Avian influenza H3N8: how dangerous it is and how to detect it in the face of recent cases in other countries

China was once again the center of attention for a new case of contagion of a virus other than COVID-19. During the past week, the country generated an alert around the world due to the detection of the first case of avian influenza of the H3N8 strain in a human.

The infected was a 4-year-old boy who lived with chickens in his home in the city of Zhumadian, Henan province. The boy developed a fever and other symptoms for several days and was admitted to a local medical center on April 10, according to the National Health Commission from China.

The Center for Disease Control and Prevention (CDC) of the Asian country carried out tests and confirmed that the infection was of the variant H3N8; thus being the first case of direct contagion between a bird and a human.

This variant of the flu has been linked to dogs, horses, seals and chickens, so it is strange that only the boy was infected and his family was not.

To understand this, we must take into account that there are four types of seasonal flu viruses that are called influenza A viruses, influenza B viruses, influenza C viruses and influenza D viruses.

All known influenza pandemics have been caused by influenza A type influenza viruses.

According to the CDC, influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N). There are 18 hemagglutinin subtypes and 11 different neuraminidase subtypes (H1 to H18 and N1 to N11, respectively).

That implies that there are potentially dozens of influenza A subtype combinations, with H3N8 being one of them.

Infected birds carry the avian influenza virus in their saliva, mucus, and feces. Human infections with avian influenza viruses can occur when the virus enters a person’s eyes, nose, or mouth, or is inhaled by a person.

Spread of avian influenza viruses from an infected person to a close contact is very rare, and when it did occur, it only spread to a few people.

Signs and symptoms of avian influenza virus infections in humans have ranged from asymptomatic cases to mild cases, such as red eyes (conjunctivitis) or mild upper respiratory symptoms similar to influenza.

However, in severe cases symptoms such as:

• Pneumonia, requiring hospitalization.
• fever (temperature of 100ºF [37.8 ºC] or more) or feeling feverish.
• Cough, sore throat, runny or runny nose, muscle or body aches.
• Headaches, fatigue, and shortness of breath or difficulty breathing.
• Less common signs and symptoms include diarrhea, nausea, vomiting, or seizures.

The CDC notes that avian influenza virus infection in people cannot be diagnosed by considering clinical signs and symptoms in isolation; but it is necessary to carry out laboratory tests.

Avian influenza virus infection is usually diagnosed by taking a nasal swab from the upper respiratory tract (nose or throat) of the sick person (a process similar to screening for COVID-19).

Tests are most accurate when samples are taken during the first few days of illness.

Human infections with avian influenza A viruses are rare, says the CDC. However, there have been sporadic cases in many countries, usually of unprotected exposures (such as not wearing eye or respiratory protection) to infected poultry or environments contaminated with the virus, which have caused mild to severe illness with a wide range of illnesses. range of symptoms and complications.

The CDC believe that the health risk to the general public posed by current H5N1 and avian influenza viruses is low, but that some people may be at increased risk of infection due to their increased exposure to birds in connection with their work or Recreational activities.

The situation of avian influenza virus H5N1 it is primarily an animal health problem, they say.