Afghanistan’s only pig quarantined in flu fear
BY Golnar Motevalli  /  May 5, 2009

Afghanistan’s only known pig has been locked in a room, away from visitors to Kabul zoo where it normally grazes beside deer and goats, because people are worried it could infect them with the virus popularly known as swine flu. The pig is a curiosity in Muslim Afghanistan, where pork and pig products are illegal because they are considered irreligious, and has been in quarantine since Sunday after visitors expressed alarm it could spread the new flu strain. “For now the pig is under quarantine, we built it a room because of swine influenza,” Aziz Gul Saqib, director of Kabul Zoo, told Reuters. “We’ve done this because people are worried about getting the flu.” Worldwide, more than 1,000 people have been infected with the virus, according to the World Health Organization, which also says 26 people have so far died from the strain. All but one of the deaths were in Mexico, the epicenter of the outbreak. There are no pig farms in Afghanistan and no direct civilian flights between Kabul and Mexico. “We understand that, but most people don’t have enough knowledge. When they see the pig in the cage they get worried and think that they could get ill,” Saqib said.

The pig was a gift to the zoo from China, which itself quarantined some 70 Mexicans, 26 Canadians and four Americans in the past week, but later released them. Some visitors were not concerned about the fate of the pig and said locking it away was probably for the best. “Influenza is quite contagious and if it passes between people and animals then there’s no need for the pig to be here,” zoo visitor Farzana said. Shabby and rundown, Kabul Zoo is a far cry from zoos in the developed world, but has nevertheless come a long way since it suffered on the front line of Afghanistan’s 1992-4 civil war. Mujahideen fighters then ate the deer and rabbits and shot dead the zoo’s sole elephant. Shells shattered the aquarium. One fighter climbed into the lion enclosure but was immediately killed by Marjan, the zoo’s most famous inhabitant. The man’s brother returned the next day and lobbed a hand grenade at the lion leaving him toothless and blind. The zoo now holds two lions who replaced Marjan who died of old age in 2002 as well as endangered local leopards. In all, it houses 42 species of birds and mammals and 36 types of fish and attracts up to 10,000 visitors on weekends.

Afghanistan’s only pig locked up: official  /  May 6, 2009

Afghanistan’s only known pig has been taken off display at Kabul Zoo and locked away to avoid panic among visitors who may be worried about swine flu, the zoo’s director said Wednesday. “We put the pig temporarily in his winter house under quarantine because of swine influenza,” director Aziz Gul Saqib told AFP. “Most people don’t have much knowledge about swine influenza and seeing a pig, they panic that they will be infected. “Just to address our visitors’ concerns, we have put the pig away from public view for the past two days,” he said. Saqib said he had sent e-mails to other international zoos to find out if they had also put their pigs in quarantine because of health fears. The WHO has officially backed away from calling the illness swine flu, going instead for influenza A (H1N1) to dispel the impression that it can be caught from eating pork products or through contact with pigs. According to latest figures from the world body, 1,490 people around the globe have been infected by the flu. In Mexico, the epicentre of the outbreak, 29 people have died. But there have been no confirmed cases of swine influenza in Afghanistan and the country does not have any direct flights with nations affected.

The interned animal — known simply as “Pig” — was one of two given to Afghanistan by China in 2002, months after the ouster of the hardline Taliban regime, to help reestablish the zoo after it was destroyed during civil war. However, the other pig — and their offspring — were killed in an attack by a bear. Despite being the only pig, it was not too lonely, Saqib said. “The pig made friends with a goat and was happy sticking to the goat in the enclosure, where some other goats and deer were on show for visitors,” Saqib said. The zoo is undergoing reconstruction but is basic, with a small variety of animals, most in poor conditions. It was on one of the frontlines of the 1992-1996 civil war between anti-Soviet factions that destroyed more than half of Kabul and killed up to 80,000 civilians in the city. It is illegal for Afghans to eat pork in the strictly Islamic country and there are no pig farms or any of the animals in the wild. Some pork products enter the country for the thousands of foreigners here, including soldiers fighting a Taliban-led insurgency.

Culling Pigs in Flu Fight, Egypt Angers Herders and Dismays U.N.
BY Nadim Audi  /  April 30, 2009

Egypt has begun forcibly slaughtering the country’s pig herds as a precaution against swine flu, a move that the United Nations described as “a real mistake” and one that is prompting anger among the country’s pig farmers. The decision, announced Wednesday, is already adding new strains to the tense relations between Egypt’s majority Muslims and its Coptic Christians. Most of Egypt’s pig farmers are Christians, and some accuse the government of using swine flu fears to punish them economically.

According to World Health Organization officials, the decision to kill pigs has no scientific basis. “We don’t see any evidence that anyone is getting infected from pigs,” said Dr. Keiji Fukuda, the World Health Organization’s assistant director general. “This appears to be a virus which is moving from person to person.” The outbreak has been dubbed swine flu — now officially called influenza A(H1N1) — because scientists believe it started in pigs, but they do not know if that was recently or years ago. The name change was designed to allay fears about pigs and eating pork.

Egypt has not reported any cases of the new virus that has hit 11 other nations, but the country has been hard hit by avian flu. The great majority of Egyptians are Muslim and do not eat pork because of religious restrictions, but about 10 percent of the population is Coptic Christian. As a result, Egyptian pig farmers are overwhelmingly Christian. And although some of the country’s Christians are middle class or wealthy, the Christian farmers are generally poor.

On Thursday, several urban pig farmers in Cairo said they see the government’s decision as just another expression of Egyptian Muslims’ resentment against Christians. Last year, there were several violent incidents that some believed were aimed at Christians, including the kidnapping and beating of monks. The Egyptian government denied the incidents had sectarian overtones, saying they were each part of other disputes, including a fight over land.

Barsoum Girgis, a 26-year-old pig farmer, lives in a poor neighborhood, Manshiet Nasser, built along the Mukatam cliffs on the eastern end of the city where most of the ramshackle, red-brick buildings were built illegally. Mr. Girgis makes his living through a combination of raising pigs and collecting garbage — two professions that are often tied together in a city where garbage collection can be an informal affair and where poor farmers rely on food scraps to feed their livestock.

He wakes up every morning around 4 a.m. to collect garbage around the city. When he gets back to Manshiet Nasser, at around 9 a.m., he sorts the trash, putting aside what can be sold at the city’s booming scrap markets and what he can use as pig feed. “The government here is going after our livelihood,” he said, nervously playing with a wooden cross he wears around his neck. “These pigs are perfectly healthy. How am I going to feed my children and send them to school without my livestock?” Mr. Girgis lives with his extended family, about 30 people, in the first two floors of a building that leans against a cliff. His 60 small pigs live on the ground floor. They have dark, furry skin, and their squeals can be heard a block away from Mr. Girgis’ home. Many of Cairo’s pig farmers live in similar conditions, sharing their small spaces in the teeming city with their animals.

After international health officials criticized Egypt’s decision to kill about 300,000 pigs, the Agriculture Ministry’s head of infectious diseases, Saber Abdel Aziz Galal, explained that the cull was “a general health measure,” according to Agence France-Presse. “It is good to restructure this kind of breeding in good farms, not on rubbish,” the agency quoted him as saying. “We will build new farms in special areas, like in Europe,” he said. “Within two years the pigs will return, but we need first to build new farms.”

It remains unclear if the government will compensate the farmers for their losses. The Health Ministry originally said the farmers would be paid, but after many in Parliament disagreed, the ministry appeared to back down. Some in Cairo, anxious over the reports of swine flu agree, with the government’s move. “Now we know there is a reason God bans pigs: they spread sickness” said Mohsen Hamady, a 50-year-old accountant who was sipping tea after work in a Cairo tea house.

But many pig farmers say they do a valuable service for the rest of Cairo that will be recognized only if they stop picking up the trash. “If they take away our pigs, why would we go collect their garbage every morning?” said Marcos Shalab, a 40-year-old pig farmer in Manshiet Nasser. Mr. Girgis echoed this feeling. “We are Christian, and we are the underclass, so it’s very easy to go after us. But this city relies on us to process its waste. It relies on the pigs.”

Search for Swine Flu’s Patient Zero Leads to Mexican Boy  /  April 29, 2009

A 5-year-old boy in Mexico is at the center of detective work around the question of who was the first human to come down with swine flu. Édgar Hernández, pictured, has a winning demeanor: He’s described in news accounts as a playful boy with quite a grin. But his mother is worried about the notoriety he may gain if he is, indeed, Patient Zero. “I don’t have words, I don’t have answers,” Édgar’s mother, María del Carmen Hernández, said as she cried under a portrait of Jesus in her living room, as described by the Washington Post. “I feel terrible about all of this, because the people are thinking that this was all my son’s fault. I don’t think this is anyone’s fault.”

Indeed, there aren’t clear answers. Édgar lives in La Gloria, Mexico, where many residents got sick in late March or early April. He ran a high fever and complained of headache and pains, but he recovered, the WSJ reports. When the CDC tested samples from La Gloria, they came back negative, except for the one that belonged to Édgar.

In addition to the differing results among residents, a confusing issue is that Édgar developed flulike symptoms after some other residents of La Gloria did, the Washington Post reports . He hasn’t infected his family, even though he shares a bed with them. Plus, he showed symptoms several days after two patients in California did. It’s possible the disease actually started in California and somebody brought it to Mexico. The strain of flu also appears to be Eurasian in origin, WaPo adds.

Meantime, some residents of La Gloria are pointing to a major pig farm nearby. But Virginia-based Smithfield Foods, which owns the farm in a joint venture with a Mexican firm, told the WSJ that the company routinely tests its swine herds for disease, including influenza, and that “this variant has never presented itself in any of our herds,” including in Mexico.

Are Factory Farms to Blame for Swine Flu?
by Pablo Paster  /   04.30.09

What Is Swine Flu?
First of all let me clarify that Swine Flu, or Swine Influenza Virus (SIV), is a strain of influenza that is endemic to pigs. You may recall the talk about the H5N1 strain last year, which refers to a human version of avian influenza. Luckily the H5N1 strain has, so far, not been transmissible from human to human, but H1N1 (swine flu) has. In a few past cases, such as in Wisconsin in 1988, swine flu was contracted by humans working in the swine industry, but the virus’ ability to spread from human to human was limited and the outbreak quickly disappeared. An outbreak in 1976 resulted in one third of the US population getting vaccinated against swine flu, but the vaccine ended up killing more people than the swine flu itself. However, back in 1918, the “Spanish Flu” believed to be a strain of swine influenza swept around the world, infecting one third of the world’s population and causing 50 million deaths.

The latest numbers on the US cases of H1N1 are available from the CDC. When compared to the CDC’s estimate of annual influenza-related deaths of 36,000 in the US, it seems like the news media and public health systems are making a big deal out of nothing. But the current overabundance of caution is well justified considering that little is known about the current strain’s mortality rate, infectiousness, resistance to medication, etc. The 2009 outbreak could fizzle away and be forgotten like Y2K or it could grow to “Spanish Flu” proportions.

But Are Factory Farms To Blame?
It is now widely believed, but not confirmed, that Édgar Hernández, a 5 year old Mexican boy from the village of La Gloria, is “Patient 0,” or the first person to have contracted the current swine flue strain. Édgar has since fully recovered and has been visited by the global media, including CNN’s Sanjay Gupta. While the villagers maintain that the source of the outbreak are the unsanitary conditions produced by a nearby factory hog farm, the farm’s owners, Virgina-based Smithfield Foods maintains that none of its animals have tested positive for the strain. The allegations against Smithfield may turn out to be false, but may be based in legitimate health concerns by the villagers, 450 of whom say that they are suffering respiratory problems due to the farm.

If the source of the current outbreak turns out to not be this particular factory farm, suspicion will undoubtedly fall on another factory farm. Bob Martin, senior officer at the Pew Environment Group and a member of the Pew Commission on Industrial Farm Animal Production believes that the current hog production system in the U.S. (and elsewhere) can act as a breeding ground for infections, including swine flu. The close proximity with which animals are held at these farms can encourage the spread of diseases such as swine flu. To counteract this, animals are given antibiotics, which make their way into our food, end up in factory effluent, and contribute to antibiotic resistant diseases. One article in the Daily Mail addresses this issue and talks specifically about the increase in drug resistant salmonella, campylobacter, MSRA (methicillin-resistant Staphylococcus aureus), and E. Coli. It is important to note that, unlike salmonella and E. coli, swine flu is not transmitted by eating pork and the USDA and CDC are emphasizing that eating pork is completely safe.

Finally, agricultural workers, who serve as a “bridging population,” can spread disease from the animals in their care and to the broader community. According to Dr. Anne Schuchat, interim Deputy Director for CDC Science and Public Health, American cases were found to be made up of “an unusually mongrelised mix of genetic sequences” from four different flu viruses – North American swine influenza, North American avian influenza, human influenza, and swine influenza virus typically found in Asia and Europe. So dense populations of pigs breed swine influenza, overuse of antibiotics breeds drug resistant strains, and close contact with humans creates hybridized strains of human and swine influenza genes that can be passed from swine to humans and between humans.

CDC Confirms Ties to Virus First Discovered in U.S. Pig Factories
By Michael Greger, M.D.  /  May 3, 2009

Factory farming and long-distance live animal transport apparently led to the emergence of the ancestors of the current swine flu threat. A preliminary analysis of the H1N1 swine flu virus isolated from human cases in California and Texas reveals that six of the eight viral gene segments arose from North American swine flu strains circulating since 1998, when a new strain was first identified on a factory farm in North Carolina.

This genetic fingerprint, first released by Columbia University’s Center for Computation Biology and the Institute for Advanced Study in Princeton,[1] has now been reportedly confirmed by researchers at the University of Edinburgh, St. Jude’s Children’s Research Hospital and virologist Ruben Donis, chief of the molecular virology and vaccines branch at the U.S. Centers for Disease Control and Prevention. Dr. Robert Webster, the director of the U.S. Collaborating Center of the World Health Organization, and considered the “godfather of flu research,”[2] is reported as saying “The triple reassortant in pigs [first discovered in the U.S. in 1998] seems to be the precursor.”

Plaguing People and Pigs
The worst plague in human history was triggered by an H1N1 avian flu virus, which jumped the species barrier from birds to humans[3] and went on to kill as many as 50 to 100 million people in the 1918 flu pandemic.[4] No disease, war or famine ever killed so many people in so short a time. We then passed the virus to pigs, where it has continued to circulate, becoming one of the most common causes of respiratory disease on North American pig farms.[5]

In August 1998, however, a barking cough resounded throughout a North Carolina pig factory in which all the thousands of breeding sows fell ill.[6] A new swine flu virus was discovered on that factory farm, a human-pig hybrid virus that had picked up three human flu genes. By the end of that year, the virus acquired two gene segments from bird flu viruses as well, becoming a never-before-described triple reassortment virus—a hybrid of a human virus, a pig virus, and a bird virus—that triggered outbreaks in Texas, Minnesota, and Iowa.[7]

Within months, the virus had spread throughout the United States. Blood samples taken from 4,382 pigs across 23 states found that 20.5% tested positive for exposure to this triple hybrid swine flu virus by early 1999, including 100% of herds tested in Illinois and Iowa, and 90% in Kansas and Oklahoma.[8] According to the current analysis, published April 30 in the journal of the European Centre for Disease Prevention and Control, it is from this pool of viruses that the current swine flu threat derives three-quarters of its genetic material.[9]

Tracing the Origins of Today’s Virus
Since the progenitor of the swine flu virus currently threatening to trigger a human pandemic has now been identified, it is critical to explore what led to its original emergence and spread. Scientists postulate that a human flu virus may have starting circulating in U.S. pig farms as early as 1995, but “by mutation or simply by obtaining a critical density, caused disease in pigs and began to spread rapidly through swine herds in North America. [emphasis added]”[10] It is therefore likely no coincidence that the virus emerged in North Carolina, the home of the nation’s largest pig production operation. North Carolina has the densest pig population in North America and reportedly boasts more than twice as many corporate pig mega-factories as any other state.[11]

The year of emergence, 1998, was the year North Carolina’s pig population hit ten million, up from two million just six years earlier.[12] Concurrently, the number of pig farms was decreasing, from 15,000 in 1986 to 3,600 in 2000.[13] How can five times more animals be raised on almost five times fewer farms? By crowding about 25 times more pigs into each operation.

In the 1980s, more than 85% of all North Carolina pig farms had fewer than 100 animals. By the end of the 1990s, operations confining more than 1,000 animals controlled about 99% of the state’s pig population.[14] Given that the primary route of swine flu transmission is thought to be the same as human flu—via droplets or aerosols of infected nasal secretions[15]—it’s no wonder experts blame overcrowding for the emergence of new flu virus mutants.

Intensive Crowding and Long-Distance Transport
Starting in the early 1990s, the U.S. pig industry restructured itself after Tyson’s profitable chicken model of massive industrial-sized units. As a headline in the trade journal National Hog Farmer announced, “Overcrowding Pigs Pays—If It’s Managed Properly.”[16] The majority of U.S. pig farms now confine more than 5,000 animals each. A veterinary pathologist from the University of Minnesota stated the obvious in Science: “With a group of 5,000 animals, if a novel virus shows up it will have more opportunity to replicate and potentially spread than in a group of 100 pigs on a small farm.”[17]

In a study published in 2008 in the journal Zoonoses and Public Health investigated the relationship between farm size and risk of Eurasian lineage swine flu infection. The researchers concluded: “Pigs from larger farms (>5000 SPP [standing pig population]) appeared to have a significantly higher risk for SI [swine influenza] H1N1 infection compared to pigs originating from smaller farms. The odds of H1N1 in pigs from those farms were five times more as compared to small farms (i.e. <1000 SPP).” The same result was found for another strain of swine flu: “Pigs from bigger farms (i.e. SPP 1000–5000 and >5000) were about twice and nine times more likely, respectively, to have SI H3N2 infection as compared to pigs from farms with SPP <1000.”[18] A recent study of pig farms in North America similarly concluded: “Increasing the number of finishers [fattening pigs] by 1000 increased by 4.4 the adjusted odds of a finisher herd being positive [for classic H1N1 swine flu].”[19]

Researchers also found that when farms were packed close together, as is increasingly the case in high pig-density areas of North America and Europe, pigs appeared to have up to 16.7 times the odds of testing positive for swine flu. “Close location,” they write, “enhances the possibility for windborne, personnel, and fomites disease transmission from one farm to another.”[20] The “spread of pig slurry [urine and feces]” on nearby land may also play a role.[21]

This new research confirms earlier work suggesting that increasing the number of pigs per pen or per municipality can significantly increase swine flu risk. A 2002 review found 26 studies linking respiratory disease with herd size.[22] A higher number of pigs per municipality “may facilitate airborne transmission [of swine flu] between the herds” and crowding more pigs per pen “allows more opportunities for direct nose-to-nose contact or for aerosol spread of the [swine flu] virus between penmates. Furthermore, a large number of pigs per pen creates physiological stress, which in turn can alter the immune system and predispose pigs to infection.”[23]

Dr. Robert Webster, one of the world’s leading experts of flu virus evolution, blames the emergence of the 1998 virus on the “recently evolving intensive farming practice in the USA, of raising pigs and poultry in adjacent sheds with the same staff,” a practice he calls “unsound.”[24] North Carolina is also one of the nation’s largest poultry producers, slaughtering nearly three-quarters of a billion chickens[25] and confining enough hens to produce nearly 3 billion eggs.[26]

Once the new viral mutant appeared in 1998, the rapid dissemination across the country has been blamed on long-distance live animal transport.[27] In the United States, pigs travel coast to coast. They can be bred in North Carolina, fattened in the corn belt of Iowa, and slaughtered in California.[28] While this may reduce short-term costs for the pork industry, the highly contagious nature of diseases like influenza (perhaps made further infectious by the stresses of transport) needs to be considered when calculating the true cost of long-distance live animal transport.

“A Recipe for Disaster”
The remaining two gene segments of the H1N1 swine flu virus now spreading in human populations around the world appear to come from a swine flu viral lineage circulating in Eurasia, where similar conditions may be to blame. “Influenza [in pigs] is closely correlated with pig density,” said a European Commission-funded researcher studying the situation in Europe.[29] As such, Europe’s rapidly intensifying pig industry has been described in Science as “a recipe for disaster.”[30] Some researchers have speculated that the next pandemic could arise out of “Europe’s crowded pig barns.”[31] In Europe in 1993, a bird flu virus had adapted to pigs, acquiring a few human flu virus genes and infected two young Dutch children, displaying evidence of limited human-to-human transmission.[32]

The European Commission’s agricultural directorate warns that the “concentration of production is giving rise to an increasing risk of disease epidemics.”[33] Concern over epidemic disease is so great that Danish laws have capped the number of pigs per farm and put a ceiling on the total number of pigs allowed to be raised in the country.[34]

No such limit exists in the United States or in Mexico. The fact that one of the first confirmed human cases of swine flu appeared in close proximity to the largest pig factory in Mexico, which slaughters nearly a million pigs a year (out of a country-wide total of 15 million), may not have been a coincidence. In Vector-Borne and Zoonotic Diseases, scientists from the University of Iowa Center for Emerging Infectious Diseases published the 2006 article “Confined Animal Feeding Operations as Amplifiers of Influenza,” in which they concluded, “A human influenza epidemic due to a new virus could be locally amplified by the presence of confined animal feeding operations in the community.”

Warnings Unheeded
The public health community has been warning about the risks posed by factory farms for years. More than five years ago, in 2003, the American Public Health Association, the largest and oldest association of public health professionals in the world, called for a moratorium on factory farming.[35] In 2005, the United Nations urged that “[g]overnments, local authorities and international agencies need to take a greatly increased role in combating the role of factory-farming,” which, they said, combined with live animal markets, “provide ideal conditions for the [influenza] virus to spread and mutate into a more dangerous form.”[36]

Last April, the Pew Commission on Industrial Farm Animal Production released its final report. The prestigious, independent panel chaired by a former Kansas Governor and including a former U.S. Secretary of Agriculture, former Assistant Surgeon General, and the Dean of the University of Iowa College of Public Health, concluded that industrialized animal agriculture posed “unacceptable” public health risks: “Due to the large numbers of animals housed in close quarters in typical [industrial farm animal production] facilities there are many opportunities for animals to be infected by several strains of pathogens, leading to increased chance for a strain to emerge that can infect and spread in humans.”[37]

Specific to the veal crate-like metal stalls that confine breeding pigs like those on the North Carolina factory from which the first hybrid swine flu virus was discovered in North America, the Pew Commission asserted that “[p]ractices that restrict natural motion, such as sow gestation crates, induce high levels of stress in the animals and threaten their health, which in turn may threaten human health.”[38] Unfortunately we don’t tend to “shore up the levees” until after the disaster, but now that we know swine flu viruses can evolve to efficiently transmit human-to-human we need to follow the Pew Commission’s recommendations to abolish extreme confinement practices like gestation crates as they’re already doing in Europe, and to follow the advice of the American Public Health Association to declare a moratorium on factory farms.

A “Reservoir of Viruses” in the U.S.
With massive concentrations of farm animals within whom to mutate, these new swine flu viruses in North America seem to be on an evolutionary fast track, jumping and reassorting between species at an unprecedented rate.[39] This reassorting, Webster’s team concludes, makes the 65 million strong U.S. pig population an “increasingly important reservoir of viruses with human pandemic potential.”[40] “We used to think that the only important source of genetic change in swine influenza was in Southeast Asia,” said Christopher Olsen, a molecular virologist at the University of Wisconsin, Madison. Now, “we need to look in our own backyard for where the next pandemic may appear.”[41]

{Dr. Michael Greger is director of public health and animal agriculture for The Humane Society of the United States.}

[1]Trifonov V, et al. 2009. The origin of the recent swine influenza A(H1N1) virus infecting humans. Eurosurveillance 14(17).
[2] Council on Foreign Relations. 2005. Session 1: Avian flu-where do we stand? Conference on the Global Threat of Pandemic Influenza, November 16.…uenza_session_1.html.
[3] Belshe RB. 2005. The origins of pandemic influenza-lessons from the 1918 virus. New England Journal of Medicine 353(21):2209-11.
[4] Johnson NPAS, Mueller J. Updating the accounts: global mortality of the 1918–1920 “Spanish” influenza pandemic. Bull Hist Med. 2002;76:105–15.
[5] Zhou NN, Senne DA, Landgraf JS, et al. 1999. Genetic reassortment of avian, swine, and human influenza A viruses in American pigs. Journal of Virology 73:8851-6.
[6] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5.
[7] Zhou NN, Senne DA, Landgraf JS, et al. 1999. Genetic reassortment of avian, swine, and human influenza A viruses in American pigs. Journal of Virology 73:8851-6.
[8] Webby RJ, Swenson SL, Krauss SL, Gerrish PJ, Goyal SM, and Webster RG. 2000. Evolution of swine H3N2 influenza viruses in the United States. Journal of Virology 74:8243-51.
[9] Trifonov V, et al. 2009. The origin of the recent swine influenza A(H1N1) virus infecting humans. Eurosurveillance 14(17).
[10] Webby RJ, Swenson SL, Krauss SL, Gerrish PJ, Goyal SM, and Webster RG. 2000. Evolution of swine H3N2 influenza viruses in the United States. Journal of Virology 74:8243-51.
[11] Environmental Defense. 2000. Factory hog farming: the big picture. November.
[12] Duke University Center on Globalization, Governance and Competitiveness. 2006. Hog farming overview. February 23.
[13] North Carolina Department of Agriculture and Consumer Services. 2001. North Carolina agriculture overview. February 23.
[14] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5.
[15] Brown IH. 2000. The epidemiology and evolution of influenza viruses in pigs. Veterinary Medicine 74:29-46.
[16] 1993. Overcrowding pigs pays-if it’s managed properly. National Hog Farmer, November 15.
[17] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5.
[18]Suriya R, et al. 2008. Seroprevalence and risk factors for influenza A viruses in pigs in Peninsular Malaysia. Zoonoses Public Health. 2008 55(7):342-51.
[19] Poljak Z, et al. 2008. Prevalence of and risk factors for influenza in southern Ontario swine herds in 2001 and 2003. Can J Vet Res. 2008 72(1):7-17.
[20] Suriya R, et al. 2008. Seroprevalence and risk factors for influenza A viruses in pigs in Peninsular Malaysia. Zoonoses Public Health. 2008 55(7):342-51.
[21] Poljak Z, et al. 2008. Prevalence of and risk factors for influenza in southern Ontario swine herds in 2001 and 2003. Can J Vet Res. 2008 72(1):7-17.
[22] Gardner IA, et al. 2002. Empirical and theoretical evidence for herd size as a risk factor for swine diseases. Anim Health Res Rev. 3(1):43-55.
[23] Maes D, et al. 2000. Herd factors associated with the seroprevalences of four major respiratory pathogens in slaughter pigs from farrow-to-finish pig herds. Vet Res. 31(3):313-27.
[24] Webster RG and Hulse DJ. 2004. Microbial adaptation and change: avian influenza. Revue Scientifique et Technique 23(2):453-65.
[25] USDA. 2009. Poultry Slaughter 2008. Annual Summary.
[26] USDA. 2009. Chickens and Eggs 2008 Summary.
[27] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5.
[28] Shields DA and Mathews KH Jr. 2003. Interstate livestock movements. USDA Economic Research Service: Electronic Outlook Report from the Economic Research Service, June.
[29] MacKenzie D. 1998. This little piggy fell ill. New Scientist, September 12.
[30] Ibid.
[31] Delgado C, Rosegrant M, Steinfeld H, Ehui S, and Courbois C. 1999. Livestock to 2020: the next food revolution. Food, Agriculture, and the Environment Discussion Paper 28. For the International Food Policy Research Institute, the Food and Agriculture Organization of the United Nations and the International Livestock Research Institute.
[32] Webster RG, Sharp GB, and Claas CJ. 1995. Interspecies transmission of influenza viruses. Americal Journal of Respiratory and Critical Care Medicine 152:525-30.
[33] MacKenzie D. 1998. This little piggy fell ill. New Scientist, September 12, p. 1818.
[34] Ibid.
[35] American Public Health Association. 2003. Precautionary moratorium on new concentrated animal feed operations. Policy number 20037.
[36] United Nations. 2005. UN task forces battle misconceptions of avian flu, mount Indonesian campaign. UN News Centre, October 24.
[37] Pew Commission on Industrial Farm Animal Production. 2008. Expert panel highlights serious public health threats from industrial animal agriculture. Press release issued April 11. Accessed August 26, 2008.
[38] Pew Commission on Industrial Farm Animal Production. 2008. Putting meat on the table: industrial farm animal production in America. Executive summary, p. 13. Accessed August 26, 2008.
[39] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5.
[40] Webby RJ, Rossow K, Erickson G, Sims Y, and Webster R. 2004. Multiple lineages of antigenically and genetically diverse influenza A virus co-circulate in the United States swine population. Virus Research 103:67-73.
[41] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5.

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