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Abstract
Raw milk is an excellent dietary source of quality animal proteins, phosphorus, vitamin A, riboflavin and other members of vitamin B–complex, in addition to milk fat of high calories, easily digestible sugar and fat soluble vitamins which are essential for health and development of infants, and as a good supplement for different diets of all ages.
Yersinia enterocolitica is widely recognized as a cause of disease in man (Langford, 1972; Winblad, 1973 and Bottone, 1977). Acute gastroenteritis or enterocolitis is the most frequent clinical form of this infection followed by an acute syndrome of the right iliac fossa (pseudoappendicitis, mesenteric lymph adenitis or terminal ileitis). Other clinical conditions are septicemia, polyarthritis, erythema nodosum and abscesses. The organism is usually isolated from faeces and less frequently from appendix, mesenteric lymph nodes, abscesses, blood, urine and from asymptomatic carriers (Schiemann and Toma, 1978). Yersinia produces a heat stable enterotoxin that is associated with food poisoning symptoms in man (Quinn et al., 1994).
The predominant disease caused by pathogenic strains of Yersinia enterocolitica is enterocolitis which accounts for two–thirds of reported cases especially in young children and characterized by fever and diarrhea which frequently accompanied by abdominal pain lasting 1 – 3 weeks (Marks, 1980). However, serious cases may occur with rectal bleeding and perforation of the ileum (Rabinovitz, 1987). Moreover, there may be secondary immunologically mediated complications such as arthritis, erythema nodosum and to a lesser extent Reiter’s syndrome, glomerulonephritis, myocarditis, exudative pharyngitis and septicemia, which is less common and often reported in immunosuppressed individuals after contaminated food products transfusion (Borg et al., 1992; Bottone, 1997 and Strobel et al., 2000). Sometimes, Yersinia enterocolitica causes a syndrome which mimes appendicitis in older children and young adults (Butler, 1998; Natkin and Beavis, 1999 and Lamps et al., 2001). This bacterium is one of the few enteric pathogens that can grow at refrigeration temperatures and so has become a major concern of the food industry (El–Shenawy and Marth, 1991).
An epidemiological study of human Yersinia infection has implicated water, animals, food and other environmental sources as reservoirs of the organism (Morris and Feeley, 1976). Moustafa (1990) reported that the incidence of Yersinia enterocolitica in raw milk was 10% isolated from 100 samples examined, while it has been isolated by many workers from raw milk (Christensen, 1982; Delmas and Vindon, 1982; Moustafa et al., 1983; Franzin et al., 1984; Boer et al., 1986 and Mercado and Ibanez, 1986).
The most common non-lactose fermenting Enterobacteriaceae which include Salmonella, Shigella, their presence in raw milk is indicative of faecal pollution and neglected hygienic measures in production and storage.
Salmonellae have been considered the most important causal agents of foodborne illness throughout the world since the first laboratory confirmed outbreak of Salmonellosis in 1988. Hundreds of outbreaks still occur in most countries every year (Bell and Kyriakides, 2002).
Three different syndromes in humans are caused by different types of Salmonellae. The most severe is typhoid fever, caused by Salmonella typhi. The symptoms of typhoid fever are quite severe. They include septicemia (i.e., the organisms get into the bloodstream and grow), high fever, headache, constipation, vomiting and diarrhea. The second syndrome is enteric fever caused by Salmonella paratyphi. The symptoms of enteric fever are very similar to those of typhoid fever but less severe. Illness usually lasts anywhere from 1 – 3 weeks, whereas typhoid fever may last from 1 – 8 weeks. The third type is a food poisoning syndrome which includes diarrhea, abdominal pain, fever, vomiting and dehydration. The severity of these symptoms varies depending on the host’s immunocompetence. Humans are the only reservoir for Salmonella typhi so, the instances of typhoid fever imply human faecal contamination of water and food. Salmonella typhi gets into water and food via raw sewage or by direct contamination by a food handler who has typhoid fever and sheds the organism in faeces (Cliver, 1990).
Shigellae are a highly infectious organism. As few as 10 cells of Shigella dysentriae given orally to adult volunteers caused illness (Cliver, 1990).
Bacillary dysentery is an important problem in developing countries where unsanitary conditions exist, and crowded living conditions occur such as in day-care schools and custodial institutions. About 15000 – 20000 cases of shigellosis were reported in the United States each year, mostly in children less than 4 years of age (Doyle, 1990).
There is no doubt that some human parasitic infections, where food acts as a vehicle, can be spread through milk. This is particularly true of these infections in which the infective stage of the parasite is liable to be shed by the milk handlers e.g. amoebic and other protozoan cysts or the eggs of Taenia solium and Enterobius. Because of the epidemiological characteristics of these infections, however, it is difficult or impossible to pin down the cause of transfer to milk, and this is no doubt the reason for the absence of reported infections of this type in the literature of milkborne diseases. The only animal parasite infective for man which is known to be excreted in cow’s milk is Toxoplasma gondii, but it is not known if human beings can be infected with it through milk. The contamination of milk and milk products with infected soil containing Ascaris or Trichuris ova, helminth larvae … etc would appear to be feasible but remote. Sanitary procedures, heat treatment of milk, and adoption of hygienic practices by milk handlers should effectively prevent transmission of this group of infections (Kaplan et al., 1962).
Therefore, this work was planned to secure the prevalence of Yersinia enterocolitica, non-lactose fermenting Enterobacteriaceae and some parasites in raw milk commonly available at consumer level in El-Behera Governorate as follows:
1. Keeping quality test of raw milk samples:
a. Determination of acidity percent.
b. Determination of pH value.
c. Methylene blue reduction test.
d. Detection of some chemical sanitizer residues.
e. Detection of preservatives.
2. Prevalence of Yersinia enterocolitica in raw milk.
3. Isolation and identification of non–lactose fermenter organisms.
4. Incidence of some parasites in raw milk.
5. Effect of processing on viability of Yersinia enterocolitica.
6. Effect of potassium sorbate addition to ice cream on viability of Yersinia enterocolitica.
7. Effect of dairy processing ice cream and Damietta cheese on viability of Ascaris