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Subject Int'l Society for Infectious Diseases - Reports: INFLUENZA A H1N1 VIRUS, SWINE, HUMAN - NORTH AMERICA
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Original Message [link to www.promedmail.org]

"We should call it swine flu as this is common parlance but there have been no cases in swine to date. We don't know if this strain has occurred in swine but there is no evidence that it has. No surveillance yet but the SIV (swine influenza virus) is endemic and controlled by vaccination here in the US and probably in Mexico. Mexico's pork production is just like that in the US, Canada and Europe -- very intensive. I do not know about the extent of backyard swine but will try to find out. - Mod.PC"

Archive Number 20090425.1552
Published Date 25-APR-2009
Subject PRO/AH/EDR> Influenza A (H1N1) virus, swine, human - N America

A ProMED-mail post
< [link to www.promedmail.org>]
ProMED-mail is a program of the
International Society for Infectious Diseases
< [link to www.isid.org>]

In this update:
[1] USA - MMWR
[2] USA, Mexico - WHO

[1] USA - MMWR
Date: 24 Apr 2009
Source: MMWR Morb Mortal Wkly Rep Dispatch 24 Apr 2009/58 (dispatch);1-3
< [link to cdc.gov]

Update: swine influenza A (H1N1) infections --- California and Texas, April 2009
On [21 Apr 2009], CDC reported that 2 recent cases of febrile respiratory illness in children in southern California had been caused by infection with genetically similar swine influenza A (H1N1) viruses. The viruses contained a unique combination of gene segments that had not been reported previously among swine or human influenza viruses in the United States or elsewhere (1). Neither child had known contact with pigs, resulting in concern that human-to-human transmission might have occurred. The seasonal influenza vaccine H1N1 strain is thought to be unlikely to provide protection. This report updates the status of the ongoing investigation and provides preliminary details about 6 additional persons infected by the same strain of swine influenza A (H1N1) virus identified in the previous cases, as of [24 Apr 2009]. The 6 additional cases were reported in San Diego County, California (3 cases), Imperial County, California (one case), and Guadalupe County, Texas (2 cases). CDC, the California Department of Public Health, and the Texas Department of Health and Human Services are conducting case investigations, monitoring for illness in contacts of the 8 patients, and enhancing surveillance to determine the extent of spread of the virus. CDC continues to recommend that any influenza A viruses that cannot be subtyped be sent promptly for testing to CDC. In addition, swine influenza A (H1N1) viruses of the same strain as those in the US patients have been confirmed by CDC among specimens from patients in Mexico. Clinicians should consider swine influenza as well as seasonal influenza virus infections in the differential diagnosis for patients who have febrile respiratory illness and who 1) live in San Diego and Imperial counties, California, or Guadalupe County, Texas, or traveled to these counties or 2) who traveled recently to Mexico or were in contact with persons who had febrile respiratory illness and were in one of the 3 US counties or Mexico during the 7 days preceding their illness onset.

Case reports
San Diego County, California. On [9 Apr 2009], an adolescent girl aged 16 years and her father aged 54 years went to a San Diego County clinic with acute respiratory illness. The youth had onset of illness on [5 Apr 2009]. Her symptoms included fever, cough, headache, and rhinorrhea. The father had onset of illness on [6 Apr 2009] with symptoms that included fever, cough, and rhinorrhea. Both had self-limited illnesses and have recovered. The father had received seasonal influenza vaccine in October 2008; the daughter was unvaccinated. Respiratory specimens were obtained from both, tested in the San Diego County Health Department Laboratory, and found to be positive for influenza A using reverse transcription--polymerase chain reaction (RT-PCR), but could not be further subtyped. Two household contacts of the patients have reported recent mild acute respiratory illnesses; specimens have been collected from these household members for testing. One additional case, in a child residing in San Diego County, was identified on [24 Apr 2009]; epidemiologic details regarding this case are pending.

Imperial County, California. A woman aged 41 years with an autoimmune illness who resided in Imperial County developed fever, headache, sore throat, diarrhea, vomiting, and myalgias on [12 Apr 2009]. She was hospitalized on [15 Apr 2009]. She recovered and was discharged on [22 Apr 2009]. A respiratory specimen obtained [16 Apr 2009] was found to be influenza A positive by RT-PCR at the San Diego Country Health Department Laboratory, but could not be further subtyped. The woman had not been vaccinated against seasonal influenza viruses during the 2008--09 season. Three household contacts of the woman reported no recent respiratory illness.

Guadalupe County, Texas. Two adolescent boys aged 16 years who resided in Guadalupe County near San Antonio were tested for influenza and found to be positive for influenza A on [15 Apr 2009]. The youths had become ill with acute respiratory symptoms on [10 Apr 2009] and [14 Apr 2009], respectively, and both had gone to an outpatient clinic for evaluation on [15 Apr 2009]. Identification and tracking of the youths' contacts is under way.

Five of the new cases were identified through diagnostic specimens collected by the health care facility in which the patients were examined, based on clinical suspicion of influenza; information regarding the 6th case is pending. The positive specimens were sent to public health laboratories for further evaluation as part of routine influenza surveillance in the 3 counties.

Outbreaks in Mexico
Mexican public health authorities have reported increased levels of respiratory disease, including reports of severe pneumonia cases and deaths, in recent weeks. Most reported disease and outbreaks are reported from central Mexico, but outbreaks and severe respiratory disease cases also have been reported from states along the US-Mexico border. Testing of specimens collected from persons with respiratory disease in Mexico by the CDC laboratory has identified the same strain of swine influenza A (H1N1) as identified in the US cases. However, no clear data are available to assess the link between the increased disease reports in Mexico and the confirmation of swine influenza in a small number of specimens. CDC is assisting public health authorities in Mexico in testing additional specimens and providing epidemiologic support. None of the US patients traveled to Mexico within 7 days of the onset of their illness.

Epidemiologic and laboratory investigations
As of April 24, epidemiologic links identified among the new cases included 1) the household of the father and daughter in San Diego County, and 2) the school attended by the 2 youths in Guadalupe County. As of April 24, no epidemiologic link between the Texas cases and the California cases had been identified, nor between the 3 new California cases and the 2 cases previously reported. No recent exposure to pigs has been identified for any of the 7 patients. Close contacts of all patients are being investigated to determine whether person-to-person spread has occurred.

Enhanced surveillance for additional cases is ongoing in California and in Texas. Clinicians have been advised to test patients who visit a clinic or hospital with febrile respiratory illness for influenza. Positive samples should be sent to public health laboratories for further characterization. Seasonal influenza activity continues to decline in the United States, including in Texas and California, but remains a cause of influenza-like illness in both areas.

Viruses from 6 of the 8 patients have been tested for resistance to antiviral medications. All 6 have been found resistant to amantadine and rimantidine but sensitive to zanamivir and oseltamivir.

Reported by: San Diego County Health and Human Svcs; Imperial County Public Health Dept; California Dept of Public Health. Dallas County Health and Human Svcs; Texas Dept of State Health Svcs. Naval Health Research Center; Navy Medical Center, San Diego, California. Animal and Plant Health Inspection Svc, US Dept of Agriculture. Div of Global Migration and Quarantine, National Center for Preparedness, Detection, and Control of Infectious Diseases; National Center for Zoonotic, Vector-Borne, and Enteric Diseases; Influenza Div, National Center for Infectious and Respiratory Diseases, CDC.

Editorial note
In the US, novel influenza A virus infections in humans, including swine influenza A (H1N1) infections, have been nationally notifiable conditions since 2007. Recent pandemic influenza preparedness activities have greatly increased the capacity of public health laboratories in the US to perform RT-PCR for influenza and to subtype influenza A viruses they receive from their routine surveillance, enhancing the ability of US laboratories to identify novel influenza A virus infections. Before the cases described in this ongoing investigation, recent cases of swine influenza in humans reported to CDC occurred in persons who either had exposure to pigs or to a family member with exposure to pigs. Transmission of swine influenza viruses between persons with no pig exposure has been described previously, but that transmission has been limited (2,3). The lack of a known history of pig exposure for any of the patients in the current cases indicates that they acquired infection through contact with other infected persons.

The spectrum of illness in the current cases is not yet fully defined. In the 8 cases identified to date, 6 patients had self-limited illnesses and were treated as outpatients. One patient was hospitalized. Previous reports of swine influenza, although in strains different from the one identified in the current cases, mostly included mild upper respiratory illness; but severe lower respiratory illness and death also have been reported (2,3).

The extent of spread of the strain of swine influenza virus in this investigation is not known. Ongoing investigations by California and Texas authorities of the 2 previously reported patients, a boy aged 10 years and a girl aged 9 years, include identification of persons in close contact with the children during the period when they were likely infectious (defined as from 1 day before symptom onset to 7 days after symptom onset). These contacts have included household members, extended family members, clinic staff members who cared for the children, and persons in close contact with the boy during his travel to Texas on April 3. Respiratory specimens are being collected from contacts found to have ongoing illness. In addition, enhanced surveillance for possible cases is under way in clinics and hospitals in the areas where the patients reside. Similar investigations and enhanced surveillance are now under way in the additional 6 cases.

Clinicians should consider swine influenza infection in the differential diagnosis of patients with febrile respiratory illness and who 1) live in San Diego and Imperial counties, California, or Guadalupe County, Texas, or traveled to these counties or 2) who traveled recently to Mexico or were in contact with persons who had febrile respiratory illness and were in one of the 3 US counties or Mexico during the 7 days preceding their illness onset. Any unusual clusters of febrile respiratory illness elsewhere in the United States also should be investigated.

Patients who meet these criteria should be tested for influenza, and specimens positive for influenza should be sent to public health laboratories for further characterization. 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, refrigerate the specimen, and then 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 promptly send all influenza A specimens that cannot be subtyped to the CDC, Influenza Division, Virus Surveillance and Diagnostics Branch Laboratory. As a precautionary step, CDC is working with other partners to develop a vaccine seed strain specific to these recent swine influenza viruses in humans.

As always, persons with febrile respiratory illness should stay home from work or school to avoid spreading infections (including influenza and other respiratory illnesses) to others in their communities. In addition, frequent hand washing can lessen the spread of respiratory illness (5). Interim guidance on infection control, treatment, and chemoprophylaxis for swine influenza is available at < [link to www.cdc.gov] Additional information about swine influenza is available at < [link to www.cdc.gov]

1. CDC. Swine influenza A (H1N1) infection in two children -- Southern California, March-April 2009. MMWR 2009; 58: 400-2. [available at < [link to cdc.gov]
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. 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.
5. Ryan MA, Christian RS, Wohlrabe J. Handwashing and respiratory illness among young adults in military training. Am J Prev Med 2001; 21: 79-83.

-- communicated by:
ProMED-mail <[email protected]>

[2] USA, Mexico - WHO
Date: 24 Apr 2009
Source: WHO Epidemic and Pandemic Alert and Response (EPR) [edited]
< [link to www.who.int]

Influenza-like illness in the United States and Mexico 24 April 2009
The United States Government has reported 7 confirmed human cases of swine influenza A/H1N1 in the USA (5 in California and 2 in Texas) and 9 suspect cases. All 7 confirmed cases had mild influenza-like illness (ILI), with only one requiring brief hospitalization. No deaths have been reported.

The Government of Mexico has reported three separate events. In the Federal District of Mexico, surveillance began picking up cases of ILI starting 18 March [2009]. The number of cases has risen steadily through April and as of 23 April there are now more than 854 cases of pneumonia from the capital, 59 of whom have died. In San Luis Potosi, in central Mexico, 24 cases of ILI, with 3 deaths, have been reported. And from Mexicali, near the border with the United States, 4 cases of ILI, none fatal, have been reported.

Of the Mexican cases, 18 have been laboratory confirmed in Canada as swine influenza A/H1N1, while 12 of those are genetically identical to the swine influenza A/H1N1 viruses from California.

The majority of these cases have occurred in otherwise healthy young adults. Influenza normally affects the very young and the very old, but these age groups have not been heavily affected in Mexico. Because there are human cases associated with an animal influenza virus, and because of the geographical spread of multiple community outbreaks, plus the somewhat unusual age groups affected, these events are of high concern.

The swine influenza A/H1N1 viruses characterized in this outbreak have not been previously detected in pigs or humans. The viruses so far characterized have been sensitive to oseltamivir, but resistant to both amantadine and rimantadine.

The World Health Organization has been in constant contact with the health authorities in the United States, Mexico, and Canada in order to better understand the risk which these ILI events pose. WHO (and the Pan American Health Organization [PAHO]) is sending missions of experts to Mexico to work with health authorities there. It is helping its member states to increase field epidemiology activities, laboratory diagnosis and clinical management. Moreover, WHO's partners in the Global Alert and Response Network have been alerted and are ready to assist as requested by the member states.

WHO acknowledges the US and Mexico for their proactive reporting and their collaboration with WHO and will continue to work with member states to further characterize the outbreak.

-- communicated by:
ProMED-mail <[email protected]>

[3] Mexico - Newswire
Date: 24 Apr 2009
Source: Yahoo News / Associated Press
< [link to news.yahoo.com]

A unique strain of swine flu is the suspected killer of dozens of people in Mexico, where authorities closed schools, museums, libraries and theaters in the capital on Friday [24 Apr 2009] to try to contain an outbreak that has spurred concerns of a global flu epidemic.

The worrisome new virus -- which combines genetic material from pigs, birds and humans in a way researchers have not seen before -- also sickened at least eight people in Texas and California, though there have been no deaths in the US "We are very, very concerned," WHO spokesman Thomas Abraham said. "We have what appears to be a novel virus and it has spread from human to human ... It's all hands on deck at the moment."

The outbreak caused alarm in Mexico, where more than 1000 people have been sickened. Residents of the capital donned surgical masks and authorities ordered the most sweeping shutdown of public gathering places in a quarter century. President Felipe Calderon met with his Cabinet Friday [24 Apr 2009] to coordinate Mexico's response.

WHO was convening an expert panel to consider whether to raise the pandemic alert level or issue travel advisories. It might already be too late to contain the outbreak, a prominent US pandemic flu expert said late on Friday.

Given how quickly flu can spread around the globe, if these are the first signs of a pandemic, then there are probably cases incubating around the world already, said Dr Michael Osterholm at the University of Minnesota.

In Mexico City, "literally hundreds and thousands of travelers come in and out every day," Osterholm said. "You'd have to believe there's been more unrecognized transmission that's occurred."

There is no vaccine that specifically protects against swine flu, and it was unclear how much protection current human flu vaccines might offer. A "seed stock" genetically matched to the new swine flu virus has been created by the US Centers for Disease Control, said Dr Richard Besser, the agency's acting director. If the government decides vaccine production is necessary, manufacturers would need that stock to get started.

Authorities in Mexico urged people to avoid hospitals unless they had a medical emergency, since hospitals are centers of infection. They also said Mexicans should refrain from customary greetings such as shaking hands or kissing cheeks. At Mexico City's international airport, passengers were questioned to try to prevent anyone with flu symptoms from boarding airplanes and spreading the disease.

Epidemiologists are particularly concerned because the only fatalities so far were in young people and adults. The 8 US victims recovered from symptoms that were like those of the regular flu, mostly fever, cough, and sore throat, though some also experienced vomiting and diarrhea.

US health officials announced an outbreak notice to travelers, urging caution and frequent handwashing, but stopping short of telling Americans to avoid Mexico.

Mexico's health secretary Jose Angel Cordoba said 68 people have died of flu and the new swine flu strain had been confirmed in 20 of those deaths. At least 1004 people nationwide were sick from the suspected flu, he said.

The geographical spread of the outbreaks also concerned the WHO -- while 13 of the 20 deaths were in Mexico City, the rest were spread across Mexico -- 4 in central San Luis Potosi, 2 up near the US border in Baja California, and one in southern Oaxaca state.

Scientists have long been concerned that a new flu virus could launch a worldwide pandemic of a killer disease. A new virus could evolve when different flu viruses infect a pig, a person or a bird, mingling their genetic material. The resulting hybrid could spread quickly because people would have no natural defenses against it.

Still, flu experts were concerned but not alarmed about the latest outbreak. "We've seen swine influenza in humans over the past several years, and in most cases, it's come from direct pig contact. This seems to be different," said Dr Arnold Monto, a flu expert with the University of Michigan. "I think we need to be careful and not apprehensive, but certainly paying attention to new developments as they proceed."

CDC says 2 flu drugs, Tamiflu [oseltamivir] and Relenza [zanamivir], seem effective against the new strain. Roche, the maker of Tamiflu, said the company is prepared to immediately deploy a stockpile of the drug if requested. Both drugs must be taken early, within a few days of the onset of symptoms, to be most effective. Cordoba said Mexico has enough Tamiflu to treat 1 million people, but the medicine will be strictly controlled and handed out only by doctors.

Mexico's government had maintained until late on Thursday that there was nothing unusual about the ffrostes, although this year's flu season had been worse and longer than past years. The sudden turnaround by public health officials angered many Mexicans. The city was handing out free surgical masks to passengers on buses and the subway system, which carries 5 million people each day. Government workers were ordered to wear the masks, and authorities urged residents to stay home from work if they felt ill.

Closing schools across Mexico's capital of 20 million kept 6.1 million students home, as well as thousands of university students. All state and city-run cultural activities were suspended, including libraries, state-run theaters, and at least 14 museums. Private athletic clubs closed down and soccer leagues were considering canceling weekend games. The closures were the first citywide shutdown of public gathering places since millions died in the devastating 1985 earthquake.

Mexico's response brought to mind other major outbreaks, such as when SARS hit Asia. At its peak in 2003, Beijing shuttered schools, cinemas and restaurants, and thousands of people were quarantined at home. In March 2008, Hong Kong ordered more than half a million students to stay home for 2 weeks because of a flu outbreak. It was the first such closure in Hong Kong since the outbreak of SARS, or severe acute respiratory syndrome.

"It's great they are taking precautions," said Lillian Molina, a teacher at the Montessori's World preschool in Mexico City, who scrubbed down empty classrooms with Clorox, soap and Lysol between fielding calls from worried parents.

US health officials said the outbreak is not yet a reason for alarm in the United States. The 5 people sickened in California and 3 in Texas have all recovered. It's unclear how the 8, who became ill between late March and mid-April, contracted the virus because none were in contact with pigs, which is how people usually catch swine flu. And only a few were in contact with each other.

CDC officials described the virus as having a unique combination of gene segments not seen before in people or pigs. The bug contains human virus, avian virus from North America and pig viruses from North America, Europe, and Asia. It may be completely new, or it may have been around for a while and was only detected now through improved testing and surveillance, CDC officials said.

The most notorious flu pandemic is thought to have killed at least 40 million people worldwide in 1918-19. Two other, less deadly flu pandemics struck in 1957 and 1968.

[byline: Mark Stevenson]

-- communicated by:
Daniel Madar
<[email protected]>

[ProMED-mail would like to thank all our subscribers who have been submitting numerous information sources on the above outbreak(s) situation that is unfolding by the hour as more and more information becomes available.

According to the above information are now 8 confirmed cases of the novel influenza A H1N1 virus infection in the USA, all mild, occurring in counties with known increased population flow/transit between the USA & Mexico. According to the official report from WHO, there have been now more than 854 cases of pneumonia reported from the capital (Mexico City) of which 59 have died (case fatality rate [CFR] 6.9 per cent). In San Luis Potosi (central Mexico) there were 24 cases of influenza-like illness (ILI) reported with 3 deaths (CFR 12.5 per cent) and in Mexicali, (near the border with the United States), there have been 4 cases of ILI reported with no deaths.

It should be noted here that the data from Mexico refers to inpatient hospitalized cases, whereas the ILI surveillance sites in the USA are predominantly from sentinel reporting outpatient facilities. This difference in surveillance sites may account for an apparent disparity in severity of the illnesses in cases reported in Mexico vs those presently reported in the USA. As more uniform active surveillance (case finding) is implemented, these disparities may lessen.

The absence of direct connection between the cases in the USA and the cases in Mexico does not rule out the outbreaks being linked, as the population flow between the 2 countries is high and 12 isolates from Mexico are reported to be genetically identical to those isolated in the USA. One suspects the epidemic curve is already multiple generations past the "index case". The virus has apparently been circulating in Mexico for several weeks, and in the USA for at least 2 weeks according to the above reports. - Mod.MPP

We should call it swine flu as this is common parlance but there have been no cases in swine to date. We don't know if this strain has occurred in swine but there is no evidence that it has. No surveillance yet but the SIV (swine influenza virus) is endemic and controlled by vaccination here in the US and probably in Mexico. Mexico's pork production is just like that in the US, Canada and Europe -- very intensive. I do not know about the extent of backyard swine but will try to find out. - Mod.PC

The map link shows the proximity of Texas, California, and Mexico < [link to healthmap.org] - Mod.SH]

[see also:
Acute respiratory disease - Mexico, swine virus susp 20090424.1546
Influenza A (H1N1) virus, swine, human - USA (02): (CA, TX) 20090424.1541
Influenza A (H1N1) virus, swine, human - USA: (CA) 20090422.1516
Influenza A (H1N1) virus, swine, human - Spain 20090220.0715
Influenza A (H1N1) virus, swine, human - USA (TX) 20081125.3715
Influenza A (H2N3) virus, swine - USA 20071219.4079
Influenza, swine, human - USA (IA): November 2006 20070108.0077]

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