What is influenza, or “flu”?
Flu is an acute contagious viral infection that affects people of all ages. It typically starts with fever, chills, headache, cough or other respiratory symptoms.
What is influenza A(H1N1)?
Influenza A(H1N1) refers to a current influenza virus, which contains some elements of a virus found in pigs, which has adapted to spread in humans.
What are the symptoms of influenza A(H1N1)?
The symptoms of influenza A(H1N1) in people are similar to the symptoms of human seasonal influenza infection and include fever, cough, sore throat, runny nose, limb/joint pain and headache. In the USA some patients have also had vomiting and diarrhoea too.
If someone is feeling ill what should they do?
Anyone who is experiencing influenza-like illness should stay at home to limit contact with others, and seek medical advice from a local health professional or by contacting NHS24 on 08454 24 24 24.
What is the difference between a suspected and confirmed case of influenza A(H1N1)?
These terms reflect the level of confidence there is in a diagnosis of influenza A(H1N1). A confirmed case is any person with laboratory confirmation of influenza A(H1N1).
A suspected case is any person with:
Or any person with:
- Severe and/or life-threatening illness suggestive of an infectious process.
In the absence of any other more likely diagnosis, a clinical diagnosis of flu would be made for patients who have these symptoms and conditions. If required, the patient would be tested for flu.
Is treatment available?
Testing has shown that influenza A(H1N1) can be treated with the antivirals oseltamivir (Tamiflu) or zanamivir (Relenza). However, most of the previously reported cases of this flu virus recovered fully from the disease without requiring medical attention and without antiviral medicines.
What measures can I take to protect against infection?
General infection control practices and good respiratory hand hygiene can help to reduce transmission of all viruses, including influenza A(H1N1). This includes:
- Covering your nose and mouth when coughing or sneezing, using a tissue when possible
- Disposing of dirty tissues promptly and carefully
- Maintaining good basic hygiene, for example washing hands frequently with soap and water to reduce the spread of the virus from your hands to face or to other people
- Cleaning hard surfaces (e.g. door handles) frequently using a normal cleaning product
- Making sure your children follow this advice.
I am pregnant. What symptoms am I likely to have if I have influenza A (H1N1)?
Clinical information on the effects of influenza A(H1N1) in pregnant women is still being gathered and assessed. Most pregnant women who are diagnosed with influenza A(H1N1) will show the same symptoms as seasonal flu – headache, cough, sore throat and fever and most will recover from this. As with seasonal flu it is possible that some women may become very unwell from influenza A(H1N1) infection.
What should I do if I am pregnant and think I have influenza A(H1N1)?
It is important that any woman who is pregnant and has the symptoms of a flu-like illness (headache, cough, sore throat and fever) should get advice from NHS 24 (08454 24 24 24) or their GP as soon as possible. Women who are diagnosed with any type of flu may require close monitoring.
Complications from flu can be serious for anyone and should they develop it is important that they are picked up quickly so that treatment can be given straight away.
If, after assessing a woman's condition, it is felt that flu is present and causing a problem then an antiviral may be offered. Relenza (zanamivir) is an antiviral that is inhaled into the lungs. This means that very little of it gets into the blood stream. It treats flu without reaching the developing fetus.
What is the difference between seasonal influenza, avian influenza, swine influenza and an influenza pandemic?
Influenza viruses are commonly circulating in the human and animal environment. Different strains can cause illness in humans, bird and pigs.
Seasonal influenza is caused by influenza viruses that are adapted to spread in humans (human influenza). Humans have some natural immunity to the strains that are in common circulation, and this immunity can be boosted by immunisation with a seasonal influenza vaccine.
Avian influenza is caused by influenza viruses adapted for infection in birds.
Swine influenza / influenza A(H1N1) is caused by influenza viruses adapted for infection in pigs.
These illnesses all elicit the same respiratory symptoms in their hosts. Sometimes, humans and animals can pass strains of influenza back and forth to one another, such as when humans become ill with avian or swine influenza, usually from direct contact with animals who are ill. Mixing of human and animal influenza viruses can lead to the development of changed viruses with the ability to cause infection and spread in the human population. There may be little or no immunity in the human population to these new viruses.
An influenza pandemic is defined as a new or novel influenza virus that spreads easily between humans. When new influenza viruses are introduced into the environment, humans don’t have any natural immunity to protect against them. Therefore, there is a risk that that new influenza viruses could develop into a pandemic if the virus passes easily from human to human.