Human Swine Flu Infection - California & Texas First Report April 21, 2009

[HenryN]

Re: Human Swine Flu Infection - California & Texas

April 24, 2009

<NYT_HEADLINE version="1.0" type=" ">Unusual Strain of Swine Flu Is Found in People in 2 States </NYT_HEADLINE>

<NYT_BYLINE version="1.0" type=" ">By DONALD G. McNEIL Jr.
</NYT_BYLINE><NYT_TEXT>An unusual strain of swine flu is circulating among people in the Southwest but is not known to have caused any deaths, the Centers for Disease Control and Prevention said Thursday.
The agency, which has found only seven cases, expects to find more now that it has begun looking intensively for them.
?We don?t yet know the extent of the problem,? said Dr. Anne Schuchat, the director of respiratory diseases for the agency, ?but we don?t think this is a time for major concern.?
Five of the people infected were in Imperial and San Diego Counties in California and two were in San Antonio. They were 9 to 54 years old.
None had any contact with pigs, and in two sets of cases ? involving a father and daughter and two 16-year-old schoolmates ? those infected had contact with each other. That convinced the authorities that the virus was being transmitted from person to person.
The seven people were apparently infected from late March to mid-April. Only one was hospitalized, and all recovered.
The A (H1N1) flu strain they had was quite unusual, said Dr. Nancy Cox, the chief of the agency?s flu division. It contained gene segments from North American swine, bird and human flu strains as well as one from Eurasian swine.
Like some human strains, it is resistant to two older flu drugs, amantadine and rimantadine. It is not resistant to Tamiflu or Relenza. However, Tamiflu resistance is common in the H1N1 human flu strain circulating this year, so the swine strain could become resistant to Tamiflu if the viruses mixed in humans or, possibly, in pigs.
Swine flus rarely infect humans. There have been about a dozen cases since 2005, but almost all were in farm workers or others in contact with pigs.
In 1976, there was a cluster of swine flu cases among soldiers at Fort Dix, in New Jersey, one of whom died. That led to a rush to make a new vaccine and administer it to 40 million Americans. No epidemic materialized, but thousands of people claimed that the vaccine had given them Guillain-Barr? syndrome, which can cause lethargy or paralysis. The episode led to the resignation of the director of the disease control center, and the agency has been wary of causing panic over influenza cases ever since.
The unusual strain this year was noticed, Dr. Schuchat said, only because the agency was trying out a new diagnostic test at a Navy laboratory and doing more testing than usual through a new Border Infectious Disease Surveillance Project along the Mexican border.
Officials at the public health agency in Canada said their Mexican counterparts had warned them this week of a ?relatively high? fatality rate for people in Mexico who have had respiratory illnesses this season, some of whom had tested positive for flu. Asked about that, American officials said they had no information. A spokesman said the disease control center had asked Mexican officials to send samples for testing.
The United States flu season is tailing off now. It has been relatively mild; the major surprise had been the widespread Tamiflu resistance in the circulating human H1N1 strain.
Dr. Cox of the disease control center said officials did not yet know whether the flu shot this year protected against the new swine strain.

http://www.nytimes.com/2009/04/24/us/24flu.html?_r=1&ref=us&pagewanted=print

[HenryN]

Re: Human Swine Flu Infection - California &amp; Texas

<TABLE style="TABLE-LAYOUT: auto" cellSpacing=0 cellPadding=0 width="100%" summary="Main Page Table" border=0><TBODY><TR><TD vAlign=top><TABLE cellSpacing=10 cellPadding=0 summary="Main Content Table" border=0><TBODY><TR><TD vAlign=top align=left colSpan=2>More US swine flu cases, Mexico illnesses raise pandemic questions

Lisa Schnirring Staff Writer

Apr 23, 2009 (CIDRAP News) ? Five more cases of an unusual swine influenza virus infection have surfaced, officials from the US Centers for Disease Control and Prevention (CDC) announced today, bringing the total to seven and raising more concerns about human-to-human transmission.
The new cases include two clusters, two 16-year-old boys in San Antonio, Tex., who attended the same school and a father and daughter from San Diego County. Anne Schuchat, MD, interim deputy director for the CDC's science and public health program, told reporters today at a teleconference that the clusters are consistent with human-to-human spread.
She also said that the World Health Organization has not raised its six-phase pandemic alert level above phase 3 (no or very limited human-to-human transmission).
The fifth new case occurred in a patient from Imperial County, which borders San Diego County. Both counties are home to the first two swine flu patients that the CDC announced on Apr 21.
News of the five new swine flu cases came on the same day Canadian officials warned its public health, medical, and quarantine workers to look for illnesses among Canadians returning from Mexico. Mexico has reported several cases of severe respiratory illness and has asked Canada to assist in finding the source of the illnesses, some of which have been fatal, according to a report today from the Canadian Press (CP).
Schuchat said no swine flu cases have been confirmed in Mexico or Canada, but that CDC officials are discussing the situation with Mexican health officials and representatives from the Pan American Health Organization (PAHO).
Novel strain, relatively mild symptoms
Concerning the seven American cases, Schuchat said, "The good news is that all of the patients have recovered, and one was hospitalized. This is not looking like a very severe influenza."
Patients experience fever, cough, and sore throat symptoms similar to typical influenza, but some of the patients who had swine influenza also experienced more diarrhea and vomiting than is typical of seasonal flu.
The CDC said genetic sequencing of samples from the first two patients, California children who lived in adjacent counties, show that the swine flu virus contains segments from four different viruses: some North American swine, some North American avian, one human influenza, and two Eurasian swine.
"This virus hasn't been recognized in the USA or elsewhere," Schuchat said.
CDC scientists have determined that the novel swine flu virus is resistant to the older antivirals rimantadine and amantadine but is susceptible to oseltamivir and zanamivir.
Schuchat said the CDC expects to see more swine flu cases and that it would provide regular updates on its Web site.
"This is not time for major concern around the country, but we want you to know what's going on," she said. Most of the public health response will focus on the California and Texas areas where cases have been identified, but the CDC is urging health departments in other states to heighten their awareness of respiratory illnesses, particularly in those who have had contact with pigs or traveled to the San Diego or San Antonio areas.
Schuchat said the CDC doesn't know yet if the H1N1 component of this season's influenza vaccine provides any protection against the swine flu virus, but she said studies are under way to determine if there is any cross-protection.
Expert reaction
Michael T. Osterholm, PhD, MPH, director of the University of Minnesota Center for Infectious Disease Research and Policy, publisher of CIDRAP News, said the findings, though concerning, don't mean that a pandemic is imminent.
However, he said health officials shouldn't take comfort in the fact that the illnesses so far have been mild. "The first wave of the 1918 pandemic was mild, too," Osterholm pointed out.
Walter Dowdle, PhD, who worked in the CDC's virology unit during the 1976 swine flu outbreak, told CIDRAP News that it's interesting but not greatly alarming that the 2009 swine flu strain contains such an unusual mix of gene segments.
"It's a real mutt," said Dowdle, who now works with the Task Force for Child Survival and Development, based in Atlanta "When you have an evolving RNA mechanism, it's hard to be surprised by anything."
The H1N1 component of the seasonal flu vaccine might provide some degree of protection, he said. And if the swine flu virus persists, federal officials could consider adding an additional H1N1 strain to next year's vaccine.
Marie Gramer, DVM, PhD, a University of Minnesota veterinarian who has studied swine flu, said her preliminary examination shows that the outbreak strain doesn't appear to closely match anything currently circulating in pigs. However, Gramer added that she has only looked at a small number of viruses and only at the hemagglutinin gene.
Risk message implications
Peter Sandman, PhD, a risk communication consultant based in Princeton, N.J., also listened in on today's CDC teleconference. While he credited the CDC with getting a clear, calm, and concise scientific message out about the swine flu cases, he said they missed a teachable moment to promote pandemic preparedness.
"Everyone needs to learn how to say 'This could be bad, and it's a good reason the take precautions and prepare' and 'This could fizzle out,'" Sandman said. "They need to simultaneously say both statements."
He added that "good risk communicators need to know how to be both scary and tentative."
Federal health officials are probably treading cautiously around the word "pandemic," because some accused them of fear mongering when they raised concerns about the H5N1 virus 2 years ago and also because of overreaction during the 1976 swine flu epidemic that led to vaccination missteps.
When talking to the public about pandemic risks, federal officials could take some cues from hurricane forecasters, Sandman said, "and speculate responsibly."
Canadian officials probe Mexico illnesses
Canada's Public Health Authority (PHAC) said today in a situation update that Mexican authorities have asked its assistance in determining the cause of two clusters of severe respiratory illnesses that have occurred this month.
A cluster in Mexico City involved 120 cases and 13 deaths; the other occurred in San Luis Potosi, where 14 cases and 4 deaths were reported. Three deaths were reported from other locations: One from Oaxaca in southern Mexico and two from Baja California Norte, near the US border.
The PHAC report said the disease outbreak struck some healthcare workers and that most patients were previously healthy young adults between the ages of 25 and 44. Symptoms included fever, headache, ocular pain, shortness of breath, and fatigue that rapidly progressed to severe respiratory distress in about 5 days.
Mexican officials detected some influenza A/H1N1 and influenza B viruses, but have apparently ruled out H5N1 virus involvement. The PHAC said it received 51 clinical samples from Mexico for testing at its National Microbiology Lab.
Mexico told the PHAC that it had a late influenza season with an increasing number of influenza-like illnesses since the middle of March. The country also had a higher proportion of influenza B viruses than previous seasons.
See also:
Apr 21 CIDRAP News story "Human swine flu cases with unique train raise concern"
Apr 22 CIDRAP News story "Swine flu cases recall 1976 episode"
CDC swine flu investigation page
CDC swine flu information

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[HenryN]

Re: Human Swine Flu Infection - California &amp; Texas

Swine flu in Texas mystifies officials

Total of 7 cases found in Texas and California; experts don't know how virus is spread.

ASSOCIATED PRESS
Friday, April 24, 2009

Health officials are investigating a never-before-seen form of the swine flu that combines pig, bird and human viruses and has infected seven people in Texas and California. All the victims recovered, but the cases pose a medical mystery because it's unclear how they caught the virus.
None of the seven people was in contact with pigs, and only a few were in contact with each other, according to the U.S. Centers for Disease Control and Prevention.
Still, health officials said it's not a cause for alarm: The five people in California and two teenagers in Texas have all recovered, and testing indicates some mainstream antiviral medications seem to work against the virus.
Two 16-year-old boys from Guadalupe County near San Antonio were confirmed to have swine flu, with one falling ill April 10 and the other April 14, the Department of State Health Services said Thursday.
But the virus was first detected in two children in Southern California, a 10-year-old boy in San Diego County and a 9-year-old girl in neighboring Imperial County.
One of the California cases ? the 10-year-old boy ? flew to Dallas this month but didn't travel to the San Antonio area, said Dr. Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases.
The two Texas teens evidently didn't travel or have any connection to the boy who flew to Dallas, officials said. The health department is trying to learn whether any of their close contacts are ill and is asking hospitals, doctors and other health authorities to be on the lookout for other possible cases.
CDC officials detected a virus with a unique combination of gene segments that haven't been seen in people or pigs before. The bug contains genes from human virus, avian virus from North America and pig viruses from North America, Europe and Asia.
Health officials have seen genetic mixes of bird, pig and human virus before but never such an intercontinental combination with more than one pig virus in the mix.
Additional material from American-Statesman staff writer Mary Ann Roser.

http://www.statesman.com/news/content/news/stories/nation/04/24/0424swineflu.html

[HenryN]

Re: Human Swine Flu Infection - California &amp; Texas

FACTBOX: New flu strain is a genetic mix

Fri Apr 24, 2009 4:02am BST
(Reuters) - U.S. health officials are investigating a strange new type of swine influenza that has infected at least seven people and which is expected to be found in more.
Here are some facts about the virus and flu viruses in general:
* The virus is an influenza A virus, carrying the designation H1N1.
* It is genetically different from the fully human H1N1 seasonal influenza virus that has been circulating globally for the past few years. The new flu virus contains DNA typical to avian, swine and human viruses, including elements from European and Asian swine viruses.
* Flu viruses mutate constantly, which is why the flu vaccine is changed every year, and they can also swap DNA in a process called reassortment. Most animals can get flu but viruses rarely pass from one species to another.
* From December 2005 through February 2009, 12 cases of human infection with swine influenza were confirmed, all but one among people who had contact with pigs. There was no evidence of human-to-human transmission.
* Symptoms of swine flu in people are similar to those of seasonal influenza -- sudden onset of fever, coughing, muscle aches and extreme tiredness. Swine flu appears to cause more diarrhea and vomiting than normal flu.
* People rarely catch avian flus. Notable exceptions include the H1N1 strain that caused the 1918 pandemic and H5N1 bird flu, which has killed 257 out of 421 infected in 15 countries since 2003, according to the World Health Organization.
* Seasonal flu kills between 250,000 and 500,000 people globally in an average year.
* When a new strain of flu starts infecting people, and when it acquires the ability to pass from person to person, it can spark a pandemic. The last pandemic was in 1968 and killed about a million people.
* In 1976 a new strain of swine flu started infecting people and worried U.S. health officials started widespread vaccination. More than 40 million people were vaccinated. But several cases of Guillain-Barre syndrome, a severe and sometime fatal condition that can be linked to come vaccines, caused the U.S. government to stop the program. The incident led to widespread distrust of vaccines in general.
(Reporting by Maggie Fox)

http://uk.reuters.com/article/healthNewsMolt/idUKTRE53N0RZ20090424

[HenryN]

Re: Human Swine Flu Infection - California &amp; Texas

Local swine flu cases attract CDC?s attention
<TABLE cellSpacing=0 cellPadding=0 width="100%"><TBODY><TR><TD>By Jessica Sanders
The Gazette-Enterprise </TD><TD align=left width=150></TD></TR></TBODY></TABLE>
Published April 24, 2009
SEGUIN ? On Thursday, health officials confirmed that two 16-year-old Steele High School students were diagnosed with swine flu earlier this month.

According to a CDC press release, ?One became ill on April 10, the other on April 14. Their illnesses were relatively mild. Neither was hospitalized. Both have recovered. Though the boys are friends, it has not been determined how either became infected.?

While the illness may sound frightening, Guadalupe County Emergency Management Coordinator Dan Kinsey said the news is no cause for panic. ?The first thing to know is that this is not severe. Everyone who contracted it has recovered or is recovering ? there have been no fatalities,? he said. ?What we have is a unique strain of influenza known as the swine flu, but is not necessarily contracted from pigs.?

Kinsey said the CDC called the press conference, not from fear of an epidemic, but in order to inform the public and seek further information about a new strain of the illness that seems to travel from person-to-person instead of from pig-to-person. He said CDC and state health officials will continue to research the cases, performing follow-up interviews with the patients and people who were in contact with them.

According to the CDC, the swine flu is a type of respiratory disease in pigs caused by type A influenza which creates a high rate of illness and a low rate of death.

All seven recent cases are of a similar unique strain of the H1N1 swine flu virus.

Contraction of swine flu by humans is more common than contraction of bird flu by humans because pigs and humans have similar physiology, Kinsey said. However, the chance of a person contracting any form of the swine flu is rare.

?There?s no need to panic,? Kinsey said again. ?You cannot get it from eating bacon or pork. Right now, we?re not sure how it?s being transmitted.?

CDC officials said one of the California patients traveled to Dallas shortly before becoming ill, so Texas health officials were already involved in the swine flu investigation when the two Guadalupe County cases broke out. However, there appears to be no connection to that California case and the two cases in Guadalupe County.

Kinsey said the symptoms of swine flu, particularly the strain seen locally, are like symptoms of the regular human flu, but include a little bit more vomiting and diarrhea. Kinsey said, in general, swine flu has been shown in CDC studies to respond well to strong antiviral treatment.

?There?s not a lot of known facts beyond what?s seen with a normal flu, like they don?t know the incubation period or the number of people who have contracted it. Because it?s not severe, not everyone would run to the doctor,? Kinsey said.

In the release, the CDC recommends that people take precautions such as frequent hand washing and cough or sneeze into a tissue or the crook of your arm.

Kinsey said it?s also important to avoid spreading illness by staying home from work or school when sick.

?If you feel like you have the flu or flu-like symptoms, see your doctor,? he said. ?Don?t go to work and spread it around.?

For more information on the swine flu, visit www.cdc.gov .

http://www.seguingazette.com/story.l...ff09097916d899<!-- Story layout ends --><!-- Optional blocks begin --><!-- Optional blocks end --><!-- Story toolbox links begin -->

[HenryN]

Re: Human Swine Flu Infection - California &amp; Texas

Map updated

http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=p&msa=0&msid=106484775090296685271.0004681a37b713f6b5950&ll=28.892779,-99.283447&spn=2.154525,3.99353&z=8

[HenryN]

Re: Human Swine Flu Infection - California &amp; Texas

In California and Texas, 5 New Swine Flu Cases


By Rob Stein
Washington Post Staff Writer
Friday, April 24, 2009

Government scientists have identified five more people who have been infected with swine flu, apparently confirming suspicions that the unusual strain of the respiratory infection is spreading from person to person, federal health officials said yesterday.
Three new cases were found in California and two in Texas, bringing the total number of confirmed cases to seven, officials at the federal Centers for Disease Control and Prevention in Atlanta said. The CDC announced Tuesday that two children had been infected in San Diego. The agency has launched an investigation to try to determine how widespread the virus is.
Officials said there was no reason for alarm despite the growing number of cases, but they urged doctors to be on the look-out for more cases and said they were intensifying their efforts. They have also taken preliminary steps to create a vaccine against the virus if necessary.
"We don't think this is time for major concern around the country," Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases, told reporters in a telephone briefing.
"We are taking steps to know more and stay on top of the situation," she said, adding that the agency had alerted the World Health Organization and the Pan American Health Organization.
Two of the new cases involved a father and a daughter in San Diego County, and two others were boys who attend the same school near San Antonio. Those cases, combined with the lack of evidence that any of the infected people had contact with pigs, led officials to believe that the virus was spreading from one person to another, Schuchat said.
"We believe at this point that human-to-human spread is occurring. That's unusual. We don't know how widely it is spreading," she said, adding that she expects more cases to be identified in coming days as the investigation unfolds.
The cases so far involve three females and four males ranging in age from 9 to 54. The first child became ill March 28. The CDC confirmed the three new California cases Wednesday and the two new Texas cases -- in 16-year-old boys -- yesterday. Laboratory testing showed that the virus does not match any known flu strains.
The infection has caused typical flu-like symptoms, including high fever, sore throat and cough, as well as vomiting and diarrhea; one person was hospitalized. But so far, the virus does not appear to be causing serious illness, Schuchat said.
"The good news is all seven of these patients have recovered," she said. The virus appears to be resistant to two drugs normally used to treat the flu, but two others appear to be effective against it.
Genetic analysis of the virus indicates it is highly unusual: It is a hybrid that resulted from a combination of four different viruses -- one that typically infects people, one that originated in North American birds and two from pigs in Europe and Asia.
"This combination has not been recognized before in the U.S. or elsewhere," Schuchat said.
Although the cases all are scattered along the U.S.-Mexico border, officials have not identified any cases in Mexico. But they are continuing to investigate.

http://www.washingtonpost.com/wp-dyn/content/article/2009/04/23/AR2009042304116_pf.html

[HenryN]

Re: Human Swine Flu Infection - California &amp; Texas

Seven people in U.S. hit by strange new swine flu

Thu Apr 23, 2009 11:02pm EDT
By Maggie Fox, Health and Science Editor
WASHINGTON (Reuters) - Seven people have been diagnosed with a new kind of swine flu in California and Texas, the U.S. Centers for Disease Control and Prevention reported on Thursday.
All seven people have recovered but the virus itself is a never-before-seen mixture of viruses typical among pigs, birds and humans, the CDC said.
"We are likely to find more cases," the CDC's Dr. Anne Schuchat told a telephone briefing. "We don't think this is time for major concern around the country."
Only one of the seven cases was sick enough to be hospitalized and all have recovered, Schuchat said.
CDC officials are unsure whether the cases are related to an unusually late and severe flu season in Mexico in which 20 people have died.
"Generally the period of infection ends during the last week of February and the first week of March, but this year there was an atypical situation where the transmission period was prolonged until April," Mexico's Ministry of Health said in a statement.
Canadian officials have asked doctors to keep an eye out for cases of respiratory illness among travelers from Mexico.
"Symptoms from those seriously ill in Mexico include high fever, headache, eye pain, shortness of breath and extreme fatigue with rapid progression of symptoms to severe respiratory distress in about five days," the British Columbia Center for Disease Control said in a statement.
In the United States, the CDC reported the new strain of swine flu on Tuesday in a boy and a girl from California's two southernmost counties.
Now, five more cases have been found via normal surveillance for seasonal influenza. None of the patients, whose symptoms closely resembled seasonal flu, had any direct contact with pigs.
Two of the new cases were among 16-year-olds at the same school in San Antonio "and there's a father-daughter pair in California," Schuchat said. The boy whose case was reported on Tuesday had flown to Dallas, but the CDC has found no links to the other Texas cases.
The agency will issue daily updates here
HUMAN TO HUMAN
"We believe at this point that human-to-human spread is occurring," Schuchat said. "That's unusual. We don't know yet how widely it is spreading ... We are also working with international partners to understand what is occurring in other parts of the world."
The CDC's Dr. Nancy Cox said virus samples from the seven appear to carry genes from swine flu, avian flu and human flu viruses from North America, Europe and Asia.
"We haven't seen this strain before, but we hadn't been looking as intensively as we have," Schuchat said. "It's very possible that this is something new that hasn't been happening before."
Surveillance for and scrutiny of influenza has been stepped up since 2003, when H5N1 bird flu reappeared in Asia. Experts fear this strain, or another strain, could spark a pandemic that could kill millions.
The influenza A strain is an H1N1, the same subtype as one of the seasonal flu viruses now circulating. Now that the normal influenza season is waning, it may be easier to spot cases of the new swine flu, Schuchat said.
The CDC is asking doctors to think about the possibility of swine flu when patients appear with flu-like symptoms, to take a sample and send it to state health officials or the CDC for testing.
Cox said the CDC is already preparing a vaccine against the new strain, just in case.
"This is standard operating procedure," he said.
(With additional reporting by Mica Rosenberg in Mexico City and Allan Dowd in Vancouver)

http://www.reuters.com/article/healthNews/idUSTRE53M63F20090424

[HenryN]

Re: Human Swine Flu Infection - California &amp; Texas

<a rel="nofollow" href="http://www.recombinomics.com/News/04240902/H1N1_Swine_CA_TX_Clusters.html">Commentary</a>

[AlaskaDenise]

Re: Human Swine Flu Infection - California &amp; Texas

<a rel="nofollow" href="http://www.recombinomics.com/News/04230902/H1N1_CA_Swine_Sustained.html">Commentary</a>

Commentary

Sustained Human Transmission of Swine H1N1 in California

Recombinomics Commentary 21:30
April 23, 2009

it is reassuring that international reporting has been rapid, there vigorous case finding is underway and that apart from some history of possible upper respiratory infections there is no indication of sustained human-to-human transmission or widespread infection of contacts of the two ill patients

The above comments by the European Centere for Disease Control and Prevention on the confirmed H1N1 swine flu in southern California ignore the glaring indication of sustained human-to-human transmission, which is the <a rel="nofollow" href="http://www.recombinomics.com/News/04220902/H1N1_CA_Swine_H2H.html">distance between the two confirmed cases</a> (see updated map).

There was no direct connection with swine or each other, so the confirmation of the same virus at distant locations was the indication, because both clusters were almost certainly caused by transmission from other humans.

Moreover, each confirmed case was linked to family members who developed symptoms before and after the confirmed case, supporting transmission within the family. However, because the symptoms were mild, none of the family members sought medical attention and were not tested.

Thus, the lack of evidence is simply due to the <a rel="nofollow" href="http://www.recombinomics.com/News/04220903/H1N1_CA_Swine_H2H_SS.html">lack of testing </a>, not the lack of transmission.

Yesterday there were reports of suspect cases in the Imperial Valley. It is likely that these cases will be confirmed and additional cases will be identified in both counties.

Moreover, it is also likely that there are additional cases in Mexico, which borders both counties. The relationship of the US cases to reported outbreaks of <a rel="nofollow" href="http://www.recombinomics.com/News/04230901/SRI_Mexico_Alert.html">influenza and atypical pneumonia in Mexico</a> remain to be determined, but the confirmed cases in California represent sustained transmission of a swine influenza in the human population, which is cause for concern.

.

[AlaskaDenise]

Re: Human Swine Flu Infection - California &amp; Texas

<a rel="nofollow" href="http://www.recombinomics.com/News/04240902/H1N1_Swine_CA_TX_Clusters.html">Commentary</a>

Commentary

California and Texas Swine Flu Clusters Raise Concerns

Recombinomics Commentary 07:03
April 24, 2009

Two of the new cases were among 16-year-olds at the same school in San Antonio "and there's a father-daughter pair in California," Schuchat said. The boy whose case was reported on Tuesday had flown to Dallas, but the CDC has found no links to the other Texas cases.

The above comments describe four of the five new swine flu cases (see updated map) recently confirmed by the CDC. The two high school students near San Antonio, Texas were friends and not linked to the San Diego case who flew to Dallas. Similarly there was no indication that the father daughter pair in San Diego Country were linked to the earlier cluster.

The two initial confirmed cases were also linked to <a rel="nofollow" href="http://www.recombinomics.com/News/04220901/H1N1_CA_Swine.html">clusters</a>, but the relatives were not tested. However, it is almost certain that the two sets of contacts for the first two cases were also infected, creating four distinct clusters. The only individual case was the fifth new case, a female from Imperial County. Thus, of the 11 confirmed or suspect cases, only one was not in a cluster.

This clustering signals efficient transmission, but none of the cases have links to swine or the other clusters. The efficient transmission signals extensive <a rel="nofollow" href="http://www.recombinomics.com/News/04220903/H1N1_CA_Swine_H2H_SS.html">silent transmission</a>. As noted earlier, only two of the six initial cases were tested, and the testing was linked to a border surveillance program.

Thus, without the border surveillance, none if these cases would have been identified, with the possible exception of the hospitalized patient who was on a ventilator. However, the swine flu would have only been identified if the sample was sub-typed. The swine flu would test positive for influenza A, and treatment and symptoms would be the same for seasonal or swine flu.

Although all cases were in locations close to the Mexican border, no cases in Mexico have been confirmed. However, without the border surveillance no case in the United States would have been confirmed.

It is likely that there are swine flu cases in Mexico, and it is likely that the current influenza outbreak includes a high number of swine flu cases. There have been 20 fatalities due to <a rel="nofollow" href="http://www.recombinomics.com/News/04230901/SRI_Mexico_Alert.html">atypical pneumonia</a>, and cases have been unusually high for mid to late April. Samples have been sent to Canada for analysis, and the CDC said they were also investigating. However, there is little doubt that a high percentage of cases in Mexico are swine flu. School closings throughout southern Mexico, affecting millions of students were just announced.

As flu season ends in the northern hemisphere, identifying swine flu cases should be easier. However, the mild nature of the illness will likely lead to spread into the southern hemisphere increasing the frequency of co-infections with H1N1 seasonal flu and acquisition of Tamiflu resistance (H274Y).

Aggressive testing of patients throughout the Americas is warranted, as well as testing in other areas.

The number of flu cases in Mexico, coupled with the high frequency of clusters in California and Texas, raises concerns that the swine flu will spread worldwide and expand into a major pandemic.

.

[AlaskaDenise]

Re: Human Swine Flu Infection - California &amp; Texas

Swine Flu Probe Widens as Mexico Finds Lung Illness (Update1)


By Jason Gale

April 23 (Bloomberg) -- An urgent probe into an unusual flu outbreak that’s infected seven people in the U.S. was widened after Mexico sought assistance to investigate more than 130 cases of severe respiratory disease that may be related.

Authorities in Mexico asked the Public Health Agency of Canada to help identify the cause of the lung illness linked to 20 deaths, including two in the state of Baja California Norte, which borders California. The Mexican cases include five health- care workers, the Ottawa-based agency said in an e-mail today.

Tests in Mexico found patients were infected with H1N1 and type-B influenza strains and the parainfluenza virus, the agency said. In the U.S., doctors discovered a new strain of H1N1 swine influenza in patients in San Diego County and Imperial County, California, and in San Antonio, the Centers for Disease Control and Prevention in Atlanta said today.

“It will be critical to determine whether or not the strains of H1N1 isolated from patients in Mexico are also swine flu,” Donald Low, an infectious diseases specialist at Toronto’s Mount Sinai Hospital, told the Canadian Press.

Canada’s National Microbiology Lab received 51 specimens from Mexico yesterday and will be testing them for a range of pathogens, the public health agency said.

Thirteen fatal cases of severe respiratory illness were reported in Mexico City, four in San Luis Potosi, a city north of the capital, and another in Oaxaca city in the south. Most cases occurred in southern and central Mexico in previously healthy adults aged 25 to 44 years old.

Fever, Headache

Symptoms include high fever, headache, eye pain, shortness of breath and extreme fatigue with rapid progression of symptoms to severe respiratory distress in about five days, the Canadian agency said. A “high proportion” of cases require mechanical respirators, it said.

In contrast, the four males and three females diagnosed with swine flu in the U.S. have had mild flu-like symptoms. The patients, aged 9 to 54 years, began feeling unwell from March 28 to April 19. All have recovered and only one was hospitalized briefly, according to the CDC.

Preliminary analyses of the virus indicate it contains four different gene components representing both North American swine and avian influenza, human flu and a European/Asian swine flu.

“We have determined that this virus is contagious and is spreading from human to human,” the CDC said in a statement on its Web site. “We have not determined how easily the virus spreads between people.”

Swine influenza is a respiratory disease of pigs caused by type-A influenza that regularly causes outbreaks among the animals, according to the CDC. Swine flu doesn’t normally infect people, though human infections do occur and cases of human-to- human spread of swine flu viruses have been documented.

‘Reassortment’ Risk

Infection in pigs is regarded as especially problematic because of the risk of “reassortment” to produce a new virus, the European Centre for Disease Prevention and Control said in a statement. There is even a risk of a pandemic strain either in pigs or in a person infected with both a human and pig strain, the center said yesterday.

“The infection of humans with a novel influenza A virus infection of animal origins as has happened here is of concern because of the risk, albeit small, that this could represent the appearance of viruses with pandemic potential,” the ECDC said.

Global flu contagions start when a novel influenza type-A virus, to which almost no one has natural immunity, emerges and begins spreading. Experts believe that the so-called 1918 Spanish Flu pandemic, which may have killed as many as 50 million people, began when an avian flu virus jumped to people.

To contact the reporter on this story: Jason Gale in Singapore at j.gale@bloomberg.net

Last Updated: April 24, 2009 00:25 EDT

http://www.bloomberg.com/apps/news?pid=20601124&sid=azAqR4.k2qEY&refer=home

[HenryN]

Re: Human Swine Flu Infection - California &amp; Texas

<a rel="nofollow" href="http://www.recombinomics.com/News/04240903/H1N1_Swine_Mexico_Pandemic.html">Commentary</a>

[vinny]

Re: Human Swine Flu Infection - California &amp; Texas

Whats its CFR so far any idea anyone.......?,thanks.

[jasonfoster]

Re: Human Swine Flu Infection - California &amp; Texas

Whats its CFR so far any idea anyone.......?,thanks.

That is very difficult to say because you don't know if there are mild cases not reported. If 800 are sick and 60 are dead then that is a 7.5% CFR