Use of Antibiotics
One of the biggest concerns is the routine administration of low doses of antibiotics to farm animals to prevent them from developing diseases and to cure any that might already have diseases. This is called nontherapeutic, sub-therapeutic, or preventative antibiotic use. Many people fear that it could lead to development of antibiotic-resistant diseases in animals and humans. Scientists already know that some bacteria are able to adjust to and tolerate low dosages of weaker antibiotics. Once they achieve this resistance it is much more difficult to kill them and requires increasingly stronger types of antibiotics.
According to data on its Web site in 2005, the Union of Concerned Scientists estimated that 70% of the antibiotics used in the United States are administered to farm animals. The American Medical Association and the World Health Organization have called for a ban on nontherapeutic use of antibiotics in farm animals. They have already been banned by the European Union.
In February 2002 McDonald's, Wendy's, and Popeye's announced that they would no longer buy chickens from suppliers that administered fluoroquinolone antibiotics to their poultry. Fluoroquinolone is similar to a powerful human antibiotic called Cipro. The HSUS says that fluoroquinolone is often administered via drinking water to entire chicken flocks because it is too difficult or costly for the producers to individually treat sick birds.
Animal-to-Human Disease Transmission
Another concern related to animal welfare is the fear that U.S. farm animals could transmit diseases to humans, either through live contact or from the consumption of tainted meat products.
Diseases that can be transmitted from animals to humans are called zoonoses. Zoonoses associated with farm animals include anthrax, scrapie, brucellosis, leptospirosis, bovine tuberculosis, streptococcus suis, orf, and ringworm. Of major concern is a group of diseases called transmissible spongiform encephalopathies (TSEs).
MAD COW DISEASE.
One TSE is called bovine spongiform encephalopathy (BSE), commonly known as mad cow disease. BSE is a neurological disease of cattle that is believed to be caused by misshapen protein cells called prions. Prions enter brain cells and disrupt normal cell operation, resulting in severe brain damage and ultimately death. BSE devastated farm animal populations in England during the 1980s and 1990s. Millions of animals were killed because they either had the disease or as a precaution against the disease. Scientists believe that BSE is a fairly new disease that emerged in cattle that had been fed animal byproducts from sheep contaminated with scrapie. Byproducts from slaughtered infected cattle were inadvertently fed to healthy cattle, leading to widespread infection.
Medical authorities suspect that humans can contract a similar brain-wasting disease by eating meat from BSE-infected animals. The human disease is called variant Creutzfeldt-Jakob disease (vCJD). This is a new form of an already known disease called Creutzfeldt-Jakob disease (CJD). The causes of classic CJD are not well understood; however, it is extremely rare and has been found mostly in older people. By contrast, most of the victims of vCJD have been in their twenties and are believed to have eaten BSE-tainted beef. CJD and vCJD cause severe brain damage and are ultimately fatal.
The Centers for Disease Control and Prevention (CDC) reported that 158 cases of vCJD existed worldwide as of August 2004. Of these, 147 cases occurred in the United Kingdom.
In December 2003 the first case of BSE in the United States was confirmed in a downer Holstein cow tested in Washington state. The test results were obtained nearly two weeks after the cow had been slaughtered. All meat products associated with cattle slaughtered as part of the same batch were recalled. However, some of the meat had already been consumed by humans. U.S. authorities believe that the infected cow had been imported from Canada.
Dozens of countries banned the importation of beef from the United States following the incident. According to the National Cattlemen's Beef Association, approximately one-third of those countries had reopened their markets by January 2005 ("Japan Critical to U.S. Beef Staging a Comeback," George Raine, http://hill.beef.org/newview.asp?DocumentID=13936). One notable exception was Japan, which had been the largest single importer of U.S. beef. In May 2005 MSNBC News reported that Japanese government officials were considering a plan to lift the ban and allow beef imports to resume. Ironically, Japanese beef has been banned in the United States since September 2001, when a BSE-infected cow was discovered in Japan.
Since 1990 the USDA has conducted a BSE surveillance program on U.S. cattle. At first the program concentrated on cattle exhibiting clinical signs of BSE or other neurological disorders. In 1993 testing was extended to downer cattle at slaughterhouses. In 2001 the program was expanded to include cattle that died of unknown causes. These target populations are believed to be the animals in which BSE is most likely to be found if it is present. In July 2004 the USDA estimated that nearly half a million cattle in the United States fell in the high-risk category. Figure 4.17 shows the number of cattle tested for BSE between May 1990 and April 2004. Of the 15,513 cattle tested during early 2004, the USDA reported that 57% were downers and 34% were dead. The remainder were not classified.
In 2004 the FDA issued a final rule prohibiting the use of certain cattle body parts in human foods, dietary supplements, and cosmetics. The body parts include the brain, skull, eyes, and spinal cords of cattle thirty months old or older and portions of the tonsils and small intestines from cattle of all ages. The use in food of meat from downer cattle and mechanically separated beef was also prohibited. (Mechanically separated beef is a paste-like product produced when bones with meat still attached are fed under very high pressure through separating machines. It can contain bits of pulverized bone, including the spinal cord.)
In January 2005 the Canadian Food Inspection Agency announced that BSE had been confirmed in two cows in the province of Alberta.
FEARS OF AVIAN INFLUENZA.
As of 2005, scientists were growing increasingly concerned about the transmission of avian influenza A to humans. Avian influenza A is a disease first detected during the late 1800s. Prior to the 1990s it was found only in birds and a few species of pigs. In 1997 the first known cases in humans appeared in Hong Kong, causing six deaths. The human outbreak coincided with a severe infection throughout the Hong Kong poultry industry. The country's entire flock of poultry (1.5 million birds) had to be destroyed. Scientists
FIGURE 4.17
Number of cattle tested under USDA's BSE Surveillance Program, May 1990–April 2004
Bacterial Foodborne Illnesses
Food poisoning from meat products has received a lot of attention in recent years. Humans can become very sick or die from ingesting bacteria that are found in the intestinal tracts and manure of some farm animals. These pathogens include Salmonella, Listeria, Escherichia coli, and Campylobacter.
In December 2002 the CDC estimated that as many as seventy-six million illnesses, 325,000 hospitalizations, and 5,000 deaths annually were caused by foodborne pathogens. However, the CDC noted that some foodborne illnesses declined dramatically between 1996 and 2001, thanks to increased public awareness, pathogen reduction measures implemented by the USDA at meat and poultry slaughterhouses and processing plants, and product recalls. When USDA or internal inspections reveal potential problems at processing plants, producers issue market recalls. In October 2002 Pilgrim's Pride had to recall twenty-seven million pounds of deli meat processed at a plant that tested positive for Listeria. This was the largest meat recall in U.S. history.
As shown in Table 4.3, there were 22,700 cases of foodborne disease recorded by the CDC in 2003 (the latest year for which data are available). The etiology (cause and origin) of the diseases was identified in only 68% of the cases. More than half of the cases of known etiology were attributed to bacterial contamination.
The USDA is advocating the use of irradiation to safeguard the U.S. meat supply. Irradiation is a process in which meat is treated with low levels of radiation to kill bacteria. In October 2002 the USDA announced that meat supplied to public schools could undergo irradiation. Some people are concerned that irradiation could cause unforeseen problems in meat that might be harmful to humans. Animal rights activists and welfarists claim that irradiation of meat would not be required if farming and
TABLE 4.3
Foodborne disease outbreaks, 2003
| Etiology | Number of outbreaks | Number of cases | |
| Bacterial | 196 | 8,047 | |
| Chemical | 54 | 415 | |
| Parasitic | 3 | 155 | |
| Viral | 149 | 6,505 | |
| Multiple etiologies | 7 | 447 | |
| Total confirmed etiology | 409 | 15,569 | |
| Total unknown etiology | 664 | 7,230 | |
| Total 2003 | 1,073 | 22,799 |
slaughtering processes were reformed to reduce animal-waste contact.
User Comments Add a comment…