Basic Epi: Differential Diagnosis of Foodborne Illnesses. One Foodborne Investigation Strategy. Second Strategy: Differential Diagnosis

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Basic Epi: Differential Diagnosis of Foodborne Illnesses John Kobayashi MD, MPH August 12, 2009 One Foodborne Investigation Strategy Pathogen known look for the source using the known incubation

1 Basic Epi: Differential Diagnosis of Foodborne Illnesses John Kobayashi MD, MPH August 12, 2009 One Foodborne Investigation Strategy Pathogen known look for the source using the known incubation period. # of cases exposure? 3-4 days outbreak Agent is E. coli O157:H7 time Second Strategy: Differential Diagnosis Pathogen unknown consider syndrome and incubation period then search for pathogens This presentation: a review of more common causes 1

2 Vomiting within Minutes After Exposure: Heavy Metal Poisoning Copper from soda fountain Soda fountain adds carbon dioxide to water from city system City waters nearby park grass at night Water pressure drops in pipes to soda fountain Carbonated water goes backwards into copper pipe (valve to prevent backflow was not present) Copper dissolves into carbonated water First children drinking soda from fountain become sick Soda Fountain Syrup CO 2 Bottle City Water Source Park Grass Vomiting 2 7 Hours After Exposure Staphylococcal food poisoning vomiting is most prominent, but fever and diarrhea possible Bacillus cereus short incubation fried rice rarely reported in USA Staphylococcal Food Poisoning Easter egg outbreak Associated with intact boiled eggs Old eggs lose about 2 cc of water per egg When hot eggs are washed in cold contaminated water, bacteria and water go through the shell into an egg 2

3 Staphylococcal Food Poisoning (cont.) Chinese mushrooms Toxin is heat stable. Can survive canning process. Illness associated with canned Chinese mushrooms used in the US on pizzas. Vomiting and diarrhea hrs after exposure At least 50% of people have vomiting Vomiting and diarrhea of short duration usually one day Usually no high fever Usually no blood in stool Suspect viral gastroenteritis (norovirus) Lab Specimens: Vomiting Syndromes Heavy metal poisoning test implicated substance in chemistry lab. Staph usually we test the implicated substance for bacteria and enterotoxin. In suspected source carriers, test nasal or lesion swabs. B. cereus stool in a sterile container spore count. Viral gastroenteritis stool in a sterile container PCR. 3

4 Clostridium perfringens Food Poisoning Diarrhea of short duration about 1 day Onset about 12 hours after exposure Fever is uncommon Vomiting is uncommon (vs viral gastroenteritis) Specimen stool in a sterile container need to do spore count usually need more than 1 million spores for a positive result C. perfringens Food Poisoning (cont.) Toxin is heat labile. C. perfringens outbreak at a prison. Contaminated food served to prisoners and guards in the main prison who became ill. Contaminated food set to prisoners in solitary confinement in hot carts, which were very hot. Heat inactivated the toxin, and the prisoners in solitary confinement did not get ill. Diarrhea and Fever 1 7 Days Post-exposure Salmonella, Vibrio parahaemolyticus, Shigella, E. coli O157, Campylobacter, Yersinia enterocolitica. Stool transport: Carey Blair. Vibrio parahaemolyticus: testing needs to be requested. Yersinia enterocolitica may require cold enrichment. 4

5 Diarrhea Several Weeks After Exposure Giardia usually waterborne, or person to person, but foodborne transmission is possible Cyclosporiasis difficult to diagnose unless suspected Cryptosporidiosis large waterborne epidemic in Milwaukee, Wisconsin: foodborne outbreaks are possible Neurologic Syndrome Parasthesia of the lips and mouth, weakness, difficulty speaking, paralysis 30 minutes to 3 hours after exposure paralytic shellfish poisoning detection of toxin in the implicated food Gastrointestinal symptoms plus blurred vision, nervousness, twitching, convulsions (cholinergic symptoms) organophosphate poisoning in food, Aldicarb poisoning (systemic insecticide). Neurologic Syndrome (cont.) Meningitis 2 6 weeks after exposure Listeria monocytogenes. Other syndromes flu like illness in pregnant women, bacteremia, premature delivery, stillbirth, gastroenteritis 5

6 Neurologic Syndrome: Botulism Cranial nerve abnormalities Fever absent Descending bilateral paralysis flaccid paralysis lower motor neuron Sensory examination normal Mental status intact Onset hours after exposure Botulism Diagnosis Predictive value for a neurologist s diagnosis is very high. Missed diagnoses occur when the disease is not considered. A report of possible foodborne botulism is a public health emergency. Other botulism types require different responses Wound botulism treatment of wound Infant botulism supportive care, and possibly human derived antitoxin. Botulism Diagnosis (cont.) Detection of toxin in blood, stool, and food Testing requires injecting mice (expensive) Differential Miller Fisher variant of Guillain Barre Syndrome (LP has elevated protein) Myasthenia gravis Tensilon test Tick paralysis 6

7 Botulism Source Investigation C. botulinum grows anaerobically in low acid foods. In continental US most frequently in home canned low acid foods (asparagus, beans, corn, spinach, etc). Canning these foods require pressure cooker (temperatures higher than 100 C) to kill spores. Water bath method is only acceptable for high acid food (pickles), or high sugar foods (jellies). In Alaska type E botulism associated with fish and other marine products. Botulism Treatment Supportive care most important Botulinum antitoxin ABE, horse serum derived Sensitivity test require for all Desensitization if allergic to horse serum Risk of serum sickness Investigation Tips Diagnosis, treatment, and investigation occur simultaneously. First interviews are sometimes not reliable. Victim frequently unable to give food consumption history. Only small amounts of food are needed cause illness test. Care must be taken on shipping suspect food. Aggressive investigation is needed to find contaminated food. 7

8 References Diagnosis and Management of Foodborne Illnesses: A Primer for Physicians MMWR, April 16, 2004, vol 53/RR-4 MMWR, January 26,

Epidemiology of Food Poisoning. Dr Varun malhotra Dept of Community Medicine

Epidemiology of Food Poisoning Dr Varun malhotra Dept of Community Medicine Definition Public Health Importance Epidemiology of Food poisoning Investigation of an Outbreak Prevention & Control Measures