Influenza Transm ission
Knowledge of transm ission can help plan control DRAFT FOR FIELD TESTING
1 | Training module: influenza transmission W hat is Influenza? (1)
ò Influenza is different from the com m on cold
ò It is caused by a different virus, with symptoms that are usually more severe
ò Influenza affects lower parts of the respiratory tract.
2 | Training module: influenza transmission W hat is Influenza? (2)
Influenza is an acute contagious infection of the airways and lungs with one of the influenza viruses.
ò Avian - rare in humans
ò Human œ Seasonal - common œ Pandemic - infrequent and unpredictable
ò There are signs that the risk of a pandemic is increasing
3 | Training module: influenza transmission Seasonal influenza
òAlmost every year there are SMALL changes on the surface of human influenza viruses • This causes seasonal influenza epidemics around the world • 1 in 5 people affected each year and elderly people are particularly at risk • A new vaccine is made each year for seasonal influenza
4 | Training module: influenza transmission Pandem ic Influenza (1)
ò Very rarely, there is a m ajor changein surface of the virus, to which all individuals lack im m unity
ò If this new virus has the capacity to spread easily from person to person, an influenza pandem iccan occur
ò An influenza pandemic has the potential of killing m illions of peoplewhen it appears
5 | Training module: influenza transmission Pandem ic Influenza (2)
ò A pandemic can start when three conditionshave been met: œ a new influenza virus subtype emerges; œ it infects humans, causing serious illness; œ it spreads easily and sustainablyamong humans.
ò Historically, pandemics occur about 3 times per century; the last one occurred in 1968
6 | Training module: influenza transmission Avian Influenza
ò Affects birds prim arily (can affect humans occasionally)
ò Avian influenzas have the potential to cause hum an pandem icsif the viruses adapt and develop the ability to transmit easily between from human-to-human.
7 | Training module: influenza transmission Influenza signs and sym ptom s
ò Rapid onset of: œ Fever > 38.5°/Chills œ Body aches / headaches œ Sore throat œ Non-productive cough
ò Range of symptoms differ by age œ Vomiting, diarrhea, encephalitis are more common in children œ Fever, often alone, in infants
8 | Training module: influenza transmission Modes of transm ission (1)
òLarge respiratory droplets (main mechanism of transmission)
ò Direct contact (touching hands ‰ self-contamination)
ò Indirect contact (contaminated surfaces or objects ‰ self-contamination)
ò Small particle aerosol (during aspiration or intubation)
9 | Training module: influenza transmission Mode of transm ission (2)
Source: Photo from the slide collection, Department of Medical Microbiology, Edinburgh University. From The Microbial W orld: Airborne Microorganisms, by Jim Deacon, Institute of Cell and Molecular Biology, The University of Edinburgh, at http://helios.bto.ed.ac.uk/bto/microbes/airborne.htm
10| Training module: influenza transmission Main transm ission m echanism
ò Exposure to largeparticle (>5 ?m) respiratory dropletswhen someone coughs or sneezes
ò These travel only short distances(usually 1 m or less) through the air
œ The droplets do not remain suspended in the air
œ Transmission via large-particle droplets requires close contact between source and recipient individuals.
11 | Training module: influenza transmission Secondary transm ission m echanism s
ò Self-contam ination through hand-to-nose, hand-to- eye, hand-to-m outh transm ission œ important, but secondary to direct large droplet respiratory transmission. œ after touching virus-contaminated clothes, objects, surfaces, or skin/hands of another person, AND then touching own nose, eye or mouth.
ò Sm all particle transm ission at several m etres œ Can be suspended as small particles in air (but only with procedures such as suction, aspiration, intubation…)
12 | Training module: influenza transmission W hat to do? (1)
ò Prepare
òPrepare Plan and then… Put into practice òPrepare now
Pandemics are naturally recurring events; sooner or later a pandem ic will arrive.
13 | Training module: influenza transmission W hat to do? (2)
ò Strengthen surveillance (help in early detection of influenza and other epidemic-prone diseases)
ò Implementation of measures to interrupt / delay transmission • R e s p ira to ry e tiq u e tte (c ov er c ough s and sneezes) • S o c ia l d is ta n c in g (k eep y our distanc e) • H a n d h y g ie n e (w ash h ands)
14 | Training module: influenza transmission Thank you!
15 | Training module: influenza transmission