Avian flu: symptoms, what risks for humans?

[Mise à jour le 9 juin 2022 à 11h02] Avian flu or rather “avian influenza” is a animal disease caused by A strains of the influenza virus. We’re talking about “epizootic“as it is a epidemic affecting animals. It is an infectious, viral, highly contagious disease affecting domestic and wild birds which can, depending on the strain, be transmitted to humans, without necessarily making them sick. Facing theimprovement of the national health situationMarc Fesneau, Minister of Agriculture and Food Sovereignty, has decided tolower the level of risk on the national territory to “negligible” as of June 8, informs the ministry. specified by a decree published today in the Official Journalthis new step makes it possible to lift the restrictions in force over the vast majority of the territory. Since May 17, 2022, no new outbreak of highly pathogenic avian influenza (HPAI) has been detected in breeding in France and, to date, only a few cases have been confirmed in wildlife. What is bird flu? A flu like the one you can get in winter? What precautions adopt ? What risks for humans if animals are contaminated? What symptoms in animals ? The man ? How come this transmission ? Lighting.

How many cases of bird flu in France?

Since November 2021, France has gone through an episode of extremely virulent highly pathogenic avian influenza (HPAI) which led to theslaughter of more than 16 million poultry. As of June 8, France has a total of 1,378 outbreaks of HPAI in livestock, 55 cases in wildlife and 35 cases in backyards. Facing theimprovement of the national health situationMarc Fesneau, Minister of Agriculture and Food Sovereignty, has decided tolower the level of risk on the national territory to “negligible” from June 8. As a reminder in the event of an epidemic “The main problem is to succeed in stop the progression of the virus and above all to avoid contamination of breeding farms for chickens, turkeys, etc. Their attack would result in the loss of many years of genetic research. We have to protect these grandparents.” In contrast, no fear for the man in France “because there are not the same risk factors as in Asia where contamination has been observed (live poultry market likely to be infected, precarious conditions with significant cohabitation with uncontrolled poultry, persistence of the virus…)” continues the specialist. In France, the protection of poultry is essential in the face of the exceptional risk for humans. It is based on drastic biosecurity measures. In Europe, 36 countries are affected by the 2021-2022 highly pathogenic avian influenza epizootic.

What is bird flu?

Avian “flu” or rather avian “plague” is a disease caused by avian influenza virus (A) highly pathogenic (HPAI). It’s a virus influenza virus family. We speak thus in a way inadequate “bird flu” whereas, in birds, it is a disease characterized by a sepsis associated with encephalitis, and not from a predominantly respiratory condition such as human flu. “The fowl plague virus was discovered in 1959 and the first case official that we had in France only happened in 2006″ emphasizes Jeanne Brugère-Picoux. This disease is particularly contagious and the virus can even be carried by the wind from one building to another. Many species of wild birds, especially those that live in wetlands and aquatic environments, harbor influenza viruses. Anseriformes (especially ducks, geese and swans) and charadriiformes (such as gulls, terns and waders) are the main natural reservoir of fowl plague virus. The infection can decimate an entire flock in less than 48 hours.

“If humans can be infected with the bird plague virus, they are not necessarily sick”

Is bird flu transmissible to humans?

“In France, no human case linked to contamination by an HPAI virus has been observed to date” recalled the Academy of Medicine in a statement from December 2021. Worldwide, cases of HPAI H5N1 viruses have been identified in humans as well as deaths (455 deaths between 2003 and 2019, none in 2020 and 2021) but they remained very rare and have been observed in people who have had close contact with infected poultry or with objects contaminated by their droppings. Otherwise, “if man can be infected with the avian plague virus, he is not necessarily sick”, emphasizes Jeanne Brugère-Picoux. “Humans are not receptive to this virus at the level of the first cells of the respiratory system, it is necessary to reach the alveoli for there to be a serological reaction with this virus, that is to say at the level of the deep respiratory system. At this time, you will have a serological reaction but not necessarily a disease. If we breathe a little bit of the virus present in the feathers during plague, we can have a serological reaction without being sick.” Finally, it should be noted that not all avian influenza viruses are transmitted to humans. Of 144 strains of avian influenza A viruses, four have caused human infections: H5N1, H7N3, H7N7 and H9N2.

What are the risks of avian flu for humans?

“The avian plague virus is very pathogenic for animals, not for humans” continues our interlocutor. Remember (again) that in France, no human case linked to contamination by an HPAI virus has been observed to date. “There is nothing to worry about for humans in relation to the foci of avian plague recorded in France, reassures Jeanne Brugère-Picoux. The problem is mainly protect yourself so as not to contaminate other farms.” Finally, “there has never been an adaptation of the avian influenza virus to the human species with human-to-human transmission. This disease was not classified as a zoonosis before the “avian flu” crisis caused by the H5N1 type HPAI virus of Asian origin discovered in Asia in 1996″.

What are the symptoms of bird flu?

→ In animals: After a generally very short incubation (from 24 hours to a few days), animals infected with HPAI show variable clinical signs depending on the viral strains and the species concerned. As indicated by the CAM “clinical signs in chickens and turkeys include severe respiratory distress with excessively moist eyes and sinusescyanosis of the wattles, comb and hocks, a edema of the head and eyelids, of the ruffled feathers, diarrhea and signs of nervousness”. Eggs laid after the onset of the disease are frequently without shells. The disease in turkeys is similar to that of chickensbut is often complicated by bacterial infections secondary such as those due to avian cholera (Pateurella multocida), turkey coryza (Hemophilus gallinarum), or colibacillosis (Escherichia coli)

→ In humans: In the rare cases of avian plague transmitted to humans, the disease was most often mild. Cases are asymptomatic or may report fever, fatigue, body aches, sore throat. The appearance of these symptoms in a person who has stayed in a risk area or who has been in contact with contaminated birds must be treated urgently. In more serious cases, fowl plague can be complicated by pneumonia with high mortality.

“There is no risk for humans to eat poultry or eggs.”

Avian plague virus spread by contact with infected birds or surfaces and objects contaminated with their droppings. To protect yourself and above all avoid contaminating other birds, you must wash your hands regularly, wear a mask and waterproof gloves (when handling dead animals or animal waste). If you travel to (or live in) an area with avian flu, many biosecurity measures are recommended:

• avoid high risk areas. The legislation prohibits any transport of birds in this case and imposes strict biosecurity measures in poultry farms: footbaths, autoluves)
• avoid direct contact with birds, especially hens, chickens, ducks and wild birds; people with “pet hens” must confine them to avoid any contact with wild birds under penalty of a fine;
• avoid surfaces contaminated with bird droppings or secretions;
• observe the rules of hand hygiene and food hygiene.

In addition, France has put in place a government plan to fight against avian flu with different steps to follow depending on the progress of a possible epidemic.

Is it safe to eat chicken and eggs?

“Yes, assures Jeanne Brugère-Picoux. There is no risk for humans to eat poultry or eggs, even a boiled or raw egg because the avian influenza virus is not dangerous for humans. Moreover, in the event of avian plague, the animals die quickly and the birds that may have been contaminated and their products are not marketed.

What are the treatments for bird flu? A vaccine ?

“We do not treat this disease in humans in France as in Europe elsewhere”, answers our interlocutor. No bird flu vaccine is authorized by the European Commission.

Thanks to Professor Jeanne Brugère-Picoux, veterinarian and member of the National Academy of Medicine.

Sources:

• Bird flu and the virus that causes it. Fao.org

• Avian influenza. Handles. 2017

• Avian plague, a disaster for farms, an exceptional risk for humans. Press release from the Academy of Medicine. December 22, 2021.

• Avian Flu, Ministry of Agriculture and Fisheries, General Directorate of Forestry and Rural Affairs, General Directorate of Food, July 2006.

• Avian flu, Institut Pasteur.

• Avian influenza, avian flu and the threat of a pandemic: a new issue in occupational health. INRS.2006.