Avian influenza

There are four types of influenza viruses: A, B, C, and D. Three of them can cause disease in humans: A (causing pandemics and seasonal epidemics), B (causing seasonal epidemics), and C (resulting in minor illness). Influenza A viruses can infect various animals and are named after the relevant host, such as avian (bird), swine (pig), equine (horse), or dog influenza viruses.

Influenza A viruses are classified into subtypes based on their surface antigens: H (hemagglutinin) and N (neuraminidase). For example, the 2009 swine flu was an influenza A(H1N1) virus, with type 1 hemagglutinin and type 1 neuraminidase.

Influenza A viruses are prone to mutation and reassortment, especially when different viruses infect the same individual simultaneously. This poses a risk for the emergence of new influenza virus subtypes, particularly if a bird flu virus infects someone already infected with a human flu virus. The same threat exists when multiple influenza viruses infect mammals like minks or pigs. This ability of influenza A to reassort and develop new subtypes, to which people have little immunity, can lead to pandemics, as seen with the Spanish flu in 1918 and the swine flu in 2009.

Ducks are natural hosts of influenza A, and birds are presumed to be the origin of most influenza virus types. Avian influenza is usually mild in wild birds but can be severe in poultry and affect various mammals, including minks, foxes, pigs, seals, whales, dogs, and cats.

Avian influenza A viruses are classified as either mild or severe (low or highly pathogenic avian influenza; LPAI or HPAI) based on their impact on birds. This classification does not apply to the severity of disease in people. So far, only subtypes H5 and H7 have caused severe avian influenza. Severe avian influenza causes significant damage to wild bird populations, can spread widely with migratory birds, and devastates poultry farms when outbreaks occur.

Global outbreaks of avian influenza A have occurred repeatedly. Some influenza types have spread significantly among bird populations and have even caused local cluster infections in humans. However, these types have not adapted to transmit between humans and cause epidemics.

Since 2021, an outbreak of avian influenza A of the H5N1 type has spread significantly in Europe and globally. Millions of birds, primarily wild waterfowl, seabirds, and poultry, have been infected in Europe. Infections have also been detected in mammals, primarily wild predators in close contact with wild birds and on fur farms. In Iceland, an H5N1 strain was first detected in wild birds in April 2022 and in domestic chickens at one location.

The H5N1 type has infrequently been detected in people, and the risk of infection to the European public from the current H5N1 strain is considered low. No cases of H5N1 infections in humans have been confirmed in EU/EEA countries. Serious illness and even deaths have occurred in people in other parts of the world, especially in Asia and South America, but most of the individuals seem to have been in prolonged or close contact with sick birds, often associated with keeping birds at home.

Bird droppings are the primary transmission route among birds, as infected birds excrete large amounts of the virus in their feces. Airborne transmission is also possible through coughing and sneezing.

Human cases of severe avian influenza have resulted from close contact with infected poultry or their body fluids, contaminated surfaces, or environments where infected birds dwell. Dust from feathers or the environment of sick birds, which becomes airborne during activities like flapping wings, skinning, high-pressure washing, or sweeping, can increase the likelihood of transmission to people.

There is an increased risk of infection from infected birds to people during the following activities:

• Close contact with poultry, products, and waste, such as working on poultry farms.

• Handling bird carcasses, especially during skinning.

• Disposing of poultry and destroying carcasses and waste.

• Cleaning and disinfecting contaminated areas.

• Sampling from birds and contaminated environments.

• Conducting veterinary examinations.

• Analyzing the virus in a laboratory.

There is no risk of infection from well-cooked eggs or meat, as the virus is killed by heat (three hours at 56°C, 30 minutes at 60°C, and one minute at 70°C). Standard washing eliminates the virus on clothing.

Symptoms prompting testing for bird flu include fever, red eyes, cough, cold, muscle or bone pain, diarrhea, pneumonia, breathing difficulties, and neurological symptoms such as headache, seizures, and altered consciousness. Remaining vigilant and adhering to preventive measures is vital for effectively managing avian influenza risks.

Basic infection prevention

Fundamental precautions must be exercised in all work involving contact with animals, regardless of whether a communicable disease is suspected. Pollution here refers to the body fluids of animals or people.

• Employer Responsibilities: Employers must ensure that staff receive the necessary instruction and training to perform their duties safely (Article 14 of Law No. 46/1980).

• Education: Those who may come into contact with infected birds, their products, waste, or environmental pollution must be educated about the symptoms and transmission of bird flu and how to prevent infection.

• Hand Hygiene: Special emphasis is placed on careful hand hygiene (hand washing and hand sanitizer) after contact with birds (infected or uninfected), contaminated areas, and after using gloves. Proper hand washing involves washing all areas of both hands with soap and water for 30 seconds, followed by the use of disposable wipes. If there is no visible dirt on the hands, an approved disinfectant, such as hand sanitizer (70% - 85% ethanol), can be used.

• Icelandic Food and Veterinary Authority (MAST)

• European Food Safety Authority (EFSA)

• Italian Institute for Animal Health, Food Safety and Zoonosis (IZSVe)

• World Organisation for Animal Health (WOAH)

• European Commission - Avian influenza