Transmission of Swine H1N1 In Japan Signals Phase 6

[Large Sarge]

http://www.recombinomics.com/News/05180 ... pan_6.html


Commentary

Transmission of Swine H1N1 In Japan Signals Phase 6
Recombinomics Commentary 14:46
May 18, 2009


Japan's four earlier suspected swine flu cases came from travelers inbound from North America, but this new bout appears to be wholly domestic. Most of the cases involve teenagers - the first confirmed infected on Saturday were high-school students on a volleyball team - but those sick with the new strain of flu now range from as young as 5 years old to 60. "It circulated silently without anybody thinking of it," says Peter Cordingley, spokesman for the WHO in Manila. "The virus is highly transmittable and signs of it breaking out of a contained area into the greater community must be watched and taken very seriously."

The above comments on community transmission of H1N1 in Japan (see updated map) again indicate that the pandemic is at phase 6.  Early definitions of pandemic phases used sustained transmission as the definition of phase 6.  However, the new definition used sustained transmission as the definition of phase 4, while phase 5 represent transmission in a region, and phase 6 was transmission worldwide.

Swine H1N1 has been transmitting worldwide for over a month.  Testing outside of North America was largely limited to travelers from North America, but H1N1 was seeding prior to the enhance surveillance at airports, and transmission would have been largely undetected.

The levels in the United States (see updated map) are approaching the reported levels in Mexico, and travel from the US would increase seeding. However, these increases would also be prior to enhanced surveillance at airports.  However, such testing is destined to fail, because travelers infected within a day or two of travel would not be detected.  Similarly, as many as 1/3 of cases have no fever.

Although the CDC estimated that the number of true cases in the US was 100,000, that estimate is likely to be 1-2 orders of magnitude too low.  Surveillance in the US detects about 0.1% of true cases, so the 1500 cases in the CDC weekly report would represent 1.5 million cases in the US alone, and this estimate may be low because many cases are mild, and those in regions not reported to have high levels are not tested.

Nationwide, the number of confirmed cases of swine H1N1 (including cases that are influenza A positive and non-typable) is close to the level reported for H3N2 for the entire season.  The number of swine H1N1 cases is rapidly increasing, and in week 18 was almost 3 times the level of influenza A (1097 vs 401).

Thus, the widespread transmission in North America (Mexico, US, and Canada) insures worldwide transmission. Community transmission has already been reported in Scotland, and now there is confirmed transmission in Japan, leaving no doubt that the spread in North America has been extended to Europe and Asia.

The raising of the pandemic level to 6 is long overdue.

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[Jenny Lake]

...while this pandemic is progressing in the media, I haven't yet found anything that isn't normal to flu at any time of year or place, except suggestions of intrigue at the CDC!
http://www.virology.ws/2009/05/01/swine ... -update-2/

[Large Sarge]

Commentary

Suspect Swine H1N1 Toddler Death in NY Raises Concerns
Recombinomics Commentary 17:02
May 19, 2009


A medical examiner will determine if the 16-month-old boy who died shortly after arriving at Elmhurst Hospital in Queens is the second death from swine flu in New York City.

Family members say the boy was turning blue as they rushed him to the hospital.

The above comments on a suspect swine flu fatality in Queens, New York raise additional pandemic concerns.  The number of confirmed and suspect cases in Queens has been high (see updated map), leading to more the a dozen school closings, due in part to the high number of students with flu like symptoms, as well as the confirmed swine H1N1 death of an assistant principal.

Yesterday, the suspect toddler developed a fever in the morning, was eating in the afternoon, and was unresponsive by evening, when he was rushed to the hospital and died.  The sudden death, coupled with rapid development of cyanosis, are classic symptoms associated with fatal influenza cases in 1918.

In 1918 an H1N1 swine flu recombined with an H1N1 seasonal flu that led to 20-50 million fatalities, as the virus spread world wide and affected approximately 1/3 of the population.  That outbreak began as mild disease in the spring and most of the fatalities were associated with outbreaks in the fall of 1918 and 1919. There were multiple waves during the outbreak, raising concerns of a similar scenario in 2009.

An efficiently transmitted swine H1N1 in the human population has not been reported since 1918,  Although WHO has not yet raised the pandemic phase from 5 to 6, the sustained transmission in North America, combined with reports of community spread in Europe and Asia leaves little doubt that the 2009 pandemic has begun.

The evolution of the H1N1 is being closely monitored by sequencing labs across the world, and most isolates to date are closely related. However, the presence of avian PB2 raises concerns that the frequency of cases will not decline in the summer in the northern hemisphere, because the avian PB2 is optimal at 41 C, which would lead to efficient transmission in the summer.  Moreover, the seasonal flu has the mammalian version of PB2, which has optimal activity at 34 C.  However, the swine H1N1 transmitting in the summer hemisphere may acquire E627K, leading to a virus efficiently transmitting in the winter aso.

Similarly, swine H1N1 in the southern hemisphere may acquire H274Y, leading to Tamflu resistance, which could complicate treatment of the more severe cases, which may involve previously healthy young adults.  Another H1N1 death (44M) was just reported in St. Louis, MO.

The strong parallels between 1918 and 2009 continue to cause concern.