When heat is used in the preparation of food, it can kill or inactivate potentially harmful organisms, such as bacteria and viruses, as well as various parasites such as tapeworms and Toxoplasma gondii. Food poisoning and other illness from uncooked or poorly-prepared food may be caused by bacteria such as pathogenic strains of Escherichia coli, Salmonella typhimurium and Campylobacter, viruses such as noroviruses, and protozoa such as Entamoeba histolytica. Parasites may be introduced through salad, meat that is uncooked or done rare, and unboiled water. The sterilizing effect of cooking will depend on temperature, cooking time, and technique used. However, some bacteria such as Clostridium botulinum or Bacillus cereus, can form spores that survive cooking, which then germinate and regrow after the food has cooled. It is therefore recommended that cooked food should not be reheated more than once to avoid repeated growths that allow the bacteria to proliferate to dangerous level.[12] Cooking prevents many foodborne illnesses that would otherwise occur if the food was eaten raw. Cooking also increases the digestibility of some foods such as grains. Many foods, when raw, are inedible, and some are poisonous. For example kidney beans are toxic when raw or improperly cooked, due to the presence of phytohaemagglutinin which can be inactivated after cooking for at least ten minutes at 100 C.[13] Slow cooker however may not reach the desired temperature and cases of poisoning from red beans cooked in slow cooker have been reported. Preparation, handling, and storage of food are other considerations in food safety. The temperature range from 41F to 135 F (5 C to 57 C) is the "Danger zone" where bacteria is likely to proliferate, food therefore should not be stored in this temperature range. Washing of hands and surfaces, and avoidance of cross-contamination are good practices in food safety.[14] Food prepared on plastic cutting boards may be less likely to harbor bacteria than wooden ones,[15] other research however suggested otherwise.[16] Washing and sanitizing cutting boards is highly recommended, especially after use with raw meat, poultry, or seafood. Hot water and soap followed by a rinse with an diluted antibacterial cleaner, or a trip through a dishwasher with a "sanitize" cycle, are effective methods for reducing the risk of illness due to contaminated cooking implements

Cestoda (Cestoidea) is the name given to a class of parasitic flatworms, commonly called tapeworms, of the phylum Platyhelminthes. Its members live in the digestive tract of vertebrates as adults, and often in the bodies of various animals as juveniles. Over a thousand species have been described, and all vertebrate species can be parasitised by at least one species of tapeworm. Several species parasitise humans after being consumed in underprepared meat such as pork (Taenia solium), beef (T. saginata), and fish (Diphyllobothrium spp.), or in food prepared in conditions of poor hygiene (Hymenolepis spp. or Echinococcus spp.). T. saginata, the beef tapeworm, can grow up to 20 m (65 ft); the largest species, the whale tapeworm Polygonoporus giganticus, can grow to over 30 m Scolex The worm's scolex ("head") attaches to the intestine of the definitive host. In some species, the scolex is dominated by bothria (tentacles), which are sometimes called "sucking grooves", and function like suction cups. Other species have hooks and suckers that aid in attachment. Cyclophyllid cestodes can be identified by the presence of four suckers on their scolex.[3] While the scolex is often the most distinctive part of an adult tapeworm, it is often unnoticed in a clinical setting as it is inside the patient. Thus, identifying eggs and proglottids in feces is important. [edit]Body systems The main nerve centre of a cestode is a cerebral ganglion in its scolex. Motor and sensory innervation depends on the number and complexity of the scolex. Smaller nerves emanate from the commissures to supply the general body muscular and sensory ending. The cirrus and vagina are innervated, and sensory endings around the genital pore are more plentiful than other areas. Sensory function includes both tactoreception and chemoreception. Some nerves are only temporary. [edit]Proglottids The body is composed of successive segments (proglottids). The sum of the proglottids is called a strobila, which is thin, and resembles a strip of tape. From this is derived the common name "tapeworm". Like some other flatworms, cestodes use flame cells (protonephridia), located in the proglottids, for excretion. Mature proglottids are released from the tapeworm's posterior end and leave the host in feces. Because each proglottid contains the male and female reproductive structures, they can reproduce independently. Some biologists have suggested that each should not be considered a single organism, and that the tapeworm is actually a colony of proglottids. The layout of proglottids comes in two forms, craspedote, meaning proglottids are overlapped by the previous proglottid, and acraspedote which indicates a non-overlapping conjoined proglottid.[4] Once anchored to the host's intestinal wall, the tapeworm absorbs nutrients through its skin as the food being digested by the host flows past it and it begins to grow a long tail, with each segment containing an independent digestive system and reproductive tract. Older segments are pushed toward the tip of the tail as new segments are produced by the neckpiece. By the time a segment has reached the end of the tail, only the reproductive tract is left. It then drops off, carrying the tapeworm eggs to the next host, since, by that point, the proglottid is, in essence, a sac of eggs