Glossary
Starting with A for "ACE inhibitor" and continuing through to Y for "Yolk Sac Tumour", we give you succinct explanations for scientific and medical terms in clear and simple words.
- InfluenzaDefinition
Also known as viral influenza or flu
Influenza is an acute endemic, epidemic or pandemic infection of the respiratory tract. (Cf. endemic disease, epidemic, pandemic).
Causes
Pathogen
Influenza is caused by the so-called influenza virus. Influenza or flu viruses are of types A, B and C. Type A influenza virus is responsible for the intense waves of influenza,as it is highly variable (see antigenic drift, antigenic shift). The viruses are transmitted by droplet infection (sneezing and coughing), but also by speaking and direct contact. After an infection, they destroy the uppermost layer of the mucous membrane from the nose to the bronchi. As a result, secondary bacterial infections can arise, particularly with Haemophilus influenzae, staphylococci and streptococci. Cf. viruses.
Symptoms
Influenza begins suddenly with high fever, chills, throat problems, and pain in the head, limbs, muscles and lower back. Additional symptoms are hoarseness and dry cough and sometimes vomiting and abdominal pain. Any organ or organ system can be toxically damaged, which can lead to the occurrence of different symptoms: excessively low blood pressure, slow heart rate, swelling of the liver, nose bleeds, coughing blood and influenza exanthema. If the course is uncomplicated, the symptoms regress after 4-8 days. Total recovery can last longer.
Complications
Complications may develop, particularly in older people and when there are secondary bacterial infections. These include:
1. Acute bronchitis and pneumonia, which is regarded as the cause of 80-100 % of influenza deaths. Secondary infections with staphylococci may lead to accumulation of pus in the pleura. 2. Paranasal sinusitis and otitis media. 3. Circulatory failure as a result of infectious and toxic inflammation of the heart muscle or damage to the smallest blood vessels (capillaries). 4. Involvement of the nervous system (inflammation of the nerves, meningitis).
Diagnosis
Diagnosis is carried out on the basis of the symptoms. Additional diagnostic tests can include the blood count, demonstration of the virus in secretions in the throat or in the stool and measurement of antibodies. Influenza should be differentiated from other viral infections, particularly adeno- and Coxsackie viruses, and also ornithosis, which is an infectious bacterial disease transmitted by birds, sepsis, Typhus abdominalis and miliary tuberculosis.
Therapy
As a first step, the symptoms are combated with drugs to reduce the fever and inflammation. If the course of the disease is threatening, treatment follows with a vaccine which contains the corresponding antibody and with virostatic drugs. antibiotics are used for secondary bacterial infections. In cases free of complications the prognosis is favourable.
Prevention
protective vaccination to influenza can be carried out as prophylaxis against infection. Vaccination is particularly important for individuals aged over 60, those who are at increased risk because of an underlying disease and for people who are at increased risk because of their work, e.g. if they work in hospitals or have much contact with the public. It is best to use the antigen combination which is currently recommended by the WHO. If at all possible, the vaccination should be carried out in autumn before the start of the influenza season. It is best to inject the vaccine into the upper arm. Revaccination should be carried out every year, as vaccination only protects for a maximum of one year. During a pandemic caused by a change in the pathogenic influenza virus (cf. antigenic shift), vaccination with broad activity is requisite. This can be of great value for the health of the population. The use of the protective vaccine depends on the epidemic situation.
Glossary entries: Roche and Walter de Gruyter, Berlin