Bacterial food borne infections:

Bacterial food borne infections:
a. Enteric Fever (Typhoid and paratyphoid fever)
Salmonella typhi and Salmonella paratyphi causes enteric fever, which is endemic in
many developing countries.
General characteristics
?? Gram negative rods
?? They are motile, non capsulated and non sporing
?? They survive freezing in water for long periods
?? Produce H2S some times
?? Salmonella grow readily on simple media but they almost never ferment lactose
or sucrose.
Diagnostic laboratory Test
?? Specimen: Blood, urine, stool and bone morrow can be used to identify the
organism.
A. Culture: Culture is the diagnostic gold standard various enrichment and selective media are used to isolate salmonellae from feces and other specimens. Fecal specimen collected and transported to hospital or referral laboratory for microbiological examination should be inserted in Cary- Blair media. If it is not possible to obtain feces rectal swab should be collected by inserting a cotton wool swab in to the rectum for about 10 second care must be taken to avoid unnecessary contamination of specimen with bacteria from the anal skin.




B. Serology
For serological examinations, paired acute and convalescent samples of serum
should be collected at an interval of about 10 days in suspected enteric fever.
Several serological tests including the classic Widal test for febrile agglutinins are available; however, it gives high rate of false positivity. The Widal test is a serological test for the presence of salmonella antibodies in patient’s serum when facilities for culturing or antigen testing are not available. Widal test if performed reliably and interpreted with care (with clinical finding) can be of value in diagnosing
typhoid and paratyphoid fever. When investigating typhoid thepatient serum is tested for O and H antibody.

b. Shigellosis
General Characteristics
Shigellae bacteria are:
?? Gram negative
?? Non-sporing non-capsulated rods
?? Shigellae are non-motile.
Diagnostic laboratory tests
?? Specimen: fecal specimen for culture and blood for antibody detection
A. Macroscopic Examination
Fecal specimens from patients with shigellosis may be watery and contain little blood and mucus in the early stages of infection.

B. Microscopic Examination
consists almost entirely of pus and blood mixed with mucus in the later stages of infection. When examined microscopically, red cells and large number of pus cells are usually found. Specimens from patients with amoebic dysentery contain red cell, and usually very few pus cells.
Since microscopic examination is not confirmatory, so a fresh fecal specimen is collected and sends to hospital or referral laboratory for culture. Cary–Blair transport media is suitable for transport fecal specimen for identification of Shigellae .
Bacterial food borne infection also can be caused by V.cholerae , E.coli ,Bacillus cereus and Brucella. To investigate such organisms send appropriate specimen to microbiology laboratory
• If V.cholerae is suspected fecal specimen from early acute case should be collected in to a sterile container. Colletion of stool specimen from a bed pan should be avoided because of the risk of contamination or the presence of disinfectant.) and transport about 1ml of specimen in to 10ml sterile alkaline peptone water, label and send to reach the microbiology laboratory with in 8 hours of collection. Cary- Blair transport media also can be used as transporting feces that may contain V.cholera species.
• If E.coli and bacillus cereus infection is suspected we can send fecal specimen to microbiology laboratory for identification of such organisms by using Cary-Blair transport media.
iii. Viral food borne infections
Hepatitis A, E and Rotavirus can cause food-borne infection .If viral enteritis is suspected, fecal specimen can be sent to virology laboratory.
Mix about 1ml of fecal specimen with 9ml of sterile phosphate buffer saline, and allow to sediment for about 30 minute. Transfer the supernatant fluid to a sterile container, label and send in an insulated cold box to reach to the virology laboratory with in a few hours.
2. Food Poisoning/ Intoxication
i. Bacterial Food Poisoning
The bacterial species S. Aureus, C. perfringens, C. Botulinum, Enterotoxigenic E. Coli and B. Cereus can cause food poisoning. If bacterial food poisoning is suspected, send feces, vomit and food sample for culture to the microbiology laboratory .
ii. Chemical Food Poisoning
Metals (lead, mercury and arsenic) and pesticides can cause chemical food poisoning. If chemical food poisoning is suspected, send serum and urine samples to the toxicology laboratory.

Factors most commonly contributing to food-borne disease
outbreaks
There are a number of factors that may lead to the occurrence of food-borne illness outbreaks. The major ones are:
?? Preparation of food more than half a day in advance of needs
?? Storage at ambient temperature
?? Inadequate cooling
?? Inadequate reheating
?? Use of contaminated processed food (cooked meats and poultry, and the like)
?? Undercooking
?? Cross contamination from raw to cooked food from utensils, and unhygienic kitchen
environment
?? Infected food handlers or poor personal hygiene of food handlers
?? Unsanitary dishware, utensils and equipment
?? Improper food handling procedures such as unnecessary use of the hands during preparation and serving of food
?? Improper food storage that may lead to cross contamination by agents of diseases (micro-organisms, poisonous chemicals), or exposure to moisture that may facilitate microbial growth
?? Insects and rodents .
Common signs and symptoms of food borne diseases
? Individuals with food-borne diseases can have many different kinds of
manifestations.
? Some of these manifestations are listed below:
1. Diarrhea (watery/mucoid/bloody), tenesmus (painful straining at defecation with
sensation of inadequate emptying), abdominal pain, nausea, vomiting, bloating ,
belching, flatulence, abdominal distention
2. Loss of appetite, loss of general sense of well-being, weakness, unusual hunger
sensation, altered taste sensation
3. Fever, chills, headache, muscle and joint pains,
4. Paralysis
5. Symptoms of fluid loss like thirst, weakness, dizziness, low blood pressure, fast
pulse rate, poor skin turgor, sunken eyeballs,
6. Yellowish discoloration of the eyes and skin, weight loss,
7. Passage of worms in the stool and sometimes through the mouth, itching and
discomfort in the perianal area
8. Growth failure in children
Common signs and symptoms of food borne diseases
? Individuals with food-borne diseases can have many different kinds of
manifestations.
? Some of these manifestations are listed below:
1. Diarrhea (watery/mucoid/bloody), tenesmus (painful straining at defecation with sensation of inadequate emptying), abdominal pain, nausea, vomiting, bloating , belching, flatulence, abdominal distention
2. Loss of appetite, loss of general sense of well-being, weakness, unusual hunger sensation, altered taste sensation
3. Fever, chills, headache, muscle and joint pains,
4. Paralysis
5. Symptoms of fluid loss like thirst, weakness, dizziness, low blood pressure, fast
pulse rate, poor skin turgor, sunken eyeballs,
6. Yellowish discoloration of the eyes and skin, weight loss,
7. Passage of worms in the stool and sometimes through the mouth, itching and
discomfort in the perianal area
8. Growth failure in children
3.4.13 Management:
? All patients suspected of having a food-borne disease should be immediately referred to the nearby health facility for determination of the specific cause and proper treatment.
? However, in the meantime, there are lots of supportive and other interventions that Health Extension Package Workers can do to help the patient and his/her family. For example:
1. Assess the level of dehydration and the presence or absence of visible blood in the stool in all patients with diarrhea; if there are evidences of significant fluid loss or if there is visible blood in the stool, refer the patient immediately to the nearby health center for proper treatment.
2. If a patient has diarrhea, advice him/her to take more of the fluid diets prepared at home such as gruel (“atmit”), tea, soup, boiled milk, etc. as long as the diarrhea is there. In addition, if there is ORS at hand provide the individual with some sachets and instruct him/her carefully on how to prepare and use the solution.
3. If a patient has fever, advice him/her and the family to use mechanical means of cooling the body such as tepid sponging;
4. Advice patients and their families on the importance of proper personal hygienic measures at home, particularly during food preparation, in order to prevent the infection from disseminating to other individuals
Prevention and Control:
The roles that Health Extension Package Workers can and should play in the prevention and control of food-borne diseases in particular and infectious diseases in general, are many.
Some of these roles are:
1. Provision of information and education on the means of transmission of foodborne diseases and their methods of prevention at household levels such as
?? Proper disposal of human excrement and other wastes,
?? Proper hand washing always after using the toilet and before and during food preparation and serving,
?? Keeping compound sanitation so as to prevent the breeding of flies, rats and roaches,
?? Keeping already prepared food items in the proper place and environmental conditions,
?? Proper cooking of animal foods before consumption,
?? Boiling of milk
?? Proper washing and cooking of vegetables
?? Other important methods that facilitate the safety of food include the following:
- Health education
- Good personal and environmental hygiene
- Availability of safe, ample and convenient water supply
- Training of food handlers and managers on hygienic food preparation
and handling
- Stringent inspection and control actions
- Legislative support (ordinances and codes), licensing
- Good-house keeping practices including separate storage and care of
toxic chemicals.
- Understanding about additives and restrictions of unauthorized use.
- Food equipment selection to avoid chemical poisoning arising from the
material constituency and or coatings of some food utensils.
- Avoidance and care of insecticide use in food processing and
preparation areas.
2. Education of the public at large on the above issues as well as avoidance of
consumption of potentially harmful plants
3. Advising patients and families to seek immediate medical help in the event of any
food-borne illness
4. Searching for cases and referring to nearby health institution for proper
management; this is particularly so when there is anyone with some form of foodborne
illness in the community since there may be several others with the same
problem who may have manifestations or may have not started to show them yet.