InfluenzaInfluenza (The flu) (The flu)

Presented by:

PoorMontaseri Z, DMInfectious Diseases and Tropical Medicine

Fasa University of Medical Science

In temperate climates, seasonal epidemics occur mainly during winter

In tropical regions, may occur throughout

the year, causing outbreaks more irregularly.

Influenza, commonly known as “the flu”, is a highly contagious infection of the airways caused by influenza viruses.

در پاندمي هاي ( و Asian flu ) 1957سالهاي

1968( Hong kong flu نيز به )نفر ميليون 2ترتيب حدود

نفر در 700/000و حدود سطح جهان کشته شده اند

The first cases of human infection with novel H1N1 influenza virus were detected in April 2009 in San Diego and Imperial County, California and in Guadalupe County, Texas.

The virus has spread rapidly.

Distribution of pandemic Distribution of pandemic H1N1H1N1

Distribution of Influenza in Iran

Iran reported an increase in influenza detections from previous weeks.

Influenza A(H1N1) viruses were predominant with some A(H3N2) and B detections reported.

RNA viruses/ Subfamily: Orthomyxoviridae. enveloped viruses that may exist in spherical or

filamentous forms of 80 to 120 nm

The Influenza VirusThe Influenza Virus

Antigenic drift?◦Minor change

Antigenic shift?◦Major change

Point Mutation of Hemagglutinin and Neuraminidase gene

Antigenic Drift

Antigenic Shift

Human H2N2

Avian H3N8

Genetic ReassortmentAntigenic Shift

Human H3N2

Generation of new Human Virus (H3N2)Possessing Hemagglutinin from Avian Virus (H3N8)

Survival of Influenza viruses in Survival of Influenza viruses in EnviromentEnviroment

Plastic and steels stuffs: more than 24 h

Cloths and papers: 8-12 h

Viable on hands: <5 minutes only at high viral titers

In virus classification influenza viruses are :

A Three known A subtypes of influenza viruses

currently circulating among humans (H1N1, H1N2, and H3N2).

B C

Bridges et al. 2008.

TypeHostClinical Importance

Pattern of Occurrence

SubtypesEpidemiology

A)seasonal, Avian, Swine(

Humans,birds, horses, other mammals

Moderate to severedisease

Sporadic,epidemics,pandemics

YesH1-H16

N1-N9

Antigenic shift /drift

B )seasonal(

Humans

Moderate to severe disease

Sporadic,epidemics

NoAntigenic drift

CHumansand swine

Milddisease

Sporadic, localized outbreaks

NoAntigenic drift

Avian InfluenzaAvian InfluenzaAvian influenza is an infectious disease of birds

caused by type A strains of the influenza virus.

 Avian influenza transmitted by birds usually through

feces or saliva.

H5N1; the strain of avian flu, ◦ Most cases of avian influenza infection in humans

have resulted from contact with infected poultry

◦ The spread of avian influenza viruses from one ill person to another person has been reported very rarely

Swine Flu Swine Flu Swine influenza (swine flu) is a respiratory disease of

pigs caused by type A influenza virus.

The main swine influenza viruses circulating in U.S. pigs in recent years are: H1N1 influenza virus, H3N2 virus, H1N2 virus.

Disease was more severe among people younger than 65 years of age than in non-pandemic influenza seasons.

With significantly higher pediatric mortality, and higher rates of hospitalizations in children and young adults.

H1N1/H5N1H1N1/H5N1

high morbidity but low

mortality rates (1%-4%).

The estimated incubation period is unknown and could range from 1-7 days, and more likely 1-4 days.

Transmission Transmission and Evolutionand Evolution

Influenza 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.

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.

Immuno-suppressed more than others.

Relationship between Relationship between mortality and involvement mortality and involvement ageage

Attack rates are generally highest in the young, (children aged 5--14 years)

whereas mortality is generally highest among older adults

SymptomsFluCold

FeverUsually 80%Rare

AchesSevere aches and painsOccasion slight body aches

ChillsFairly common (60%)Uncommon

TirednessModerate to severeMild

Sudden symptoms

Sudden often within 3-6h(chills /aches)

Not sudden develop over a few days

CoughNon-productive, dry cough (80%)

Hacking, productive cough

SneezingNot commonly present Commonly present

Stuffy noseNot commonly presentCommon but resolves within 1 week

Sore throatCan be presentCommon due to inflammation

Chest discomfort Severe, felt along front of body, neck to abdomen

Mild to moderate

HeadacheVery common (80%)Fairy uncommon

ComplicationPneumonia, can be life threatening

Sinus /ear infection

Complications of InfluenzaComplications of Influenza Pulmonary Complications

◦ primary influenza viral pneumonia and secondary bacterial infection (Streptococcus pneumoniae and Staphylococcus aureus)

Other Pulmonary Complications◦ Bronchiolitis◦ Croup◦ Acute exacerbation of chronic bronchitis◦ Exacerbations of asthma and worsening

pulmonary function in children with cystic fibrosis

Nonpulmonary Complications◦ Myositis

◦ Cardiac Complications )myocarditis and pericarditis , myocardial infarction)

◦ Toxic Shock Syndrome

◦ Central Nervous Complications (Guillain-Barré syndrome, Reye Syndrome)

DiagnosisDiagnosis

Clinical DiagnosisRapid Influenza Diagnostic TestsMolecular Diagnostic Tests (nucleic

acid hybridization and PCR)

Serology (complement fixation and hemagglutination inhibition)

Virus Isolation

InfluenzaInfluenza

Type A Influenza Can not be EradicatedType A Influenza Can not be Eradicated

Continous emergence of new virus variant

Prevention:Prevention:

1.Primary2.Secondary

Prevention in the HealthPrevention in the HealthCare SettingCare Setting

Patients with seasonal influenza can generally be managed under droplet precautions, except when undergoing aerosol-generating procedures, such as bronchoscopy, sputum induction, elective intubation and extubation, and autopsies, during which management requires airborne precautions.

Primary preventionPrimary prevention

VaccinationVaccination

www.fightflu.com

Vaccination/ Common side effects include:Vaccination/ Common side effects include:

Local reactions at the injection site (soreness, swelling, redness).

Possibly some systemic reactions (fever, headache, muscle or joint aches). these symptoms are mild, self-limited and last 1-2 days.

Guillian-Barre syndrome (1/1000000)

Secondary preventionSecondary prevention

Watch for emergency warningsignsMost people should be able to recover at home, but watch for emergency warning signs that mean you should seek immediate medical care.

In adults:Difficulty breathing or shortness of breathPain or pressure in the chest or abdomenSudden dizzinessConfusionSevere or persistent vomitingFlu-like symptoms improve but then return with fever and worse cough

Emergency warning signs inchildrenIf a child gets sick and experiences any of these warning

signs, seek emergency medical care.

In children:Fast breathing or trouble breathingBluish or gray skin colorNot drinking enough fluidsSevere or persistent vomitingNot waking up or not interactingIrritable, the child does not want to be heldFlu-like symptoms improve but then return with fever and worse

Secondary preventionSecondary prevention

Thanks for

your attention