Swine Flu Updates and Issues

[indigo girl]

http://www.washingtonpost.com/wp-dyn/content/article/2009/05/16/AR2009051601850.html?hpid=moreheadlines

The swine-origin influenza A (H1N1) virus that burst into public consciousness a month ago is starting to behave like a mixture of its infamous, pandemic-causing predecessors.

It seems to have a predilection for young adults, as did its notorious ancestor, the 1918 Spanish influenza. Many of the young victims who have become deathly ill turned out to have other medical problems -- a phenomenon first clearly seen with the 1957 Asian flu.

Pandemic flu strains -- and this new H1N1 strain is all but certain to cause the 21st century's first pandemic -- are unpredictable. Any contagious disease that most of the world's 6.8 billion people can catch is inherently dangerous.

"Our message to everybody is, of course, do not over-worry about these things, [but] it is important to know it is serious," the WHO's Keiji Fukuda said last week.

Perhaps the most worrisome features so far are the number and severity of cases in teenagers and young adults. This was noticed early, and the pattern has not changed much now that there are 5,000 laboratory-confirmed infections and probably more than 100,000 overall. The average age of the confirmed and probable cases is 15 years. Two-thirds are younger than 18.

Compared with seasonal outbreaks, all flu pandemics cause a higher percentage of severe cases and deaths in younger groups. Although the overall mortality rate from the current swine flu is low, this trend is already apparent.

Last Thursday, when Fukuda announced that the global death total was 65, he noted that "half of them are healthy people who have no predisposing conditions. This is a pattern different from what we see with normal influenza."

There have been too few deaths in the United States to draw any conclusions. But of the 173 people who have been sick enough to be hospitalized, more than half are in the 5-to-24 age group.

[indigo girl]

http://www.dailyrecord.com/article/20090618/COMMUNITIES/906180308/1005/NEWS01/Half+of+Rockaway+Valley+eighth-grade+class+out+sick

No! It can't be swine flu even though the sypmtoms are the same, and some of the students tested positive for Type A, and it's summertime, and it's everywhere in the community. No, it's anything else but that...LOL!!!

I needed a moment of levity after reading some of the more depressing stories. I think that the reporter was very much aware of what was really going on since she made sure to include so many details of swine flu occurrence in the area.

Many with swine flu have N/V especially kids.

About half the graduating class of eighth-graders at Rockaway Valley School was out sick on Wednesday with various ailments, but school officials say swine flu is not the culprit.

School nurse Jan Vitcavich said 18 eighth-graders were absent from the K-8 school, but their absences were attributed to fevers, respiratory infections and various stomach bugs.

No students have required hospitalization, school officials said. Vitcavich said a few students were confirmed to have Type A flu, but no students have been diagnosed with the H1N1 virus known as swine flu.

"(There are) no confirmed cases of swine flu at Rockaway Valley School," Vitcavich said.

The swine flu has caused two deaths in New Jersey, and sickened more than 320, according to state health officials. Cases of swine flu have been reported throughout Morris County...

At Rockaway Valley School, Vitcavich noted that the majority of the eighth-grade class attended a bar mitzvah this past weekend where the host had Type A flu, as well as banquets in the past week with various members of the class.

School Superintendent Roseann Humphrey said she has not received any calls from concerned parents, with graduation scheduled for today at 7 p.m. The ceremony was moved from the school on Valley Road to the auditorium of Mountain Lakes High School because of inclement weather in the forecast.

(Thank you PFI for the laugh)

[lamazeteacher]

I just read this week's MMWR from CDC, and the article about H1N1 was surprising, in that it found (in a very small n23) that Registered Nurses are less likely to wear PPE than CNAs, and physicians said they "always" wear N95 masks and gloves (sure, they do!). LOL

[indigo girl]

Experts look for clues in 1918 pandemic virus family tree

http://www.cidrap.umn.edu/cidrap/content/influenza/swineflu/news/jun2909history-jw.html

To outside observers, the novel H1N1 virus spreading quickly to every corner of the globe must seem like it came out of nowhere, but the organism is a fourth generation of the 1918 pandemic virus and comes from an H1N1 family tree that is colorful and complex, according to two historical reviews that appear today in the New England Journal of Medicine (NEJM).

Understanding the history of swine influenza viruses, particularly their contribution to the 1918 pandemic virus, underscores the need to better comprehend zoonotic viruses as well as the dynamics of human pandemic viruses that can arise from them, the authors report in an early online NEJM edition.

The world is still in a "pandemic era" that began in 1918, wrote three experts from the National Institute of Allergy and Infectious Diseases (NIAID), senior investigator David Morens, MD, medical epidemiologist Jeffery Taubenberger, MD, PhD, and NIAID director Anthony Fauci, MD.

The 1918 virus has used a "bag of evolutionary tricks" to survive in humans and pigs and to launch other novel viruses, they wrote. "The 2009 H1N1 pandemic virus represents yet another genetic product in the still-growing family tree of this remarkable 1918 virus."

The novel H1N1 virus' complex evolutionary history involved genetic mixing within human viruses and between avian- and swine-adapted viruses, gene segment evolution in multiple species, and evolution from the selection pressure of herd immunity in populations at different times, the group wrote, adding. "The fact that this novel H1N1 influenza A virus has become a pandemic virus expands the previous definition of the term,"

Though any new virus is unpredictable, Fauci and his colleagues wrote that in this pandemic era, severity appears to be decreasing over time, with an evolutionary pattern that appears to favor transmissibility over pathogenicity.

Two researchers from the University of Pittsburgh, in a review article on the emergence of H1N1 viruses, wrote that viral adaptation to a new host species is complex, but the 1918 influenza A H1N1 virus was unusual because it emerged from a bird source in pigs and humans at the same time. In contrast, researchers have said the new H1N1 virus probably emerged from swine to humans. The authors are Shanta Zimmer, MD, from the medical school, and Donald Burke, MD, from the graduate school of public health.

Previous research suggests that antibody specificity against the 1918 human influenza virus diverged quickly from swine influenza viruses, and genetic differences in hemagglutinin (HA) continue to show the same type of rapid divergence between human and swine viruses, they wrote.

Researchers still don't know why H1N1 retreated in 1957 for the next 20 years, though likely factors include high levels of existing homologous immunity plus the sudden appearance of heterologous immunity from a new H2N2 strain, Zimmer and Burke wrote.

Cross-species transfers of swine influenza H1N1 cropped up a few times over the next two decades, and human H1N1 didn't surface again until 1977, presumably because of a laboratory accident in the former Soviet Union. This event marked a first in interpandemic history: the cocirculation of two influenza A viruses.

The authors wrote that it's difficult to predict how well the pandemic strain will compete against the seasonal H1N1 virus. Both viruses share three gene segments with their remote 1918 descendant: nucleocapsid, nonstructural, and HA. They pointed out that studies of B-cell memory response in 1918 pandemic survivors showed that the neutralizing body against HA was specific and long-lasting.

Cell-mediated immunity may also affect competition between the two viruses, the authors wrote. Though it's not clear if cytotoxic T lymphocytes clinically protect humans, they have been shown to reduce viral shedding, even in the absence of antibodies against HA and neuraminidase.

"Cytotoxic T lymphocytes that are generated by seasonal influenza viruses against conserved epitopes might provide heterotypic immune responses that could dampen transmission, even in the absence of measurable antibody protection," Zimmer and Burke wrote.

[hat tip Avian Flu Diary}