Today we received the official notification that five weeks ago a case of influenza in South Dakota was of the swine flu variety. Unfortunately, there is no definitive determination on how or where the young man became infected with a virus that usually confines itself to pigs, crossing to humans only on very rare occasions.
From the Sioux City Journal:
PIERRE, S.D. (AP) – The state Health Department says South Dakota has reported a human case of swine flu.
A 19-year-old South Dakota State University student was ill with the disease five weeks ago.
The state Public Health Laboratory identified a portion of the virus. This week, the Centers for Disease Control and Prevention influenza lab identified the swine components of the virus.
State Epidemiologist Dr. Lon Kightlinger says swine flu in humans is rare but does occur.
The Centers for Disease Control and Prevention receives about one report of the swine flu virus in a human each year. The South Dakota case is believed to be the state’s first case.
Lisa Schnirring at CIDRAP gives us a bit more detail about humans and swine flu…
[snip]
Lon Kightlinger, PhD, epidemiologist for the SDDH, said in the statement that swine influenza in humans is rare. “Most often the cases occur in people with direct exposure to pigs, such as swine farm workers,” he said. “Human-to-human transmission is very rare.”
Kightlinger told CIDRAP News that an investigation into the source of the man’s illness did not reveal direct contact with pigs; however, officials are exploring whether he had indirect contact.
Human infections with novel influenza A subtypes now are nationally notifiable diseases in the United States.
In a recent report in the September issue of Emerging Infectious Diseases on a 2005 Wisconsin case, the authors wrote that triple reassortant H1N1 subtypes are the predominant genotype in North American pigs and that human swine flu illnesses often mimic seasonal flu infections. They recommended that clinicians ask patients with unexplained influenza-like illnesses about exposure to animals, including pigs, and visits to petting zoos and county fairs.
The CDC had noted that swine flu outbreaks in pigs typically occur in late fall and winter and that seasonal influenza vaccines are likely to partially protect against swine H3N2 viruses, but not the H1N1 subtype.
Animal diseases have probably infected humans on occasion for as long as humans have been around. Our understanding that sometimes our animals make us sick with their diseases is a fairly new understanding, historically speaking.
Swine Flu no longer engenders the fear it inspired in 1976, and to be sure, we know a lot more about influenza now than we did in 1976. We will never know with certainty whether or not the 1976 Swine Flu incident was a false alarm or whether the actions taken by the Ford administration prevented a wider outbreak, an epidemic, or even a pandemic. We will never know, though there are strong opinions to support both beliefs, opinions supported by sound logic.
Should we be concerned about human infections of Swine flu? Probably not overly so. Should we pay attention to what animal diseases that can infect humans “are up to”? Probably.
It is in the spirit of paying attention that we take note of these human infections. And, perhaps, if we are lucky, our influenza knowledge base may even expand a bit more, maybe even in some crucial and fundamental way.
SZ
