The new swine flu virus infecting humans is very unusual. It's somehow acquired genes from swine, bird, and human flu bugs. And it's also got genes from Eurasian swine flu viruses that aren't supposed to be in North America..
Do Humans Get Swine Flu?
Normally, swine flu bugs don't infect people. Historically, there's a case every year or two in the U.S. among people who have contact with live pigs.
But from December 2005 to January 2009 there was an uptick in swine flu cases. There were 12 human swine flu infections during this time. Eleven of these people had direct or indirect contact with pigs; in the twelfth case it was not known whether there was pig contact.
It's possible this uptick was due to improved reporting systems, but the CDC says "genetic changes in swine flu viruses and other factors might also be a factor."
The new swine flu virus is different. It's not yet clear that it's here to stay. But it is infecting humans, and that has world health officials keeping a close eye on it.
What Are the Symptoms of Swine Flu?
Swine flu symptoms are similar to regular flu symptoms and include cough, sore throat, fever, chills, headache, and fatigue. Some patients have also reported nausea and diarrhea. There is no easy way to distinguish swine flu from other types of flu or other germs. It takes a lab test to tell whether it's swine flu.
Can Swine Flu Spread From Person to Person?
The U.S. residents infected with swine flu virus had no direct contact with pigs. The CDC says it's likely that the infections represent widely separated cycles of human-to-human infections.
Have There Been Previous Swine Flu Outbreaks?
If swine flu sounds familiar to you, it's probably because you remember or have read about the 1976 swine flu outbreak at Fort Dix, N.J., among military recruits. It lasted about a month and then went away as mysteriously as it appeared. As many as 240 people were infected; one died.
The swine flu that spread at Fort Dix was the H1N1 strain. That's the same flu strain that caused the disastrous flu pandemic of 1918-1919, resulting in tens of millions of deaths.
Concern that a new H1N1 pandemic might return with winter led to a crash program to create a vaccine and vaccinate all Americans against swine flu. That vaccine program ran into all kinds of problems -- not the least of which was public perception that the vaccine caused excessive rates of dangerous reactions. After more than 40 million people were vaccinated, the effort was abandoned.
As it turned out, there was no swine flu epidemic.
I Got a Flu Shot. Am I Protected Against Swine Flu?
No. There is currently no swine flu vaccine.
It's possible that the seasonal flu vaccine might provide partial protection against H3N2 swine flu bugs. But the strain that appeared in California is the H1N1 swine flu strain. It is very different from the H1N1 human flu strain included in the seasonal flu vaccine.
It's not known whether previous infection with human type A H1N1 flu might provide partial protection against the type A H1N1 swine flu in the current outbreak.
However, the CDC has made a "vaccine seed" from swine flu isolated from an infected person, and has begun the process of developing a vaccine should the need arise. Whether a vaccine could be produced in quantity by next flu season is a huge question.
How Serious Is the Public Health Threat of a Swine Flu Epidemic?
Any flu epidemic is worrisome, especially when a new strain of flu bug is involved.
"Influenza A viruses new to the human population that are able to efficiently transmit from person to person and cause illness may represent a pandemic threat," the CDC warns.
It's worrisome that, unlike seasonal flu, the swine flu outbreak in Mexico is attacking healthy young people. That's a hallmark of pandemic flu bugs..
But it takes more than a new virus spreading among humans to make a pandemic. The virus has to be able to spread efficiently from one person to another, and transmission has to be sustained over time. In addition, the virus has to spread geographically.
Is There a Treatment for Swine Flu?
Yes. While the swine flu bug is resistant to older flu medicines, it remains sensitive to Tamiflu and to Relenza.
Can You Get Swine Flu by Eating Pork?
No. You can only catch swine flu from being around an infected pig - or, if it's the new swine flu virus, from an infected person