These infectious agents enter the human body through the digestive tract. They are caused by the consumption of contaminated food with infectious agents, which leads to food poisoning. These infections lead to gastroenteritis that typically involves diarrhoea, vomiting, and abdominal cramps.
These symptoms usually begin 12—72 hours after contracting the infectious agent and if due to viral agent usually lasts less than one week. Some viral causes may also be associated with fever, fatigue, headaches, and muscle pains. If the stool is bloody the cause is less likely to be viral and more likely to be bacterial.
The Epidemiology of Alimentary Diseases | John M. Duggan | Springer
Some bacterial infections may be associated with severe abdominal pain and may last for weeks without treatment. This is a systemic disease transmitted by the ingestion of food or water contaminated with the faeces of an infected person, the aetiological agents is Salmonella typhi , and man is the reservoir.
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Less commonly, a rash of flat, rose-colored spots may appear. Its occurance is worldwide,and multi-drug resistant strains have been reported from asia, middle east and latin America. Sanitation and hygiene are the critical measures that can be taken to prevent typhoid. Typhoid does not affect animals and therefore transmission is only from human to human.
Typhoid can only spread in environments where human feces or urine are able to come into contact with food or drinking water.
Careful food preparation and washing of hands are crucial to preventing typhoid. Aetiological agent is numerous serotypes of salmonella. In most countries which maintain salmonella surveillance.
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Typhimurium and S. Enteritidis are two most commonly reported. The reservoir is domestic and wild animals including poultry also humans ie patients, carriers. The mode of transmission is by ingestion of the organism in food derived from infected food animals or contaminated by faeces of infected animal or person.
The Epidemiology of Alimentary Diseases
This includes raw and undercooked eggs and egg products, raw milk and raw milk products, meat and meat products,poultry andpoultry products. Its occurrence is worldwide and more extensively reported in north America and Europe. Aetiological agent is four species of genus shigella. As the water and electrolytes leave the body, it causes rapid dehydration and electrolyte imbalance. Cholera is diagnosed by taking a stool sample and culturing for Vibrio.
The bacteria are oxidase positive and show non-lactose fermentation on MacConkey agar. Gram-positive bacteria will not grow on MacConkey. Lactose fermentation is commonly used for pathogen identification because the normal microbiota generally ferments lactose while pathogens do not. Cholera may be self-limiting and treatment involves rehydration and electrolyte replenishment.
Although antibiotics are not typically needed, they can be used for severe or disseminated disease. Recent evidence suggests that azithromycin is also a good first-line antibiotic. They often lie on a cot with a hole in it and a bucket underneath to allow for monitoring of fluid loss. The bacteria produce a heat-stable hemolysin , leading to dysentery and possible disseminated disease.
It also sometimes causes wound infections. As with V. Tetracycline and ciprofloxacin can be used to treat severe cases, but antibiotics generally are not needed. Vibrio vulnificus is found in warm seawater and, unlike V.
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The bacteria can be found in raw seafood, and ingestion causes gastrointestinal illness. It can also be acquired by individuals with open skin wounds who are exposed to water with high concentrations of the pathogen. In some cases, the infection spreads to the bloodstream and causes septicemia. Skin infection can lead to edema, ecchymosis discoloration of skin due to bleeding , and abscesses. It is of particular concern for individuals with chronic liver disease or who are otherwise immunodeficient because a healthy immune system can often prevent infection from developing.
Two other vibrios, Aeromonas hydrophila and Plesiomonas shigelloides , are also associated with marine environments and raw seafood; they can also cause gastroenteritis. Like V. In some cases, it can also cause septicemia. Other species of Aeromonas can cause illness. Culture can be used to diagnose A. When necessary, tetracycline and ciprofloxacin , among other antibiotics, may be used for treatment of A. Campylobacter is a genus of gram-negative, spiral or curved bacteria.
They may have one or two flagella. Campylobacter jejuni gastroenteritis , a form of campylobacteriosis , is a widespread illness that is caused by Campylobacter jejuni. The primary route of transmission is through poultry that becomes contaminated during slaughter. Handling of the raw chicken in turn contaminates cooking surfaces, utensils, and other foods. Unpasteurized milk or contaminated water are also potential vehicles of transmission.
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In most cases, the illness is self-limiting and includes fever, diarrhea, cramps, vomiting, and sometimes dysentery. More serious signs and symptoms, such as bacteremia, meningitis, pancreatitis, cholecystitis, and hepatitis, sometimes occur. HUS following infection can also occur. The virulence in many strains is the result of hemolysin production and the presence of Campylobacter cytolethal distending toxin CDT , a powerful deoxyribonuclease DNase that irreversibly damages host cell DNA.
Diagnosis involves culture under special conditions, such as elevated temperature, low oxygen tension, and often medium supplemented with antimicrobial agents. Antibiotic treatment is not usually needed, but erythromycin or ciprofloxacin may be used. The gram-negative bacterium Helicobacter pylori is able to tolerate the acidic environment of the human stomach and has been shown to be a major cause of peptic ulcers , which are ulcers of the stomach or duodenum. According to the CDC, approximately two-thirds of the population is infected with H. These bacteria produce urease , which stimulates an immune response and creates ammonia that neutralizes stomach acids to provide a more hospitable microenvironment.
The infection damages the cells of the stomach lining, including those that normally produce the protective mucus that serves as a barrier between the tissue and stomach acid. As a result, inflammation gastritis occurs and ulcers may slowly develop. Ulcer formation can also be caused by toxin activity.
VacA has no primary sequence homology with other bacterial toxins, and in a mouse model, there is a correlation between the presence of the toxin gene, the activity of the toxin, and gastric epithelial tissue damage. Signs and symptoms include nausea, lack of appetite, bloating, burping, and weight loss. Bleeding ulcers may produce dark stools. If no treatment is provided, the ulcers can become deeper, more tissues can be involved, and stomach perforation can occur.
Because perforation allows digestive enzymes and acid to leak into the body, it is a very serious condition. Helicobacter infection decreases mucus production and causes peptic ulcers. To diagnose H. In a breath test, the patient swallows radiolabeled urea. Blood testing can also be used to detect antibodies to H. The bacteria themselves can be detected using either a stool test or a stomach wall biopsy.
Antibiotics can be used to treat the infection. However, unique to H. The current protocols are 10 days of treatment with omeprazole , amoxicillin , and clarithromycin OAC ; 14 days of treatment with bismuth subsalicylate , metronidazole , and tetracycline BMT ; or 10 or 14 days of treatment with lansoprazole , amoxicillin , and clarithromycin LAC. Omeprazole, bismuth subsalicylate, and lansoprazole are not antibiotics but are instead used to decrease acid levels because H.
Although treatment is often valuable, there are also risks to H. Infection with H. Clostridium perfringens gastroenteritis is a generally mild foodborne disease that is associated with undercooked meats and other foods.
At high temperatures, the bacteria can form endospores that will germinate rapidly in foods or within the intestine. Food poisoning by type A strains is common. This strain always produces an enterotoxin , sometimes also present in other strains, that causes the clinical symptoms of cramps and diarrhea. A more severe form of the illness, called pig-bel or enteritis necroticans , causes hemorrhaging, pain, vomiting, and bloating.
Gangrene of the intestines may result. This form has a high mortality rate but is rare in the United States. Diagnosis involves detecting the C. The bacteria itself may also be detected in foods or in fecal samples. Treatment includes rehydration therapy, electrolyte replacement, and intravenous fluids. Antibiotics are not recommended because they can damage the balance of the microbiota in the gut, and there are concerns about antibiotic resistance. The illness can be prevented through proper handling and cooking of foods, including prompt refrigeration at sufficiently low temperatures and cooking food to a sufficiently high temperature.
Clostridium difficile is a gram-positive rod that can be a commensal bacterium as part of the normal microbiota of healthy individuals. When the normal microbiota is disrupted by long-term antibiotic use, it can allow the overgrowth of this bacterium, resulting in antibiotic-associated diarrhea caused by C. Antibiotic-associated diarrhea can also be considered a nosocomial disease.