Influenza viruses include A, B, and C. Influenza A is the virus that causes the worldwide epidemic. The virus is periodically mutated and causes epidemics: sporadic outbreaks every 1 to 3 years are caused by small antigenic mutations, and global pandemics every 10 to 15 years are caused by large antigenic mutations. Is. Since the twentieth century, there have been about 5-6 cases of influenza pandemic worldwide.
In particular, the global epidemic between 1918 and 1919 during World War I is a major pandemic of about 20 million deaths. In 1957, the reported incidence rate exceeds 50% of the urban population. It is becoming. In the most recent pandemic of 2009, up to 570,000 deaths from respiratory and cardiovascular events were estimated. This global epidemic is caused only by the hepatitis A virus, which occurs when mutations in the genetic structure are greater than 50%, resulting in a completely new antigenic form.
Path Path of infection
Flu is rapidly spread from person to person by small drops produced when a patient coughs or sneezes. Airborne infections can also be found in densely populated areas such as schools, ships, and public transportation. It can survive up to 48 hours on the surface of items contaminated with nasal discharge or pharyngeal discharge (phones, computer keyboards, doors, cups of coffee, etc.), allowing for indirect transmission. The incubation period is 2 to 3 days and the transmission period is 3 to 4 days from the onset of clinical symptoms. The infected person is immune to the virus strain.
◇ Symptoms and complications
Influenza usually begins suddenly after an incubation period of one to four days (average of two days). Initially, systemic symptoms such as fever, chills, headache, muscle pain, fatigue, and loss of appetite are prevalent. Muscle pain and headaches are usually the most painful, and calf muscle pain is significant in children. Joint pain, tears, burning eyes and gastrointestinal symptoms such as abdominal pain, diarrhea and vomiting may occur. Systemic symptoms usually last about three days. Suddenly, body temperature rises to 38-40 degrees with constant fever, but it can also be an intermittent fever. Respiratory symptoms, such as hoarseness and sore throat, appear as systemic symptoms subside and become more severe, lasting 3 to 4 days after fever.
Influenza B is similar to influenza A, but goes through a milder course. Influenza C, on the other hand, is not common and does not cause epidemics. Children have more severe fever and more frequent cervical lymphadenitis than adults. It causes upper respiratory tract infections, laryngeal bronchitis, bronchitis, capillary bronchitis, pneumonia, etc., and is often accompanied by temporary occasional rash. Babies are often associated with sepsis.
Complications may result in pneumonia. Song Young-gu, professor of medicine for infections at Gangnam Severance Hospital, said: “There is viral pneumonia caused by the influenza virus itself, bacterial pneumonia caused by secondary bacterial infection and pneumonia caused by mixed virus and bacterial infection. In the elderly, the incidence of pulmonary complications is much higher than in other age groups. Other complications include otitis media in children, myositis during influenza B infection, myocarditis and pericarditis, and Reye's syndrome. "
Injection of antiviral drugs may reduce the duration of the flu. However, a more important treatment than antiviral therapy is to get enough rest and sleep. Drink plenty of fluids and increase the humidity with a humidifier. Increasing humidity can prevent the influenza virus from reproducing well in a dry environment, making patients with fever and cough more comfortable and in the case of sputum cough. This helps. If you don't eat well in children, add calories, sugar or honey water such as light or ionic drinks. You can give juice, milk or fruit juice slowly, but children with fever often have vomiting or diarrhea; so take small portions and drink slowly.
Adjuvant medications include aspirin and acetaminophen as antipyretic analgesics, which can reduce high fever, headaches and muscle aches, but should be consulted with a doctor when using aspirin in children, which can cause side effects called lys syndrome. . Professor Song said: “Even if you are under 3 years old or have an adult with high fever for more than 3 days, the cough lasts a long time and becomes severe, accompanied by chest pain, shortness of breath or sputum. I made it.
◇ Management and prevention
In high-risk groups, such as the elderly, chronic disease patients, and immunosuppressive patients, it is important to avoid colds. As a general precautionary measure, it is best to avoid places where there are many people and to keep hands, feet and face clean after leaving. You must wash your back and brush your teeth. Sufficient nutrition and avoid overwork.
Inoculate vaccines for proactive prevention. All children 6 months and older should be vaccinated. If vaccine supply is limited, the following groups may be given priority. The first is a high-risk group with high complications and mortality when the flu develops. And transplant patients, etc.), and the second group is able to spread the influenza virus to these high-risk groups. A representative example is a medical person who contacts a patient in a hospital.
Therefore, if there is a high-risk group in the family, vaccination is effective not only for the individual but also for the whole family. In addition, people who directly care for high-risk patients, those whose absence can be a problem due to influenza or upper respiratory tract infections (for example, are in critical positions in the workplace or are essential to society), work in very dense environments If the risk of transmission is extremely high, people who wish to be vaccinated for influenza are eligible for vaccination.
Professor Song said: “If you have a severe hypersensitivity reaction, such as anaphylaxis, after previous influenza vaccination or if you have Guillain-Barre syndrome within 6 weeks of the previous vaccination, you should avoid reinoculation. It is contraindicated in babies and adolescents taking aspirin (due to the risk of Reye's syndrome) and pregnant women when taking a disease, cardiovascular disease, diabetes, kidney failure, chronic diseases with hemoglobinosis, immunodeficiency or immunosuppressive drugs. I do.