Bird Flu by DR Nayak
Bird Flu by DR Nayak
Bird Flu by DR Nayak
Bird flu
SUBMITTED TO :Dr. (Mrs) Rajani Joshi By:-ME
What is influenza?
An acute illness resulting from infection by an influenza virus Highly infectious Can spread rapidly from person to person Some strains cause more severe illness than others
Bird flu (also called avian influenza, avian flu, bird influenza, or grippe of the birds) Virology
Influenza Types Type A Hosts Humans, birds, pigs and horses
Type B Type C
Influenza A (H5N1)
Children and young adults Abdominal symptoms common Diarrhoea Vomiting Abdominal pain Pneumonia Lymphopenia Deranged LFTs
Change
Influenza A viruses undergo frequent changes in their surface antigens or proteins Minor changes - antigenic drift Epidemics Major changes - antigenic shift Pandemics
Antigenic drift
Occurs among influenza A viruses resulting in emergence of new variants of prevailing strains every year New variants result in seasonal flu each winter Some years are worse than others partly related to degree of drift
Antigenic shift
Major changes in surface antigens of influenza A viruses By mutation or by reassortment between viruses Changes more significant than drift Creating a virus that is markedly different from recently circulating strains Pandemic potential
Antigenic shift
Genetic exchange or re-assortment produces a new virus capable of causing a pandemic in humans Can occur when an animal becomes infected with human and animal flu virus at the same time
Antigenic shift
Population will have little or no immunity to new virus: Lack of immunity allows virus to spread more rapidly and more widely than ordinary flu viruses
SYMPTOMS
Mild bird flu symptoms Ruffled feathers Reduced egg production Minor respiratory disease Severe bird flu symptoms Serious respiratory disease Attacks multiple organs and tissues Massive internal haemorrhaging
Uncomplicated influenza
Incubation 2-4 days Abrupt onset fever 38-40C Peak within 24 hours 3 day duration Dry cough Resolves in 7 days Cough, weakness, fatigue may persist for weeks
Range of symptoms
Cough (~85%) Malaise (~80%) Chills (~70%) Headache (~65%) Anorexia (~60%) Coryzal symptoms (~60%) Myalgia (~53%) Sore throat (~50%)
Complications of influenza
Worsening of existing medical condition Influenza-related pneumonia Primary viral Secondary bacterial Mixed viral-bacterial pneumonia ECG changes Myositis CNS
Vaccine
Not yet
Antivirals (Tamiflu)
Roche Capacity Generic licence Cipla 1million 10-capsule courses per month by July
Vaccine 1
Potential vaccine since 2004 Problem of production Predicted 900 million doses in 6 months 15 micrograms (normal flu dose) However would need at least 2 doses Trial in 2004 2 x 90 microgram doses So, 75 million only
Vaccine 2
Vaccine boosting Adjuvant Vaccine against relatives of H5 Adjuvant 2 x 1.9 micrograms Vaccine companies not determining the lowest dose acceptably immunogenic
Pandemic: epidemic spreading around the world affecting hundreds of thousands of people,
across many countries
History of Influenza
412 BC - first mentioned by Hippocrates 1580 - first pandemic described 1580 - 1900 - 28 pandemics
Who is at risk?
Everyone is at risk Certain groups may be at greater risk Until the virus starts circulating we will not know for sure who is at most risk
Pandemic waves
Past experience teaches us that following the emergence of a new pandemic virus: More than one wave of influenza is likely Gaps between the waves may be weeks or months Subsequent wave could be worse than the first
Impact of a pandemic
25% population may be affected Hospital admissions Acute respiratory infections Admissions increase by 50%, at least 20,000 new admissions per week, at peak 25% of the workforce will take 5-8 working days off Absenteeism