Meat borne Bacterial diseases
Bacterial infection occurs when we eat the meat infected by bacteria or its toxins. Toxins presnt in meat may not alter the appearance, odour or flavor but will cause infection in the body. Some of the meat borne bacterial diseease are described as follows:
Salmonellosis
It is one of the most common food-borne diseases world-wide. Salmonella species are enteric bacteria and can be found in the intestinal tract of animals, including birds. The organism is ubiquitous in nature and can survive several weeks in a dry environment and several months in water depicting hardness and survivability in unfavourable conditions. Salmonella typhimurium and S. enteritidies accounts for most non-typhoidal salmonella infection in humans in both developed and developing countries among the different serotypes of Salmonella enteric.They are transmitted from animals to humans in the most parts of the world, causing gastroenteritis, which can be severe in the young, the elderly
and patients with compromised immunity. The general symptoms of salmonellosis include headache, diarrhoea, abdominal pain, nausea, fever and vomiting. As such it can frequently be isolated from raw meat and from environmental contaminants, although generally at lower numbers. Their presence in ready-to-eat foods may be a result of undercooking, poor handling practices and cross contamination.
Escherichia coli infection
Coli consists of a diverse group of bacteria. coli has been receiving much greater importance due to its pathogenicity by certain strains both in man and animals. Worldwide contamination of this group of bacteria occurred in meat through soiling of the carcass and plant environment with faecal materials during slaughter process. Pathogenic E. coli strains are categorized into pathotypes. One of the important pathotypes is Shiga toxin[1]producing E. coli (STEC) which may also be called as verocytotoxin producing E. coli (VTEC) or enterohemorrhagic E. coli (EHEC) and is the one most commonly associated with food-born outbreaks. The other pathotypes are enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC). enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC) and diffusely adherent E. coli (DAEC). The most commonly identified serotypes is E. coli O157. E. coli O157 has been reported to cause diarrhea, abdominal pain, and fever in approximately 70,000 Americans each year and may cause intense pain, high blood pressure, kidney failure and even death. Prevalence of verotoxic E. coli in meat and meat products has been recorded at an alarming rate invarious countries. Presence of E. coli in poultry meat reflects faecal contamination, indicating a possible contamination by enteric pathogens. Cross contamination during processing and human-to-food contamination via food handlers also play important role in transmission.
Campylobacteriosis
Campylobacter can be found in the intestinal tract of wild and domesticated animals. There are 17 species and 6 sub-species belong to the genus Campylobacter, of which the most frequently reported in human diseases are C. jejuni and C. coli and it is the most common bacterial pathogen that cause gastroenteritis. They are most
prevalent in raw meats and poultry. There has been increase in number of outbreak of acute campylobacteriosis in humans worldwide especially in children, the elderly and immune-suppressed patients and most cases are associated with handling raw meat, eating raw or undercooked meat or cross-contamination to cooked foods. Handling, preparation and consumption of broiler meat may account for 20-30% of human cases of campylobacteriosis, while 50-80% may be attributed to the
chicken reservoir as a whole (EFSA2010). The intestinal tract of chicken, especially the caecum and colon, can harbour a large number of Campylobacter spp.; during processing, the intestinal tract may leak or rupture and the contents are transferred to the skin of the carcass. Campylobactershould not be present in ready-to-eat foods as consumption of food containing this pathogen may result in food borne illness. In poultry, the spread of Campylobacter in the flock is because of high levels of shedding and efficient faecal-oral
transmission compounded by contaminated water and feed. Horizontal transmission from environmental sources can also occur. In broiler chickens, C. jejunicolonization can persist for 6-7 weeks, leading to carcass contamination at the processing plant during slaughter as a result of evisceration.
Listeria monocytogenes
monocytogenes is widely distributed in the environment and can be isolated from a wide variety of foods including all meat foods and poultry. As such it is expected to be present in ready-to-eat foods that contain raw ingredients. Moreover, this organism is able to multiply slowly at 4°C. Among the six species, L. monocytogenes is an opportunistic pathogen in human beings as well as in various animal and poultry birds such as chickens, ducks, turkeys, geese, etc. Chickens are thought as reservoirs and carriers of this pathogen, whereas, L. ivanovii primarily affects bird and animal species. However, incidences of L. monocytogenes in meat vary widely from 0% to 92% and the contamination mostly occurred on the surface of meat and meat products (Farber and Peterkin, 1991). The organism may also thrive in interior of muscle tissues of frozen beef. Outbreaks of listeriosis usually follow exposure to raw or uncooked poultry products but have also occurred after contaminated ready-to-eat poultry meat products were eaten. In contrast to young birds, adults may not be reservoirs of L. monocytogenes, but may be transiently colonized by consuming contaminated feed or water. Thus, L. monocytogenes may enter the packing plant at low levels in the intestine of birds, survive in biofilm, and ultimately contribute to both environmental and product contamination. The risk posed by L. monocytogenes is dependent on the food and how long it is stored. Foods in which all components have been cooked in the final food preparation, or have received some other listericidal treatment, should be Listeria free. Additionally, the detection of L. monocytogenes in foods which have been prepared specifically for ‘at risk’ population groups such as the elderly, immunocompromised and infants should be considered as potentially hazardous.
Staphylococcal infection
Staphylococcus aureus can be routinely isolated from humans and associated environments. As such, the presence of coagulase positive staphylococci (CPS) is an indication of human contact. Some CPS strains produce a toxin which can cause food poisoning. Even minimal handling can result in coagulase positive staphylococci being present in meats at low levels. This is unlikely to be a food safety concern provided that meat product is either consumed immediately or stored under temperature control since these bacteria get into warm food and multiply. In raw or fermented meat foods, coagulase positive staphylococci are likely to be outgrown or inhibited by the naturally occurring microorganisms. In fully cooked meat foods that support the growth of coagulase-positive staphylococci, the absence of competing microorganisms may provide the opportunity for growth and toxin production. The general symptoms of staphylococcal infection are abdominal cramos, vomiting, severe diarrhoea and so on. The illness seldom is fatal.
Clostridium perfringens illness
perfringens can be isolated from a variety of environments and foods. As the spores of C. perfringens can survive cooking, it is of most concern in cooked foods that have been temperature abused as this provides the opportunity for spores to germinate and grow. Potential temperature abuse scenarios include holding cooked foods at warm temperatures for extended periods of time, and cooling foods too slowly. C. perfringens is of particular concern for cooked
meats (large joints or rolled meats), gravy and meat. C. prefringens type-A infection, has been reported as the most important cause of food poisoning worldwide. The pathogen has been isolated from the intestine of the poultry birds and other large and small animals; hence, they serve as the source of contamination to varieties of meats and environment. The main symptoms in human beings include acute abdominal pain, profuse diarrhea, nausea, and rarely vomiting. C. prefringenscauses necrotic enteritis in poultry and the mechanism of colonization of the avian small intestinal tract are the factors involved in toxin production. It is generally accepted, however, that predisposing factors are required for these bacteria to colonize and cause disease in poultry. The best known predisposing factor is mucosal damage, caused by coccidiosis. Diets with high level of indigestible, water-soluble non-starch polysaccharides, known to increase the viscosity of the intestinal contents, also predispose to necrotic enteritis.