Tired of hearing about swine flu? The other flu, avian, can be much worse

The threat of swine H1N1 flu is expected to increase as we move into flu season later this year, but swine flu while readily transmitted, doesn't make most people too sick.

The opposite appears to be true with another virus: avian H5N1, which isn't transmitted too readily to humans, but is fatal it 60 percent of the people who get it.

It's not yet in the United States, but has been identified in much of the rest of the world. And over time, it is adopting more and more hosts. If it changes to readily pass from human to human, it could be a far worse epidemic than swine.

Here are some basic facts, from the Centers for Disease Control. http://www.cdc.gov/flu/avian/outbreaks/current.htm.

Most people who get this avian flu get it from poultry—often ducks and geese, but also swans and chickens. It rarely is transmitted human to human in its current form.

Few humans have immunity to it.

“If H5N1 viruses gain the ability for efficient and sustained transmission among humans, an influenza pandemic could result, with potentially high rates of illness and death worldwide,” CDC says.

The strain is resistant to two of the four major antiviral drugs. There are no vaccines.

It has shown up in cats, dogs and zoo animals, suggesting it is gaining a wider range of hosts. “Avian influenza A (H5N1) virus strains that emerged in Asia in 2003 continue to evolve and may adapt so that other mammals may be susceptible to infection as well.”

One caution for travelers, particularly in Asia: Stay out of poultry markets.

This flu was first identified in geese in China's Guangdong Province in 1996. The first human cases appeared in Hong Kong the next year.

In 2003, zoo leopards and tigers in Thailand died after being fed chickens. The next year, a Thailand cat got it after eating a pigeon. The disease has since been identified in Vietnam, Korea, Japan, Cambodia. Malaysia, Laos.

It was found in Russia, Mongolia and Kazakhstan in migratory birds in 2005, and then began moving into Europe, often in migratory birds like ducks and swans.

Cases in humans remain fairly rare, but there are intriguing family clusters, in which multiple members of the same family get the disease. Are they getting it from each other? Is it because of a genetic predisposition to infectability? That's not yet clear.

As of August 31, 2009, the World Health Organization reported 440 cases globally, of which 262 were fatal. http://www.who.int/csr/disease/avian_influenza/country/cases_table_2009_08_31/en/index.html

Most of the deaths have been in Indonesia and Vietnam, but Egypt, Thailand and China are also hot spots.

© Jan TenBruggencate 2009