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April 21, 2009 -- Two California children have come down with a mysterious new strain of swine flu virus -- even though they had no contact with pigs or each other.
What do we know about swine flu? WebMD answers your questions.
Like humans, pigs get the flu. Four different type A swine flu strains commonly circulate among pigs. Most recent swine flu viruses have belonged to the H1N1 and H3N2 subtypes. Pigs typically get sick but usually don't die from 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 two California children appear to have had no contact with pigs. That makes it more likely that they got swine flu from another, as yet unknown, source. Before they fell ill, both kids had family members who had flu-like illnesses. Unfortunately, no virus samples were obtained from these people. Fortunately, all of them got better -- including the two children with proven swine flu.
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 to 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.
No. There is 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.