Bird flu: Virus H5N1 also dangerous for humans

Influenza viruses: cause of the infectious disease

Different subtypes of the influenza A virus can cause the infectious disease. People who have previously contracted this type of virus all had close contact with infected domestic or commercial poultry and their excretions – for example when they slaughter poultry or clean the barn.

The viruses are present in particularly large numbers in the bird droppings of sick chickens and turkeys. It is believed that the viruses enter the human body when inhaled. Hand hygiene also seems to play a crucial role in avian influenza infection.

Since ducks, swans and geese are also common carriers of the virus, people in avian flu areas are advised to keep their distance from these animals.

The virus mutates very quickly, so far the following subtypes are known:

• H5N1: Original subtype of bird flu, most common until 2012
• H5N8: So far appears to be a less dangerous subtype than H5N1 for humans
• H7N9: According to the WHO, the H7N9 variant of the bird flu pathogen has shown signs of adapting to mammals. This allows the virus to dock onto mammalian cells. It also grows at the normal body temperature of mammals.

The risk of becoming infected through poultry meat is estimated to be significantly lower than through direct intensive contact with infected poultry. In Germany, poultry meat and eggs are considered free from bird flu viruses. Nevertheless, as a precautionary measure, it is recommended that poultry meat is only well cooked or well fried, and the same applies to eggs.

Avian flu symptoms

It usually takes two to five days from infection to the first symptoms, but the incubation period can be up to 14 days. Typical signs of bird flu are high fever, sore throat , cough and shortness of breath. In addition, there is often diarrhea, and abdominal pain and vomiting can also occur.

It is typical of bird flu that those affected develop inflammation of the lungs (pneumonia), which can lead to lung failure and death.

Often changes in the blood count in bird flu

The blood picture often shows a lack of the white blood cells leukocytes and lymphocytes (leukopenia), erythrocytes (anemia) and thrombocytes (thrombocytopenia). An increase in liver values ​​and a deterioration in kidney function up to and including kidney failure were also observed, and ultimately multi-organ failure can also occur. Many patients with bird flu develop pneumonia, and some patients also develop cardiac arrhythmia and acute heart failure .

Diagnosing Avian Influenza: Examine blood and bodily fluids

Bird flu has similar symptoms to regular flu. Therefore, the doctor will first ask the person concerned about possible risk factors. If the sick person has come into contact with animals infected with bird flu or their excretions about a week before the onset of the illness, bird flu is likely. Infection is also possible through the raw or undercooked products of infected poultry.

Various laboratory tests are available to diagnose the condition. The nose and throat mucus, bronchial secretion and blood are examined. Special procedures help to identify the pathogen itself. Alternatively, a search is made for H5 antibodies – proof that the bird flu virus has already penetrated and is calling on the organism to defend itself.

 

Avian influenza therapy

In order to prevent further transmission of bird flu, those affected are initially isolated. Viral diseases such as bird flu can be treated with virus-killing drugs (antivirals). Neuraminidase inhibitors such as oseltamivir and zanamivir are suitable. In addition, the symptoms that occur are alleviated with, for example, antipyretic drugs or drugs for sore throats and coughs.

Can you prevent bird flu?

Because avian influenza is primarily transmitted through infected poultry and animal excrement, the following should be avoided in affected areas:

• direct contact with live or dead poultry
• Contact with chicken and turkey droppings
• Visit to bird or poultry markets

It is also advisable to wash or disinfect your hands thoroughly with soap and water – especially before eating.

There is currently no approved human vaccine against H5N1 influenza A virus. To avoid co-infection with common flu and bird flu, the best way for vulnerable people to protect themselves is to get the flu vaccine .