Food borne and Waterborne Infections

1. Food borne and Waterborne Infections CLS 212: Medical Microbiology

2. Food borne and Waterborne Infections Food borne infections Any disease that can be acquired: • By eating food contaminated with a pathogen. • By getting the pathogen into the digestive system through dirty hands or surfaces. Waterborne infections Any disease that can be acquired: • By drinking water contaminated with a pathogen. • By getting water into your mouth during recreational sports such as: fishing, swimming, or boating,.. • By letting contaminated water come into contact with open areas on the skin.

3. Types of Food borne Illness • Infection • Eating food contaminated with pathogens. 2-Intoxication • Eating food contaminated with the toxins formed by bacteria. • Eating food contaminated with other biological or chemical toxins (poisons). 3-Toxin-mediated infection • Eating food contaminated with pathogens that grow in the body and form toxins. 4-Allergy

4. Common Features • In rare instances, symptoms may come on as early as 30 minutes to 8 hours after eating contaminated food, but they may not develop symptoms for several days or weeks. • Symptoms of viral or parasitic illnesses may not appear for several weeks after exposure. Symptoms usually last only one to two days, but in some cases can persist for between seven and ten days. • For most healthy people, food borne illnesses are neither long-lasting nor life-threatening. However, they can cause severe consequences in the very young, the very old, and immunocompromised people.

5. Diarrheal disease in developing countries cause death of children. Childs chance of dying of a diarrheal illness before the age of 7 years can be as high as 50%. In developed countries, mortality rate is very much lower, but it is still significant.

6. Sources of Microbial Contamination • Soil: contaminating plants and animals with bacteria and parasites. • Irrigation and fertilization: watering plants with sewage or contaminated water. • Farms and slaughter houses: infected animals and products (milk, eggs,..). • Food processing: equipment, packages, staff. • Food storage: temperature, time,.. • Food handling: poor hygiene and inadequate cooking in restaurants and at home.

7. Major Microbial Factors The microorganisms that cause most food borne and waterborne infections are: • Bacteria. • Viruses. • Parasites.

8. Transmission of infection • Ingestion of contaminated food or water. • Contact with infected animals. • Fecal-oral person to person contact.

9. Treatment • Usually it is self-limiting disease, and symptoms resolve within hours or days. • However if symptoms are sever, the victim should see a doctor or get emergency help. This is especially important for those who are at high risk. • Maintenance of fluid and electrolyte balance is very important. The individual should drink plenty of liquids to replace fluids lost through vomiting and diarrhea.

10. Digestive System InfectionsDefinitions • Diarrhea:Abnormally frequent discharge of semisolid or fluid fecal matter. • Dysentery:Frequent watery stool that contain blood and/or mucus, with abdominal pain, fever, and dehydration. • Gastroenteritis: Inflammation of both stomach and intestine. • Hepatitis: Inflammation of the liver. Usually a result of viral infection but can be caused by toxic agents. • Cholera: Sever watery diarrhea caused by VibrioCholerae

11. Common Symptoms • The most common symptoms GIT infection are: • Diarrhea. • loss of appetite. • Nausea. • Vomiting. • Abdominal cramps. • Fever. • Dehydration. • Fatigue.

12. Common Food borne Bacteria • Toxin Producing Bacteria • Bacillus cereus • Clostridium botulinum • Clostridium perfringens • Staph. aureus • Vibrio • Less Common • Yersinia • Listeriamonocytogenes • Enteric Bacteria • Salmonella typhi • Salmonella non-typhi • Shigella • E. coli (O157:H7) • Campylobacter • Brucella

13. Common Bacterial Food Borne Infections. • Salmonellosis. • Shigellosis. • Brucellosis.

14. Salmonellosis • The disease is called Salmonellosis. • Large outbreaks are usually due to commercially distributed products contaminated by animal feces. • Infection mainly from poultry and eggs (80% cases from eggs). • Incubation period: range from 6 hours to 7 days (average of 12-36 hours).

15. Salmonellosis • Symptoms: • Gastroenteritis: • Abdominal cramps, Nausea, Vomiting, Headache, Fever. • The symptoms vary depending on the virulence of the strain and the number of infective organism. • Symptoms are usually short-lived and mild . • Enteric Fever,Tyhpoid: • Few strains cause symptoms of enteric fever. • Increasing fever , severe headache, constipation and abdominal pain, that maybe followed by intestinal rupture, internal bleeding, shock and death. • This happens because the organism have the ability to penetrate the small bowel and spread outside the bowel. • Salmonella typhiwhich cause typhoid fever. • Salmonella paratyphicause similar but less sever infection.

16. Salmonellosis • Etiologic Agent: • Salmonella spp. • Motile gram negative rods. • Gastroenteritis: Non-typhoidal salmonella spp. (e.g. S. enteritidis, S. typhimurium) • Typhoid (enteric fever): Salmonella typhi.

17. Salmonellosis • Transmission: • Domestic animals such as cattle, turtles….etc. • Ingestion of contaminated food. (e.g. Poultry, meat, vegetables, eggs …..etc). • Fecal oral transmission from food handlers. • Contaminated water supplies. • NOTE: infected human for tayphoid and para-typhoid may become carriers following infection , and shed the pathogen in their feces or urine.

19. Mary Mallon caused several typhoid outbreaks, moving from household to household, always disappearing before an epidemic could be traced back to the particular household Mary was working in. All together, she had worked for seven families, with 22 cases of typhoid and one death. • She was finally overtaken by the authorities in 1907 and committed to an isolation center on North Brother Island, NY. There she stayed until she was released in 1910, on the condition that she never accept employment involving food handling. • But she was found to work as a cook and to cause typhoid outbreaks again. She was admitted back to North Brother Island, where she lived until her death in 1938.

20. Shigellosis, Bacillary Dysentery • Infection is more common in infants and children. • Incubation period: 1-3 days (range 12-69 hours). • The disease is distributed worldwide wherever sanitary practices are lacking. • Antibiotic treatment is recommended for malnourished children, immunocompromised, food handlers, healthcare workers, and children in daycare centers.

21. Shigellosis, Bacillary Dysentery • Symptoms: • The classic symptom is dysentery (=blood, mucus and pus in stool). • Other symptoms are headache, vomiting , fever, stiff neck, convulsions, and joint pain. • The disease is commonly fatal for infants in developing countries. • Etiologic Agent: • Shigella spp.  is a gram negative bacilli. • There are four species of ShigellaS.flexneri, S.boydii, S.sonnei, and s.dysenteriae. • Some strains have plasmid that is associated with toxin production and virulence.

22. Shigellosis, Bacillary Dysentery • Transmission: • Fecal-oral-transmission from patients or carriers. • Fecally contaminated hands and fingernails. • Fecally contaminated food, milk, drinking water. • Flies can transfer organisms.

23. Brucellosis (=Malta Fever) • It is common in Latin America, Middle East, Mediterranean, eastern Europe, Asia, and parts of Africa. • Up to 78 cases/100,000 people/year • Arabic Peninsula 20% • Incubation period: 1-3 weeks (range 3 to 60 days).

24. Brucellosis (=Malta Fever) • Symptoms: • The onset of the disease is gradual and symptoms are vague. • Typically patients have mild fever, sweating weakness, aches and pain. • Fever is the most common symptom and sign of brucellosis, occurring in 80-100% of cases. • Other symptoms include: Bone & Joint pain, GI symptoms, . • Etiologic Agent: • Brucella spp. • It is small gram negative intracellular, coccobacilli.

25. Brucellosis (=Malta Fever) • Transmmition: • Main source of infection is domestic animals • Drinking of unpasteurized milk • Also farmers, pet doctors and lab workers are at risk. • Organisms ingested or inhaled and taken up into the reticuloendotheial system.

26. Common Food Borne Viral Infections • Viral infections of the lower digestive system are common in all age groups. • The intestines and accessory organs such as the liver can be affected. • Example of some of these viruses: • Rotavirus  cause most cause of gastroenteritis in infants and children. • Norovirus. • Hepatitis A Virus.

27. Type A Hepatitis (=Epidemic Hepatitis=Infectious Hepatitis): • Symptoms: • Acute viral infection characterized by dark urine and jaundice. • Varies in clinical severity from a mild illness lasting 1-2 weeks to a severe disabling disease lasting several months. • It’s a self-limiting disease: • 20% require hospitalization • while 85% fully recovered within 3 months. • There is no chronic infection. • Etiologic Agent: • Hepatitis A virus. .

28. Type A Hepatitis (=Epidemic Hepatitis= Infectious hepatitis): • Transmission: • Highly infectious, requiring only a few virus particles to cause infection. • Associated with community outbreaks & 40% of cases are sporadic • Fecal-oral transmission, infected food handlers, fecally contaminated foods and water. NOTE: Protective antibodies develop in response to infection -confers lifelong immunity. and vaccine is valuable.

30. Geographic Distribution of Hepatitis A Infection

32. Common FoodborneParasites • Giardia • Cryptosporidium • Cyclospora • Tinea • Toxoplasma • Trichinella

33. Gardiasis • In a usual epidemic of giardiasis, about 2/3 of exposed individuals develop symptoms. • Incubation period is generally 6-20 days. • Giardiasis is found worldwide mostly in warm climates and usually in children. • Symptoms: • Range from mild indigestion and nausea to severe vomiting, explosive diarrhea and abdominal cramps , fatigue and weight loss. • Characterized by presence of excess fat in the stool. • The symptoms usually disappear without treatment in 1-4 weeks but my become chronic. • Both symptomatic and asymptomatic persons can become long-term carriers.

34. Giardialamblia • Etiologic Agent: • Gardialablia • Flagellated protozoan. • It attaches to the mucosa and absorbs nutrients that it gets from the intestinal wall. • Transmision: • Fecal oral route, especially via fecally contaminated water.

36. Prevention of Foodborne and Waterborne Infections Prevention measures include: • Improved sanitation. • Adequate personal hygiene. • Proper sewage treatment. • Exclusion of infected individuals as food-handlers and health care providers. • Foods of animal origin should be thoroughly cooked.

37. WHO Ten Golden Rules • Food processed for safety • Thoroughly cook • Eat immediately • Store carefully • Reheat thoroughly No contact between raw & cooked Wash hands Keep food preparation surfaces clean Protect from pests 10.Use potable water

39. When Traveling Heat it Peal it or Don’t Eat it