Flu (influenza) is a common infectious viral illness spread by coughs and sneezes.
- Flu virus is contained in the millions of tiny droplets that come out of the nose and mouth when an infected person coughs or sneezes.
- Flu may also be transmitted by touching surfaces that infected droplets have landed on, if you pick up the virus on your hands and then touch your nose or mouth.
- Crowed conditions increase the risk of infection.
Three different virus types of human flu are recognised, A, B and C:
- types A and B are the most common
- type A has further subtypes, for example A(H1N1).
Seasonal epidemics of flu occur almost every year and are caused primarily by type A viruses:
- November - April in northern hemisphere
- April - September in southern hemisphere.
In tropical areas there is no clear seasonal pattern but peaks tend to occur during the rainy season.
- If you have been infected with flu virus, you generally start to feel ill within a few days of being infected.
- Most people begin to feel better within a week or so, although you may feel tired for much longer.
Risk of Severe Illness
Complications of flu mostly affect people in high-risk groups:
- the elderly
- pregnant women
- those who have a long-term medical condition or weakened immune system.
Complications can include:
- viral inflammation of lung tissue
- bacterial inflammation of lung tissue
- middle ear infection
- worsening of existing medical conditions
- flu can cause complication in pregnancy.
Signs and Symptoms
Flu can cause any of the following symptoms:
- sore throat
- blocked or runny nose
- aching muscles and joints
- tiredness and weakness
- diarrhoea or abdominal (tummy) pain
- nausea and vomiting.
Treatment of flu is mainly supportive and the relief of symptoms.
There are antiviral drugs available that can be used to prevent or treat flu but only under special circumstances and medical advice.
If you are visiting a country during its flu season you will be at a similar risk of infection as the local residents.
Crowded conditions encourage spread of infection; travellers at increased risk of flu include those attending pilgrimages such as the Hajj, festivals, cruises, in airports and other transport hubs.
When to Consider Vaccination
Vaccination should be considered under the following circumstances and is dependent on the individual risk assessment.
If you are in the flu risk groups in the UK you should ensure you have received your seasonal flu vaccine before travel:
- pregnant women at any stage of pregnancy
- children aged between 6 months to 5 years
- those aged over 65 years
- individuals with chronic medical conditions.
- if you are travelling to the southern hemisphere during the destination flu season you may not be able to obtain southern hemisphere vaccine in the UK prior to travel, you should therefore try to arrange for vaccination after arriving at your travel destination.
You may wish to be vaccinated to reduce the risk of an trip being disrupted by flu, or if you are attending a large gathering, festival or sporting event, particularly if during flu season in the destination country.
The Saudi Ministry of Health recommends seasonal flu vaccine for Hajj attendees before arrival, especially for those in the flu risk groups above. Please see our Hajj page for further information.