Flu - how to prevent its spread

How is flu transmitted?

Respiratory virusesMicrobes that are only able to multiply within living cells., the virusesMicrobes that are only able to multiply within living cells. responsible for conditions such as fluA viral infection affecting the respiratory system. (influenzaA viral infection affecting the respiratory system.) and the common cold, may be spread in various ways. It is only by learning more about these potential routes of infectionInvasion by organisms that may be harmful, for example bacteria or parasites. that we can hope to develop effective techniques to prevent further transmission. Evidence suggests that simple precautionary measures such as isolating people and adopting good hygiene practices, for example, are the best ways to prevent the spread of fluA viral infection affecting the respiratory system..

Airborne droplets

Airborne droplets containing the fluA viral infection affecting the respiratory system. virusA microbe that is only able to multiply within living cells. have long been recognised as the main way in which the infectionInvasion by organisms that may be harmful, for example bacteria or parasites. is spread. These droplets are released into the air when someone with a viral respiratory infectionInvasion by organisms that may be harmful, for example bacteria or parasites. coughs, sneezes or simply talks. The virusesMicrobes that are only able to multiply within living cells. contained within the droplets can then infect any other person with whom they come into contact.[1]

Generally, sneezing and coughing will generate more droplets into the air from respiratory secretions, than, say, speaking loudly or even shouting. However, people may actually vary in their ability to spread virusesMicrobes that are only able to multiply within living cells. in this way. Some people can release these droplets just by breathing.[2]

With fluA viral infection affecting the respiratory system., for example, although people tend not to show symptoms until 1-4 days after infectionInvasion by organisms that may be harmful, for example bacteria or parasites., the virusA microbe that is only able to multiply within living cells. may be shed from the day before symptoms are first seen, and for up to 10 days afterwards. Furthermore, children may shed the virusA microbe that is only able to multiply within living cells. for a longer period of time.[1] This may be partly because the length of time over which a person sheds the virusA microbe that is only able to multiply within living cells. is related to the severity of the illness.

Contaminated surfaces and direct contact

The everyday contamination of objects and surfaces is acknowledged as a major route for the spread of infectionInvasion by organisms that may be harmful, for example bacteria or parasites.. You may become infected if you touch a contaminated surface, then touch your own nose, mouth or eyes.[1]

Similarly, having personal contact such as shaking hands with someone who has a respiratory infectionInvasion by organisms that may be harmful, for example bacteria or parasites. before touching your own nose, mouth or eyes can also transmit the infectionInvasion by organisms that may be harmful, for example bacteria or parasites..[3]

Some people may be surprised to hear that virusesMicrobes that are only able to multiply within living cells. actually survive better - in other words, for longer periods - on hard surfaces, rather than on the hands, say, or on porous surfaces. One respiratory virusA microbe that is only able to multiply within living cells., called respiratory syncytial virusA microbe that is only able to multiply within living cells., will remain infectious on a surface for 6 hours or even longer, whereas it will survive for just 20-30 minutes on paper tissues, and for less than 20 minutes on skin. Even this short time, though, is enough to cause infectionInvasion by organisms that may be harmful, for example bacteria or parasites.. Flu virusesMicrobes that are only able to multiply within living cells. remain infectious for similar periods of time. However, rhinoviruses and adenoviruses, which cause symptoms similar to those of the common cold, can survive on hard surfaces for days.[2]

Activities that may contribute to the spread of infectionInvasion by organisms that may be harmful, for example bacteria or parasites. through contamination include switching on a light and using the telephone.[3]

Many researchers now believe that contamination through such everyday activities may have a bigger role in transmission than was earlier thought.[4,5]

Household surfaces that may become contaminated include:[3]

  • Light switches
  • Telephone handsets
  • Door handles
  • Pens
  • Computer keyboards
  • TV remote controls
  • Taps.

Still, it can be difficult to gauge exactly how important each of these various factors is in terms of the spread of infectionInvasion by organisms that may be harmful, for example bacteria or parasites.; in fact, the primary mode of transmission may vary according to changing environmental conditions.[2] For example, it is thought that the lower vapour pressure present in the winter (in temperate climates) may help airborne fluA viral infection affecting the respiratory system. virusA microbe that is only able to multiply within living cells. particles to survive for longer periods of time.[6]

Measures to prevent spread

Fortunately, a number of effective, easy-to-implement measures exist to prevent the spread of respiratory virusesMicrobes that are only able to multiply within living cells..

Frequent hand washing

Personal hygiene measures - particularly frequent hand washing - are vital.[7,8] One study examined the promotion of hand hygiene and availability of hand gel sanitiser in several campus halls of residence. It found that these measures led to fewer episodes of colds and fluA viral infection affecting the respiratory system., and fewer missed classes owing to either illness.[9] Adding antiseptics to normal hand-washing solutions may also help, although at present it is uncertain how effective this is in reducing the transmission of respiratory disease.[4,7]

The most effective way to prevent the spread of respiratory virusesMicrobes that are only able to multiply within living cells. in the general population is thought to be the use of such hygienic measures in younger children. This may be because younger children are more likely to spread infectionInvasion by organisms that may be harmful, for example bacteria or parasites. because they are less able to adopt these measures themselves, and they tend to have longer-lived infections and a greater degree of social contact, for example, at school.[4,7]

Disinfection of environmental surfaces

While hand washing is important in reducing the transmission of cold and fluA viral infection affecting the respiratory system. virusesMicrobes that are only able to multiply within living cells., the hands may quickly become contaminated again if the surrounding environment is contaminated. Because of this, disinfection of environmental surfaces such as worktops and desktops is a useful measure to further reduce the spread of virusesMicrobes that are only able to multiply within living cells.. One study found that both disinfectant spray and bleach could reduce a virusA microbe that is only able to multiply within living cells.'s ability to cause infectionInvasion by organisms that may be harmful, for example bacteria or parasites. by almost 100 per cent.[10]

Barrier methods

The use of barrier methods such as masks can help to prevent transmission during epidemics.[7,8] In fact, one study suggested that the use of face masks could reduce the daily risk of getting a respiratory infectionInvasion by organisms that may be harmful, for example bacteria or parasites. by 60-80 per cent.[11]

Isolation

Isolation can also play an important role in limiting spread - for example, asking people who are likely to have an infectionInvasion by organisms that may be harmful, for example bacteria or parasites. to remain at home rather than going to school or work.[7,8]

There is strong evidence to support the effectiveness of these simple physical interventions - personal hygiene, barriers and distancing - in helping to prevent the spread of respiratory virusesMicrobes that are only able to multiply within living cells.. In contrast, there is actually less evidence for the efficacy of vaccines and antiviralA substance that acts against viruses, for example and antiviral drug. drugs. This is partly because vaccines target only influenzaA viral infection affecting the respiratory system., which is responsible for only a small proportion of all respiratory infections. Yet vaccines and antiviralA substance that acts against viruses, for example and antiviral drug. drugs are often much more strongly promoted even though, unlike physical measures, they are costly and may have side-effects. This disparity has been described as 'striking' by an international group of researchers.[4] The fact remains, however, that the primary mode of transmission is still uncertain, and in fact may change with the time of year, changing environment and type of virusA microbe that is only able to multiply within living cells.. Bearing this in mind, tackling all possible routes of infectionInvasion by organisms that may be harmful, for example bacteria or parasites. is clearly the smartest approach.

References: 
  1. Santibañez S, Fiore AE, Merlin TL et al. A primer on strategies for prevention and control of seasonal and pandemicAn outbreak of infection that affects numerous people in different countries. influenzaA viral infection affecting the respiratory system.. American Journal of Public Health 2009; Supplement 2: S216-24.
  2. Hall CB. The spread of influenzaA viral infection affecting the respiratory system. and other respiratory virusesMicrobes that are only able to multiply within living cells.: complexities and conjectures. Clinical Infectious Diseases 2007; 45: 353-9.
  3. Winther B, McCue K, Ashe K et al. Environmental contamination with rhinovirus and transfer to fingers of healthy individuals by daily life activity. Journal of Medical Virology 2007; 79: 1606-10.
  4. Jefferson T, Del Mar C, Dooley L et al. Physical interventions to interrupt or reduce the spread of respiratory virusesMicrobes that are only able to multiply within living cells.: systematic review. BMJ 2009; 339: b3675.
  5. Broderick MP, Hansen CJ and Russell KL. Exploration of the effectiveness of social distancing on respiratory pathogen transmission implicates environmental contributions. The Journal of Infectious Diseases 2008; 198: 1420-6.
  6. Lipsitch M and Viboud C. Influenza seasonality: lifting the fog. PNAS 2009; 106: 3645-6.
  7. Jefferson T, Foxlee R, Del Mar C et al. Interventions for the interruption or reduction of the spread of respiratory virusesMicrobes that are only able to multiply within living cells.. The Cochrane Library 2009; Issue 4.
  8. Bloomfield SF, Exner M, Fara GM et al. Prevention of the spread of infectionInvasion by organisms that may be harmful, for example bacteria or parasites. - the need for a family-centred approach to hygiene promotion. Eurosurveillance 2008; 13
  9. White C, Kolble R, Carlson R et al. The impact of a health campaign on hand hygiene and upper respiratory illness among college students living in residence halls. Journal of American College Health 2005; 53: 175-81.
  10. Sattar SA, Jacobsen H, Springthorpe VS et al. Chemical disinfection to interrupt transfer of rhinovirus type 14 from environmental surfaces to hands. Applied and environmental microbiology 1993; 59: 1579-85.
  11. MacIntyre CR, Cauchemez S, Dwyer DE et al. Face mask use and control of respiratory virusA microbe that is only able to multiply within living cells. transmission in households. Emerging Infectious Diseases 2009; 15: 233-41.