Bird flu symptoms in humans
Bird flu is an infectious disease caused by various types of influenza viruses. They are normally found only in poultry and are harmless to humans. However, some viral types can overpower humans and become very dangerous.
Depending on the pathogen, up to half of all infected people die from it. Here you can read everything you need to know about bird flu and bird flu symptoms.
Under bird flu, experts generally understand an animal disease caused by bird influenza viruses. It is also referred to as avian influenza or avian flu, and affects mostly chickens, turkeys, ducks and also wild birds, which they enter into the fattening farms.
It is caused by influenza A viruses. Bird flu is not infectious for humans. Some forms do not appear to be jumping over to humans; in others, an infection is possible with very close contact with the poultry.
So far, around 1000 cases of avian influenza are known worldwide – most of them in Asia. Between 20 and 50 percent of the infected persons died from bird flu.
In the headlines of the last few years, names such as H7N9, H5N1 or H7N2 have increased. This is used to describe the triggering virus. Influenza viruses carry certain proteins on their surface, which are characteristic of them.
Bird flu symptoms
If a person suffers from bird flu, the following symptoms typically occur two or five days after the infection.
These symptoms are usually similar to flu:
- High fever
- Difficulty in breathing
- Sore throat
In approximately half of the cases, patients complain about complaints of the gastrointestinal tract. These include:
- Stomach pain
Because the bird flu viruses mainly affect the respiratory tract, severe pneumonia can occur, which in many cases leads to death.
Often it is a secondary infection with bacteria, which exploit the fact that the immune system of the body is just weakened. Patients suffer from severe dyspnoea. In some cases they cough blood.
Bird flu causes and risk factors
The bird flu occurs in humans when flu viruses transmitted to humans by poultry animals.Usually very close contact with the animals is necessary. In many cases, it is known that sufferers lived closely together with their livestock. In fact, the highly pathogenic avian flu viruses are not well adapted to the conditions in the human organism.
In the case of infection, the viruses are mainly attached to superficial cells of the respiratory tract, the epithelium. These epithelia are different in humans and birds. Therefore, not every contact with the virus leads to the disease.
Above all the types H7N9 and H5N1 have been transferred to humans in the past. In these cases, it can not be ruled out in individual cases that human-to-human infection has occurred.
In order to minimize the risk of infection, the entire bird population of a poultry farm is usually killed when a infected animal is discovered.
Bird flu virus H5N1
H5N1 infected people in the 90s, especially in Southeast Asia and Egypt. To date, more than 668 cases have been reported worldwide, 393 of them died (as of October 2014). The World Health Organization regularly publishes the latest figures. It is still unclear why this virus subtype is so fatal for humans.
Bird flu virus H7N9
Mainly in China, H7N9 affected humans as a new subtype of avian influenza. The first cases were known in 2013. There are 450 confirmed cases of disease, of which 165 died (as of October 2014). The average age of onset was 58 years, with more men than women infected with this bird flu.
Furthermore, individual cases are known in which humans are infected with the influenza subtypes H5N6, H7N2 and H3N2.
Bird flu risk
Due to the globalization and the many journeys that people do today, there is the danger that bird flu viruses can be brought anywhere in the world. In principle, the following groups of persons are considered to be at risk:
People working in poultry farming or meat processing industry
Veterinarians and employees of special laboratories
Wild birds or when poultry is not cooked properly before consumption
Theoretically, there is the possibility that a person will be infected at the same time with a “normal” flu virus and a bird flu virus. The viruses sometimes exchange their genes among themselves. So it could happen that the avian flu virus can be better adapted to humans through an exchange of information. This would result in a highly contagious, highly dangerous bird flu virus. So far, there is no evidence that this scenario has already taken place.
Bird flu diagnosis
In order to diagnose avian flu, your doctor will first consult you about your medical history (anamnesis). He will ask you the following questions:
- Have you been on vacation lately?
- Have you touched wild birds?
- Have you come into contact with raw poultry meat?
- Since when do you feel sick? Did the symptoms suddenly occur?
- Do you suffer from shortness of breath?
Subsequently, he examines you physically. He listens to the lungs and stomach, measures your temperature and looks at your throat. To prove a bird flu disease, a nasal or throat smear can be taken from the patient. Then, this is investigated in a laboratory for the genome of the pathogen.
How to treat bird flu?
In the case of suspected bird flu, the patient is first isolated in order to prevent possible transmission to other people and to spread.
The medicines, which are used directly against the influenza viruses (antiviral drugs) are effective only within a short time after the contagion. Neuraminidase inhibitors are used, for example zanamivir or oseltamivir. They prevent the viruses from spreading in the body.
If the infection has been too long, bird flu can only be treated symptomatically. That means as trying to alleviate the discomfort. Symptomatic treatment of bird flu includes:
- Adequate liquid and salt intake
- Oxygen supply
- Children should not be given acetylsalicylic acid for fever as they may lead to a life-threatening condition, the Reye syndrome, in connection with the bird flu virus
It is possible that bacteria cause an additional pneumonia, as the physical defence system is severely weakened by avian flu. In this case, antibiotics that are only effective against bacteria are used for treatment. These include the antibiotic classes betalactamase inhibitors, cephalosporins and macrolides.
How to prevent bird flu?
It is still very unlikely that you are infected with bird flu. However, in principle, the same applies to bird flu as to other diseases: To prevent it, contact with the pathogen should be avoided. This applies to:
- If you are not aware of sick or dead birds (especially waterbirds or migratory birds), please inform the authorities (veterinary office, municipality, county)
- Fry or cook poultry meat and eggs; The virus dies quickly during heat, but it survives at low temperatures in the freezer
- Wash your hands after handling raw poultry meat (during cooking)
- Do not touch live birds or land with which the animals have been in contact in holiday countries
- Already the suspicion of bird flu disease is notifiable, so that disease control measures are initiated in time and spread can be prevented
The vaccine, which is offered annually against the “normal” flu, does not protect against bird flu. However, it is advisable that people who are among the most vulnerable groups (such as poultry workers) be vaccinated against the flu. This prevents the “normal” and the avian influenza virus from affecting the same human beings at the same time and can exchange their genetic material.
Bird flu disease history and prognosis
The time after infection with the bird flu virus and the onset of the disease (incubation period) is on average two to five days. It can also take up to 14 days. Suddenly, flu-like symptoms appear. In the course of the disease, bird flu patients often develop pneumonia.