Influenza A (h1n1)

Influenza A (H1N1) On the brink of a pandemic 22 may 2009 Hospital tuanku ja’afar Seremban Dr koh kwee choy Lecturer Dept of medicine International medical university

Types of Influenza Virus  The influenza virus is an RNA virus of the family Orthomyxoviridae,

which comprises five genera:  Influenzavirus A  Influenzavirus B  Influenzavirus C  Isavirus  Thogovirus  Distantly related to the human parainfluenza viruses, which are RNA

viruses belonging to the paramyxovirus family that are a common cause of respiratory infections in children

What’s with the ‘H’ and ‘N’? • Influenza A virus strains are categorized according to two proteins found on the surface of the virus: hemagglutinin (H) and neuraminidase (N) • The structure of these proteins differs from strain to strain due to rapid genetic mutation in the viral genome • Influenza A virus strains are assigned an H number and an N number based on which forms of these two proteins the strain contains

• There are 16 H and 9 N subtypes known in birds, but only H 1, 2 and 3, and N 1 and 2 are commonly found in humans

History of Influenza Pandemics

*J.K., Taubenberger; Morens D.M. (January 2006). “1918 influenza: the mother of all pandemics". Emerging Infectious Diseases (Center for Disease Control) 12 (1). http://www.cdc.gov/ncidod/eid/vol12no01/05-0979.htm. **World Health Ogranization Communicable Disease Surveiillance @ Response (CSR) *** As of 21 May 2009

A mongrelized virus The strain contained genes

from four different flu viruses: North American swine influenza; North American avian influenza; Human influenza; and Swine influenza virus typically found in Asia and Europe. http://en.wikipedia.org/wiki/ H1N1

What is its name?!!!

When did it start?

ONE WEEK LATER…

TWO WEEKS LATER…

THREE WEEKS LATER…

PANDEMIC PHASES – WHERE ARE WE NOW?

Transmission •

The main route of transmission of the new influenza A(H1N1) virus seems to be similar to seasonal influenza, via droplets that are expelled by speaking, sneezing or coughing.

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Large droplets do not stay airborne for > 6 feet

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Contact with contaminated surfaces is another possible source of transmission and transmission via small-droplet nuclei (also called “airborne” transmission) might also occur, but the contribution of these modes of transmission to influenza epidemiology is uncertain.

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All respiratory secretions and bodily fluids (diarrheal stool) of novel influenza A (H1N1) cases should be considered potentially

 Transmission from infected persons to

close contacts might be common

 Close contact: a person who cared for or

lived with a person who is a confirmed, probable or suspected case of novel influenza A (H1N1), or having been in a setting where there was a high likelihood of contact with respiratory droplets and/or body fluids of such a person.  Examples of close contact include kissing

or embracing, sharing eating or drinking utensils, physical examination.

 Close contact typically does not include

activities such as walking by an infected person or sitting across from a symptomatic patient in a waiting room or office.

High risk groups  Children <5 years old. The risk for severe complications from

seasonal influenza is highest among children <2 years old.  Adults 65 years of age and older.  Persons with the following conditions: 

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Chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, hematological (including sickle cell disease), neurologic, neuromuscular, or metabolic disorders (including diabetes mellitus); Immunosuppression, including that caused by medications or by HIV; Pregnant women; Persons younger than 19 years of age who are receiving long-term aspirin therapy; (risk of Reye Syndrome) Residents of nursing homes and other chronic-care facilities.

Signs and symptoms •Fever •Headache •Cough, sore throat •Rhinorrhea, SOB •Body aches •Chills •Fatigue •Diarrhea •Vomiting

Warning Signs Adults

Children

 Difficulty breathing or

 Fast breathing or trouble

shortness of breath  Pain or pressure in the chest or abdomen  Sudden dizziness  Confusion  Severe or persistent vomiting  Flu-like symptoms improve but then return with fever and worse cough

breathing  Bluish or gray skin color  Not drinking enough fluids  Severe or persistent vomiting  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

Complications  Clinical syndromes range from mild respiratory illness, to lower

respiratory tract illness, dehydration, or pneumonia.  exacerbation of underlying chronic medical conditions  upper respiratory tract disease (sinusitis, otitis media, croup)  lower respiratory tract disease (pneumonia, bronchiolitis, status asthmaticus)  cardiac (myocarditis, pericarditis)  musculoskeletal (myositis, rhabdomyolysis)  neurologic (acute and post-infectious encephalopathy, encephalitis, febrile seizures, status epilepticus),  toxic shock syndrome  secondary bacterial pneumonia with or without sepsis

Infectious period  The duration of shedding with novel influenza A (h1N1) virus

is unknown. Therefore, until data are available, the estimated duration of viral shedding is based upon seasonal influenza virus infection  Infected persons are assumed to be shedding virus from one day prior to illness onset until resolution of symptoms  In general, persons with novel influenza A (H1N1) virus infection should be considered potentially infectious from one day before to 7 days following illness onset  Children, especially younger children, might be infectious for up to 10 days

What can you do to protect yourself? 

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avoiding close contact with people who show influenza-like symptoms (trying to maintain a distance of about 1 metre if possible) and taking the following measures avoid touching your mouth and nose clean hands thoroughly with soap and water, or cleanse them with an alcohol-based hand rub on a regular basis (especially if touching the mouth and nose, or surfaces that are potentially contaminated) avoid close contact with people who might be ill reduce the time spent in crowded settings if possible improve airflow in your living space by opening windows practise good health habits including adequate sleep, eating nutritious food, and keeping physically active

Should you wear a mask? • No need if you are not sick • If you are caring for a sick person, you can wear a mask when you are in close contact with the ill person and dispose of it immediately after contact, and cleanse your hands thoroughly afterwards • If you are sick and must travel or be around others, cover your mouth and nose • Using a mask correctly in all situations is essential • Incorrect use actually increases the chance of spreading infection • HCW encouraged to use respirators (N95)

Treatment  A (H1N1) is resistant to

rimantadine and amantadine

 Treatment is recommended

for: 

 Susceptible to Oseltamivir

and Zanamivir

 Persons with suspected

novel H1N1 influenza who present with an uncomplicated febrile illness typically do not require treatment unless they are at higher risk for influenza complications

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All hospitalized patients with confirmed, probable or suspected novel influenza (H1N1). Patients who are at higher risk for seasonal influenza complications

 Treatment with zanamivir or

oseltamivir should be initiated as soon as possible after the onset of symptoms, within 48 hours

Post-exposure prophylaxis  The indication for post-exposure chemoprophylaxis is based upon

close contact with a person who is a confirmed, probable or suspected case of novel influenza A (H1N1) virus infection during the infectious period of the case

 For antiviral chemoprophylaxis of novel (H1N1) influenza virus

infection, either oseltamivir or zanamivir are recommended

 Duration of antiviral chemoprophylaxis post-exposure is 10 days after

the last known exposure to novel (H1N1) influenza.

 Other measures:  appropriate infection control,  restricting staff movement between wards or buildings  restricting contact between ill staff or visitors and patients  active surveillance for new cases.

Pre-exposure prophylaxis antiviral medications should be given during the

potential exposure period and continued for 10 days after the last known exposure to a person with novel (H1N1) influenza virus infection during the cases infectious period. Oseltamivir can also be used for chemoprophylaxis for children less than 1 year of age

H1N1 in pregnancy  Oseltamivir and zanamivir are

"Pregnancy Category " medications, indicating that no clinical studies have been conducted to assess the safety of these medications for pregnant women.

 Although a few adverse effects have

been reported in pregnant women who took these medications, no relation between the use of these medications and those adverse events has been established.

 Pregnancy should not be considered

a contraindication to oseltamivir or zanamivir use.

 Because of its systemic activity,

oseltamivir is preferred for treatment of pregnant women.

 The drug of choice for

chemoprophylaxis is less clear. Zanamivir may be preferable because of its limited systemic absorption  However, respiratory complications that may be associated with zanamivir because of its inhaled route of administration need to be considered, especially in women at risk for respiratory problems.  Breastfeeding should be encouraged.

A n d f o r m y f el l o w n o n - m u s l i m Colleagues

• Yes. Influenza A(H1N1) has not been shown to be transmissible to people through eating properly handled and prepared pork (pig meat) or other products derived from pigs. • The influenza A(H1N1) virus is killed by cooking temperatures of 160°F/70°C • There is no confirmation of transmission between pigs and humans at this point

Thank you