Do Pigs Catch Swine Flu?

October 17, 2009

Can pigs catch swine flu (a.k.a. Pandemic Influenza A:H1N1)? In a word, YES.

Since the swine flu pandemic began earlier this year, there have been several reports of swine herds becoming infected with the swine flu virus after coming into contact with an infected farm worker.

The first report – in June 2009 – of human-to-pig transmission of this virus strain came from Alberta, Canada. Since then, the Republic of Ireland, Norway and, most recently, the United States have discovered this strain of influenza virus in one or more swine herds. A second Canadian province – Québec – also has reported an infected herd.

Can infected swine pass the virus to humans? Probably.

While there is no iron-clad proof so far of swine-to-human transmission, two Canadian government workers are thought to have become infected with the pandemic swine flu virus as a result of their close contact with the infected Alberta herd. The workers had been furnished with protective gear to use while obtaining samples from the infected herd, but had not been shown the proper way to wear it. A different swine flu virus also was reported to have passed from infected pigs to humans at a county fair in Ohio (USA) in 2007.

Can the virus be passed to poultry and other birds? Definitely.

The pandemic swine flu virus strain was found in a flock of turkeys in Chile.

Does eating meat from infected pigs or poultry put you at risk of catching swine flu? In a word, NO.

Influenza is a respiratory virus. Slaughterhouse workers may be at risk of infection from inhaling aerosols generated during slaughter of the animals and handling of the carcasses.

But the virus – as USDA assures us – is not normally present in muscle meat.

Also, according to the World Health Organization, cooking meat to an internal temperature of 160ºF (70ºC) will inactivate any stray virus particles that might find their way into meat.

The bottom line?

Pigs can, and do, catch the flu from people. People probably can catch the flu from close contact with infected live pigs. There will be a lot of opportunities during this pandemic for people to catch the flu. But eating properly cooked pork is not one of them.

World Health Organization Declares Flu Pandemic

June 11, 2009

According to the BBC, the WHO is raising its swine flu (Influenza A/H1N1) alert to Level 6, declaring a full-fledged pandemic.

Today's change in alert status comes 50 days after the first warning – issued April 24 – that a novel strain of influenza A had appeared in Mexico and parts of the United States. In the last 50 days, the new virus, which contains genetic components of swine, bird and human flu strains, has spread to 74 countries, infecting 27,737 victims, and killing 141.

As early reports of the spread of the disease piled up, WHO quickly raised its alert levels from Level 3 to Level 4 (April 28) and from Level 4 to Level 5 (April 29). The decision to proclaim a Level 6 alert makes the pandemic official.

What does Level 6 mean? Simply that the new influenza virus has become established in communities in two or more different regions of the world. Illnesses caused by the new flu already were reported all over North America and in several European countries – notably the United Kingdom and Spain.

The illnesses in North America and Europe weren't enough to convince WHO to declare a flu pandemic. Apparently, though, the recent rapid and extensive spread of the virus in Australia and New Zealand was impossible to ignore.

The Southern Hemisphere is now entering winter – prime influenza season. The performance of the new flu strain over the next few months will provide a good indication of what to expect in the North America, Europe and Asia during the 2009-2010 flu season.

National and international health agencies will be watching closely for any signs that the relatively mild strain is mutating into something more dangerous before the next Northern Hemisphere flu season begins.

Swine Flu and Snake Oil

May 28, 2009

The (unofficial) swine flu pandemic continues to claim victims and disrupt lives. As of yesterday:

• 95 people have died
  
• 13,398 people have been infected (lab-confirmed)
  
• 48 countries have reported at least one confirmed case.
  

International, national, state and local health authorities have spent millions of dollars on lab tests to track the progress of the pandemic. South Dakota, for example, has confirmed 6 cases of swine flu, out of 3,082 people tested. The state has tested nearly 0.4% of its entire population – 4 out of every 1,000 residents –  for swine flu.

Pork producers in North America have been badly hurt by the disease. In knee-jerk reactions to the term "swine flu", Russia, China, Ukraine, and several other countries banned the importation of swine and pork products from Mexico, the United States and Canada. Those bans are gradually – and quietly – being lifted.

While the cost of tracking and treating this virus continues to rise as the disease spreads to every corner of the world, some entrepreneurs are seeing a silver lining.

Sales of protective face masks skyrocketed during the early days of the epidemic, even though these masks offer little or no protection. Companies that produce anti-viral medications –including Roche, the manufacturer of Tamiflu – will reap the benefits of increased sales. And vaccine manufacturers such as Sanofi Pasteur already have received orders for swine flu vaccine. 

FDA reported recently that some unscrupulous web sites are taking advantage of people's fears to flog their anti-flu products. The agency has posted a Fraudulent 2009 H1N1 Influenza Products List and is updating the list daily. 

FDA has been warning these modern snake oil salespeople to stop making false or unsupported claims. As a result, many of the sites listed by FDA have removed their swine flu claims or have indicated that their products are unavailable in the USA. Nevertheless, consumers must remain on guard.

Avoid getting ripped off by fraudulent anti-swine flu claims.

• Check to see whether a product or web site is on the FDA's warning list
• Be skeptical of claims such as "Recommended by the U.S. Centers of Disease Control and World Health Organization to prevent a pandemic flu virus." 
  
• Think twice before relying on "microbial rebalancing"
  
• Disbelieve miracle cures that sound too good to be true; they probably are – and might even be harmful.
  
• Run the other way from web sites that practices fear-mongering.
  

We live in a free enterprise society. We expect companies to take risks, make investments, market their products and services honestly, and earn profits. Marketing untested products by making unsupported or false claims is not free enterprise. It is fraud, and must be treated as fraud.

We urge the FDA, the US Consumer Products Safety Commission, and their counterparts in other countries, to stamp out "snake oil" web sites.

Influenza A(H1N1): Let Them Eat Pork!

May 7, 2009

Earlier today, the World Health Organization (WHO, together with the Food and Agriculture Organization (FAO, a UN body) and the World Organization for Animal Health (OIE) reissued the following joint statement in an attempt to clarify their stance on the safety of eating pork during the current influenza outbreak.

"In the ongoing spread of influenza A(H1N1), concerns about the possibility of this virus being found in pigs and the safety of pork and pork products have been raised.

Influenza viruses are not known to be transmissible to people through eating processed pork or other food products derived from pigs.

Heat treatments commonly used in cooking meat (e.g. 70°C/160°F core temperature) will readily inactivate any viruses potentially present in raw meat products.

Pork and pork products, handled in accordance with good hygienic practices recommended by the WHO , Codex Alimentarius Commission and the OIE, will not be a source of infection. 

Authorities and consumers should ensure that meat from sick pigs or pigs found dead are not processed or used for human consumption under any circumstances."

eFoodAlert has been reviewing research reports on the subject, in an effort to clarify this food safety issue for our readers. Here is what we've found.

Influenza Virus Is Restricted To The Respiratory System In Swine

USDA researchers deliberately infected pigs (through the nose) with both swine influenza viruses and with highly pathogenic avian influenza viruses. They collected organ samples from the infected pigs to determine how far the viruses spread through the body. In all cases, the influenza viruses were limited to the respiratory system – the lungs, trachea, nasal passages and tonsils. None of the other organs showed any evidence of influenza virus infection.

The researchers also investigated whether pigs could develop influenza when fed meat from chickens that were infected with avian influenza. Although the animals developed an antibody reaction to the virus, none of the pigs developed symptoms of influenza. The virus was recovered from nose and tonsil samples, but not from rectal swabs. It is likely that the pigs developed mild infections as a result of contact between the infected meat and their tonsils.

Influenza Virus Is Inactivated By Heating

Influenza viruses are inactivated within 5-6 minutes at 51ºC (125ºF), and in no more than a second or two at 70º-74ºC (158º-165ºF). USDA already recommends that poultry meat be cooked to an internal temperature of 160ºF to ensure that bacterial pathogens have been killed. 

Influenza Virus Survives For Longer Periods On Non-porous Surfaces Than On Porous Surfaces

Influenza virus particles can remain active at room temperature for hours – even days – on some inert, non-porous surfaces. These include plastic,  stainless steel (the particles are inactivated much more quickly on copper), and even Swiss banknotes, which are made using a non-porous resin. The virus particles die far more rapidly on porous surfaces, such as facial tissues; they also are inactivated rapidly on human skin.

What does this mean for someone who likes to eat pork?

• All of the federal and state agencies who have weighed in on this issue claim that a pig suffering from influenza would not be approved for slaughter. Even so, it's possible that an infected pig that is not yet exhibiting symptoms might get past this initial screening.
  
• While the influenza virus doesn't appear to invade organs outside of the respiratory system, it's possible that some live virus particles may be spread over other parts of the carcass during organ removal (evisceration) in the slaughterhouse.
  
• Stray influenza virus particles that happen to land on edible parts of the carcass almost certainly would become inactivated between the slaughterhouse and the supermarket.
  
• Any residual stray virus particles that manage to survive the trip from slaughterhouse to household kitchen will be killed by standard, recommended cooking procedures.
  

In a nutshell, it is safe to prepare and eat pork.

Influenza A(H1N1): In The Beginning

May 6, 2009

The World Health Organization today reported that the number of confirmed cases worldwide has reached 1,893. Twenty-three countries have confirmed cases; Mexico still leads the list with 942 cases, including 29 deaths. The United States is next with 642 cases and two deaths, followed by Canada (165 cases) and Spain (73 cases).

". . . in the US swine industry, transmission of influenza viruses between swine and humans is fairly common and is bidirectional."

E. Thacker & B. Janke, writing in Journal of Infectious Diseases

In 1988, a pregnant woman was admitted to a community hospital in Wisconsin. She was complaining of fever, headaches, muscle aches, dry cough and shortness of breath. She delivered a healthy baby four days after entering hospital, and died as a result of respiratory failure four days later. After testing clinical samples submitted to it by the state, CDC concluded that the woman had suffered a case of swine influenza. Specifically, she was infected with a strain of Influenza A(H1N1).

The victim had visited a pig barn display at the local county fair four days before falling ill. According to the CDC report, veterinarians at the county fair confirmed that some of the pigs had displayed symptoms of swine influenza. No other human cases were reported in the surrounding communities.

Fast-forward to 2005. A 17-year old boy receives his flu shot on November 11th. On December 4th, he holds the front end of a freshly-slaughtered pig while his brother eviscerates the carcass. Three days later, he begins to complain of headaches, low back pain, a cough and a runny nose. He has no fever. The following day, he visits a local out-patient clinic, where his nasal passage is swabbed. In a couple of days, the youth recovers fully. His clinical specimen yields an influenza virus that is ultimately identified by CDC as an unusual strain of Influenza A(H1N1) – a triple reassortment virus that contains components of swine, human and avian influenza virus genetic material. 

Transmission of influenza virus from infected pigs to humans, while not common, has been documented a number of times. In most cases, the infection is an occupational hazard. Pig farmers, lab workers, and meat-packing workers are at greatest risk, as are visitors to pig farms and livestock shows. Occasionally, an individual becomes infected without having been exposed directly to swine.

This month, Canadians learned that a farm worker in Alberta apparently had passed the current Influenza A(H1N1) strain to a herd of swine. One-tenth of the herd – 220 out of 2,200 pigs – were infected. The herd was quarantined, and the affected pigs are recovering. So far, none of the other workers on the farm have tested positive for the virus, although some of them have complained of symptoms.

Canada's National Microbiological Laboratory has determined that the influenza virus that is responsible for the illnesses in Mexico is identical to the virus that has been isolated from flu-stricken Canadians. It has not yet mutated. Unfortunately, this doesn't provide us with any insight into how the virus strain arose, whether or not it is related to the 2005 virus, or how long it was circulating in Mexico before the country's health authorities became aware of it. In time, some of these questions will be answered.

Meanwhile, there are other questions, including whether pork – especially Canadian pork – is safe to eat. We'll explore that question next.

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Influenza A(H1N1), aka Swine Flu: One Week Later

May 4, 2009

In the week since we first looked at the swine flu (oops, H1N1) outbreak, the number of confirmed cases – though not necessarily the number of actual illnesses – has increased substantially. As often happens, it takes time for reference labs to catch up to the backlog of suspect cases and either confirm or discard them.

Today, we're taking a virtual world tour to check on the status of this month's international public health panic.

International Overview

The World Health Organization, in its daily update of outbreak statistics, reported today that 21 countries have now reported at least one confirmed case of what WHO now refers to as "Influenza A(H1N1). 

More than half of the 1,085 confirmed cases – 590 of them – are from Mexico. Twenty-five of the Mexican victims have died. The United States has reported one death – a toddler from Mexico who had traveled to visit family in Texas. No other countries have recorded fatalities.

According to the WHO update, confirmed outbreak victims have been identified in Mexico (590), the United States (286), Canada (101), Spain (54), the United Kingdom (18), Germany (8), New Zealand (6), France (4), Israel (4), El Salvador (2), Italy (2), Austria (1), Hong Kong (1), Costa Rica (1), Colombia (1), Denmark (1), Ireland (1), Netherlands (1), Portugal (1), Republic of Korea (1), and Switzerland (1).

But these numbers already are outdated. The Pan American Health Organization today reported 1,118 confirmed cases in 6 Western Hemisphere countries, including 727 in Mexico, 286 in the United States and 101 in Canada  – and 27 deaths. Canada now reports 140 confirmed cases; the US total, according to CDC, is 279.

While a "case count" is a useful snapshot of the status of an outbreak, it's far from being the most important – or the most accurate – information. Of equal or greater interest are: the timing and geography of new cases, the nature of transmission, and how various countries are reacting to the situation.

Over the next several days, we'll be examining some of  these issues. Here's a hint of things to come.

Mexico

Mexico's Secretary of Health told reporters over the weekend that the epidemic in that country had peaked and the number of new cases was on the decline. He also complained that some countries – most notably China – had reacted inappropriately by quarantining some travelers arriving from Mexico, even though they showed no symptoms of influenza. We'll look at how various countries have acted – even over-reacted in some cases – to protect their borders and their citizens from the possible pandemic.

Canada

The 140 confirmed cases in Canada are spread over eight provinces. British Columbia has been hardest hit with 39, followed by Nova Scotia (38), Ontario (31) and Alberta (24). Québec (3), New Brunswick (2), Prince Edward Island (2) and Manitoba (1) also have reported cases.

Canada, which was instrumental in confirming Mexico's outbreak, also has reported the first instance of transmission of the virus from an infected human to a swine herd. An Alberta farm worker who had traveled to Mexico was the vector. The herd has been quarantined to prevent transmission to other swine herds. We'll have a closer look at the implications of this human-to-swine transmission. 

United States

An article in Newsweek by Laurie Garrett (author of the 1994 book The Coming Plague: Newly Emerging Diseases in a World Out of Balance) suggests that a precursor to the Influenza A(H1N1) virus strain that is raising such a ruckus worldwide may have actually evolved in the United States in 2005. Is Garrett correct? What does it mean for the future of this influenza strain?

Finally, is pork still safe to eat? Should herds be culled as Egypt has decided to do? Should farms be closed to visitors until this outbreak has burned itself out? Are slaughterhouse workers at risk of contracting influenza?

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Putting Mexican Swine Flu In Perspective

April 29, 2009

Ninety-one years ago, the world was on the precipice of what was to become the most devastating influenza pandemic in recorded history. 

By the time it burned out, 20% of the world's population – including 28% of the US population – had been infected; an estimated 20 million to 100 million people died. The death rate was a staggering 2.5% (see Footnote). 

The US population in 1918 (excluding members of Armed Forces serving overseas) was approximately 103 million. This means that almost 29 million Americans were infected by the 1918 pandemic flu strain, and more than 720,000 of them died from their infection. The impact of the 1918 pandemic was so severe that the US population decreased by approximately 60,000 in 1918. In comparison, the country's population increased by 1.3 million people in both 1917 and 1919.

In contrast to the 1918 pandemic, seasonal influenza outbreaks in the years 1976-1999 were responsible for an average of 34,470 deaths annually. This toll represented 19.6 deaths per 100,000 population. The 1918 death toll of 720,000 translates to 699 deaths per 100,000. The 1918 pandemic strain – based on US statistics – was 35 times more lethal than the typical seasonal influenza strains that pop up each year.

How does the Mexican swine flu strain fit this picture?

Taken on the surface, the latest official World Health Organization statistics from Mexico seem frightening – 7 deaths out of just 26 confirmed human cases; a 27% lethality rate. But these numbers are deceiving. Mexico does not have the lab facilities to confirm swine flu cases. Its initial samples were sent to Canada's national reference lab, located in Winnipeg, for analysis. 

The Mexican government suspects that the current outbreak may be responsible for as many as 2,498 illnesses and 159 deaths. More than one-half of the suspected swine flu victims – 1,311 people – are still hospitalized. But these number don't account for the likelihood that many more Mexicans have suffered milder symptoms and either never consulted a doctor or were seen by a doctor but did not require hospital treatment. 

The story that is evolving outside of Mexico may eventually give us a better picture of the lethality of this latest influenza strain. As of this morning, cases of Mexican swine flu have been confirmed or classified as "probable" in a number of countries:

• United States: 64 cases; one death
  
• Canada: 13 cases
  
• New Zealand: 14 cases
  
• United Kingdom: 5 cases
  
• Israel: 2 cases
  
• Spain: 4 cases
  
• Germany: 3 cases
  
• Austria: 1 case
  

According to a report released this morning by the Texas Department of State Health Services, the US death involved a 22-month old child from Mexico City who was visiting family in Brownsville, TX. The child fell ill 4 days after leaving Mexico City with his parents, was hospitalized in Brownsville, and then transferred to a Houston-area hospital for treatment. The child, who had other underlying health issues, passed away while in the Houston-area hospital. No one who was in close contact with him has developed symptoms of influenza.

The potential of this influenza strain to cause illness should not be underestimated. But neither should we panic. Certainly, canceling or postponing travel to severely affected areas is appropriate. Avoiding large crowds in confined areas is appropriate. Staying home when ill is appropriate. Paying careful attention to personal hygiene – frequent hand-washing, covering nose and mouth with a tissue when sneezing or coughing, avoiding touching one's eyes or nose with one's hands – is appropriate.

Wearing a face mask is of limited value. Face masks, if fitted correctly, can stop aerosols and large dust particles on which the influenza virus may have hitched a ride. But a face mask is not able to filter virus particles out of the air and may give its wearer a false sense of security.

What about the risk of eating pork?

The influenza virus is a respiratory virus. People become infected by inhaling it. Countries – Russia, Ukraine, China, and others – that have placed an embargo on Mexican and US pork are acting based on politics, not science. And Russia's announced ban on US beef and poultry because of the current outbreak is completely out of line.

USDA announced yesterday that the Mexican swine flu virus has not been detected in any swine herds in the United States. Indeed, not one infected swine herd has been found in any areas where human cases have been reported. Secretary of Agriculture Tom Vilsack said, in part,

"I want to reiterate that U.S. pork is safe. While we in the U.S. are continuing to monitor for new cases of H1N1 flu, the American food supply is safe.

There is no evidence or reports that U.S. swine have been infected with this virus. USDA is reminding its trading partners that U.S. pork and pork products are safe and there is no basis for restricting imports of commercially produced U.S. pork and pork products.

This is not an animal health or food safety issue. This discovery of the H1N1 flu virus is in humans. Any trade restrictions would be inconsistent with World Organization for Animal Health (OIE) guidelines."

What's next?

More countries will confirm cases. The number of new confirmed cases worldwide will increase, peak, and decline. There will, sadly, be more deaths. It's too soon to speculate on the ease with which the virus spreads person-to-person, or how lethal it will prove to be. 

The virus might remain in circulation, might mutate further, or it may simply disappear into the background noise of other influenza strains that have popped up and then faded away. 

And, sooner or later, another new influenza strain will appear to test our pandemic preparedness.

Footnote: The statistics quoted in the introductory paragraphs are taken from Gina Kolata's excellent book, "FLU: The Story of the Great Influenza Pandemic of 1918 and the Search for the Virus That Caused It", published in 1999 by Farrar, Straus and Giroux.

Food Safety and Swine Flu - Update #1

April 27, 2009

A deadly outbreak of "swine flu" may have killed as many as 149 victims in Mexico so far, and sickened hundreds more. Twenty-six of the Mexican deaths have been confirmed as swine flu victims.

Confirmed cases of swine flu – none of them life-threatening – have been reported in the United States (40), Canada (6) and Spain (1). Health agencies in several more countries – including Australia, Brazil, France, Israel, New Zealand, Sweden and Switzerland – are investigating suspect cases.

The World Health Organization has declared a "Level 4" pandemic alert, indicating that the likelihood of a pandemic has increased, but that a pandemic is not inevitable. Governments around the world have issued travel advisories, and many countries have instituted airport screening of passengers arriving from Mexico. Schools in Mexico and all 14 schools in one Texas district have been closed and many public events in Mexico cancelled.

What is swine flu and how is it spread?

Live pigs can become infected with an influenza virus, just as humans can. The form of the virus that typically infects pigs – swine flu – occasionally is passed from infected pigs to humans. As with other influenza viruses, individuals become infected by breathing contaminated air – not by eating contaminated meat.

The virus that is behind the present outbreak is not a pure-bred swine flu virus. It is a hybrid virus that contains portions of swine, bird and human influenza viruses. Health professionals are still in the dark as to how easily this particular virus can be transmitted from person to person, how dangerous it is, and how much protection the current influenza vaccine provides. Fortunately, the virus appears to be sensitive to anti-viral drugs such as Tamiflu.

While monitoring airline passengers who arrive from Mexico and other countries that have confirmed cases of swine flu is a sensible precaution, and placing an embargo on the importation of live pigs from affected countries is understandable, some countries have gone overboard in their efforts to prevent the disease from crossing their borders. 

Since swine flu is not transmitted by eating contaminated pork meat, why have Russia and China embargoed the importation of pork meat from Mexico and the United States? According to Tom Johnston, reporting in Meatingplace.com, Thailand, Jordan, Indonesia and the Philippines have taken similar steps. Ukraine has gone even farther, adding Canada and New Zealand to its embargo list, even though New Zealand has yet to confirm a single case of swine flu.  There is no scientific basis for these embargoes.

It's understandable when individuals who are not schooled in medicine or microbiology make panic-based decisions. It's unconscionable for national health authorities to do so. 

Swine flu is not a food-borne disease.