducks, geese, shorebirds, gulls, terns, auks • Recent outbreaks − The Netherlands, Australia, Mexico, U.S., SE Asia, Eurasia • Altered avian ecosystems have created new niche for AI viruses
- 16. Human diseases caused by purely avian influenza viruses (without prior re-assortment with human virus) Human diseases caused by purely avian influenza viruses (without prior re-assortment with human virus) H5N1- Cambodia; Thailand; Vietnam; Indonesia; China 95 cases, 41 deaths 2005 H 7 disease in Canada2004 H5N1 – Azerbaijan; Cambodia; China; Djibouti; Egypt; Indonesia; Irag; Thailand; Turkey; Vietnam 84 cases, 54 deaths 2006 till (20/06/2006) H5N1 - Vietnam: 29 cases; 20 deaths Thailand: 17 cases; 12 deaths 2004 H7N7 ( Holland) – 78 conjunctivitis, 7 with flu-like illness, 4 other, 1 death 2003 H5N1: Fujian/ Hong Kong : 2 patients , 1 death2003 H9N2 ( Hong Kong ; Guangdong)1998, 1999 and 2003 H5N1 ( Hong Kong) : 18 patients ; 6 deaths1997: sporadic conjunctivitis-H7N7Pre-1997 Emergence of H5 InfluenzaH5 Influenza
- 17. The Species Barrier Broken!! The species barrier that previously confined the H5N1 virus to birds and water fouls had been breached and now it is able to infect various species The Species Barrier Broken!! The species barrier that previously confined the H5N1 virus to birds and water fouls had been breached and now it is able to infect various species Birds and Water FoulsBirds and Water Fouls:: (e.g. Ducks, geese) Natural carrier of avian flu, can be symptomatic or asymptomatic ChickenChicken New to H5N1 virus Invariable fatal when attacked PigsPigs Avian flu in pigs are particularly worrisome as they possess bird flu and human flu receptors. They act as a reservoir for genetic reassortment for flu virus HumanHuman FelineFeline (Cats, Tigers and Leopards)
- 18. How can the species barrier be broken? How can the species barrier be broken? Method 1 H5N1 virion Affect water fouls & wild birds Mutation Affect domestic poultry like chicken Mutation Affect several mammalian species include felines, pigs, and human
- 19. Human FluAvian Flu Reassortment It is important to remember that H1 & H3 viral subtypes are prevalent in pigs Method 2 How can the species barrier be broken? How can the species barrier be broken?
- 20. Transmission
- 21. Animal TransmissionAnimal Transmission • Initial source of infection − Other poultry, migratory waterfowl, pet birds • Spread by aerosol, shared drinking water, fomites • Virus in respiratory secretions and feces • Virus present in eggs but eggs unlikely to survive and hatch
- 22. Human TransmissionHuman Transmission • Previously considered non-pathogenic for humans • 1997, Hong Kong − 18 humans infected, 6 died − H5N1 virus linked to outbreak in live bird market and area farms (droplet) • 2003, the Netherlands − 83 confirmed cases in humans, 1 death − H7N7 strain
- 23. Human TransmissionHuman Transmission • 2004-2005, SE Asia − 118 cases, 61 deaths § Indonesia, Viet Nam, Thailand, Cambodia − H5N1 strain − Within the vicinity of poultry outbreaks − Evidence for human-to-human transmission • Role of swine − Proposed “mixing vessel”
- 25. Clinical SignsClinical Signs • Incubation period: 3-14 days • Birds found dead • Drop in egg production • Neurological signs • Depression, anorexia, ruffled feathers • Combs swollen, cyanotic • Conjunctivitis and respiratory signs
- 26. Post Mortem LesionsPost Mortem Lesions • Lesions may be absent with sudden death • Severe congestion of the musculature • Dehydration • Subcutaneous edema of head and neck area
- 27. Post Mortem LesionsPost Mortem Lesions • Nasal and oral cavity discharge • Petechiae on serosal surfaces • Kidneys severely congested • Severe congestion of the conjunctivae
- 28. SamplingSampling • Before collecting or sending any samples, the proper authorities should be contacted • Samples should only be sent under secure conditions and to authorized laboratories to prevent the spread of the disease
- 29. DiagnosisDiagnosis • Clinically indistinguishable from virulent Newcastle Disease • Suspect with: − Sudden death − Drop in egg production − Facial edema, cyanotic combs and wattles − Petechial hemorrhages • Virology and serology necessary for definitive diagnoses
- 30. TreatmentTreatment • No specific treatment • Supportive care and antibiotics for secondary infections • Antivirals (amantadine) effective in reducing mortality − Not approved in food animals − Results in resistant viruses
- 32. Clinical Signs in HumansClinical Signs in Humans • 1997: Hong Kong (H5N1) − Fever, respiratory, vomiting, diarrhea, pain − Fatal cases: severe bilateral pneumonia, liver dysfunction, renal failure, septic shock • 1979: MP AI in harbor seals (H7N7) − Conjunctivitis in humans in contact
- 33. Clinical Signs in HumansClinical Signs in Humans • 2003: Netherlands (H7N7) − Conjunctivitis − Mild influenza or respiratory symptoms − Fatal case: acute respiratory distress syndrome • 2004-2005: S.E. Asia, EurAsia
- 34. Morbidity/MortalityMorbidity/Mortality • Approaches 100% in commercial poultry flocks • Deaths within 2 to 12 days after first signs of illness • Survivors in poor condition
- 35. Public Health SignificancePublic Health Significance • Risk is low • Strains vary in ability to infect humans • High occupational exposure may increase risk • 2003: 83 cases − Human infections from non-compliance with personal biosafety measures − Weak evidence of human-to-human transmission
- 37. How is human infection prevented?How is human infection prevented? • Vaccines are the primary preventative for influenza. Currently there is no vaccine to protect humans. • Scientists need a sample of the new strain before they can produce a vaccine against it. • Every dose must be made in a hen’s egg (i.e. requires billions of eggs). • For the first several months of a pandemic, there will be no effective vaccine.
- 38. Infection preventionInfection prevention • There are measures to develop new technologies for vaccine production… i.e., cell-based systems for production of vaccines. (this will vastly improve the speed, quality & quantity of vaccine production) • Research studies to test a vaccine began in April 2005. Human trials are ongoing.
- 39. VaccinationVaccination • Drawbacks to vaccination − Expensive − No cross protection between 15 H subtypes − Possible creation of reassortant virus
- 40. • Current human influenza vaccines have no efficacy against avian influenza • Inactivated H5 and recombinant vaccine licensed in the U.S. for emergency in HPAI outbreaks
- 41. Basic Infection Control PrecautionsBasic Infection Control Precautions • Hand hygiene (most important thing anyone can do!) • Covering your mouth when coughing. • Spatial distancing: at least three feet when in public crowed. • Daily sanitizing commonly used surfaces (phones, keyboards, machines, etc). • Staying home if ill.
- 42. Basic Infection Control PrecautionsBasic Infection Control Precautions • Avoid contact of house birds or pets with wild ones. • Avoid dealing with live poultry or birds in markets or for leisure • Proper cooking & heating of eggs & chicken (or any edible poultry) • Care for avoiding contact with bird fecal matter.
- 43. Basic Infection Control PrecautionsBasic Infection Control Precautions • Antiviral drugs like Tamiflu and Relenza can possibly reduce the severity of the illness when taken within 24 hours of getting sick.
- 44. Recommended ActionsRecommended Actions • Notification of Authorities − Ministry of health & population §105 any land line − Ministry of agriculture §08005553555 any land line • Quarantine
- 46. What is Pandemic What is Pandemic Endemic − stable pattern of occurrence of the disease. Epidemic − occurrence of the disease greatly in excess of the expected rate. Pandemic − worldwide spread of a disease, outbreaks or epidemics occurring in many countries & in most regions of the world
- 47. PandemicPandemic ： Health careHealth care system rapidly overburdenedoverburdened Social Disruption & PanicSocial Disruption & Panic Pandemic
- 48. Progression of pandemicProgression of pandemic Sporadic cases No human-to-human transmission Sporadic cases No human-to-human transmission Clusters of cases Inefficient human-to- human transmission Clusters of cases Inefficient human-to- human transmission On-going cluster related transmission Substantial pandemic risk On-going cluster related transmission Substantial pandemic risk PandemicPandemic
- 49. 3 conditions before a pandemic begins: 3 conditions before a pandemic begins: 1. A new influenza subtype that has not previously circulated in humans must emerge. (Rare event) (occurred) 2. Must be capable of causing disease in humans. (occurred) 3. Must be capable of being passed easily among humans. (?)
- 50. Sustained human to human transmission of the new influenza strain will be the “trigger” for the start of a pandemic. Sustained human to human transmission of the new influenza strain will be the “trigger” for the start of a pandemic. To date, H5N1 has not spread beyond one generation of close contacts.
- 51. Previous FLU PandemicsPrevious FLU Pandemics >2 million excess mortality Human & Birds H2N2 Asian Flu1957 1 million excess mortality Human & Birds H3N2 Hong Kong Flu1968 40-50 million death Swine & Birds H1N1 Spanish Flu 1918 ResultSourceSubtypeYear
- 54. An avian flu pandemic would be especially dangerous due to the lethal nature of the present virus and the lack of immunity among the world’s population. An avian flu pandemic would be especially dangerous due to the lethal nature of the present virus and the lack of immunity among the world’s population.
- 55. Economic Impact
- 56. Economic ImpactEconomic Impact • Direct losses: − Depopulation and disposal − High morbidity and mortality − Quarantine and surveillance • 1978-2003: Seasonal outbreaks of LPAI in Minnesota cost growers $22 million
- 57. Economic ImpactEconomic Impact • 1983: U.S. outbreak (H5N2) − $65 million in losses − Destruction of 17 million birds − 30% increase in egg prices • 1999-2000: Italy outbreak (H7N1) − $100 million in compensation to farmers − 18 million birds destroyed − Indirect losses of $500 million
- 58. Economic ImpactEconomic Impact • 1997: Hong Kong outbreak (H5N1) − $13 million for depopulation and indemnities − 1.4 million birds • 2001: Hong Kong outbreak (H5N1) − 1.2 million birds − $3.8 million
- 59. Economic ImpactEconomic Impact • 2003: European outbreak (H7N7) − Over 33 million birds destroyed − ¼ of Netherlands’ poultry stock − Cost? • 2003-2004: SE Asia (H5N1) − 8 countries − >100 million birds destroyed − Cost? • 2004-2005: SE Asia and Eurasia − Spread to Eurasia by migratory birds
- 61. Internet ResourcesInternet Resources • World Organization for Animal Health (OIE) − www.oie.int • USAHA Foreign Animal Diseases – “The Gray Book” − www.vet.uga.edu/vpp/gray_book/index • World Health Organization − www.who.int
- 62. Additional ResourcesAdditional Resources • CDC – Centers for Disease Control and Prevention − Avian influenza (bird flu) home page § www.cdc.gov/flu/avian • U.S. Department of Agriculture − Biosecurity for the birds § www.aphis.usda.gov/vs/birdbiosecurity − Avian influenza § www.aphis.usda.gov/vs/birdbiosecurity/hpai .html
- 65. Basic InformationBasic Information • December 2003 – August 2006, 241 human cases and 141 deaths caused by the H5N1 strain.
- 66. Avian Influenza InformationAvian Influenza Information • The H5N1 flu virus primarily attacks the lower respiratory tract (the lungs) — quite unlike seasonal flu that attacks the upper respiratory tract (nose, sinuses and pharynx.) • Characterized by high fever, headache, malaise, cough and sore throat and difficulty breathing. • Acute infection usually lasts about 2 weeks, but may have significant residual long term effects… not the flu as we know it!!
- 67. What are the symptoms? AGAIN What are the symptoms? AGAIN • Symptoms in humans have ranged from typical flu-like (fever, cough, sore throat and muscle aches) to red eye, pneumonia, acute respiratory distress (SOB), viral pneumonia and other severe and life- threatening complications.
- 68. • Basic personal hygiene (Hand wash) • Care of domestic birds & pets • Avoid crowd • Use mask when necessary (crowd & markets) • Proper cooking (eggs & poultry) • No effective vaccine yet • Suspect if Cough, High fever, red eye, SOB and history of contact • Report immediately to authorities • Tamiflu ASAP
- 69. Risk of PandemicRisk of Pandemic • Given the heavy volume of international travel in the 21st century, it is likely that a pandemic would spread globally within about 3 months.
- 70. Frequently Asked QuestionsFrequently Asked Questions • Should I stock up on Tamiflu? • Are masks useful? • Who will keep us notified about conditions in our communities? • Should I eat poultry & eggs? • How do I buy poultry products? • Is there really a risk of pandemic? What is my role?