Is There A New Outbreak Of Avian Flu?

On March 31, 2013, the Centre for Health Protection (CHP) of the Department of Health of China announced that three people in two widely separated locations in China had been infected with H7N9, a relatively new strain of avian, or "bird," flu. Two people infected with the virus in Shanghai, and 27-year-old man and an 87-year-old man, died of the infection.

Do these three cases of a previously unreported strain of the flu presage a pandemic spreading around the world? Or are these deaths likely to be among the last caused by the virus? We'll get to those questions in a moment, but first it helps to clarify some of the terminology of the disease.

What Is "Bird" Flu?

Bird flu, or avian flu, as its name suggests, is an influenza virus that occurs in birds. There are also strains of the virus denoted swine flu, horse flu, dog flu, and human flu. Not all flu viruses make the jump from their animal hosts to people, although in at least three cases, H7N9 has.

Bird flu is an "influenza type A" virus. All strains of influenza type A are found in birds, although the "A" doesn't refer to "avian." The important difference between influezavirus A, influenzavirus B, and influenzavirus C is the speed at which viruses mutate so that the immune system cannot build a permanent defense against them. Type A flu viruses mutate faster than type B flu viruses, and type B flu viruses mutate faster than type C flu viruses. 

Why Is Bird Flu So Often in the News?

The reason avian, or bird, flu gets so much attention from doctors, public health officials, and the media is that it is always changing. From year to year, the flu virus changes enough that last year's flu shot or last year's case of flu fails to protect against the newly emerging strain. Just as vaccine manufacturers have to guess what to put in their flu shots, the immune system can only muster very generalized defenses against the infection. And bird flu is particularly hard to vaccinate against.

What Do the "H" and "N" in H7N9 Stand For?

Both "H" and "N" in the name of a flu virus identify the antigen activated by the virus. An antigen is an "antibody generator," a substance that activates the immune system to respond to a disease. There are 17 different H antigens and 9 different N antigens known to science, but not all combinations have actually appeared outside the laboratory. These are the first known cases of H7N9 in people.

Is Bird Flu Really Spread by Birds?

Of course, avian influenzaviruses are spread from place to place by migrating birds. Because the virus that killed millions during the Great Flu Epidemic of 1918 was an avian flu virus, many people are especially wary of the emergence of any new kind of bird flu. The better adapted a virus is to living in birds, that is multiplying in birds but not killing them before they have a chance to fly to another location, the deadlier it typically is in humans.

Do You Need To Worry About H7N9?

The reason public health officials are alarmed by the appearance H7N9 infections in people in China is that the virus is already known to be relatively harmless in birds. Scientists at the Centre de Recerca en Sanitat Animal (CReSA) in Barcelona (Spain) identified this strain of the flu virus in red-legged partridges in Spain in 2010. Since there haven't been any widespread bird kills in Europe over the past three years, it is especially alarming that the virus has spread at least from Spain to China and mutated to a form that can spread from birds to people.

Partridges spread the virus through their nasal secretions. The virus is known to spread from partridges to chickens, turkeys, and quail. Farmers, butchers, cooks, and diners could then catch the virus from handling or eating undercooked chicken, turkey, or quail. 

Like most flu viruses, this strain is only readily transmissible at cool temperatures, at the beginning of winter and again at the end of winter. The virus disappears when the air is too cold or too hot. Wild birds that catch the virus, carry it with them to cool climates, spread it among their flocks at their cool-weather nesting sites, and reinfect domestic birds again and again with the changes of the seasons.

Here are five frequently asked questions about the new bird flu:

1. If I travel to China, do I need to worry about catching H7N9?

Unless you spend time on a poultry farm in eastern China, or you are one of a very few visitors who goes bird hunting to shoot and collect migrating quail or partridges, or you pluck your own chickens for dinner, it is highly unlikely you will encounter the virus. It's currently spread from birds to people, but not from people to people.

2. Do I need to have a flu shot to protect myself against H7N9?

No. At this time, and probably for several years, there is no vaccination against this particular strain of the flu.

3. Is there anything I can do to prevent infection with H7N9?

Yes! It's always beneficial to wash your hands before you eat and before you touch your face.  If you tend to touch your face frequently without thinking about it, then it's a good idea to wear a face mask.

There are not, as far as scientists know, any H7N9 particles floating in the air, even where the infection is found in China and Europe. What wearing a face mask does is to keep you from transferring mucus secretions from public surfaces to your face. This also protects you against many other kinds of infections, of course.

Since elderberry extracts tend to prevent influenza type A in general, it might be helpful to take this over-the-counter herb prophylactically--or it might not. We simply don't know.

4. Has H7N9 reached North and South America?

All the human cases of H7N9 have occurred in China, but migratory ducks infected with this strain of teh virus have been found in Guatemala since 2007. The blue-winged teal is the only species known to carry this strain of influenza in the Americas.

5. Is there anything else I need to know to protect myself against avian influenza?

It's a little gross, and maybe it's also obvious, but don't handle, walk through, or stand on bird poop. While H7N9 has not yet been detected in bird feces, other influenza type A viruses have. It's especially important not to come in contact with duck droppings, or if you have, to wash affected skin thoroughly with warm (not hot) soap and water. Hot water tends to crack the skin, actually letting more viruses through.