Từ điển khoa học động vật vần P | Pathogens in Animal Products Major Biological Hazards John N. Sofos Colorado State University Fort Collins Colorado . INTRODUCTION The most severe biological hazards in foods are pathogenic bacteria which may cause illness as direct agents infection or through production of various toxins intoxication while additional biological hazards include parasitic and viral agents. Typical clinical symptoms of foodborne bacterial and viral diseases include acute diarrhea abdominal cramps vomiting or some other manifestation in the gastrointestinal tract. In addition syndromes associated with the central nervous system or various organs as well as various chronic sequelae may also be the direct or indirect result of foodborne pathogenic bacteria. Individuals with suppressed or compromised immune systems are more susceptible to severe foodborne microbial illness. Prions found in animal central nervous tissue are considered a potential newer type of hazard leading to development of transmissible spongiform encephalopathies TSE . According to the . Centers for Disease Control and Prevention CDC it is estimated that for the period 1993 1997 meat and poultry were responsible for of the total outbreaks of known vehicle of transmission and for of the corresponding cases . BACTERIAL PATHOGENS Escherichia coli O157 H7 E. coli are mostly harmless colonizers of the gastrointestinal tract of warm-blooded animals including humans certain strains however cause diarrheal illness. 1 Some strains produce Shigalike toxins SLT or verotoxins VT and are classified as enterohemorrhagic E. coli EHEC or Shigalike toxin producing STEC or as verocytotoxigenic VTEC with E. coli O157 H7 being the predominant EHEC serotype. E. coli O157 H7 are Gram-negative facultatively anaerobic non-spore-forming rods that are mostly motile. They can grow at temperatures of 7 46 C optimum 35 40 C in water activities of and at pH values of optimum . 1 E. coli O157 H7 .
