A number of tests can be done in the laboratory to identify flu, using swabs or washings from the nose or throat for example. These can give results within 15 minutes but may not identify the exact strains of flu involved, only that influenza type A or B is present.
These rapid tests are only 50-70 per cent sensitive for detecting flu and so may give a negative result when a person does in fact have flu.
More reliable tests, which also identify exactly which sub-type or strain of flu is present, may involve growing or culturing the virus in the laboratory, and can therefore take a couple of days to give a definite result. These tests may be needed to confirm a specific strain such as swine flu.
If you think you have developed flu-like symptoms, you should stay at home and avoid contact with other people. Call your doctor to discuss your symptoms - they may decide to come and take samples from you. It's important to tell them if you have recently been in contact with someone else with flu or if you have recently travelled abroad.
Treat symptoms as they arise. Try to keep well hydrated with plenty of clear fluids. Take paracetamol or ibuprofen (not for children because of the risk of Reyes syndrome) for aches and pains, and use simple remedies such as cough syrups and vapour rubs. Try to rest as much as possible.
If your doctor is concerned they may prescribe anti-viral medication such as Tamiflu (Oseltamivir) or Relenza (Zanamivir). Swine flu seems to respond to these medicines in the same way as seasonal flu.
The treatments are not a cure but can reduce the risk of infection for those who have been exposed to the virus, reduce the ability of a person with the virus to pass it on, and shorten the course of the illness when someone has flu. Most importantly these drugs treatments reduce the risk of serious complications and death. For maximum effect, the drugs should be given as early as possible to someone who has the flu.
There is not yet a vaccine specifically for the strain of H1N1 swine influenza virus which has caused the 2009 Mexico outbreak, and it will take several months to develop one. It's not yet clear whether current flu vaccines may offer a degree of protection.
As with all infections, good hygiene is absolutely essential to reduce the risk of spread or contact with the virus:
Wash your hands regularly
Cover your mouth and nose when you cough or sneeze
Use tissues and dispose of them carefully
Clean hard surfaces regularly with a standard cleaning fluid
Avoid close contact with people who have fever and a cough
The effectiveness of wearing a face mask in preventing transmission of the flu virus isn't yet clear, although it may give some protection to those people such as health professionals who work closely with someone with symptoms of flu