Swine Flu 4.6: The Undiscovered Country

Well, this is a new experience for us: a major, rapidly progressing epidemic that is being tracked in real time with the most modern tools.  It is, still excellent training for all involved for the event of a really dangerous epidemic (which this is NOT.)
Still seeing lots of sick children; 10 tested positive for Flu A on Thursday, 21 positive for Flu A yesterday (Friday); at least one of the positives was negative 2 days previously, on the first day of fever, underscoring the importance of not running to the doctor immediately as soon as symptoms start.  The CDC surveillance says swine flu now accounts for 73% of all flu tested.  The newest incidence and mortality curves continue to confirm my suspicions: there’s lots and lots of swine flu around, and it is no more dangerous than regular flu, and most probably less dangerous:

(from cdc.gov/flu/weekly)

The increase in the percentage of specimens testing positive for influenza by WHO and NREVSS collaborating laboratories may be due in part to changes in testing practices by healthcare providers, triaging of specimens by public health laboratories, an increase in the number of specimens collected from outbreaks, and other factors.

INFLUENZA Virus Isolated
View WHO-NREVSS Regional Bar Charts| View Chart Data | View Full Screen

Antigenic Characterization:

CDC has antigenically characterized 1,368 seasonal human influenza viruses [827 influenza A (H1), 140 influenza A (H3) and 401 influenza B viruses] collected by U.S. laboratories since October 1, 2008.

All 827 influenza seasonal A (H1) viruses are related to the influenza A (H1N1) component of the 2008-09 influenza vaccine (A/Brisbane/59/2007). All 140 influenza A (H3N2) viruses are related to the A (H3N2) vaccine component (A/Brisbane/10/2007).

Influenza B viruses currently circulating can be divided into two distinct lineages represented by the B/Yamagata/16/88 and B/Victoria/02/87 viruses. Fifty-eight influenza B viruses tested belong to the B/Yamagata lineage and are related to the vaccine strain (B/Florida/04/2006). The remaining 343 viruses belong to the B/Victoria lineage and are not related to the vaccine strain.

Two influenza-associated pediatric deaths were reported to CDC during week 19 (Arizona); one was due to influenza A virus (rapid test positive) and one was due to influenza B virus infection. The deaths reported this week occurred between April 12 and April 25, 2009. Since September 28, 2008, CDC has received 61 reports of influenza-associated pediatric deaths that occurred during the current season.

Of the 31 children who had specimens collected for bacterial culture from normally sterile sites, 13 (41.9%) were positive; Staphylococcus aureus was identified in eight (61.5%) of the 13 children. Three of the S. aureus isolates were sensitive to methicillin and five were methicillin resistant. Twelve of the 13 children with bacterial coinfections were five years of age or older and 10 (76.9%) of the 13 children were 12 years of age or older. An increase in the number of influenza-associated pediatric deaths with bacterial coinfections was first recognized during the 2006-07 influenza season. In January 2008, interim testing and reporting recommendations were released regarding influenza and bacterial coinfections in children and are available at (http://www2a.cdc.gov/HAN/ArchiveSys/ViewMsgV.asp?AlertNum=00268).

Influenza-Associated Pediatric Mortality
(end quote from cdc.gov)

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