Influenza (seasonal)

Key facts

• Every year there are around billion cases of seasonal influenza, including 3 to 5 million cases of serious illnesses.
• It causes 290,000 to 650,000 breathing frames annually.
• Nine -and -ninth percentage of deaths in children under 5 years with influenza -related infections of the lower respiratory tract are located in developing countries.
• The symptoms start 1-4 days after the infection and usually last about a week.

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overview

Seasonal influenza (the flu) is an acute respiratory infection caused by influenza viruses. It is common in all parts of the world. Most people recover without treatment.

Influenza spreads easily between people when they cough or sneeze. Vaccination is the best way to prevent the disease.

The symptoms of influenza include acute use of fever, cough, sore throat, body pain and fatigue.

The treatment should aim to relieve symptoms. People with the flu should rest and drink many liquids. Most people will recover alone within a week. In serious cases and in people with risk factors, medical care may be required.

There are 4 types of influenza viruses, type A, B, C and D. Influenza A and B viruses circulate and cause Seasonal epidemics of diseases.

• Influenza -a -viren are divided into subtypes according to the combinations of the proteins on the surface of the virus. In humans, subtype A (H1N1) and A (H3N2) are currently circulating. The A (H1N1) is also written as (H1N1) PDM09 because it caused the 2009 pandemic and replaced the previous A (H1N1) virus (H1N1), which was rebuilt before 2009. It is known that only influenza -type -a viruses have caused pandemic.
• Influenza B viruses Are not divided into subtypes, but can be divided into lines. Influenza -Typ -b viruses are either part of the B/Yamagata or the B/Victoria line.
• Influenza -c virus Is less often recognized and usually causes mild infections, which means that no importance of public health is presented.
• Influenza d -viren First and foremost cattle are affected and is not known that they infect people or cause diseases.

Signs and symptoms

The symptoms of influenza usually start about 2 days after infection of someone who has the virus.

Symptoms include:

• sudden start of fever
• Cough (usually dry)
• Headache
• Muscle and joint pain
• Severe discomfort (feel uncomfortable)
• Sore throat
• running nose.

The cough can be serious and take 2 weeks or more.

Most people recover from fever and other symptoms within a week without demanding medical help. However, influenza can cause serious illnesses or deaths, especially in people with high risk.

Influenza can make the symptoms of other chronic diseases worse. In severe cases, influenza can lead to pneumonia and sepsis. People with other medical problems or with severe symptoms should look for medical care.

Hospital stay and death due to influenza mainly occur under high -risk proposals.

In industrialized countries, most of the deaths associated with influenza occur in people aged 65 and over (1).

The effects of seasonal influenza epidemics in developing countries are not fully known, but research estimates that 99% of deaths in children under 5 years with influenza -related infections of the lower respiratory tract are located in developing countries (2).

Epidemiology

All age groups can be affected, but there are groups that are more at risk than others.

• People with a serious risk of serious illnesses or complications in infections are pregnant women, children under 5 years, older people, people with chronic diseases (e.g. chronic diseases (chronically cardiac, lungs, kidney, metabolic, neurological development, liver or hematological diseases) and people with immunosuppressants (HIV, HIV, hematological diseases or steroids or steroids Steroids or steroids or malignancy).
• Health and nursing workers have a high risk of acquiring influenza virus infections due to increased exposure to the patient and the further spread in particular to people in need of protection. Vaccinations can protect health workers and people around them.

Epidemics can lead to a high level of absenteeism and loss of productivity from workers/school. Clinics and hospitals can be overwhelmed during top disease times.

transmission

The seasonal influenza is slightly spreading, with fast gears in overcrowded areas such as schools and nursing homes. If an infected person coughs or sneezes, droplets that contain viruses (infectious droplets) are distributed in the air and can infect people in the immediate vicinity. The virus can also be distributed by hands that are contaminated with influenza viruses. To prevent the transmission, people should cover their mouth and nose with a tissue if they cough and wash their hands regularly.

In moderate climates, seasonal epidemics occur mainly in winter, while in tropical regions of influenza can occur all year round and cause outbreaks more irregular.

The time from the infection to the illness, which is referred to as incubation period, is about 2 days, but is between 1 and 4 days.

diagnosis

Most cases of human influenza are diagnosed clinically. In times with low influenza activity or outside of epidemic situations, the infection of other breathing virus (e.g. Sars-Cov-2, rhinovirus, breathing syncytial virus, parainfluenza and adenovirus) can also be present as an influenza disease, which has indicated the differentiation of adenovirus.

The collection of suitable breath samples and the use of a laboratory diagnostic test are required to determine a final diagnosis. The proper collection, storage and transport of breathing samples is the main first step for the laboratory recognition of influenza virus infections. The laboratory is usually confirmed using a direct antigen defense, virus insulation or after the detection of influenza-specific RNA by reverse transrectase polymerase chain reaction (RT-PCR). Various guidelines for laboratory techniques are published and updated by WHO.

Fast diagnostic tests are used in clinical environments, but they have less sensitivity compared to RT-PCR methods, and their reliability largely depends on the conditions under which they are used.

Treatment

Most people will recover from influenza. People with severe symptoms or other diseases should look for medical care.

People with mild symptoms should:

• Stay at home to avoid infecting other people
• relax
• Drink many liquids
• Treat other symptoms like fever
• Find medical care when the symptoms worsen.

People with high risk or with severe symptoms should be treated with antiviral drugs as soon as possible. This includes people who are:

• pregnant
• Children under 59 months
• from 65 years and older
• live with other chronic diseases
• Reception chemotherapy
• Living with oppressed immune systems due to HIV or other conditions.

The WHO Global Influenza Surveillance and Response System (GISRS) monitors the resistance to antivirals in circulating influenza viruses in order to provide timely evidence of national politics in connection with antiviral use.

prevention

Vaccination is the best way to prevent influenza.

Safe and effective vaccines have been used for more than 60 years. The immunity of vaccination disappears over time, so that an annual vaccination is recommended to protect against influenza.

The vaccine may be less effective in older people, but makes the disease less serious and reduces the likelihood of complications and death.

Vaccination is particularly important for people who have a high risk of influenza complications and their supervisors with a high risk.

The annual vaccination is recommended for:

• Pregnant women
• Children aged 6 months to 5 years
• People over 65 years
• People with chronic diseases
• Health staff.

Other options for preventing influenza:

• Wash and dry your hands regularly
• Cover your mouth and nose when coughing or sneezing
• Dispose of tissue properly
• Stay at home when you feel uncomfortable
• Avoid close contact with sick people
• Avoid touching your eyes, nose or mouth.

Vaccinations

Vaccines are routinely updated with new vaccines containing viruses that correspond to the circulation. Several inactivated influenza vaccines and recombinant influenza vaccines are available in jicable form. Living muffled influenza vaccines are available as a nasal spray.

Who reacts

Anyone who, in cooperation with other partners through the global influenza program and in cooperation with other partners, recommends the worldwide continuous influenza viruses and activities twice a year. Member States for the development of prevention and control strategies.

Who is working on the strengthening of national, regional and global influenza reaction capacities, including diagnostics, antiviral susceptibility surveillance, disease surveillance and outbreak reaction, to increase the vaccine cover between high-risk groups as well as to support research and development of new therapeutics and other countermeasures.

1. Estimates of the US influenza-associated deaths with four different methods.
Thompson WW, Weintraub E., Dhankhar P., Cheng Oy, Brammer L., Melzer Mi, et al. Influenza other Respi viruses. 2009; 3: 37-49

2. Global stress due to respiratory infections due to seasonal influenza in small children: a systematic review and meta -analysis.
Nair H., Abdullah Brooks W., Katz M. et al. Lancet 2011; 378: 1917–3