Bird flu

Synonyms

Bird plague; avian influenza

Microbiological: H5N1, H7N2, H7N9

introduction

Bird flu initially manifests itself in general flu symptoms such as a high fever.

Bird flu is an infectious disease that is caused by certain forms of the flu virus. In a broader sense, the bird flu is also under the name "Avian influenza"Or"avian influenza" known.

Usually, bird flu mainly affects poultry (especially chickens, turkeys and ducks), but extensive mutations in the causative virus can also infect humans.

This disease is a rapidly spreading, potentially life threatening infection. The virus subtypes H7N9, H5N1 and H7N2 in particular have made headlines in recent years.The naming of the virus subtype is based on specific surface structures (Egg whites) back. These surface structures include above all the Enzymes Hemagglutinase (short: H) and Neuraminidase (short: N). These specific proteins enable the virus to attack and damage the host organism. Around 16 different hemagglutinases and 9 different neuraminidases are now known. The composition of the respective enzyme subtypes on the virus envelope is decisive for the designation of the virus.

In general, bird flu and its viral pathogens are between highly pathogenic (causing serious illness) and low pathogenic (provoking only mild symptoms) differentiated.

causes

In the Bird flu Just like all other types of flu, it is through Virus-induced infectious disease. In contrast to the original assumption that avian flu only affects poultry, a transmission potential to mammals has now been demonstrated for some subtypes. The underlying virus is mainly found in the secretions of the respiratory tract and in the feces of infected animals.

After excretion, the bird flu virus remains infectious in liquid manure for more than 100 days. The bird flu virus can be found in feces and poultry meat and in eggs stored at four degrees Celsius 30 to 35 days outlast. At a room temperature of around 20 degrees Celsius, the survival time of the viral pathogen is reduced to approximately 20 days.

At temperatures over 22 degrees Celsius however, the stability of the viral envelope is reduced. The viruses responsible for the development of bird flu perish accordingly quickly.

The Killing the bird flu viruses succeeds at temperatures of 55 to 60 degrees Celsius even within a very short time.

The Transmission to mammals (mainly on humans) takes place mainly on that respiratory tract instead of. Inhaling dust particles containing virus is enough to trigger the disease. In addition, the Contact with infected animals in the case of insufficient hand hygiene as high risk. In addition to the transmission of bird flu from animals to humans, one is now also assumed direct human-to-human infection out. However, this theory has not yet been confirmed with certainty.

Symptoms

The typical symptoms in the presence of avian flu show up in each of the affected patients, depending on the immune situation, in different ways. Since the incubation period bird flu (period between infection and the outbreak) is around 14 days, the first symptoms can be expected after this period.

The symptoms of bird flu are similar to the symptoms of one common influenza caused. Most of the affected patients develop in the first few days of the disease extremely high fever. Core body temperatures of 40 to 41 degrees Celsius are not uncommon in bird flu patients. In addition, the causative viral pathogens affect the respiratory tract. For this reason, the affected patients often suffer from pronounced cough and Shortness of breath. Also the appearance of Sore throat is one of the most common symptoms of bird flu. In many of the known cases a pronounced one could also be found Affecting the gastrointestinal tract to be watched. The majority of those affected developed over the course of the disease Stomach discomfort. In addition, many bird flu patients suffer from it diarrhea and or Vomit.

At a limited body defense avian flu can take a highly risky course. In severe cases, inflammatory processes develop in the area of the lungs (lung infection; pneumonia), too strong Stomach discomfort, Inflammation of the intestines and one Increase in liver values. Occasionally, affected patients develop one Kidney weakness (Renal failure), the worst in one complete kidney failure can flow.

The bird flu runs roughly 50 percent of the cases fatal. The ultimate cause of death for those affected is the emergence of a Lung failure. Pre-stressed and / or immunocompromised patients often die of a so-called Multiple organ failure in which several organs can no longer perform their normal function.

diagnosis

Diagnosing bird flu involves several steps. With all these measures, however, it must be noted that as soon as the presence of this disease is suspected, special precautionary measures must be taken.

The first step in the diagnosis of avian flu includes an extensive doctor-patient discussion (anamnese). During this conversation, the symptoms should be described in as much detail as possible. In addition, possible stays abroad and previous illnesses should be discussed. If a bird flu infection is suspected, direct contact with animals and / or infected people also plays a decisive role.

The most important questions to be dealt with during the anamnesis interview are:

Has the patient been abroad in the last few months?
Has the patient touched wild birds?
Has the patient come into contact with raw poultry meat?
What are the symptoms of the patient?
Are there other people around the patient who are currently suffering from infections?
When did the patient begin to experience symptoms?
Did these symptoms come on suddenly?
Does the patient suffer from shortness of breath?

If the suspicion arises during this informative doctor-patient discussion, further diagnostic measures must urgently be initiated. In the case of bird flu, it is necessary to secure the diagnosis by means of direct pathogen detection. Reliable test procedures are available in everyday clinical practice, with the help of which the causative avian flu virus can be detected within a few hours.

Similar to a common flu infection, the diagnosis of bird flu can also be carried out by a throat or nose swab. In addition, there are usually enough pathogens in the coughed up bronchial secretion to successfully detect the disease. This can also be done using a quick test.

Find out more at: Rapid flu test

If the diagnosis is confirmed, a blood sample should also be taken with a subsequent laboratory examination of the blood samples. In this way, first impairments of various organ systems (for example the liver) can be detected.

The physical examination of the cardiovascular system and the abdominal cavity should not be neglected in the affected patient.

therapy

Even the suspicion of a bird flu infection is enough to justify isolation of the affected patient. This is the only way to prevent the viral pathogen from spreading and being transmitted to other people.

The actual treatment of bird flu is quite difficult, because most of the known drugs that are aimed directly against the bird flu virus (so-called "antiviral drugs“) Are only effective within a very short time after infection. Especially Neuraminidase inhibitors which are directed against the surface proteins of the avian influenza viruses have shown good effectiveness. The most commonly administered drugs in this context are: Zanamivir and Oseltamivir. These drugs work by inhibiting the spread of the virus within the host body.

Once the viral pathogens have penetrated the body cells, however, no effectiveness can be proven. In such cases, bird flu treatment can only be symptomatic. This means that only the patient's symptoms are alleviated. The virus itself has to be fought by the body's immune system.

The most important measures in the symptomatic treatment of avian flu include:

intravenous (vein) hydration
Oxygen supply
Antipyretic drugs such as paracetamol or ibuprofen
Pain relief

Medicines containing acetylsalicylic acid should not be used in children to relieve pain or reduce fever (aspirin) can be used. This is because aspirin, linked to the avian flu virus, can cause a life-threatening disease called Reye's syndrome. This disease is an impairment of the brain that can be observed approximately three to five days after the first symptoms of bird flu appear. The reason for the development of Reye's syndrome after taking acetylsalicylic acid-containing drugs in children with bird flu is a malfunction of the smallest cell structures (mitochondria). These malfunctions mainly affect the mitochondria of the liver, skeletal muscles and the brain. As a result of the structural changes, the energy supply to the affected cells almost completely comes to a standstill.

As the bird flu progresses, bacterial pathogens can attack the lungs and cause pneumonia (pneumonia) to lead. The risk of developing accompanying pneumonia is particularly high in patients suffering from bird flu because the immune system of those affected is already severely weakened. So if there is accompanying pneumonia, this must also be treated specifically. In this context, antibiotics of the classes come first Beta lactamase inhibitors, Cephalosporins and Macrolides for use.

Course and complications

Of the Course of the bird flu can take a completely different course in every person. In a few cases, the affected patients develop no symptoms at all or only suffer from mild ones Cold symptoms. Other patients, however, make an impression clearer clinical picture with a high fever, strong cough and Shortness of breath out.

Particularly severe courses are shown by the occurrence of acute organ involvement. Especially the development of inflammatory processes in the respiratory tract (lung infection; pneumonia) plays a crucial role in this context.

In the case of bird flu, however, the infection in humans is very severe. The possible complications that can arise during the infection are decisive for the healing process of an affected patient. The most common complications are acute Respiratory syndrome, of the septic shock and the Failure of various organs. In the case of bird flu patients who develop such a severe course of the disease, intensive care treatment is and often one artificial respiration necessary.

An infection with bird flu becomes particularly dangerous if the affected person comes into contact with it at the same time common flu viruses come. In these cases, the genetic make-up of the different virus strains can mix with one another (mutation) and change in the process.

In general, infections with these mixed virus forms are essential easier from person-to-person transferable. The formation of a so-called "pandemic" (global mass disease) is then particularly easy.

prevention

Infection with the viral pathogens that cause bird flu can be prevented. In danger regions, the Contact with infected birds be avoided. However, the direct risk of infection for humans is rather low even when they come into contact with infected animals. Nevertheless, compliance with special protective measures must urgently be observed.

To the relevant preventive measures belong:

regular Hand hygiene with soap and water
regular disinfection of the hands
Avoid direct contact with any poultry
sick or dead wild birds never touch it
After contact with dead or sick birds, wash hands immediately with soap and water and then disinfect
Poultry meat before the distortion absolutely boil or fry (Bird flu viruses can be killed by heating to around 70 degrees Celsius)
no distortion of raw or undercooked poultry meat

The transmission of bird flu from person to person has not yet been proven, but infected people should be isolated and protective measures taken in the event of contact.

In addition, bird flu infection can be partially due to a vaccination be prevented. There are various bird flu vaccines that have also been approved in Germany for some time. These vaccines primarily protect against the virus subtypes H5N1. Against the virus subtypes H7N9 However, no suitable vaccine is currently available. The one to prevent the common flu vaccine available has no effect on avian flu prevention. Nevertheless, an appropriate flu vaccination should be carried out regularly. In this way, serious disease courses can be prevented in the event of a later infection with the bird flu virus. It also reduces the risk of dangerous crossbreeds between influenza and avian influenza viruses. In the course of this, the risk of a spread decreases pandemic.