Swine flu (new influenza A/H1N1 , new flu)

The so-called swine flu, or new flu as it is known in specialist circles, first appeared in the spring of 2009. This form of influenza is caused by an influenza virus that was unknown at the time, namely type A/H1N1. This virus was created by mixing the genetic material of other influenza viruses that normally infect either humans, pigs or birds.

The main route of transmission of New Influenza is from person to person, which is also the case with conventional seasonal influenza. It has not yet been observed that infection can also be transmitted from animals to humans.

The first case of New Influenza occurred in April 2009 in Mexico, where relatively large numbers of people soon fell ill with this novel form. However, the wave of illness did not remain confined to Mexico, but soon spread to large parts of the world. Therefore, a pandemic of the highest degree (6) was declared by the World Health Organization (WHO) soon after, on June 11, 2009. This pandemic lasted for over a year, until August 10, 2010. However, it is believed that the influenza virus is still circulating and may continue to cause more waves of illness in the future.

Seasonal flu vs. new flu

Both seasonal and new influenza are transmitted via droplet infections, mainly by sneezing or coughing. The symptoms of the different forms of influenza are also very similar, but in the case of the new flu there are additional complaints in the gastrointestinal tract. In contrast to seasonal flu, which occurs almost exclusively in the winter months, people can also fall ill with swine flu in the summer months. While the seasonal flu mainly affects older people, it is mainly healthy, young people who fall ill with the new flu.

Due to genetic changes, which subsequently led to an altered envelope of the virus, the conventional flu vaccination could not provide sufficient protection against the New Flu. The vaccines that are now available protect against both conventional (seasonal) influenza and the New Influenza.

Incubation period and transmission

The incubation period, i.e. the time between infection and the appearance of the first symptoms, is approximately one to four days.

There is a risk of infection from the beginning of the infection, i.e. even before any symptoms have appeared. As soon as symptoms appear, there is still a risk of transmission for about three to five days, in the longest case for up to seven days. Children have been observed to release higher doses of the virus and to be contagious for a longer period of time.

Elderly people and people suffering from a chronic illness, as well as medical personnel, have an increased risk of contracting the new flu. But also people who have a lot of contact with other people because of their job are more often infected by the virus.

Swine flu is caused by the influenza virus type A/H1N1. This type of virus has evolved from a genetic combination of other influenza viruses that normally infect birds, pigs or humans. It is assumed that these influenza viruses have infected one host at the same time, resulting in an exchange of genetic information. In particular, such a mixture of influenza viruses can occur in pigs, as they can also be infected by viruses that normally infect humans or birds.

As with seasonal flu, the route of transmission is by droplet infection, mainly through sneezing or coughing. Furthermore, it is also possible to become infected by touching contaminated objects or by shaking hands, which is known as smear infection. The virus can then get into the mouth, eyes or nose via the hands and subsequently into the rest of the body, which is why regular hand disinfection is very important.

The symptoms of swine flu are very similar to those of seasonal flu:

- A rapid rise in body temperature (fever over 38.5°C)

- Dry, irritating cough - Limb pain and headache

The following symptoms may also occur:

- Sore throat

- tiredness and fatigue

- Reduced appetite

Unlike the common (seasonal) flu, swine flu often includes symptoms of the gastrointestinal tract, such as nausea, vomiting and diarrhea. These symptoms can occur in combination with the typical flu symptoms mentioned above, but also in isolation.

By means of a patient interview, in which the patient should describe the course of the disease and symptoms as precisely as possible, and by means of a physical examination, the doctor can usually already make a tentative diagnosis, especially in the winter months. However, as a number of diseases can cause symptoms similar to influenza, a definitive diagnosis can only be made by examining a secretion from the respiratory tract. For this purpose, a swab of the mucous membrane from the nasal or pharyngeal cavity should be taken soon after the onset of the disease and examined in the laboratory. It should be borne in mind that cultures may only be taken in special laboratories. Examinations to determine the type of influenza virus can also only be carried out in such special laboratories.

In most cases, the new flu does not have a life-threatening course, which is why often only symptomatic therapy, i.e. treatment of the symptoms, is appropriate. This includes, for example, the treatment of fever by means of antipyretic drugs or other methods, such as compresses. Since the epithelium of the respiratory tract is damaged by the influenza viruses, this can promote a bacterial infection (superinfection). In these cases, therapy with antibiotics is usually necessary.

Antiviral drugs: Only in cases with severe courses or in people with chronic disease should specific antiviral therapy with neuraminidase inhibitors be started. These include Tamiflu (oseltamivir) and Relenza (zanamivir). These drugs inhibit a viral surface protein called neuraminidase, which is necessary for the virus to spread in the human body. However, treatment can only be expected to be successful if the drugs are administered within the first 48 hours (at the latest within the first 72 hours) after the onset of symptoms. After this time frame, because of the advanced spread of the virus, antiviral treatment is not of as much benefit.

Before administering the drug should take into account special side effects and exceptions in special groups of patients (children, pregnant women).

In the majority of cases, swine flu has a fairly mild course, but sometimes the disease can be more severe or fatal. The exact number of people who have fallen ill or died from the new flu can unfortunately not be determined. During the flu pandemic, the death rate was between one and five people per million population, depending on the geographic location. However, there are also studies that calculated the death rate during the swine flu pandemic to be as high as over 100 people per 1 million inhabitants. The new flu can take a more severe course in people who are counted among risk groups. Those at risk include young children, pregnant women and people with chronic illnesses (diabetes, cardiovascular disease, liver and kidney disease).

Consequential diseases

Like seasonal flu, the new flu can lead to various diseases of other organs and tissues of the body:

- Upper respiratory diseases (sinusitis, middle ear infections).

- Deep respiratory diseases (pneumonia, bronchitis)

- Diseases of the heart (inflammation of the heart muscle or pericardium)

- Diseases of the muscular system (inflammation of the muscle, destruction of the muscle fibre)

- Diseases of the nervous tissue (inflammation of the brain or meninges, epileptic seizures)

- severe, systemic infections with bacteria

General safety measures

The risk of contracting swine flu can be significantly reduced by taking a few easy-to-implement hygiene measures. It is important that as few virus particles as possible get into the nose or throat or into the eyes.

- You should make sure to wash your hands regularly, especially if you have frequent contact with other people or possibly contaminated objects (doors, banisters, etc.).

- You should have as little contact as possible with infected people.

- Since the influenza virus usually enters the body through the nose, mouth or eyes, you should touch these parts of the body as little as possible with your hands.

- You should avoid being sneezed on or coughed on directly by others.

- Shaking hands can also transmit the virus, so avoid shaking hands as much as possible.

Special safety measures

Although conventional respirators cannot protect against infection with the virus, wearing such masks can prevent infected people from excreting the virus in large quantities. Paper handkerchiefs should be used to blow the nose or when sneezing and should be disposed of immediately afterwards.

If you are ill with the new flu, you should stay in bed for about seven days and not leave the house, both to protect yourself and to avoid infecting other people. This can also reduce the risk of a superinfection with bacteria.

Vaccination

The best way to protect yourself from infection is through vaccination. Although there was no suitable vaccine at the beginning of the swine flu pandemic, there is now a combination vaccine that offers effective protection not only against seasonal flu but also against the new flu. Above all, medical personnel, people who have a lot of contact with other people (teachers, kindergarten teachers) and easily contagious people (children and people with chronic illness) should be vaccinated.