As US swine flu cases double, some travel to Mexico discouraged

Apr 27, 2009 (CIDRAP News) – The US Centers for Disease Control and Prevention (CDC) today confirmed 20 more swine influenza cases, all connected to previous cases at a New York City high school, and said federal officials will issue new travel advice urging against nonessential travel to Mexico.

The additions raise the number of US cases to 40, said Richard Besser, MD, the CDC's acting director, at a press conference today. Besser added that the CDC is focusing less on the case numbers and more on what the case patterns reveals about transmission.

He said the new case total represents additional testing in people linked to Saint Francis Preparatory School in Queens, but not a pattern that suggests widespread transmission. "This virus is acting like a flu virus, spreading person to person," he said.

Only one of the 40 US case-patients, who range in age from 7 to 54, has been hospitalized, he said, adding that the CDC expects to see a broader range of illness severity as the swine flu outbreak progresses.

The New York City Department of Health and Mental Hygiene said in a statement today that it has identified 17 more probable cases linked to the Saint Francis school cluster and that confirmation tests are under way at the CDC. The department said the city's syndromic surveillance system noted a moderate increase in flulike illness indicators over the weekend, but it's not clear how significant the rise was.

President Barack Obama, during a speech on new federal research investments before the National Academy of Sciences (NAS) in Washington, D.C., today, said the swine flu outbreaks are concerning, but are not a cause for alarm.

"Our capacity to deal with a public health challenge of this sort rests heavily on the work of our scientific and medical community. This is one more example why we can't allow our nation to fall behind," he said.

Travel advisory
Besser said the new travel advisory urging people to avoid nonessential trips to Mexico will be issued out of an abundance of caution, and that the federal government will also pair that message with safety steps they can take if they need to travel to the area.

The new travel advice came on the same day European Union (EU) health commissioner Androulla Vassiliou issued a statement warning Europeans to avoid nonessential travel to areas where swine flu clusters have been detected. The World Health Organization (WHO) said in a statement today that it advises no restrictions on travel or border closures.

Besser said that the EU commissioner's travel advice is premature, based on the current evidence.

Call for preparations, vaccine development
Eleven million antiviral courses, 25% of the nation's Strategic National Stockpile, have been sent to affected states and other states around the country, he said. However, Besser emphasized the importance of the roles of each individual in limiting the spread of the disease and the disruptions a large swine flu epidemic could cause.

He advised parents to think now about what they'd do if their children's schools were closed to limit the spread of the disease. "This is a time for businesses to review their plans, such as 'What would I do if my workers couldn't come to work?,'" Besser said.

Federal officials are still in discussions on what approach to take with a potential vaccine against the novel influenza virus, though production of a seed strain is already progressing. He said it's difficult to balance the February recommendation for next year's northern hemisphere's seasonal flu vaccine with the possibility of adding another strain to the mix.

Tim Uyeki, MD, a medical epidemiologist in CDC's Influenza Division, said during a conference call for clinicians today that efforts are under way to make candidate vaccines through different production techniques, including classic reassortment, reverse genetics, and live attenuated.

Further cases
Late this afternoon, more states announced additional swine flu cases. The California Department of Public Health (CDPH) said a patient from Sacramento County has been diagnosed as having a swine flu infection, raising the state's total to eight cases.

Texas officials also announced an additional case-patient from Guadalupe County, a student who attended the same school as the state's two previously announced cases. In addition, Dallas County Health and Human Services announced three new cases in that county.

Once the CDC adds the new cases to its total, the number of US cases will rise to 45.

New CDC guidance
In other developments, the CDC today released interim guidance for facemask and respirator use in communities in which the swine flu virus has been detected. Emphasizing that the evidence on the effectiveness of facemasks and respirators for controlling influenza in communities is extremely limited, the CDC urges local officials to reduce the risk of transmission through a combination of actions—such as limiting contact and time spent with ill people—and not to rely just on facemasks or respirators.

The CDC also released two other sets of recommendations for clinicians and public health officials managing swine flu outbreaks, one on antiviral medications and the other on community mitigation.

See also:

Apr 27 New York City health department press release

Apr 27 EU press release

Apr 27 NAS news release

Apr 27 WHO statement

CDC swine flu page

CDPH news page

Texas Department of State Health Services news update page

CDC interim recommendations for facemask and respirator use in swine flu areas

CDC antiviral recommendations for swine flu

CDC community mitigation recommendations for swine flu

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