What To Know About Bird Flu, Including the H10N3 Strain

Bird flu, as it commonly known, is usually referred to as avian influenza in the medical community. Like other types of influenza, bird flu is caused by a virus. While most types of bird flu viruses don't affect people, sometimes the virus mutates and causes illness in people.

This is what happened in the spring of 2021 when China's National Health Commission (NHC) announced that a 41-year-old man in the city of Zhenjiang, in the Jiangsu province, was infected with the H10N3 strain of bird flu. It was the first—and only—reported case of human infection with H10N3 as of December 2022.

With public health anxiety at an all-time high due to the COVID-19 pandemic, it's understandable that news of another new virus detected in a human was alarming. But luckily, this virus did not turn out to be a widespread threat.

Here's what you need to know about H10N3 and other bird flu viruses, including what your chances of getting infected with a bird flu virus are.

What Is H10N3?

H10N3 is a form of avian influenza. These viruses normally infect wild aquatic birds, as well as domestic poultry and other bird and animal species. Normally they don't infect humans. Uncommon cases of other strains of avian influenza have been reported.

In those uncommon cases, saliva, mucus, or feces from infected birds get into a person's eyes, nose, or mouth. These infections have occurred after unprotected contact with infected birds or surfaces contaminated with avian influenza viruses.

Since there were no other cases of H10N3 among people in close contact with the patient in Zhenjiang, it's unknown if H10N3 can be spread via human-to-human transmission. But the fact that the individuals who had been in contact with the patient didn't show signs of having been infected with the strain was considered good news.

Apparently, H10N3 wasn't able to spread to other people. And because it affected only one person, H10N3 didn't became a public health threat.

Other Avian Influenza Virus Infections

Currently, there are a few avian influenza strains known to infect humans: H5, H6, H7, H9, and H10. The ones most likely to cause disease in humans are H5 (including H5N1) and H7 (including H7N7 and H7N9).

As was mentioned above, these infections are rare in the general population. Bird flu viruses usually are transmitted from bird to bird. Bird flu can infect chickens, turkeys, ducks, and other birds. When people get infected with a bird flu virus, it's usually people who have been in close contact with the birds.

More often than not, that's where the virus stops too. Its rare for the bird flu virus to spread from one infected person to another. But rare mutations that cause an outbreak among people do happen, as was seen with one strain of H5N1.

Asian H5N1 was first detected in 1996 in geese in Southern China and then in humans in Hong Kong the next year. The virus later spread from Asia to more than 50 countries in Africa, Asia, Europe, and the Middle East. But there have not been any reports of this virus in the United States to date, not in birds and not in people.

A similar outbreak occurred with the H7N9 strain. The first human infections of this strain were reported to the WHO in March 2013. People who were infected had been in contact with "animals or with an animal environment." According to an update from the WHO posted in September of 2018, among 1,567 laboratory-confirmed cases of the strain, there were 615 deaths.

Here is something worth repeating, however: "Asian H5N1 and Asian H7N9 viruses have not been detected in people or birds in the United States." What's important here is the word "Asian." That's because the Asian viruses are different from the North American version of the same virus. Asian H5N1 and Asian H7N9 have been known to cause serious illness and death. North American H5N1 and North American H7N9 have not.

Symptoms of Bird Flu

Generally speaking, the symptoms are usually the same as what you would expect from the normal flu:

• Fever
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle or body aches
• Fatigue (tiredness)
• Headaches
• Eye redness (conjunctivitis)
• Difficulty breathing
  

Avian influenza viruses, however, cannot be diagnosed by signs and symptoms alone—laboratory testing is needed, usually through swabs collected from the upper respiratory tract of an infected person.

As for treatment of avian influenza viruses, the CDC recommends what's known as a neuraminidase inhibitor. This type of antiviral drug can block reproduction of the virus. Examples include oseltamivir, peramivir, and zanamivir. And the best way to avoid avian influenza viruses is to avoid exposure, which includes direct or close contact with infected poultry.

A Quick Review

In most cases, getting infected with the bird flu virus isn't something to worry about. It's rare for this virus to spread from human to human.

The bird flu virus usually spreads from bird to bird. In the rare cases where it spreads from bird to human, people who work with poultry are most likely to get infected. And again, it's rare for the virus to spread from one infected person to someone else.

When outbreaks do happen, they usually don't last long. Symptoms are similar to what you would see with the flu. Severe symptoms require medical attention.