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

[Laidback Al]

Swine flu cases in Calif. worry health officials 44 minutes ago

ATLANTA (AP) — Health officials have diagnosed a unique type of swine flu in two California children, but it's unclear whether many people will be susceptible to the infection.

The two children were diagnosed last week. One was a 10-year-old boy in San Diego County, and the other a 9-year-old girl in neighboring Imperial County. Both recovered.

The U.S. Centers for Disease Control and Prevention alerted doctors Tuesday, but said there's no reason for the public to take unusual measures.
The virus is resistant to two common antiviral medications, and health officials think the seasonal flu vaccine may not protect against it.

http://www.google.com/hostednews/ap/article/ALeqM5gzz357patY4-QaJFvo9O95zMM_EQD97N164G2

[sharon sanders]

Re: Human Swine Flu Infection - California

CDC - Interim Guidance on Infection Control and Antiviral Recommendations for Patients with Confirmed or Suspected Swine Influenza A Virus Infection


http://www.flutrackers.com/forum/showthread.php?t=99765

[sharon sanders]

Re: Human Swine Flu Infection - California

from MMWR - April 17th Issue

"...Novel Influenza A Viruses

A case of human infection with a novel influenza A virus was reported by the Iowa Department of Public Health during the week ending February 28, 2009. A male aged 3 years was infected with a swine influenza A (H1N1) virus. An investigation revealed that the child had close contact with ill pigs. The child has fully recovered from the illness, and no additional cases were identified among the child's contacts or other persons exposed to the ill pigs. This is the third human infection with swine influenza virus identified in the United States this influenza season. None of the cases were related to occupation. The other two human infections with swine influenza identified during the 2008--09 influenza season occurred in a person aged 14 years from Texas and a person aged 19 years from South Dakota..."

http://www.flutrackers.com/forum/showthread.php?p=220087#post220087

[Giuseppe]

Re: Human Swine Flu Infection - California

New type of flu found in two U.S. children: CDC - Reuters

New type of flu found in two U.S. children: CDC

Tue Apr 21, 2009 7:43pm BST
WASHINGTON (Reuters) -

A new type of swine flu has infected at least two children in California and, while they have recovered, U.S. health officials said on Tuesday they were concerned.


The influenza strain is an H1N1, the same family as one of the seasonal flu viruses now circulating. But genetically, it resembles a virus found in pigs and not in people, officials at the U.S. Centers for Disease Control and Prevention said.

CDC experts described two of the cases in a special notice to doctors and public health officials.

They say it is possible the children were infected by other people and not by pigs, and said they have consulted with officials in Canada, Mexico and at the World Health Organization although there is no evidence that this new virus is circulating widely.

(Reporting by Maggie Fox; Editing by Julie Steenhuysen and Bill Trott)
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<cite cite="http://uk.reuters.com/article/healthNews/idUKTRE53K4XU20090421">New type of flu found in two U.S. children: CDC | Science & Health | Reuters</cite>

[sharon sanders]

Re: Human Swine Flu Infection - California

Key Facts about Swine Influenza (Swine Flu)

What is Swine Influenza?

Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza that regularly cause outbreaks of influenza among pigs. Swine flu viruses cause high levels of illness and low death rates among pigs. Swine influenza viruses may circulate in swine throughout the year, but most outbreaks among swine herds occur during the late fall and winter months similar to humans. The classical swine flu virus (an influenza type A H1N1 virus) was first isolated from a pig in 1930.

How common is swine flu among pigs?

H1N1 and H3N2 swine flu viruses are endemic among pig populations in the United States and something that the industry deals with routinely. Outbreaks among pigs normally occur in colder weather months (late fall and winter) and sometimes with the introduction of new pigs into susceptible herds. Studies have shown that the swine flu H1N1 is common throughout pig populations worldwide, with 25 percent of animals showing antibody evidence of infection. In the U.S. studies have shown that 30 percent of the pig population in the U.S. has antibody evidence of having had H1N1 infection. More specifically, 51 percent of pigs in the north-central U.S. have been shown to have antibody evidence of infection with swine H1N1. Human infections with swine flu H1N1 viruses are rare. There is currently no way to differentiate antibody produced in response to flu vaccination in pigs from antibody made in response to pig infections with swine H1N1 influenza.

While H1N1 swine viruses have been known to circulate among pig populations since at least 1930, H3N2 influenza viruses did not begin circulating among US pigs until 1998. The H3N2 viruses initially were introduced into the pig population from humans. The current swine flu H3N2 viruses are closely related to human H3N2 viruses.

Can humans catch swine flu?

Swine flu viruses do not normally infect humans. However, sporadic human infections with swine flu have occurred. In the past several years, on average CDC has received about one influenza virus isolate from a human that tests positive for swine flu each year. Most commonly, these cases occur in persons with direct exposure to pigs (workers in the swine industry, for example). In addition, there have been rare documented cases of one person spreading swine flu to others. For example, an outbreak of apparent swine flu infection in pigs in Wisconsin in 1988 resulted in multiple human infections, and, although no community outbreak resulted, there was antibody evidence of virus transmission from the patient to health care workers who had close contact with the patient.

How does swine flu spread?

• Pigs infected with influenza virus have a runny nose, lethargy, cough and decreased appetite. The virus likely spreads from pig to pig through contact with infected mucous secretions. (When the pigs are really sick, their mucus carries high levels of virus.)
• Strains of swine flu virus can also be directly transmissible to humans. Most human infections have occurred following direct contact with infected pigs. However, there has been at least one documented case of human-to-human transmission of swine flu.

What do we know about human-to-human spread of swine flu?

In September 1988, a previously healthy 32-year-old pregnant woman was hospitalized for pneumonia and died 8 days later. A swine H1N1 flu virus was detected. Four days before getting sick, the patient visited a county fair swine exhibition where there was widespread influenza-like illness among the swine.

In follow-up studies, 76% of swine exhibitors tested had antibody evidence of swine flu infection but no serious illnesses were detected among this group. Additional studies suggest that one to three health care personnel who had contact with the patient developed mild influenza-like illnesses with antibody evidence of swine flu infection.

What other examples of swine flu outbreaks are there?

Probably most well known is an outbreak of swine flu among soldiers in Fort Dix, New Jersey in 1976. The virus caused disease with x-ray evidence of pneumonia in at least 4 soldiers and 1 death; all of these patients had previously been healthy. The virus was transmitted to close contacts in a basic training environment, with limited transmission outside the basic training group. The virus is thought to have circulated for a month and disappeared. The source of the virus, the exact time of its introduction into Fort Dix, and factors limiting its spread and duration are unknown. The Fort Dix outbreak may have been an animal anomaly caused by introduction of an animal virus into a stressed human population in close contact in crowded facilities during the winter. The swine influenza A virus collected from a Fort Dix soldier was named A/New Jersey/76 (Hsw1N1).

How many swine flu viruses are there?

Like all influenza viruses, swine flu viruses change constantly. Pigs can be infected by avian influenza and human influenza viruses as well as swine flu viruses. When influenza viruses from different species infect pigs, the viruses can reassort (i.e. swap genes) and new viruses that are a mix of swine, human and/or avian influenza viruses can emerge. Over the years, different variations of swine flu viruses have emerged. At this time, there are four main influenza type A virus subtypes that have been isolated in pigs: H1N1, H1N2, H3N2, and H3N1. However, most of the recently isolated influenza viruses from pigs have been H3N2 and H1N1 viruses.

Is the H1N1 swine flu virus the same as human H1N1 viruses?

No. The H1N1 swine flu viruses are antigenically very different from human H1N1 viruses.

Is there a vaccine for swine flu?

Vaccines are available to be given to pigs to prevent swine influenza. There is no vaccine to protect humans from swine flu. The seasonal influenza vaccine will likely help provide partial protection against swine H3N2, but not swine H1N1 viruses.

What are the public health implications of human infections with swine influenza viruses?

Human infections with animal influenza A viruses against which the human population has little immunity should be investigated to determine the source of infection, and the extent of spread and evidence of human to human transmission. Influenza A viruses new to the human population that are able to efficiently transmit from person to person and cause illness may represent a pandemic threat.

Although immunity to swine H1N1 viruses is low in the human population, a high proportion of persons occupationally exposed to pigs (such as pig farmers or pig veterinarians) have been shown in several studies to have antibody evidence of prior swine H1N1 flu infection. And, for swine H1N1 viruses, only rare person to person transmission has been documented in the past. Thus, human infections with swine H1N1 viruses should be investigated particularly when they are detected among non-occupationally exposed persons to ensure that human to human transmission is not occurring and to monitor for changes in circulating viruses and the emergence of novel viruses.


Because most persons have some antibody to influenza H3N2 viruses since H3N2 viruses occur commonly in humans and because the swine and human H3N2 viruses are similar, swine H3N2 virus infections in humans would not represent a possible pandemic threat.

http://www.cdc.gov/flu/swine/key_facts.htm

[Giuseppe]

Re: Human Swine Flu Infection - California

Reuters AlertNet - New type of flu affects a few US children - CDC

New type of flu affects a few US children - CDC

21 Apr 2009 19:02:26 GMT
Source: Reuters

*New type of swine flu never seen before
*Flu may have spread person to person

By Maggie Fox, Health and Science Editor
WASHINGTON, April 21 (Reuters) -

A new type of swine flu has infected at least two children in California, and while both have recovered, U.S. health officials said on Tuesday they were concerned.


They say it is possible the children were infected by other people and not by pigs, and said they have consulted with officials in Canada, Mexico and at the World Health Organization although there is no evidence that the new virus is circulating widely.

In a special alert, the CDC asked doctors in California's San Diego and Imperial counties, on the border with Mexico, to test anyone with flu-like symptoms and send the samples in for testing.

"Both of these kids came to our attention because they were seen in clinics which do routine surveillance for influenza infections," the CDC's Dr Lyn Finelli told reporters in a telephone briefing.

Neither child, a 10-year-old boy and a 9-year-old girl, had especially severe symptoms, although the girl had had a fever of 104 degrees, Finelli said.

The influenza strain is an H1N1, the same family as one of the seasonal flu viruses now circulating. But it genetically resembles a virus found in pigs and not in people, officials at the U.S. Centers for Disease Control and Prevention said.

"The viruses from the two cases are closely related genetically, resistant to (the antiviral drugs) amantadine and rimantadine, and contain a unique combination of gene segments that previously had not been reported among swine or human influenza viruses in the United States or elsewhere," they wrote.

"Neither child had known contact with pigs. The source of infection is unknown," they added. "The lack of known exposure to pigs in the two cases increases the possibility that human-to-human transmission of this new influenza virus has occurred."

In the past two or so years, Finelli said, 12 known cases of infection with swine flu have been reported but 11 of them followed known contact with pigs.

People who had contact with the children were being questioned by CDC investigators and tested if they remember having been sick recently. The boy flew to Texas with his brother and is still there, the officials added.

Blood tests may show if people were infected in the past with the same virus.

The virus is usually fairly mild but it still kills between 250,000 and 500,000 people in an average year. And every few decades, a completely new strain pops up and it can cause a pandemic, a global epidemic that kills many more than usual.

CDC officials said that they do not believe these two cases represent the beginning of such a pandemic.

(Reporting by Maggie Fox, editing by Patricia Zengerle)
-

<cite cite="http://www.alertnet.org/thenews/newsdesk/N21490866.htm">Reuters AlertNet - New type of flu affects a few US children - CDC</cite>

[Shiloh]

Re: Human Swine Flu Infection - California

Source: http://www.google.com/hostednews/ap/...MM_EQD97N25U80

Swine flu cases in Calif. worry health officials

ATLANTA (AP) ? Health officials alerted doctors Tuesday to a unique type of swine flu diagnosed in two California children, but it's unclear whether many people will be susceptible to the infection.

The children were diagnosed last week. One was a 10-year-old boy in San Diego County, and the other a 9-year-old girl in neighboring Imperial County. Both recovered.

U.S. Centers for Disease Control and Prevention officials said there's no reason for the public to take unusual measures against it.

"CDC is concerned, but that's our job," said CDC spokesman Tom Skinner.

Health officials have long feared the emergence of a deadly form of flu. They have not noted a spike in flu cases or a rash of severe illnesses. But they are continuing to investigate the genetics of the virus and track down and test people who may have been in contact with the children.

Both children became sick in late March and experienced fever and cough. The boy also vomited.

The two had not been in contact with each other, CDC officials said.

The boy's mother and brother also had a flu-like illness recently, as did a brother and a cousin of the girl. None of those relatives were tested for flu at the time of their illness.

The San Diego County boy and his 8-year-old brother flew from California to Dallas in early April and are currently with relatives in Texas. Health officials also are trying to contact the plane's flight crew and two children who sat near the boys, CDC officials said.

In the past, CDC received reports of approximately one human swine influenza virus infection every one or two years. But more than a dozen cases of human infection with swine influenza have been reported since late 2005.

Most cases occur in people who were exposed to pigs. Neither child had touched a pig, according to their families, although the girl had been at an agricultural fair four weeks before she got sick.

The jump in cases in the past few years could be because of technological improvements and expansion of public health laboratories, which have improved testing capacity. But genetic mutations could also play a role.

The new flu contains a unique combination of gene segments that have not been seen in swine or human flu viruses before, CDC officials said.

Early tests indicate this type of flu is resistant to amantadine and rimantadine, two common antiviral medications. It is not unique in that respect ? a more common virus that's been infecting people this flu season also is resistant to those drugs.

Health officials think the current seasonal flu vaccine may not protect against it.

Swine flu is an infamous disease in public health circles. In 1976, health officials were frightened by unusual cases of swine flu in soldiers at Fort Dix, N.J. The virus appeared to be similar to a deadly flu that killed millions around the world in 1918 and 1919.

Federal officials vaccinated 40 million Americans during a national campaign. The pandemic never materialized, but thousands who got the shots filed injury claims, saying they suffered a paralyzing condition and other side effects from the vaccinations.

The government is more sophisticated now in how it diagnoses and tracks diseases, said Dr. Lyn Finelli, a CDC epidemiologist.

[sharon sanders]

Re: Human Swine Flu Infection - California

"..The new flu contains a unique combination of gene segments that have not been seen in swine or human flu viruses before, CDC officials said.

Early tests indicate this type of flu is resistant to amantadine and rimantadine, two common antiviral medications. It is not unique in that respect ? a more common virus that's been infecting people this flu season also is resistant to those drugs.

Health officials think the current seasonal flu vaccine may not protect against it..."

[Giuseppe]

Re: Human Swine Flu Infection - California

The Canadian Press: Unrelated cases of swine flu in humans have U.S. officials on alert

Unrelated cases of swine flu in humans have U.S. officials on alert

U.S. authorities are investigating two cases of swine flu in unrelated children in California.


Discovery of the two cases, in children who apparently had no contact with pigs or with each other, is raising questions about whether swine flu viruses are circulating there.

Officials of the U.S. Centers for Disease Control say they have informed the World Health Organization of the cases and the investigation that is underway.

The 10-year-old boy and nine-year-old girl were infected with influenza A swine viruses of the H1N1 subtype.

Officials say it's not yet clear whether a swine H1N1 virus could trigger a human pandemic, because there is a lot of immunity in humans to human H1N1 viruses.

A senior official with the WHO says the organization is following the situation closely but there is no need to change the pandemic alert level at this point.
-

<cite cite="http://www.google.com/hostednews/canadianpress/article/ALeqM5gkfP4auwE6t3ik_obgTg9PH2t6mg">The Canadian Press: Unrelated cases of swine flu in humans have U.S. officials on alert</cite>

[Giuseppe]

Re: Human Swine Flu Infection - California

Reuters AlertNet - US officials track new flu strain

US officials track new flu strain

21 Apr 2009 20:20:38 GMT
Source: Reuters

* New type of swine flu never seen before
* Flu may have spread person to person

(Adds quotes, details, paragraphs 6, 8, background paras 14-16)

By Maggie Fox, Health and Science Editor
WASHINGTON, April 21 (Reuters) -

A new type of swine flu has infected at least two children in California and while both have recovered, U.S. health officials said on Tuesday they were looking for more cases.


They say it is possible the children were infected by other people and not by pigs, and said they have consulted with officials in Canada, Mexico and at the World Health Organization although there is no evidence that the new virus is circulating widely.

In a special alert, the CDC asked doctors in California's San Diego and Imperial counties, on the border with Mexico, to test anyone with flu-like symptoms and send the samples in for testing.

"Both of these kids came to our attention because they were seen in clinics which do routine surveillance for influenza infections," the CDC's Dr. Lyn Finelli told reporters in a telephone briefing.

Neither child, a 10-year-old boy and a 9-year-old girl, had especially severe symptoms, although the girl had had a fever of 104 degrees, Finelli said.

"We are not making the assumption that there are widespread infections out there and there is not any action that the public should take right now," Finelli said.


The influenza strain is an H1N1, the same family as one of the seasonal flu viruses now circulating. But it genetically resembles a virus found in pigs and not in people, officials at the U.S. Centers for Disease Control and Prevention said.

It has never been seen before, the CDC said.

"Neither child had known contact with pigs. The source of infection is unknown," they added. "The lack of known exposure to pigs in the two cases increases the possibility that human-to-human transmission of this new influenza virus has occurred."

CONTACT TRACING
In the past two or so years, Finelli said, 12 known cases of infection with swine flu have been reported but 11 of them followed known contact with pigs.

People were near the children were being questioned by CDC investigators and tested if they remember having been sick recently. The boy flew to Texas with his brother and is still there, the officials added.

Blood tests may show if people were infected in the past with the same virus.

The virus is usually fairly mild but it still kills between 250,000 and 500,000 people in an average year. And every few decades, a completely new strain pops up and it can cause a pandemic, a global epidemic that kills many more than usual.

Flu experts are afraid a pandemic could come at any time and are monitoring for new strains. One big fear is that the H5N1 avian flu virus now mostly affecting flocks in Asia, the Middle East, Europe and Africa might mutate into a form that could cause a pandemic.

It currently only rarely infects people but has killed 257 out of 420 infected in 15 countries since 2003, according to the World Health Organization.

CDC officials said that they do not believe these two cases represent the beginning of such a pandemic.

(Reporting by Maggie Fox,)
-

<cite cite="http://www.alertnet.org/thenews/newsdesk/N21430559.htm">Reuters AlertNet - US officials track new flu strain</cite>

[HenryN]

Re: Human Swine Flu Infection - California

HA, NA, and MP sequences have been released at GISAID for one of the California isolates.

[sharon sanders]

Re: Human Swine Flu Infection - California

from a friend of FT -

<table border="0" cellpadding="0" cellspacing="0" width="100&#37;"><tbody><tr><td align="center" bgcolor="#efefef" valign="middle">April 21, 2009 / 58 (Dispatch);1-3</td></tr> <tr> <td bgcolor="#efefef"></td></tr> </tbody></table> <!-- closing 1px line --> <table border="0" cellpadding="0" cellspacing="0" width="100%"> <tbody><tr> <td bgcolor="#333333" valign="middle" width="630"> </td> </tr> </tbody></table> <!--webbot bot="Include" endspan i-checksum="61288" --> <table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td rowspan="2" width="10"> </td> <!-- report Title --> <td valign="top" width="100%">

<!-- content area --> <!-- body area --> Swine Influenza A (H1N1) Infection in Two Children --- Southern California, March--April 2009

On April 17, 2009, CDC determined that two cases of febrile respiratory illness occurring in children who resided in adjacent counties in southern California were caused by infection with a swine influenza A (H1N1) virus. The viruses from the two cases are closely related genetically, resistant to amantadine and rimantadine, and contain a unique combination of gene segments that previously has not been reported among swine or human influenza viruses in the United States or elsewhere. Neither child had contact with pigs; the source of the infection is unknown. Investigations to identify the source of infection and to determine whether additional persons have been ill from infection with similar swine influenza viruses are ongoing. This report briefly describes the two cases and the investigations currently under way. Although this is not a new subtype of influenza A in humans, concern exists that this new strain of swine influenza A (H1N1) is substantially different from human influenza A (H1N1) viruses, that a large proportion of the population might be susceptible to infection, and that the seasonal influenza vaccine H1N1 strain might not provide protection. The lack of known exposure to pigs in the two cases increases the possibility that human-to-human transmission of this new influenza virus has occurred. Clinicians should consider animal as well as seasonal influenza virus infections in their differential diagnosis of patients who have febrile respiratory illness and who 1) live in San Diego and Imperial counties or 2) traveled to these counties or were in contact with ill persons from these counties in the 7 days preceding their illness onset, or 3) had recent exposure to pigs. Clinicians who suspect swine influenza virus infections in a patient should obtain a respiratory specimen and contact their state or local health department to facilitate testing at a state public health laboratory.

Case Reports

Patient A. On April 13, 2009, CDC was notified of a case of respiratory illness in a boy aged 10 years who lives in San Diego County, California. The patient had onset of fever, cough, and vomiting on March 30, 2009. He was taken to an outpatient clinic, and a nasopharyngeal swab was collected for testing as part of a clinical study. The boy received symptomatic treatment, and all his symptoms resolved uneventfully within approximately 1 week. The child had not received influenza vaccine during this influenza season. Initial testing at the clinic using an investigational diagnostic device identified an influenza A virus, but the test was negative for human influenza subtypes H1N1, H3N2, and H5N1. The San Diego County Health Department was notified, and per protocol, the specimen was sent for further confirmatory testing to reference laboratories, where the sample was verified to be an unsubtypable influenza A strain. On April 14, 2009, CDC received clinical specimens and determined that the virus was swine influenza A (H1N1). The boy and his family reported that the child had had no exposure to pigs. Investigation of potential animal exposures among the boy's contacts is continuing. The patient's mother had respiratory symptoms without fever in the first few days of April 2009, and a brother aged 8 years had a respiratory illness 2 weeks before illness onset in the patient and had a second illness with cough, fever, and rhinorrhea on April 11, 2009. However, no respiratory specimens were collected from either the mother or brother during their acute illnesses. Public health officials are conducting case and contact investigations to determine whether illness has occurred among other relatives and contacts in California, and during the family's travel to Texas on April 3, 2009.

Patient B.

CDC received an influenza specimen on April 17, 2009, that had been forwarded as an unsubtypable influenza A virus from the Naval Health Research Center in San Diego, California. CDC identified this specimen as a swine influenza A (H1N1) virus on April 17, 2009, and notified the California Department of Public Health. The source of the specimen, patient B, is a girl aged 9 years who resides in Imperial County, California, adjacent to San Diego County. On March 28, 2009, she had onset of cough and fever (104.3&#176;F [40.2&#176;C]). She was taken to an outpatient facility that was participating in an influenza surveillance project, treated with amoxicillin/clavulanate potassium and an antihistamine, and has since recovered uneventfully. The child had not received influenza vaccine during this influenza season. The patient and her parents reported no exposure to pigs, although the girl did attend an agricultural fair where pigs were exhibited approximately 4 weeks before illness onset. She reported that she did not see pigs at the fair and went only to the amusement section of the fair. The Imperial County Public Health Department and the California Department of Public Health are now conducting an investigation to determine possible sources of infection and to identify any additional human cases. The patient's brother aged 13 years had influenza-like symptoms on April 1, 2009, and a male cousin aged 13 years living in the home had influenza-like symptoms on March 25, 2009, 3 days before onset of the patient's symptoms. The brother and cousin were not tested for influenza at the time of their illnesses.

Epidemiologic and Laboratory Investigations

As of April 21, 2009, no epidemiologic link between patients A and B had been identified, and no additional cases of infection with the identified strain of swine influenza A (H1N1) had been identified. Surveillance data from Imperial and San Diego counties, and from California overall, showed declining influenza activity at the time of the two patients' illnesses. Case and contact investigations by the county and state departments of health in California and Texas are ongoing. Enhanced surveillance for possible additional cases is being implemented in the area.

Preliminary genetic characterization of the influenza viruses has identified them as swine influenza A (H1N1) viruses. The viruses are similar to each other, and the majority of their genes, including the hemagglutinin (HA) gene, are similar to those of swine influenza viruses that have circulated among U.S. pigs since approximately 1999; however, two genes coding for the neuraminidase (NA) and matrix (M) proteins are similar to corresponding genes of swine influenza viruses of the Eurasian lineage (1). This particular genetic combination of swine influenza virus segments has not been recognized previously among swine or human isolates in the United States, or elsewhere based on analyses of influenza genomic sequences available on GenBank.* Viruses with this combination of genes are not known to be circulating among swine in the United States; however, no formal national surveillance system exists to determine what viruses are prevalent in the U.S. swine population. Recent collaboration between the U.S. Department of Agriculture and CDC has led to development of a pilot swine influenza virus surveillance program to better understand the epidemiology and ecology of swine influenza virus infections in swine and humans.

The viruses in these two patients demonstrate antiviral resistance to amantadine and rimantadine, and testing to determine susceptibility to the neuraminidase inhibitor drugs oseltamivir and zanamivir is under way. Because these viruses carry a unique combination of genes, no information currently is available regarding the efficiency of transmission in swine or in humans. Investigations to understand transmission of this virus are ongoing.

Reported by: M Ginsberg, MD, J Hopkins, MPH, A Maroufi, MPH, G Dunne, DVM, DR Sunega, J Giessick, P McVay, MD, San Diego County Health and Human Svcs; K Lopez, MD, P Kriner, MPH, K Lopez, S Munday, MD, Imperial County Public Health Dept; K Harriman, PhD, B Sun, DVM, G Chavez, MD, D Hatch, MD, R Schechter, MD, D Vugia, MD, J Louie, MD, California Dept of Public Health. W Chung, MD, Dallas County Health and Human Svcs; N Pascoe, S Penfield, MD, J Zoretic, MD, V Fonseca, MD, Texas Dept of State Health Svcs. P Blair, PhD, D Faix, PhD, Naval Health Research Center; J Tueller, MD, Navy Medical Center, San Diego, California. T Gomez, DVM, Animal and Plant Health Inspection Svc, US Dept of Agriculture. F Averhoff, MD, F Alavrado-Ramy, MD, S Waterman, MD, J Neatherlin, MPH, Div of Global Migration and Quarantine; L Finelli, DrPH, S Jain, MD, L Brammer, MPH, J Bresee, MD, C Bridges, MD, S Doshi, MD, R Donis, PhD, R Garten, PhD, J Katz, PhD, S Klimov, PhD, D Jernigan, MD, S Lindstrom, PhD, B Shu, MD, T Uyeki, MD, X Xu, MD, N Cox, PhD, Influenza Div, National Center for Infectious and Respiratory Diseases, CDC.

Editorial Note:

In the past, CDC has received reports of approximately one human swine influenza virus infection every 1--2 years in the United States (2,3). However, during December 2005--January 2009, 12 cases of human infection with swine influenza were reported; five of these 12 cases occurred in patients who had direct exposure to pigs, six in patients reported being near pigs, and the exposure in one case was unknown (1,4,5). In the United States, novel influenza A virus infections in humans, including swine influenza infections, have been nationally notifiable conditions since 2007. The recent increased reporting might be, in part, a result of increased influenza testing capabilities in public health laboratories, but genetic changes in swine influenza viruses and other factors also might be a factor (1,4,5). Although the vast majority of human infections with animal influenza viruses do not result in human-to-human transmission (2,3), each case should be fully investigated to be certain that such viruses are not spreading among humans and to limit further exposure of humans to infected animals, if infected animals are identified. Such investigations should include close collaboration between state and local public health officials with animal health officials.

The lack of known exposure to pigs in the two cases described in this report increases the possibility that human-to-human transmission of this new influenza virus has occurred. Clinicians should consider animal as well as seasonal influenza virus infections in the differential diagnosis of patients with febrile respiratory illness who live in San Diego and Imperial counties or have traveled to these areas or been in contact with ill persons from these areas in the 7 days before their illness onset. In addition, clinicians should consider animal influenza infections among persons with febrile respiratory illness who have been near pigs, such as attending fairs or other places where pigs might be displayed. Clinicians who suspect swine influenza virus infections in humans should obtain a nasopharyngeal swab from the patient, place the swab in a viral transport medium, and contact their state or local health department to facilitate transport and timely diagnosis at a state public health laboratory. CDC requests that state public health laboratories send all influenza A specimens that cannot be subtyped to the CDC, Influenza Division, Virus Surveillance and Diagnostics Branch Laboratory.

Interim guidance on infection control, treatment, and chemoprophylaxis for swine influenza is available at http://www.cdc.gov/flu/swine/recommendations.htm. Additional information about swine influenza is available at http://www.cdc.gov/flu/swine/index.htm.

References

1. Vincent AL, Ma W, Lager KM, Janke BH, Richt JA. Swine influenza viruses: a North American perspective. Adv Virus Res 2008;72:127--54.
2. Myers KP, Olsen CW, Gray GC. Cases of swine influenza in humans: a review of the literature. Clin Infect Dis 2007;44:1084--8.
3. Wells DL, Hopfensperger DJ, Arden NH, et al. Swine influenza virus infections. Transmission from ill pigs to humans at a Wisconsin agricultural fair and subsequent probable person-to-person transmission. JAMA 1991;265:478--81.
4. Vincent AL, Swenson SL, Lager KM, Gauger PC, Loiacono C, Zhang Y. Characterization of an influenza A virus isolated from pigs during an outbreak of respiratory disease in swine and people during a county fair in the United States. Vet Microbiol 2009;online publication ahead of print.
5. Newman AP, Reisdorf E, Beinemann J, et al. Human case of swine influenza A (H1N1) triple reassortant virus infection, Wisconsin. Emerg Infect Dis 2008;14:1470--2.

* Available at http://www.ncbi.nlm.nih.gov/Genbank.

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[HenryN]

Re: Human Swine Flu Infection - California

A/California/04/2009

is at GISAID. I do not see it at Genbank.

[HenryN]

Re: Human Swine Flu Infection - California

HA is North American swine
NA is European swine

[HenryN]

Re: Human Swine Flu Infection - California

Scientists Studying 2 Cases of Unknown Swine Flu Strain(Washn)

<TABLE cellSpacing=0 cellPadding=0 width=428 border=0><TBODY><TR vAlign=bottom><TD class=byln width=328>4/21/2009, 6:39 p.m. ET David Brown
The Associated Press</TD><TD width=3> </TD><TD width=97></TD></TR></TBODY></TABLE>
(AP) ? WASHINGTON ? Public health authorities are investigating two highly unusual cases of a previously unknown strain of swine flu that occurred in the San Diego area late last month.
The cases occurred almost simultaneously in children who had no contact with pigs or each other, a scenario that raised the possibility the illnesses might be the sign of an emerging pandemic strain of influenza.
More than 50 scientists and epidemiologists at the Centers for Disease Control and Prevention in Atlanta are studying the strain, and dozens of public health investigators in Southern California are looking for more cases among the those who had contact with the children.
"While we have a low index of suspicion that this is a pandemic, we're being very careful in our investigation to rule out every possibility," said Lyn Finelli, an epidemiologist in CDC's influenza division.
Neither of the children ? a 10-year-old boy in San Diego County and a 9-year-old girl in Imperial County, just to the east ? was seriously ill. The cases were detected because both were treated at clinics that took nose or throat swabs looking for influenza and passed the samples on to health department labs when they could not identify the strains they found.
"It was a very fortunate lightning strike," Finelli said Tuesday.
Both children have recovered. The San Diego boy, however, took an airplane trip to Texas with his younger brother while at the tail-end of his illness before it was know he had an unusual strain of flu. Health officials in the Dallas area are looking for cases there, as well as among airline employees who assisted the two children, who traveled as "unaccompanied minors."
Public health officials in the two California counties, which both border Mexico, are urging physicians and hospitals to look carefully for cases of flu and report any to local health departments.
Flu season, which officially ended this month, was mild this year. But Imperial County's health officer, Stephen Munday, said his jurisdiction saw a blip of cases late in March, although not enough to qualify as an outbreak. Whether any other cases involved swine flu remains unknown.
The Imperial County girl fell ill on March 28 with cough and a high fever. The San Diego boy came down with similar symptoms, plus vomiting, two days later. People in both households fell ill before and after the children did, although health officials have not determined whether those were also swine flu.
Munday said his department has drawn blood from more than 20 people to be tested for antibodies to the swine flu strain, which would indicate those people had been infected even if they never had symptoms. He said some had traveled into Mexico recently but would not describe them further.
"As of yet we have not been able to come up with any explanation of why anyone would have swine flu," he said.
Molecular analysis of the virus suggests it is the product of a rare event called a gene reassortment. In a reassortment, two distinct strains of virus infect the same cell. The viruses take over the cell's genetic machinery to make new copies of themselves, mingling the genes of the two strains to create a new, essentially hybrid, strain. Six of the eight genes in the new strain are from the North American lineage of swine flu; two are from the Eurasian lineage.
The reassortment probably occurred in a pig sometime in the last decade. Both the sets of genes are slightly different from those of their original lineage, a sign that time has passed. But it's unlikely they have been in human beings very long.
"If these viruses had been circulating at low levels in humans for several years, we probably would have detected them," said Nancy Cox, head of CDC's influenza division.
The ability to find and identify rare strains of influenza virus has improved greatly in the last decade, spurred in part by the "bird flu" outbreak in Asia and the 2001 anthrax attacks.
In the last three years, 12 cases of human illness caused by swine flu strains have been investigated by the CDC. In 11 of the cases, however, those infected had direct or indirect exposure to pigs.
In 1976, a strain of swine flu caused illness in 13 soldiers at Fort Dix, in New Jersey, killing one. Fearing a pandemic, the federal government ordered emergency production of a vaccine and planned to administer it to millions of elderly and vulnerable Americans. Mass immunization was halted, however, when the virus failed to spread and some vaccine recipients got a rare neurological disorder called Guillain-Barre syndrome.

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