Influenza

Influenza is a contagious viral infection of the nose, throat and lungs which often occurs in the winter.
Alternative names of the disease are: Flu; Influenza A; Influenza B; Influenza C

Causes, incidence, and risk factors
Influenza is a common viral infection. It is caused by three viruses - Influenza A, B and C. Type A is usually responsible for the large outbreaks and is a constantly changing virus. New strains of Type A virus develop regularly and cause new epidemics every few years. Type B causes smaller outbreaks, and Type C usually causes mild illness.Influenza is transmitted from person to person via contagious droplets that are spread when an infected person sneezes or coughs.

Certain individuals are at higher risk from complications of influenza and therefore should be vaccinated:
� People aged 50 or older
People with conditions such as the following:
� diabetes
� conditions affecting the heart
� conditions affecting the lungs (such as asthma)
� conditions affecting the kidneys

Health care workers
Anyone with a weakened immune system (such as transplant recipients or people with HIV)

Prevention
Flu shots are recommended annually for people who are 50 years of age or older, anyone with chronic heart, lung or kidney conditions, and those living in institutions. The vaccine has a 60% to 70% success rate in preventing infection among individuals with normal immune systems; efficacy is lower in individuals with weakened immune systems. The influenza vaccine should not be given to people who are allergic to eggs.

Approximately 8 million children and adolescents between 6 months and 17 years of age have one or more medical conditions that put them at increased risk of influenza-related complications and should be given the first vaccine available:
� Children with chronic disorders of the heart or lungs (such as asthma and cystic fibrosis)
� Children who have required regular medical follow-up or hospitalisation during the preceding year because of conditions such as the following:
� chronic metabolic diseases (including diabetes)
� kidney dysfunction
� sickle cell anaemia
� immuno-suppression

Children and teenagers receiving long-term aspirin therapy and therefore might be at risk for developing Reye's syndrome after influenza infection

Adolescent girls who will be in the second or third trimester of pregnancy during the influenza season

For unvaccinated individuals who have been exposed to people with known influenza, especially if the exposed individual has risk factors, potential use of antiviral medication for more than 2 weeks and vaccination may help prevent illness.

Symptoms
� fever - up to 104 degrees
� headache
� muscle aches and stiffness
� nasal discharge
� cough
� shortness of breath
� chills
� fatigue
� malaise
� sweating
� loss of appetite
� stuffy, congested nose
� sore throat

Signs and tests
The evaluation of an individual with symptoms of influenza should include a thorough physical exam and in cases where pneumonia is suspected, a chest X-ray.

Additional blood work may be warranted during the evaluation, which may include a complete blood count, blood cultures and sputum cultures.

The most common methods for diagnosing influenza include antigen detection tests, which are done on nose and throat secretions by swabbing these areas with a dacron swab and then sending a sample to the laboratory for testing.

The results of these tests can be available rapidly, and can help decide if specific treatment is appropriate, but the diagnosis can often be made by identifying symptoms without further testing.

Source: YahooHealth