April 21, 2009 -- Two California children got sick with a mysterious new strain of swine flu -- and the CDC thinks they got the pig virus via person-to-person contact.
Both kids, a 10-year-old boy from San Diego County and a 9-year-old girl from Imperial County, are now well. However, the girl had a 104.3-degree fever before she recovered. And the boy traveled by airplane from San Diego to Dallas while he still had flu symptoms.
"While we have a low index of suspicion this is a pandemic, we are being careful to rule out any possibility," Finelli says. "We don't know yet."
"We have here detection of two cases of swine flu virus in children. We are trying to figure out where they came from and how serious they are," says Dan Jernigan, MD, MPH, deputy director of the CDC's influenza division.
The CDC has dozens of people tracing the children's contacts, beginning with close family members. Each of the children had two family members come down with the flu -- in both cases, one family member had the flu before the child had the flu, and one after.
All recovered, but flu virus was not obtained from any of these family members while they still had symptoms. Over the weekend, the CDC developed a specific test for the new swine flu virus; testing of the children's contacts is now under way. It's likely that the tests will reveal other people who recovered from the infection.
CDC has not activated its Atlanta-based command center. But California has, Finelli says, and is putting all available health care workers on the job of tracking down the children's contacts.
Both children attended school, and California authorities are planning to trace the children's school contacts.
So far, the CDC says, Texas health authorities have not found any new infections. The boy traveled to Texas with three other children unaccompanied by adults; crew members who assisted the children are now being tested.
The CDC is withholding the name of the airline that flew the boy and his three companions from San Diego to Dallas on April 3.
Swine flu viruses don't normally infect humans. When they do, it's almost always because of contact with an infected pig. But neither child had any direct contact with pigs.
Moreover, the viruses recovered from the children are not like the swine flu viruses common among pigs. That raises the specter of human-to-human spread of the virus, Finelli says.
"This virus is different, very different from that circulating in pigs. That was a red flag," Finelli told WebMD and several other news organizations. "The other red flag is both cases appeared almost simultaneously, 100 miles apart. When we see two cases [of swine flu] without animal contact that occur simultaneously and they have a different virus [than in pigs], we are concerned."
What worries the CDC is that the two cases might signal the beginning of a flu pandemic with a virus new to humans. But CDC spokesman Tom Skinner notes that it's the CDC's job to be worried. Several things about the cases are reassuring:
- Both cases were detected by routine flu surveillance.
- Southern California has unusually excellent flu surveillance -- and there has not been a large number of flu cases from unusual flu strains.
- The virus is the H1N1 strain of swine flu. There are human strains of H1N1, raising at least the possibility of cross-protection -- especially in adults.
Not reassuring is the finding that the new swine flu strain carries three genes from Eurasian swine flu bugs not known to be circulating in the U.S. The new strain apparently is a reassortant virus that assembled itself from the genes of at least two different swine flu viruses. It carries no human flu genes.
Swine flu last spurred headlines in 1976 when an outbreak of swine flu at Fort Dix, N.J., killed one healthy recruit, caused four cases of serious pneumonia, and spread to some 230 soldiers before it vanished.
It's still not clear where the 1976 virus came from or why it went away -- but it spurred widespread public alarm and a vaccination program that badly misfired before being terminated.
The CDC, the California Department of Public Health, and the health departments of Imperial and San Diego counties urge all of those counties' residents and visitors who develop flu-like symptoms to seek medical attention.
Doctors who see these patients are advised to send swab samples to state or local health authorities. They are also asked to get full interviews to ask about other family members or contacts who may be ill.
Here's the CDC's advice for all people who get flu-like symptoms, whether it's normal seasonal flu or swine flu:
- Stay home when you are sick to avoid spreading illness to co-workers and friends.
- Children with flu-like symptoms should stay home to avoid spreading illness to classmates and staff.
- Cough or sneeze into your elbow or a tissue and properly dispose of used tissues.
- Wash your hands thoroughly with soap and warm water or use an alcohol-based hand sanitizer to get rid of most germs, and avoid touching your eyes, nose, and mouth.
- Stay healthy by eating a balanced diet, drinking plenty of water, and getting adequate rest and exercise.
The CDC announced the swine flu cases in a special MMWR Dispatch published today.