Brittany Schmidt
Kendra Birnley
English 102
10 March 2010
Factory Harm: The Dangers of Livestock Farming in Today’s Factory Farms
When you drive down a busy street in your town you’re bound to see countless fast food restaurants, and sometimes you may stop to order a $2.69 Whopper or a $2.99 Big Mac for lunch. The average American now consumes over two hundred pounds of meat a year (Food Inc.). Have you ever wondered where the beef, chicken, and pork you eat comes from, or why it is so cheap? Probably not, but the answer will shock you. A recent increasing demand for fast food results in an increasing demand for beef, poultry, and pork. With that comes an increase in farms that can raise and butcher as many livestock as possible, as cheaply as possible. These farms are called an industrial farm, a factory farm, or a concentrated animal feeding operation (CAFO). Menus at restaurants now advertise bigger portions for less money and although getting a lot of food for only a few dollars may sound excellent, it doesn’t come without its consequences. In the past decade people are finally opening their eyes to see the atrocious consequences of these factory farms. Although the farms themselves deny having a direct correlation with issues such as air and water pollution, the rise in antibiotic resistant diseases, and the health hazards of not only the farm animals but the workers as well, they have been implicated in these infractions time and time again. By creating and enforcing laws that support smaller, greener farms and that also support animal welfare in the factory farms, we can eventually reverse the damage that has been done and start not only eating healthier but smarter as well.
Industrialized farms have several benefits, including providing a massive amount of meat to consumers at any point in time and also providing them with low purchase costs for beef, poultry, and pork. Danielle Nierenberg, a research associate at the Worldwatch Institute, states that “industrial systems today generate seventy four percent of the world’s poultry products, fifty percent of the pork, forty three percent of the beef, and sixty eight percent of the eggs” (Nierenberg). However these benefits are few and far between; they certainly do not outweigh the risks in both processing and consuming the meat and egg. Nierenberg reports that “livestock cover one third of the planet’s total surface area and use more than two thirds of its agricultural land” (Nierenberg). Although the number of livestock is ever increasing, the number of actual farms is decreasing. There are far fewer farms today than there were fifty years ago, but the ones that are still running are much larger and much more powerful than ever before. One of the biggest issues with large factory farms is that there are so many livestock in such a small space (a typical headcount is in the thousands) and there also isn’t sufficient room to dispose of their waste products properly. In her book about the global meat industry Nierenberg explains that “[i]n the United States livestock produce more than six hundred million tons of waste annually. In pig operations twenty thousand or so sows will have approximately twenty piglets a year. One sow and her piglets create one point nine tons of manure a year” (Nierenberg). Farmers used to utilize the livestock manure as fertilizer for their crops due to its high nutrient content. They would spread it out over the fields to help the soil develop and maintain a better structure, so there was less of a chance of erosion. Manure also helps soil maintain appropriate moisture levels by absorbing some excess moisture. However, manure application does come with its downfalls. José Martinez and Alonso Lopez confirm that “[r]epeated soil over-applications of manure, above crop requirements, lead to the accumulation of not only macro nutrients such as N [nitrogen], P [phosphorus], and K [potassium], but also heavy metals particularly Cu [copper] and Zn [zinc], impacting animal health through grazing and crop feeding” (Lopez qtd in Martinez). Researchers from the Worldwatch Institute, Alan B. Durning and Holly B. Brough, explain that in recent years this has become less of a health hazard since livestock no longer graze outdoors and only “one sixth of hog manure (from factory farms) is used as fertilizer” (Durning and Brough); even if the animal were to graze outdoors it is unlikely they would consume any contaminated crops.
One of the biggest problems with soil pollution is that it is a main cause of both water and air pollution. Water pollution is a rising issue in the United States, especially in states with large amounts of CAFOs (especially North Carolina) and therefore needs to be taken more seriously than it currently is. Water pollution that is associated with livestock waste typically comes from the leaching and/or runoff of waste and polluted soil. Both nitrogen and phosphorus have the potential to contaminate groundwater, but there is another chemical that is more harmful: ammonia. In his extensive article about livestock waste treatment systems, Martinez claims that the, “biggest culprit of water pollution is ammonia due to its toxicity” (Martinez). In a 1991 book about worldwide livestock farming and the environmental effects it has, Durning and Brough point out that “[i]n the United States one fifth of ground water wells [in Iowa, Kansas, and Nebraska] have unsafe nitrate levels.” They go on to say that “if manure gets into rivers and streams, it fertilizes algae which grows rapidly, cutting oxygen levels and suffocating aquatic life” (Durning and Brough). Not only are rivers and streams affected by livestock waste, but so is the local ground and well water. Besides leaching and runoff, another way manure gets into ground water is by accidents and natural disasters:
On June 22, 1995, the wall of an artificial waste lagoon gave way at a pig operation in North Carolina, spilling over ninety five million liters of urine and feces across several fields and into a nearby river, killing millions of fish. A few weeks later, thirty four million liters of waste flowed down a creek and into Northeast Cape Fear River from another farm. Then that August, another three point eight million liters trickled through a network of tidal creeks into the Cape Fear Estuary. Then in 1998 and 1999 massive floods in North Carolina [caused by back to back hurricanes] drowned thousands of pigs trapped in factory farms, and spilled untold millions of liters of waste. (Nierenberg).
Editors of Environmental Science: In Context, Brenda Wilmoth Lerner and K. Lee Lerner confirm that during the 1999 hurricane season that affected the mid-Atlantic United States, “one spill alone released twenty five million gallons of feces-laden water into the New River, killing an estimated eight to ten million fish” (Lerner and Lerner). Water pollution isn’t the only kind of harmful damages these farms do to the environment.
In the past decade researchers are discovering more and more how industrialized farming is impacting our air quality in general, the health of the neighboring population, and even how it contributes to global warming. The air in CAFOs is filled with toxins and high levels of ammonia, which in turn are transferred to the outside air through ventilation systems. As Martinez points out, “the air in livestock housing contains over a hundred gaseous compounds released into the atmosphere by the ventilation system… the loss of ammonia to the atmosphere occurs from animal housing, manure storage facilities, and from the application of manure to land” (Martinez). This polluted air is then carried not only down-wind but also sometimes up-wind of the farm, harming all those who breath it in for an extended period of time. In an elaborative study of over fifty eight thousand twelve to fourteen year olds living within three miles of hog CAFOs, Maria C. Mirabelli and colleagues from the American Academy of Pediatrics discovered that “the prevalence of wheezing within the past year was five percent higher at schools that were located within three miles of an operation… and twenty four percent higher at schools in which livestock odor was noticeable indoors twice per month.” They summed up their study and report by saying, “[o]ur findings identify a plausible association between exposure to airborne pollution from swine CAFOs and wheezing symptoms among adolescents” (Mirabelli). As this study clearly points out, CAFOs have become a health hazard to innocent civilians who are just living close to the farm.
Humans are not the only ones who are affected by the air pollution in the industrialized farms. Laura Sayre from Mother Earth News reports that “the stress of factory farm conditions weakens animals’ immune systems; ammonia from accumulated waste burns lungs and makes them more susceptible to infection; the lack of sunlight and fresh air…facilitates the spread of pathogens” (Sayre). So not only do the conditions in the farms encourage disease, but the animals are at risk even more so because their natural defenses are weakened. To prevent the livestock from getting sick, they are given routine antibiotics from birth to slaughter. Farmers have found that injecting chickens with antibiotics makes them gain weight more quickly, which is great for the consumer but potentially devastating for the chicken. Nierenberg reports that in the mid 1940’s it typically took a chicken one hundred and twelve days to reach one point seven kilograms (at which point they were butchered). However, today, chickens reach over two kilograms in as little as one third the time. It used to take four to five years before a cow was large enough to slaughter; now it takes about fourteen months (Nierenberg). The downfall to the chickens getting larger faster is that their leg bones don’t have time to get used to the added weight before they start breaking or before the chicken collapses from sheer exhaustion from carrying around the extra weight (Food, Inc). Farmers then found that by giving the chickens certain growth hormones mixed with the antibiotics, they could raise chickens with unusually large breasts and smaller wings and thighs (since chicken breast meat is the most popular) (Nierenberg). Farmers didn’t stop with just chickens though; soon dairy cows and beef cattle were all given antibiotics and growth hormones to gain weight fast so they could be butchered and sold to supermarkets much quicker than ever before. In an article titled A Brave New World: Genetic Engineering, rBGH and Mad Cow Disease, authors Jim Motavalli and Tracey C. Rembert report that the agricultural company Monsanto invested a billion dollars into “Posilac,” which is the first FDA approved recombinant bovine growth hormone (rBGH), or artificial growth hormone. This hormone is injected into a dairy cow’s pituitary gland every other week to increase its milk supply by as much as twenty five percent (Motavalli and Rembert). A side effect of producing this massive amount of milk is the risk of getting an infection like mastitis in their udders. If a cow does develop a mastitis infection, it must receive high doses of antibiotics, which in turn are passed through the meat and milk to the human consumer. A New Statesmen writer Alexander Cockburn explains that “the antibiotic injected into the cow passes on to the human consumer, where it can attack the immune system” (Cockburn qtd in Motavalli and Rembert). Motavalli and Rembert continue to discuss Cockburn’s findings: “rBGH works by stimulating production of an insulin-like growth factor known as IGF-1, which is also found… in humans…. [high levels of IGF-1 have] been linked to colon, prostate, ovarian and breast cancer. [The] use of hormones in cow production has also led to earlier onset of puberty” (Motavalli and Rembert). Clearly we see here that the only person these growth hormones are benefiting is the farmer. However, Monsanto’s CEO Robert Shapiro disputes this fact by saying that “[t]here is a need for agricultural productivity and increased dairy products. We will need to double production if we want to feed all the new people who will be joining us. The milk produced is the same milk as that from cows that are not being treated” (Motavalli and Rembert). Motavalli and Rembert disassemble Shapiro’s argument by stating that the U.S. government buys up over a billion dollars worth of extra milk each year; proving that there is no shortage of milk products, therefore there is no need to be injecting cows with rBGH at this time.
As previously stated, injecting livestock with antibiotics harms consumers since they are ingesting the antibiotics through the animal meat and milk. Additionally, though, since the increase in popularity with antibiotics and livestock farmers, there has also been an increase in newly found zoonotic diseases. Zoonotic diseases are simply diseases that once were only within a certain animal species, and have since jumped the barrier and are now infecting humans. The recent H1N1 (Swine Flu) outbreak is an example of a zoonotic disease and is a perfect example of what happens when animals are given mass amounts of antibiotics: it creates a resistance and then is passed to humans. In a September 2009 article about hog farms and the recent outbreak of the H1N1 disease in the Environmental Health Perspectives journal, author Charles Schmidt discusses his thorough research into the H1N1 outbreak of 2009. Schmidt says that the employees of the swine CAFO’s are partially to blame for the vast spread of this potentially deadly disease. Schmidt reveals the results of a study done by Gregory Gray, director of the Center for Emerging Infectious Diseases at the University of Iowa college of Public Health: “In a 2-year prospective study of 803 rural Iowans,… [Gray] found that CAFO workers were 50 times more likely to have elevated H1N1 antibodies than non-exposed controls. Equally important, their spouses were 25 times more likely to harbor these antibodies, reflecting how the viruses can jump from farm workers to their intimate contacts” (Schmidt). From this we can clearly see that it would be extremely easy for a virus outbreak to happen in a short amount of time. Steven Wing, the associate professor of Epidemiology at the University of North Carolina, claims that, “there’s no evidence to suggest that communities living near CAFO’s have elevated rates of infectious diseases,” and the farming industry itself argues that it is much safer to raise animals in CAFOs, because then the livestock are not exposed to the weather conditions outside or viruses from other animals (Schmidt). While this may be true, it does not disprove the fact that the CAFO workers themselves are transferring the zoonotic diseases (such as H1N1) to the outside world, where the disease has billions and billions of potential victims that have no antibodies to protect them. According to the Centers for Disease Control and Prevention (CDC), the H1N1 flu virus outbreak of 2009 was extremely fast and extremely powerful, infecting approximately fifty five million people and killing approximately eleven thousand one hundred and sixty people between April 15th and December 15th (CDC). Those numbers are astonishing considering the fact that these deaths could potentially have been prevented if farmers didn’t vaccinate pigs as much as they currently do. H1N1 isn’t the only zoonotic disease that Americans need to worry about. Diseases such as Bovine Spongiform Encephalopathy (Mad-Cow Disease), Foot-and-Mouth Disease, Salmonella, and food borne illnesses such as Campylobacter and Escherichia coli 0157:H7 (E. coli) are all just as dangerous as the H1N1 virus. Nierenberg points out that “[a]ccording to the USDA, if foot-and-mouth disease were introduced in the US, it could spread to twenty five states in just five days” (Nierenberg). This is not only because the workers in industrial farms are transporters of diseases, but because livestock may travel over multiple state lines on their way to the slaughterhouse or supermarket, infecting everything they come in contact with on the way. Laura Sayer explains that “every step in the industrial farm animal production system holds the potential for disease transmission, from transportation and manure handling, to meat processing and animal rendering” (Sayre). Bovine Spongiform Encephalopathy (BSE) or commonly referred to as Mad-Cow Disease, is a disease that is one hundred percent fatal to the infected cow. Mad-Cow Disease is transferred through the spinal nerves and brain tissue of an infected cow to another. When the disease becomes transmissible and transfers to humans through consumption of infected meat, then it becomes known as either Creutzfeldt-Jakob disease (CJD) or variant Creutzfeldt-Jakob disease (vCJD) depending on the age of the infected person (USDA and WHO). According to the USDA vCJD is a fatal disease that causes psychiatric and sensory problems, ultimately resulting in death. Because it is a relatively new disease (unlike regular CJD) there is little research as to the incubation period of the disease. However, it is known that by the time a person starts to show symptoms, it is safe to assume they consumed the affected meat a decade or more earlier (USDA).
Almost all diseases associated with livestock meat consumption are bacterial. Sayre reports that up to eighty percent of chickens in supermarkets today are infected with Campylobacter (Sayre), which is a bacterium that lives in the intestinal tracts of chickens. Campylobacter does not typically affect the chicken, however, if a human consumes raw or undercooked poultry and develop Campylobacteriosis they typically will have a fever, nausea/vomiting, and/or bloody diarrhea for up to a week (WHO). According to Steve Roach, a director for the Food Animal Concerns Trust, and Sayre, “’one in two human cases of Campylobacter, and one in five cases of Salmonella are now antibiotic-resistant… And when you have antibiotic resistance, you have more complications, more blood infections, more mortality’” (Roach qtd. in Sayre). According to the USDA, Salmonella is a bacterium similar to Campylobacter that also lives in the intestinal tracts of livestock, causing fever, nausea/vomiting, and/or abdominal cramps and diarrhea in infected humans for up to a week after infection. Salmonella is spread from any livestock animal through its meat, eggs, and milk. It can also be contracted from consuming raw fruits and vegetables that came into contact with the infected livestock feces and wasn’t properly washed/cooked. There are now over twenty three hundred different types of Salmonella bacterium, making it the top cause of food-borne illness in the US today (USDA). Bacterial infections such as Campylobacter and Salmonella, are typically harmless after the initial onset of symptoms, and rarely have lasting effects on the victim. However, Nierenberg points out that, thanks to antibiotic resistance, in 1998 a twelve year old boy in Nebraska contracted Salmonella, which turned out to be resistant to thirteen different antibiotics (Nierenberg).
Like Campylobacter and Salmonella, Escherichia coli 0157:H7 (also known as E. coli) is a bacterial disease that has short lasting symptoms such as diarrhea but sometimes can “…cause urinary tract infections, respiratory illness and pneumonia” (CDC). E. coli is transferred to the meat product by coming in contact with the infected animal’s feces. R. A. Oot and colleagues performed a study of E. coli in cattle feces on a factory farm to show just how common it really is. They used a farm that contained over fifty thousand cattle and collected six samples from each of the ten pens that held over one hundred and fifty cattle each. The feces were all tested for E. coli, and the results were shocking: E. coli was found in seven out of the ten feedlot pens screened with a total of about twenty seven of the individual samples being positive. If slaughterhouse workers did not handle the cattle properly during slaughter and meat transportation it would be extremely easy for an entire batch of meat to become contaminated. According to Oot the “US Food Safety and Inspection Service has a zero tolerance policy that requires destruction of the entire batch of adulterated meat” (Oot et al.). Michael Moss of the New York Times wrote an extensive article titled E. Coli Path Shows Flaws in Beef Inspection where he discusses E. coli and how often it is slipping past food inspectors at processing plants/slaughter houses. Moss reports that “unwritten agreements between some companies appear to stand in the way of ingredient testing. Many big slaughterhouses will only sell to grinders who agree not to test their shipments [of meat] for E. coli,… slaughterhouses fear that one grinder’s discovery of E. coli will set off a recall of ingredients they sold to others” (Moss, “E. Coli Path”). Moss says that some companies, such as Costco, are now doing their own E. coli testing before the grinding process has started, since the grinding companies themselves are not consistent. The problem with a company finding that their shipment of meat is tainted after the grinding process has started is that it is nearly impossible to trace it back to the farm that had the infected livestock. Moss explains that today’s industrialized farms will sometimes sell their livestock to more than one slaughterhouse, who in turn may sell the meat to more than one grinder. At the grinding house meat from all over the US (and sometimes even the world) is mixed together into giant batches of ground beef (Moss, “E. Coli Path”). As this clearly points out, the beef is potentially spread out all over the country and once it has been mixed with other slaughterhouse’s beef it is nearly impossible to discover which slaughterhouse had the infected meat to begin with. Moss points out that “[g]round beef is usually not simply a chunk of meat run through a grinder. Instead, records and interview show a single portion of hamburger meat is often [a mixture] of various grades of meat from different parts of cows and even from different slaughterhouses. These cuts of meat are particularly vulnerable to E. coli contamination…” (Moss, “E. Coli Path”). In 1972 the FDA conducted approximately fifty thousand food safety inspections… in 2006 they conducted just over nine thousand (Food, Inc.). Moss also reported in his article that “[a]n Agriculture Department survey of more than 2,000 plants… showed that half of the grinders did not test their finished ground beef for E. coli; only 6 percent said they tested incoming ingredients at least four times a year” (Moss, “E. Coli Path”). One way to help relieve pressure from the grinders on testing all meat coming in is that the slaughterhouses themselves could start testing their meat before shipping it out. This, however, may not be as easy as it seems when some slaughterhouses such as the Smithfield Hog Processing Plant slaughter over two thousand hogs and hour and over thirty two thousand hogs per day (Food, Inc.). The testing would take some time but even if they did periodic checks it would still benefit everyone in the process: they’d save transportation costs since they wouldn’t send any tainted meat to the grinders, the grinders would have less meat to test, and the consumer has less of a chance of contracting E. coli (or any other bacterial disease mentioned above).
In another article by Michael Moss about beef called Safety of Beef Processing Method is Questioned, he reports that in 2001 Beef Products Inc. commissioned a study that found if ammonia is injected into beef, it will kill all traces of Salmonella and E. coli. He explains that the USDA not only endorsed their ammonia treatment, but they also exempted Beef Products Inc. from routine testing. However, “[f]rom 2005 to 2009, Beef Products had a rate of 36 positive results for salmonella per 1,000 tests, compared to a rate of nine positive results per 1,000 tests [from] other suppliers” (Moss, “Safety of Beef”). If Beef Products Inc has a positive testing rate higher than other meat suppliers, and they’re using ammonia to kill most of the Salmonella and E. coli in their meat, what are their positive numbers before the ammonia treatment? Moss says that “Beef Products maintains that its ammonia process remains effective… and has found E. coli in only 0.06% of the samples this year” (Moss, “Safety of Beef”). What they neglected to say was how many samples they did that year.
Although there are several benefits to industrialized farming, such as low meat costs and a mass amount of meat available to consumers at any point in time, there are far more consequences that make these farms not worth it. As factory farming becomes more common, researchers are conducting studies on how the farms are effecting livestock’s’ health, consumers health, the air, water, and land near CAFOs, and how dangerous zoonotic diseases are quickly spreading and why. Nierenberg backs this up by explaining how “[f]actory farming is an inefficient, ecologically disruptive, dangerous, and inhumane way of making meat” (Nierenberg). However, the livestock industry continues to claim that keeping animals confined inside is safer than letting them roam free, because confining them reduces their risk of contracting diseases and being exposed to potentially harsh weather conditions. They also claim that there is a “need” to give livestock antibiotics and growth hormones, which forces dairy cows to produce more milk than their bodies are designed to produce, and chickens to gain weight too fast, resulting in them collapsing or having broken leg bones.
By buying from smaller, more organic farms, there is also a much smaller risk of eating meat that has been treated with hormones or antibiotics. According to Nierenberg two thirds of all beef cattle and one third of all dairy cows are treated with some type of growth hormone. She also reports that each year livestock consume eight times as many antibiotics as humans. Sayre shows the consequences of this by saying that “[s]ome medical investigators suggest that we may be entering a ‘post-antibiotic era,’ one in which there would be no effective antibiotics available for treating many life-threatening infections in humans” (Sayre). Not only are industrialized farms harboring and spreading dangerous zoonotic diseases… they’re now preventing us from being able to treat them. An easy way to help stop this from happening is by creating laws that restrict or prohibit the use of uncontrolled antibiotics and growth hormones on all livestock animals. By reducing our meat intake, we can reduce the demand for high numbers of livestock animals, resulting in less of a need for huge industrialized farms. The Humane Society of the United States says that “[r]eplacing meat with healthy vegetarian foods helps prevent against obesity, heart disease, stroke, many cancers, diabetes, and other serious diseases” (The Humane Society). If we choose to continue consuming meat, we can at least get it from smaller, more local farms, or those that are completely organic: “Heritage Foods USA ships grass fed, humanely raised pigs, chickens, turkeys, and lambs all over the US” (Nierenberg). The average meal travels “fifteen hundred miles from the farm to the supermarket” (Food, Inc), but by buying from a local farmers market or local farms, we can greatly reduce that to less than one hundred miles.
Work Cited:
Durning, Alan B, and Holly B. Brough. Taking Stock: Animal Farming and the Environment. Washington, DC: Worldwatch Institute, July 1991. Print.
“Factory Farms, Adverse Effects of.” Environmental Science: In Context. Ed. Brenda Wilmoth Lerner and K. Lee Lerner. Detroit: Gale, 2009. 302-305. Gale Virtual Reference Library. Web. 14 January 2010.
Food, Inc. Dir. Robert Kenner. Perf. Eric Schlosser. Magnolia Home Entertainment, 2009. DVD.
Martinez, José, et al. “Livestock Waste Treatment Systems of the Future: A Challenge to Environmental Quality, Food Safety, and Sustainability.”
ScienceDirect. 100.22 (November 2009): 5527-5536. Bioresource Technology. Web. 10 February 2010.
Mirabelli, Maria C., et al. “Asthma Symptoms Among Adolescents Who Attend Public Schools That Are Located Near Confined Swine Feeding Operations.” Pediatrics: Official Journal of the American Academy of Pediatrics. 118.e66-e75 (6 January 2006): n. pag. American Academy of Pediatrics. American Academy of Pediatrics. Web. 8 February 2010.
Moss, Michael. “E. Coli Path Shows Flaws in Beef Inspection.” New York Times 4 October 2009, n. pag., New York Times. The New York Times Company. Web. 7 February 2010.
Moss, Michael. “Safety of Beef Processing Method is Questioned.” New York Times 31 December 2009, n. pag., New York Times. The New York Times Company. Web. 7 February 2010.
Motavalli, Jim and Tracey C. Rembert. “Brave New World: Genetic Engineering, rBGH and Mad Cow Disease.” E/ The Environmental Magazine (2009): n. pag., E/ The Environmental Magazine. Web. 2 February 2010.
Nierenberg, Danielle. Happier Meals: Rethinking the Global Meat Industry: Washington, DC: Worldwatch Institute, September 2005. Print.
Oot, R. A., et al. “Prevalence of Escherichia coli 0157 and 0157:H7-Infecting Bacteriophages in Feedlot Cattle Feces.” Letters in Applied Microbiology 45.4 (4 June 2007): 445-453. Letters in Applied Microbiology. The Society for Applied Microbiology. Web. 10 February 2010.
Sayre, Laura. “The Hidden Link Between Factory Farms and Human Illness.” Mother Earth News 1.232 (February/March 2009): 76-83. Academic Search Premier. Web. 25 January 2010.
Schmidt, Charles W. “Swine CAFOs & Novel H1N1 Flu: Separating Facts from Fears.” Environmental Health Perspectives. 117.9 (September 2009): A394-A401. Print.
United States. Centers for Disease Control and Prevention. Escherichia coli 0157:H7. CDC. Centers for Disease Control and Prevention. 17 July 2009. Web. 9 March 2010.
United States. The Humane Society of the United States. Compass Launches Landmark “Flexitarian” Initiative. Humane Society. The Humane Society of the United States, 5 January 2010. Web. 3 February 2010.
United States. United States Department of Agriculture Food Safety and Inspection Service. Foodborne Illness & Disease. USDA. United States Department of Agriculture, March 2005/April 2006/September 2006. Web. 2 February 2010.
United States. World Health Organization. Media Centre: Fact Sheets. WHO. World Health Organization, 2010. Web. 2 February 2010.
