This is how the flu virus often spreads:
An infected person "sheds" the virus from their nose and throat. The virus is then transmitted in two ways:
The virus is "aerosolised" (infected droplets) by speaking, sneezing or coughing. Sneezing propels the flu virus at about 167km/h over a distance of 5m - all within a tenth of a second, according to Prof Barry Schoub, head of the National Institute of Virology in Johannesburg.
The virus can also contaminate hands, or objects such as hankies, utensils, doorknobs, toys, kitchen counters, washbasins, handrails, escalator rails and pencils.
By touching your nose, mouth or eyes after touching an infected object (which has been touched by an infected person or "sprayed" by infected droplets), you've completed the cycle. The risk of infection is very high through infected hands. That's why it's so important to wash your hands regularly.
Alternatively, you can also get the flu by inhaling infectious particles in the air (such as respiratory secretions from a cough or sneeze, as in step 2).
Reviewed (2006) by Dr Jane Yeats MBChB, BSc(Med)(Hons)Biochem, FCPathSA(Virology).