Bird Flu in the News Again: Is a Springtime Epidemic Possible?

A new strain of bird flu that first appeared in early 2013 in China is not going away. Instead, it has developed an ability to resist the effects of the world's most commonly used flu medication, Tamiflu.

The H7N9 version of the influenza A virus seems to have originated in wild birds that passed it to ducks, which gave the virus to chickens, which in turn transmitted it to humans who handled chicken feces or "guts" when killing and preparing live chickens bought in urban poultry markets in southeastern China.

Deadly to Humans But Not to Birds

H7N9 is deadly for humans. During the first month after the first wave of infection, about 20% of people who get this strain of influenza die, about 20% recover, and the remaining 60% stay extremely sick with pneumonia. By July of 2013, the death rate had greatly increased, with 33% of new victims dying in the first month after infection. And in August, the first human-to-human transmission of the virus was recorded, from an infected father to his caretaker father.

Harbinger of Epidemics to Come?

Even more alarmingly, government officials in China have found that a closely related virus, H7N7, has been circulating among ducks since 2010. As yet, this second virus has not mutated in ways that allow it to infect humans. Chinese researchers, however, have devised a test to see if it could.

The Chinese scientific team tested the virus as cause of flu in ferrets, which show symptoms from influenza virus infection similar to those that appear in humans. When the scientists gave the virus to ferrets, the furry animals developed sniffles, sneezing, coughing, and fever, suggesting that when this second virus develops the ability to infect humans, it also will cause serious symptoms.

Resistant to Tamiflu

Even worse, the H7N9 virus has mutated over the last year so that its effects can no longer be stopped by taking the antiviral drug oseltamivir, marketed as Tamiflu. With most strains of influenza, taking Tamiful can stop symptoms in their tracks, as long as the medication is taken during the first 48 hours after symptoms start.

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Now doctors who do not have access to testing for the strain of the virus will have to offer their patients Relenza or herbal medicines, such as Sambucol (elderberry extract) or Chinese herbal medicines (many of which contain the largely-banned herb ephedra or the safe and legal herb kudzu root). 

Chinese officials announced the development of a vaccine for the H7N9 strain in October of 2013, but it has not been mass produced. There has been discussion about closing down live poultry markets, but the Chinese government has limited itself to issuing warnings about the potential for infection and urging citizens to use herbal medicine.

Frequently Asked Questions About H7N9 Influenza

1. What is H7N9 influenza virus?

The "H" and "N" designations of the influenza virus refer to the genes that code the proteins on the outside of the virus that determine how the virus infects birds, people, and other mammals. The H in the virus name refers to its hemagluttinin gene, which provides the virus to attach to cells in its host. The N in a flu virus name refers to the neuraminidase gene, which codes the protein that allows the progeny of the virus to escape the host cell and infect other cells in its host's body.  

The H7 influenza viruses are a group of infections that ordinarily become an epidemic among birds. The H7N9 virus first spread primarily from ducks but also from pigeons and chickens to people in early 2013, and through mutations that occurred between April and August of 2013 it has acquired the ability to spread from human to human, although it is not yet highly contagious.

2. What kinds of symptoms does H7N9 cause?

This particular H7 virus tends to cause pneumonia in people. In some cases, it just causes shortness of breath, cough, and fever.

3. Why are public health officials concerned about H7N9?

In addition to causing severe symptoms, the H7N9 virus is resistant to the most commonly used medication for relieving the symtoms of flu, Tamiful (oseltamivir). However, it can be treated with Relenza (zanamivir).

4. How many people have come down with this strain of flu?

The National Health and Family Planning Commission of China typically reports 2 to 4 new cases a day, victims of this strain of flu almost always placed in critical care units in hospitals. As this article is being written the number of cases worldwide is only in the hundreds. The World Health Organization updates information about the spread of H7N9 daily. We have posted a link to the Wolrd Health Organization website below.

5. Who is most at risk for infection from this virus?

Typically chickens raised for human consumption catch the virus from ducks, and ducks catch the virus from migrating birds. It is primarily poultry raised in or near Hong Kong that has been infected with the virus. Cooked chicken does not transmit the virus, but killing, gutting, plucking, or cooking a bird infected with this strain of flu can transmit the disease.

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6. Should I cancel my trip to China because of this virus?

No, but you should not plan on taking a job as a chicken plucker. It may also be prudent to avoid visiting live poultry markets and eating undercooked or raw chicken.

7. If someone I know comes down with this form of flu, should I be worried.

No. At least as of January, 2014, the virus has not been shown to spread from person to person in families, despite contact with saliva and mucus from household members.