Sources of organismSources of organism

Water supplies Water supplies contaminated with faecal contaminated with faecal mattermatter

Unhygienic practices by the Unhygienic practices by the handlershandlers

Infected animals excrete Infected animals excrete may gain access into milkmay gain access into milk

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Disease in relation to man. Disease in relation to man. Both Both LTLT and and ST ST toxins of toxins of E. coli E. coli can cause can cause food poisoning syndromes in man. food poisoning syndromes in man. Although children are more Although children are more susceptible, the sensitive adults may susceptible, the sensitive adults may also be afflicted with also be afflicted with E. coli E. coli poisoning through ingestion of poisoning through ingestion of contaminated milk and milk contaminated milk and milk products.products.

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Symptoms.Symptoms. The symptoms produced as The symptoms produced as a result of ingestion of a result of ingestion of LTLT toxin toxin resemble those of cholera. There is resemble those of cholera. There is massive watery diarrhoea due to massive watery diarrhoea due to accumulation of fluid in the intestine. accumulation of fluid in the intestine. In case of In case of ST ST type, the symptoms type, the symptoms include, diarrhoea, with or without include, diarrhoea, with or without vomition, which is nonbloody and vomition, which is nonbloody and without inflammatory exudate in the without inflammatory exudate in the stool. Fever may be caused in children stool. Fever may be caused in children but not in adults.but not in adults.

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Incubation period.Incubation period. It is 8-24 h. It is 8-24 h.Prevention and control. Prevention and control. The control of The control of E. E.

colicoli poisoning is similar to that for any poisoning is similar to that for any other enteric disease. However, the other enteric disease. However, the following precautions should be taken in following precautions should be taken in this connection.this connection.

i)i) The faecal contamination of water The faecal contamination of water supply should be avoided.supply should be avoided.

ii)ii) Handlers should strictly follow hygienic Handlers should strictly follow hygienic practices.practices.

iii)iii) Cross contamination from infected Cross contamination from infected animals should also be avoided.animals should also be avoided.

4. Cholera4. Cholera

Cholera is one of the acute diarrhoeal Cholera is one of the acute diarrhoeal disease caused by disease caused by Vibrio cholerae. Vibrio cholerae. It It frequently occurs in the form of frequently occurs in the form of massive epidemics, and unhygienic massive epidemics, and unhygienic practices appear to be chiefly practices appear to be chiefly responsible for the eruption of responsible for the eruption of outbreaks. Although cholera is mainly outbreaks. Although cholera is mainly a water-borne illness, the involvement a water-borne illness, the involvement of milk and milk products may also of milk and milk products may also transmit the disease. transmit the disease.

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The organism adheres to the epithelial The organism adheres to the epithelial cells lining the crypts of mucosa in cells lining the crypts of mucosa in the small intestine where it the small intestine where it produces enterotoxin that causes produces enterotoxin that causes loss of fluid and electrolytes from loss of fluid and electrolytes from the body followed by dehydration.the body followed by dehydration.

Causative agent. Vibrio cholerae.Causative agent. Vibrio cholerae.

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Sources of the causative organismSources of the causative organism

i)i) Milk may be infected by soiled Milk may be infected by soiled hands of a patient or a convalescent hands of a patient or a convalescent carrier.carrier.

ii)ii) Use of infected water for dairy Use of infected water for dairy purposes.purposes.

iii)iii) adulteration of milk with adulteration of milk with contaminated water may also be one contaminated water may also be one of the causes.of the causes.

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Disease in relation to human beings.Disease in relation to human beings. V. V. cholerae cholerae organisms penetrate the mucosa organisms penetrate the mucosa of the intestines and accumulate in layers of the intestines and accumulate in layers next to the sub-mucosa.next to the sub-mucosa.

Symptoms. Symptoms. In mild cases of cholera, In mild cases of cholera, diarrhoea appears to be the only diarrhoea appears to be the only symptoms. However in severe cases, the symptoms. However in severe cases, the symptoms are diarrhoea, vomiting, rice symptoms are diarrhoea, vomiting, rice water stools, abdominal pain, thirst, water stools, abdominal pain, thirst, dehydration symptoms, etc. The disease dehydration symptoms, etc. The disease runs a short course terminating in death, runs a short course terminating in death, sometimes within 12 h after the sometimes within 12 h after the appearance of symptoms. appearance of symptoms.

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Incubation period. Incubation period. It is usually for 3 days (few It is usually for 3 days (few hours to 5 days).hours to 5 days).

Diagnosis. V. cholerae Diagnosis. V. cholerae can be isolated fromcan be isolated from faeces of both infected individuals and faeces of both infected individuals and carriers. The intraperitoneal inoculation of carriers. The intraperitoneal inoculation of guinea pigs with pure cultures results in the guinea pigs with pure cultures results in the death of the animals within 24 hours.death of the animals within 24 hours.

Susceptibility and immunity. Susceptibility and immunity. Natural resistance Natural resistance varies in different individuals. Clinical attacks varies in different individuals. Clinical attacks confer a temporary immunity which may last confer a temporary immunity which may last for several years. Active artificial immunity for several years. Active artificial immunity may last for 6-12 months and may be induced b may last for 6-12 months and may be induced b the use of vaccines. the use of vaccines.

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Prevention and controlPrevention and control

i)i) Proper pasteurization of milk and Proper pasteurization of milk and milk products.milk products.

ii)ii) Sanitary disposal of human excreta.Sanitary disposal of human excreta.

iii)iii) Protection of water by boiling.Protection of water by boiling.

iv)iv) Sanitary preparation and handling Sanitary preparation and handling of products.of products.

v)v) Control or destruction of house flies.Control or destruction of house flies.

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vi)vi) Education of public in personal Education of public in personal cleanliness.cleanliness.

vii)vii) Isolation of patients.Isolation of patients.viii)viii) Disinfection of stools and vomits and Disinfection of stools and vomits and

articles soiled by these.articles soiled by these.ix)ix) Food left by patients should be burnt.Food left by patients should be burnt.x)x) Room of patient should be thoroughly Room of patient should be thoroughly

cleaned and disinfected.cleaned and disinfected.xi)xi) Carriers should be isolated.Carriers should be isolated.xii)xii) Use of cholera vaccine in exposed Use of cholera vaccine in exposed

population groups.population groups.

5.5. Fungal intoxicationsFungal intoxications

The common types of fungal The common types of fungal intoxications that result through intoxications that result through milk and milk products are those milk and milk products are those caused by caused by Aspergillus Aspergillus and other and other molds likemolds like penicillium Fusarium penicillium Fusarium etc.etc.

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a)a)AflatoxicosisAflatoxicosisAflatoxicosis is a common type of Aflatoxicosis is a common type of

fungal intoxication caused by the fungal intoxication caused by the common molds common molds Asoergukkys flavusAsoergukkys flavus and and A. parasiticus A. parasiticus by virtue of their ability by virtue of their ability of produce aflatoxin. Te aflatoxin can of produce aflatoxin. Te aflatoxin can be present in milk as preformed toxin be present in milk as preformed toxin or it can be secreted in milk by the or it can be secreted in milk by the milch animal which has been fed with milch animal which has been fed with aflatoxin containing feeds. aflatoxin containing feeds.

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Therefore, even with an exceptionally Therefore, even with an exceptionally satisfactory sanitation and hygiene satisfactory sanitation and hygiene observed during production and observed during production and processing of milk, the mycotoxins can processing of milk, the mycotoxins can be transferred to the consumers. Upon be transferred to the consumers. Upon ingestion, the Aspergillus-toxins are ingestion, the Aspergillus-toxins are metabolised by the milch animals and metabolised by the milch animals and are secreted into the milk in the form are secreted into the milk in the form of M1 and M2 which are also toxic to of M1 and M2 which are also toxic to the milk consumers. the milk consumers.

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Types of aflatoxins.Types of aflatoxins. A. flavus can A. flavus can produce the following distinct types of produce the following distinct types of aflatoxins in milk and milk products, aflatoxins in milk and milk products, apart from M1 and M2 toxins.apart from M1 and M2 toxins.

i)i) B1, B2, B2a aflatoxin B1 is the most B1, B2, B2a aflatoxin B1 is the most abundant and most toxic of the abundant and most toxic of the aflatoxins.aflatoxins.

ii)ii) G1, G2 and G2a. G1, G2 and G2a.

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These toxins are extremely heat stable, These toxins are extremely heat stable, potent and exhibit very strong toxicity potent and exhibit very strong toxicity apart form being highly carcinogenic.apart form being highly carcinogenic.

Raw milk, ice-cream powder, Raw milk, ice-cream powder, evaporated milk, dried milks and evaporated milk, dried milks and cheese are the common foods cheese are the common foods implicated with aflatoxins. The implicated with aflatoxins. The recommended upper permissible limit recommended upper permissible limit of aflatoxins in foods is 90 ppm.of aflatoxins in foods is 90 ppm.

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Sources of the causative organisms. Sources of the causative organisms. The main The main sources of sources of AspergillusAspergillus spp. Which are spp. Which are capable of producing aflatoxins are as capable of producing aflatoxins are as follows:follows:

i)i) Environment: aerial contamination is one of Environment: aerial contamination is one of the most important sources of mold spores.the most important sources of mold spores.

ii)ii) Soil and contaminated foods may also Soil and contaminated foods may also introduce mold spores in milk and milk introduce mold spores in milk and milk products.products.

iii)iii) Poor storage conditions. Poor storage conditions.

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Disease in relation to man and animals. Disease in relation to man and animals. As a As a result of ingestion of aflatoxins through result of ingestion of aflatoxins through contaminated milk and milk products, acute contaminated milk and milk products, acute aflatoxicosis may result in the consumers.aflatoxicosis may result in the consumers.

Symptoms. Symptoms. The main symptoms of the The main symptoms of the aflatoxicosis are liver hyperplasia, tissue aflatoxicosis are liver hyperplasia, tissue haemorrhage, anorexia, hepatitis and finally haemorrhage, anorexia, hepatitis and finally death in animals. The vital organs like death in animals. The vital organs like spleen, pancreas and kidney may also be spleen, pancreas and kidney may also be involved in aflatoxicosis.involved in aflatoxicosis.

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Prevention and control. Prevention and control. The system The system for controlling aflatoxins in milk for controlling aflatoxins in milk and milk products as well as feeds and milk products as well as feeds are essentially the same as for are essentially the same as for controlling any microbial toxin. In controlling any microbial toxin. In this regard, the following measures this regard, the following measures are required to be taken.are required to be taken.

i)i) Prevent contamination of milk and Prevent contamination of milk and milk products as well as feed by milk products as well as feed by taking approprite precautions.taking approprite precautions.

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ii)ii) Prevent fungal growth by storing Prevent fungal growth by storing the products under proper the products under proper conditions and by the use of conditions and by the use of fungistatic agents.fungistatic agents.

iii)iii) Detoxification of aflatoxins by Detoxification of aflatoxins by physical, chemical or biological physical, chemical or biological agents. However, this measure is agents. However, this measure is relatively impractical in dairy relatively impractical in dairy products.products.

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b)b) Other MycotoxicosesOther MycotoxicosesApart from aflatoxins, molds can Apart from aflatoxins, molds can also produce a variety of other also produce a variety of other toxins which can cause other toxins which can cause other human illnesses or mycotoxicoses, human illnesses or mycotoxicoses, as a result of consumption of as a result of consumption of intoxiated milk and ilk products. A intoxiated milk and ilk products. A few such mycotoxins along with the few such mycotoxins along with the producing organisms have been producing organisms have been given in table below (Table 4.6). given in table below (Table 4.6).

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Like aflatoxins, some of these toxins Like aflatoxins, some of these toxins are also resistant to processing are also resistant to processing conditions and a variety of milk and conditions and a variety of milk and milk products can be implicated in milk products can be implicated in such mycotoxicoses. The diagnosis of such mycotoxicoses. The diagnosis of the disease in man, however, has been the disease in man, however, has been achieved only on a few occasions. This achieved only on a few occasions. This is mainly based on the detection of the is mainly based on the detection of the mycotoxin in the food. mycotoxin in the food.

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Since clinical manifestations of Since clinical manifestations of different types of toxicoses are more different types of toxicoses are more or less similar, the diagnosis can’t be or less similar, the diagnosis can’t be made on the basis of these made on the basis of these symptoms. In addition to their acute symptoms. In addition to their acute effects on different parts of the body, effects on different parts of the body, certain mycotoxins have been shown certain mycotoxins have been shown to have terratogenic and to have terratogenic and carcinogenic effects. carcinogenic effects.

ContCont……Prevention and control.Prevention and control. The control of The control of

different mycotoxicoses requires the different mycotoxicoses requires the prevention or reduction of mycotoxin prevention or reduction of mycotoxin contamination in milk and milk contamination in milk and milk products as has already been products as has already been discussed under aflatoxicoses. discussed under aflatoxicoses.

C.C. Milk-borne toxi-Milk-borne toxi-infectionsinfections

The organisms like The organisms like Clostridium Clostridium perfringens perfringens and and B. cereusB. cereus cause cause toxi-toxi-infections through milk and milk products, infections through milk and milk products, as discussed in the following pages:as discussed in the following pages:

1.1. Clostridium perfringens (Clostridium perfringens (welchii) welchii) poisoning poisoning

The perfringens type of food-poisoning The perfringens type of food-poisoning can also occur due to the ingestion of can also occur due to the ingestion of contaminated milk or milk products. contaminated milk or milk products. C. C. Perfringens Perfringens causes gas gengrene causes gas gengrene

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Since this organism is anaerobic in Since this organism is anaerobic in nature like nature like Cl. Botulinum, Cl. Botulinum, the the anaerobic conditions as observed in anaerobic conditions as observed in canned products could be favourable canned products could be favourable for this type of toxi-infection. There for this type of toxi-infection. There are at least five antigenically distinct are at least five antigenically distinct types of this organism according to the types of this organism according to the type of toxins it produces, namely A, B, type of toxins it produces, namely A, B, C, D, and E. Two of their ability to C, D, and E. Two of their ability to produce enterotoxins which are lethal produce enterotoxins which are lethal and emetic.and emetic.

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Sources of the causative organismSources of the causative organismi)i) Cl. perfringensCl. perfringens is commonly found is commonly found

in soil and faeces of man and in soil and faeces of man and animals from where it can find its animals from where it can find its way into milk and its products way into milk and its products through dust, fodder and through dust, fodder and unsanitary handling.unsanitary handling.

ii)ii) Water supplies contaminated with Water supplies contaminated with sewage or faecal matter may also sewage or faecal matter may also introduce this organism into milk. introduce this organism into milk.

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As it is a sporeforming organism, the As it is a sporeforming organism, the highly resistant spores survive almost highly resistant spores survive almost indefinitely in dust and are widely indefinitely in dust and are widely prevalent in cowsheds and dairies.prevalent in cowsheds and dairies.

Disease in relation to human beings.Disease in relation to human beings. The The disease caused in human beings is disease caused in human beings is gastroenteritis which occurs due to the gastroenteritis which occurs due to the production of exotoxin/enterotoxins by production of exotoxin/enterotoxins by this organism which are excreted during this organism which are excreted during sporulation and the release of the spores. sporulation and the release of the spores.

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The enterotoxin is resistant to The enterotoxin is resistant to intestinal juices and, therefore, intestinal juices and, therefore, affects the intestinal walls. Children affects the intestinal walls. Children are more susceptible. The MLD are more susceptible. The MLD (minimum lethal dose) of the toxin is (minimum lethal dose) of the toxin is 2,000 mice/mg nitrogen.2,000 mice/mg nitrogen.

Symptoms.Symptoms. Diarrhoea, vomiting, Diarrhoea, vomiting, nausea, abdominal pain etc. are the nausea, abdominal pain etc. are the common symptoms of this type of common symptoms of this type of poisoning.poisoning.

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Incubation period.Incubation period. It varies from 8-22 h and It varies from 8-22 h and duration is generally one day or less. duration is generally one day or less. However, it is not very fatal.However, it is not very fatal.

Prevention and controlPrevention and control

i)i) Proper heat treatment of milk.Proper heat treatment of milk.

ii)ii) Milk should not be stored under conditions Milk should not be stored under conditions suitable for the spores to vegetate and suitable for the spores to vegetate and multiply.multiply.

iii)iii) After pasteurization, a rapid cooling and After pasteurization, a rapid cooling and storage of milk at temperatures below 15°C storage of milk at temperatures below 15°C is required.is required.

iv)iv) Environment hygiene should be observed. Environment hygiene should be observed.

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2.2. Bacillus cereusBacillus cereus poisoning poisoning B. cereus B. cereus poisoning is yet another type of poisoning is yet another type of ‘toxi-infection’ which can occur as a result ‘toxi-infection’ which can occur as a result of ingestion of milk and milk products of ingestion of milk and milk products contaminated with contaminated with B. cereus B. cereus or its spores.or its spores. Bacillus cereus, Bacillus cereus, the causative agent of the causative agent of this poisoning, is an aerobic, sporeforming this poisoning, is an aerobic, sporeforming organism which occurs in almost all raw organism which occurs in almost all raw milk supplies as well as in pasteurized milk supplies as well as in pasteurized milk, cream cakes, pastry, confectionary milk, cream cakes, pastry, confectionary fillings and processed cheese. fillings and processed cheese.

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Sources of the causative organismsSources of the causative organisms

i)i) Since Since B. cereus B. cereus is one of the causatives for is one of the causatives for mastitis, the herd raw milk sometimes gets mastitis, the herd raw milk sometimes gets B. cereus B. cereus from mastitis animals.from mastitis animals.

ii)ii) The raw milk may also get spores from The raw milk may also get spores from animal’s teat and skin, and the milking animal’s teat and skin, and the milking equipments, especially cans.equipments, especially cans.

iii)iii) Soil may also introduce Soil may also introduce B. cereus B. cereus directly directly or indirectly in milk and ilk products. or indirectly in milk and ilk products.

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Toxins.Toxins. The following three types of The following three types of toxins are elaborated by toxigenic toxins are elaborated by toxigenic strains of strains of B. cereus B. cereus in milk and in milk and milk products.milk products.

i)i) Haemolysin Haemolysin

ii)ii) Lecithinase (phospholipase C)Lecithinase (phospholipase C)

iii)iii) EnterotoxinEnterotoxin

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Enterotoxin is responsible for food Enterotoxin is responsible for food poisoning outbreaks, while lecithinase poisoning outbreaks, while lecithinase and haemolysin play an important role in and haemolysin play an important role in the pathogenesis of the organism. the pathogenesis of the organism.

Disease in relation to man. B. cereus Disease in relation to man. B. cereus causes two types of poisoning, viz. (i) causes two types of poisoning, viz. (i) diarrhoeal type, and (ii) vomiting type.diarrhoeal type, and (ii) vomiting type.

Symptoms.Symptoms. The main symptoms are The main symptoms are nausea, diarrhoea, abdominal pain etc. nausea, diarrhoea, abdominal pain etc.

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Incubation period. Incubation period. The incubation The incubation period is about 12 h and the period is about 12 h and the duration is one day or less (6-12 h).duration is one day or less (6-12 h).

Prevention and control. Prevention and control. The following The following practices should be strictly practices should be strictly observed to minimize observed to minimize B. cereus B. cereus poisoning through milk and milk poisoning through milk and milk products:products:

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i)i) Prompt cooling of milk/milk products Prompt cooling of milk/milk products during storage.during storage.

ii)ii) Environment hygiene should be Environment hygiene should be maintained and the aerial contamination maintained and the aerial contamination should be avoided.should be avoided.

iii)iii) Precautions should be taken during Precautions should be taken during transition of milk.transition of milk.

iv)iv) General hygiene conditions should be General hygiene conditions should be maintained during production of milk maintained during production of milk and marketing of dairy products. and marketing of dairy products.

D. Other milk-borne disorders D. Other milk-borne disorders of uncertain pathogenesisof uncertain pathogenesis

1.1. ProteusProteus infectioninfection

Illness caused by Illness caused by Proteus vulagrisProteus vulagris through milk and milk products is through milk and milk products is of rare occurrence. However, in of rare occurrence. However, in some cases, some cases, Proteus mirabilis Proteus mirabilis may may cause summer diarrhoea in human cause summer diarrhoea in human beings, through its exact role in beings, through its exact role in milk-borne milk-borne Proteus Proteus infection is infection is debatable. debatable.

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Since this organism is easily destroyed Since this organism is easily destroyed by heat treatment, proper by heat treatment, proper pasteurization will render milk safe pasteurization will render milk safe for consumption. Similarly, by for consumption. Similarly, by following proper sanitizing following proper sanitizing practices, it may also be possible to practices, it may also be possible to control control Proteus Proteus infections through infections through milk and milk products.milk and milk products.

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2.2. Aeromonas Aeromonas infectioninfection

AeromonasAeromonas is mainly associated is mainly associated with animals that live in water. with animals that live in water. However, certain species have been However, certain species have been isolated from humans. A few species isolated from humans. A few species like like Aeromonas hydrophilia Aeromonas hydrophilia appears appears to be enterotoxigenic, through the to be enterotoxigenic, through the exact role of this organism in food exact role of this organism in food poisoning through milk and milk poisoning through milk and milk products is not known at present. products is not known at present.

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Contaminated water may be the Contaminated water may be the source of this organism in milk. The source of this organism in milk. The incidence of this organism in milk incidence of this organism in milk and milk products can be controlled and milk products can be controlled by following appropriate hygienic by following appropriate hygienic practices during production and practices during production and processing of milk and also by giving processing of milk and also by giving suitable treatment to the suitable treatment to the contaminated water supplies. contaminated water supplies.

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3.3. CitrobacterCitrobacter infectioninfectionThis organism is very rarely This organism is very rarely associated with gastroenteritis associated with gastroenteritis through ingestion of contaminated through ingestion of contaminated foods including milk and milk foods including milk and milk products. A few strains of products. A few strains of Citrobacter Citrobacter produce enterotoxins. produce enterotoxins. However, the exact aetiology of However, the exact aetiology of Citrobacter Citrobacter include illness is not include illness is not known as yet. known as yet.

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4.4. KlebsiellaKlebsiella infectioninfectionThe involvement of The involvement of Klebsiella Klebsiella in milk-borne in milk-borne gastrointestinal illnesses appears to be gastrointestinal illnesses appears to be quite rare. Among its different species, quite rare. Among its different species, K. K. pneumoniae pneumoniae can produce heat stable and can produce heat stable and heat labile toxins which are comparable to heat labile toxins which are comparable to those of those of E. coliE. coli. However, there are . However, there are conflicting reports concerning the food-conflicting reports concerning the food-poisoning potentials of these organisms. poisoning potentials of these organisms. Hence, there is a need to study this Hence, there is a need to study this organism extensively before associating it organism extensively before associating it with such food-borne illnesses. with such food-borne illnesses.

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5.5. PseudomonasPseudomonas infectioninfectionThe various species of The various species of PseudomonasPseudomonas encountered in milk encountered in milk and milk products are and milk products are Ps. Ps. Putrefaciens, Ps. Fluorescens, Ps. Putrefaciens, Ps. Fluorescens, Ps. fragi, Ps. viscosa fragi, Ps. viscosa and and Ps. Ps. aeruginosa. aeruginosa. Of these, Of these, Ps. Ps. Aeruginosa Aeruginosa appears to play an appears to play an important role in food poisoning important role in food poisoning through milk and milk products. through milk and milk products.

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Ps. aeruginoa Ps. aeruginoa has been incriminated has been incriminated in several food poisoning outbreaks in several food poisoning outbreaks in human beings as well as in in human beings as well as in mastitis cases in animals. This mastitis cases in animals. This organism has been isolated from raw organism has been isolated from raw milk and other milk products by milk and other milk products by Grover and Srinivasan (1989) and its Grover and Srinivasan (1989) and its pathogenicity was ascertained in pathogenicity was ascertained in different animal model systems. different animal model systems.

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Sources of the causative organismSources of the causative organismi)i) Water supply is the initial source of Water supply is the initial source of

this organism.this organism.ii)ii) Improperly cleaned utensils, Improperly cleaned utensils,

equipments, pipelines, milk cans, equipments, pipelines, milk cans, churns, holding cans, valves, milking churns, holding cans, valves, milking machines, etc. constitute the other machines, etc. constitute the other sources.sources.

iii)iii) Udder teats and cowshed environment Udder teats and cowshed environment may also be the potential sources.may also be the potential sources.

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Disease in relation to human beings Disease in relation to human beings and animalsand animals

Human beings. Human beings. In human beings,In human beings, Ps. Ps. aeruginosaaeruginosa can produce urinary tract can produce urinary tract infections, eye infections, ear infections, eye infections, ear infections, septicaemia, abscess, infections, septicaemia, abscess, meningitis and enteritis. The meningitis and enteritis. The gastrointestinal distrubances dur to gastrointestinal distrubances dur to enterotoxin produced by enterotoxin produced by Ps. Ps. aeruginosa aeruginosa have also been recorded.have also been recorded.

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ii)ii) Animals. Ps. aeruginosa Animals. Ps. aeruginosa can cause can cause mastitis, necrotizing enteritis, mastitis, necrotizing enteritis, abortion, vaginitis and endometritus abortion, vaginitis and endometritus in cattle, swine and horse.in cattle, swine and horse.

Prevention and controlPrevention and control

The following are precautions required to The following are precautions required to be taken for the control of be taken for the control of pseudomonaspseudomonas infection through milk: infection through milk:

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i)i) Proper heat treatment of milk.Proper heat treatment of milk.

ii)ii) Hygienic conditions during Hygienic conditions during production and processing.production and processing.

iii)iii) Microbicidal treatment of dairy Microbicidal treatment of dairy water supply.water supply.

iv)iv) Proper cleaning and sanitization of Proper cleaning and sanitization of dairy utensils and equipments. dairy utensils and equipments.

E.E. New emerging pathogensNew emerging pathogens

1.1. ListeriosisListeriosis

Listeriosis is yet another food-Listeriosis is yet another food-borne illness which has attracted borne illness which has attracted worldwide attention during recent worldwide attention during recent years. years. Listera monocytogenes, Listera monocytogenes, the the causative agent of the disease, can causative agent of the disease, can easily gain access into milk and easily gain access into milk and milk products. milk products.

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The presence of this organism in milk The presence of this organism in milk and milk products has caused a and milk products has caused a great concern to the dairy industry great concern to the dairy industry and the general public in view of and the general public in view of high rate of human mortality. There high rate of human mortality. There has been an increase in the number has been an increase in the number of outbreaks of listeriosis due to of outbreaks of listeriosis due to ingestion of contaminated milk and ingestion of contaminated milk and milk products. milk products.

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Although, there has been tremendous impact Although, there has been tremendous impact and the necessary efforts for the combat of and the necessary efforts for the combat of this disease in developed countries, on this disease in developed countries, on serious effort has been initiated by the serious effort has been initiated by the developing countries to investigate the developing countries to investigate the causative organism of the disease from causative organism of the disease from public health point of view. Hence, there is public health point of view. Hence, there is a need to carry out extensive investigations a need to carry out extensive investigations in this country as well in respect of this in this country as well in respect of this organism to understand its pathogenic organism to understand its pathogenic potentials potentials

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Incidence in milk and milk products.Incidence in milk and milk products.

Since Since L. monocytogenes L. monocytogenes is known to is known to cause mastitis in milch animals, it cause mastitis in milch animals, it can be secreted in milk. There have can be secreted in milk. There have been a number of reports indicating been a number of reports indicating the involvement of raw and the involvement of raw and pasteurized milk with the outbreaks pasteurized milk with the outbreaks of listeriosis. of listeriosis.

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According to one such report (March, According to one such report (March, 1986), the incidence of 1986), the incidence of L. L. monocytogenes monocytogenes in milk was similar in milk was similar to that of to that of SalmonellaSalmonella comprising comprising about 5% of the sample tested. about 5% of the sample tested. Besides milk, other milk products Besides milk, other milk products like cheese have also been like cheese have also been implicated in such outbreaks.implicated in such outbreaks.

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Causative agent. Listeria Causative agent. Listeria monocytogenes, monocytogenes, the causative agent, the causative agent, is a Gram-positive, non-sporulating is a Gram-positive, non-sporulating rod capable of growing at a wide rod capable of growing at a wide range of temperature (1° to 45°C). range of temperature (1° to 45°C). The pathogenicity of the culture is The pathogenicity of the culture is associated with the production of associated with the production of extracellular haemolysin (aplha, beta) extracellular haemolysin (aplha, beta) by this organism.by this organism.

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Source of the causative organism.Source of the causative organism. The The following sources of contamination following sources of contamination may introduce the causative may introduce the causative organism in milk and milk products.organism in milk and milk products.

i)i) Infected animals are a major source Infected animals are a major source of this organisms in milk through of this organisms in milk through infected udders.infected udders.

ii)ii) Handlers carrying the disease Handlers carrying the disease organism may also introduce the organism may also introduce the organism in milk and milk products.organism in milk and milk products.

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iii)iii) Unhygienic practices observed Unhygienic practices observed during production and processing during production and processing of milk may also contribute the of milk may also contribute the organism.organism.

iv)iv) Faecal contamination of milk and Faecal contamination of milk and water is yet another source.water is yet another source.

v)v) Contaminated refrigerators and Contaminated refrigerators and dish clothes may also introduce the dish clothes may also introduce the organism in milk. organism in milk.

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Heat resistance of the organism. Heat resistance of the organism.

Although there have been conflicting Although there have been conflicting reports concerning the heat reports concerning the heat resistance of resistance of L. monocytogenes L. monocytogenes in in milk and milk products, it definitely milk and milk products, it definitely appears to survive some of the appears to survive some of the processing conditions of milk and processing conditions of milk and milk products. milk products.

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The possible reason for survival of this The possible reason for survival of this organism during processing like organism during processing like pasteurization may be attributed to pasteurization may be attributed to the ingestion of these organisms by the ingestion of these organisms by leucocytes in milk which may give leucocytes in milk which may give this organism some protection this organism some protection against heat treatment. against heat treatment.

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However, according to a survey However, according to a survey conducted by Food and Drug conducted by Food and Drug Administration (FDA, USA), Administration (FDA, USA), pasteurization appears to be a safe pasteurization appears to be a safe process that reduce the number of process that reduce the number of L. L. monocytogenes in milk to a level monocytogenes in milk to a level that does not pose any risk to the that does not pose any risk to the consumer. consumer.

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Disease in relation to man and animals.Disease in relation to man and animals.

The ingestion of The ingestion of L. monocytogenes L. monocytogenes through milk and milk products may through milk and milk products may cause listeriosis in man which may cause listeriosis in man which may sometimes become lethal, leading to sometimes become lethal, leading to the heath of consumers. However, the heath of consumers. However, the exact pathogenesis of the disease the exact pathogenesis of the disease is not known. In animals, the is not known. In animals, the organism cause mastitis, infections organism cause mastitis, infections bovine keratitis and bovine keratitis and meningioencephalitis.meningioencephalitis.

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Symptoms. Symptoms. The symptoms of The symptoms of listeriosis are acute meningitis with listeriosis are acute meningitis with or without septicaemia. The onset of or without septicaemia. The onset of meningitis is usually sudden with meningitis is usually sudden with fever, nausea, headache, vomiting, fever, nausea, headache, vomiting, followed by delirium, coma, collapse followed by delirium, coma, collapse and shock resulting in death it not and shock resulting in death it not treated promptly and properly.treated promptly and properly.

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Prevention and control.Prevention and control.

i)i) Strict hygiene practices should be Strict hygiene practices should be followed during production and followed during production and processing of milk.processing of milk.

ii)ii) The human carriers should not be The human carriers should not be allowed to handle milk and milk allowed to handle milk and milk products.products.

iii)iii) Culling of the infected animals.Culling of the infected animals.

iv)iv) Proper heat treatment of milk.Proper heat treatment of milk.

v)v) Proper storage conditions.Proper storage conditions.

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2.2. Campylobacter jejuniCampylobacter jejuni poisoning poisoning (Campylobacteriosis)(Campylobacteriosis)

Campylobacter jejuni Campylobacter jejuni is a relatively new is a relatively new bacterium which has been found to be bacterium which has been found to be involved in milk-borne campylobacteriosis. involved in milk-borne campylobacteriosis. A number of outbreaks of this type of A number of outbreaks of this type of illness have been reported in different illness have been reported in different parts of the world and the vehicle of parts of the world and the vehicle of almost all the outbreaks was traced to be almost all the outbreaks was traced to be raw milk. A wide variety of warm-blooded raw milk. A wide variety of warm-blooded animals have been found to be infected animals have been found to be infected with with Campylobacter jejuni.Campylobacter jejuni.

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Sources of the causative organismSources of the causative organism

i)i) The organism has been isolated from The organism has been isolated from intestinal tracts and faecal matter of intestinal tracts and faecal matter of man, goat, sheep, etc. Faecal matter man, goat, sheep, etc. Faecal matter is thus the chief source of this is thus the chief source of this organism.organism.

ii)ii) Polluted water contaminated with Polluted water contaminated with C. C. jejuni jejuni can also be an important source can also be an important source for the entry of this organism in milk for the entry of this organism in milk and milk products.and milk products.

iii)iii) Infected personnel and animals. Infected personnel and animals.

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Diseases in relation to man and Diseases in relation to man and animals.animals.

C. Jejuni C. Jejuni is now well recognized as a is now well recognized as a common cause of acute gastro-common cause of acute gastro-enteritis in man. This organism is enteritis in man. This organism is also implicated in mastitis in milch also implicated in mastitis in milch animalsanimals

Symptoms.Symptoms. Severe abdominal pain and Severe abdominal pain and diarrhoea.diarrhoea.

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Prevention and control.Prevention and control.i)i) Milk should be properly pasteurized and Milk should be properly pasteurized and

heat treated as the organism does not heat treated as the organism does not survive efficient pasteurization.survive efficient pasteurization.

ii)ii) Public water supplies should be Public water supplies should be adequately treated such as chlorination.adequately treated such as chlorination.

iii)iii) Good hygiene should be practised by Good hygiene should be practised by dairy personnel.dairy personnel.

iv)iv) Persons suffering from disease should Persons suffering from disease should not be allowed to handle milk and milk not be allowed to handle milk and milk products. products.

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3. Yersinia enterocolitica3. Yersinia enterocolitica poisoning poisoning (Yersiniosis)(Yersiniosis)

Yersinia enterocolitica Yersinia enterocolitica is yet another is yet another potential pathogen which can cause potential pathogen which can cause yersiniosis in man and the raw milk yersiniosis in man and the raw milk has been suspected to be an has been suspected to be an important vehicle for the transmission important vehicle for the transmission of the disease. Several incidences of of the disease. Several incidences of this illness/diseae through raw and this illness/diseae through raw and pasteurized milk have been reported. pasteurized milk have been reported.

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Sources of the causative organismSources of the causative organism

i)i) Water or streams often contain this Water or streams often contain this organism, hence it constitutes the organism, hence it constitutes the common source.common source.

ii)ii) Faecal contamination may also Faecal contamination may also introduce causative organisms.introduce causative organisms.

iii)iii) Infected animals.Infected animals.

iv)iv) Contaminated raw materials.Contaminated raw materials.

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Disease in relation to man.Disease in relation to man.

Yersiniosis is produced in human beings. Yersiniosis is produced in human beings. The illness causes acute syndrome The illness causes acute syndrome with appendicitis. Animals are also with appendicitis. Animals are also frequently infected with the organism.frequently infected with the organism.

Symptoms. Y. enterocolitica Symptoms. Y. enterocolitica produces produces several disease syndromes in human several disease syndromes in human beings on ingestion of contaminated beings on ingestion of contaminated milk. milk.

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The gastro-intestinal illness caused by The gastro-intestinal illness caused by the organism in human beings its the organism in human beings its characterized by abdominal pain and characterized by abdominal pain and fever. The other symptoms include fever. The other symptoms include vomiting and diarrhoea. The vomiting and diarrhoea. The pathogenesis of the organism pathogenesis of the organism appears to be due to enterotoxin appears to be due to enterotoxin production as well as by production as well as by invasiveness of the organism. invasiveness of the organism.

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Prevention and control.Prevention and control.

The disease can be controlled by The disease can be controlled by taking the following precautions:taking the following precautions:

i)i) Avoiding faecal contamination.Avoiding faecal contamination.

ii)ii) Following hygienic practices.Following hygienic practices.

iii)iii) Avoiding handling of the products Avoiding handling of the products by infected personnel.by infected personnel.

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4.4. Vibrio parahaemolyticus Vibrio parahaemolyticus PoisoningPoisoning Vibrio parahaemolyticus Vibrio parahaemolyticus is the is the causative agent of gastro-enteritis in causative agent of gastro-enteritis in human beings. This organism human beings. This organism although is not as important as although is not as important as cholera, the prevalence of this illness cholera, the prevalence of this illness appears to be increasing through the appears to be increasing through the world. Among the enteric world. Among the enteric pathogens, pathogens, V. parahaemolyticusV. parahaemolyticus is a is a recent addition. recent addition.

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Now this organism has been recognized Now this organism has been recognized as a common agent of food-borne as a common agent of food-borne illnesses, particularly in Japan as well illnesses, particularly in Japan as well as USA. There have been quite a few as USA. There have been quite a few number of outbreaks are fish, crabs number of outbreaks are fish, crabs and canned sea foods. However, milk and canned sea foods. However, milk and milk products are very rarely and milk products are very rarely implicated in such outbreaks. The implicated in such outbreaks. The exact mechanism by which this exact mechanism by which this organism causes gastroenteritis is not organism causes gastroenteritis is not yet known. yet known.

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Sources of causative organismSources of causative organism

Contaminated water supply is the Contaminated water supply is the main source of this organism in milk main source of this organism in milk and milk products.and milk products.

Disease in relation to man. Disease in relation to man. The The ingestion of contaminated food ingestion of contaminated food products typical gastroenteritis.products typical gastroenteritis.

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Symptoms. Symptoms. Diarrhoea is the main Diarrhoea is the main symptom of this gastroenteritis. The symptom of this gastroenteritis. The other symptoms include abdominal other symptoms include abdominal cramps, nausea, vomiting, headache, cramps, nausea, vomiting, headache, chills and fever. In some cases, chills and fever. In some cases, watery diarrhoea resembling cholera watery diarrhoea resembling cholera may also develop. In severe cases, may also develop. In severe cases, death may also occur.death may also occur.

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Incubation period. Incubation period. This varies from 12-24 h. This varies from 12-24 h. The symptoms persist from few hours The symptoms persist from few hours to 10 days with the usual duration of 2-3 to 10 days with the usual duration of 2-3 days. days.

Prevention and controlPrevention and control

i)i) Contamination of marine or water Contamination of marine or water environment should be avoided.environment should be avoided.

ii)ii) Application of good sanitary practices Application of good sanitary practices and personnel hygiene should help in and personnel hygiene should help in preventing the cross-contamination.preventing the cross-contamination.

F.F. Other milk-borne Other milk-borne diseasesdiseases

a)a) Bacterial diseasesBacterial diseases

1)1) TuberculosisTuberculosis (TB) (TB)

Tuberculosis has been recognized Tuberculosis has been recognized as one of the most important as one of the most important infectious diseases in the world infectious diseases in the world because of its high global impact because of its high global impact and its chronic debilitating and its chronic debilitating character, particularly in the poor character, particularly in the poor section of society. section of society.

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Milk-borne tuberculosis is directly or Milk-borne tuberculosis is directly or indirectly related to the consumption of indirectly related to the consumption of raw milk from infected dairy herds. raw milk from infected dairy herds. Although extensive work has been Although extensive work has been carried out in several parts of the carried out in several parts of the world on the incidence and world on the incidence and transmission of TB through milk and transmission of TB through milk and milk products, there is paucity of milk products, there is paucity of information in India on this aspect, information in India on this aspect, except for few sporadic reports. except for few sporadic reports.

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Causative agent. Causative agent. The most common The most common causative agent is causative agent is Mycobacterium Mycobacterium tuberculosis. tuberculosis. There are two types of There are two types of tuberculosis: (a) pulmonary type, and tuberculosis: (a) pulmonary type, and (b) non-pulmonary type, pulmonary (b) non-pulmonary type, pulmonary type of tuberculosis is caused by human type of tuberculosis is caused by human type of this organism which mainly type of this organism which mainly affects the respiratory tract. Bovine affects the respiratory tract. Bovine type bacillus causes non- pulmonary type bacillus causes non- pulmonary type of TB. type of TB.

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Tuberculosis of cattle is produced by Tuberculosis of cattle is produced by bovine bacillus called bovine bacillus called Mycobacterium Mycobacterium bovis.bovis. Avian type of the organism Avian type of the organism may cause both types of tuberculosis. may cause both types of tuberculosis. Anonymous or atypical type bacillus Anonymous or atypical type bacillus changes its character. The principal changes its character. The principal species of species of Mycobacterium Mycobacterium which are which are pathogenic in man and animals are pathogenic in man and animals are shown in Table 4.7. shown in Table 4.7.

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Table 4.7 Principal pathogenic species Table 4.7 Principal pathogenic species of of MycobacteriumMycobacterium

SpeciesSpecies HostHost

M. tuberculosisM. tuberculosisManMan

M. bovisM. bovis Cattle and Cattle and manman

M. aviumM. avium Birds and swine; Birds and swine; rarely manrarely man

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M.microtiM.microti Field Field mouse mouse

M.LapraeM.Laprae ManMan

M.ParatuberculosisM.ParatuberculosisCattle, sheepCattle, sheep

M.ulceransM.ulcerans ManMan

M.marinumM.marinum Fish and Fish and manman

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Incidence of mycobacteria in milk and Incidence of mycobacteria in milk and their sources.their sources. There are a There are a number of reports available from number of reports available from different countries concerning the different countries concerning the incidence of mycobacteria in raw incidence of mycobacteria in raw and and pasteurized milks. and and pasteurized milks.