Swine flu: pigging language
Updated on 01 May 2009
It's a suspected case of transmissible, low virulent influenza A that may indicate an imminent pandemic. Know what we mean? Review our swine flu glossary of key terms.
Epidemic: An epidemic is loosely defined as a disease outbreak in a region or community that is outside the normally expected range.
Pandemic: an epidemic that's gone global. It is defined by the World Health Organisation (WHO) as "community level outbreaks" in at least one country in a WHO region (Africa, Americas, Eastern Mediterranean, Europe, South East Asia, Western Pacific) in addition to the region where human-to-human transmission has occurred in at least 2 countries to prompt a level 5 alert.
The current pandemic alert is at level 5 because there has been human-to-human transmission (Spain/Europe) outside the original country (Mexico/Americas) where the infection started.
A pandemic does NOT necessarily imply a high death rate. Pandemics of mild illness are possible, which have a largely economic impact because people are off work. Mild illnesses, though, may nevertheless cause some deaths.
Pandemics can last weeks or months. The duration depends on transmissibility and virulence.
Remember, flu kills 250,000 to 500,000 people worldwide every winter, mainly the elderly and the very young, because they have weak or undeveloped immune systems. So "killer flu" is a tautology.
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Transmissibility: a measure of how easily the virus is transmitted from one person to another. Many factors affect transmissibility - the genetics of the virus, it's interaction with the human body, people's behaviour and health protection measures. They affect both the speed of transmission through the population and whether or when the infection stalls and peters out.
Virulence: a measure of the strength of the virus to cause severe illness. Highly virulent strains cause dangerous illness that may result in significant numbers of fatalities.
Suspected cases: those where people have presented with flu-like symptoms and who tested positive for flu. Relatively fast tests are used in hospitals to identify flu within hours, both they cannot identify the strain.
Confirmed cases: strictly defined by the WHO as those cases of influenza where the strain of the virus (in this case, H1N1) has been identified by laboratory testing, usually using PCR. This can take 24-48 hours, so there is always a delay between notification of illness and confirmation.
Close contact: defined by WHO as someone has cared for, lived with, or had direct contact with respiratory secretions or body fluids of a probable or confirmed case of influenza.
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