Foodborne and Waterborne Diseases

Foodborne and Waterborne Diseases - overview

• big picture: pathogens (in fecal matter) → contaminate food & water → pathogens ingested → dz in host (worldwide distribution)

• involves fecal-oral route:

1. mode of transmission: contaminated food & water

2. portal of entry (oral cavity): mucous membranes of GI tract

reservoirs

• 1° (primary) reservoir = mainly

• 2° (secondary) reservoir = sometimes

symptoms & diagnosis

• typically GI symptoms (ex. nausea, vomiting, diarrhea, abdominal cramps)

• diagnosis: based on GI symptoms

  • look for pathogen in food/water or in stool sample

  • serology (pathogen/Ab(IgM))

predisposing factors

• inadequate cooking

• improper food handling (temp)

• poor personal hygiene

• unsanitary conditions

best preventative measures & tx

• preventative: washing hands, well-cooked food

• tx: medications, antitoxins (Ab against a toxin), supportive therapy (oral rehydration)

bacterial infection

• pathogen is consumed in food/water

• invade & multiply in intestinal lining

• incubation period: long/slow (hrs to days)

  • no s/s yet

• s/s happen slowly (@ prodromal period)

  • nausea, vomiting, diarrhea, usually fever

bacterial intoxication

• toxin is consumed in food

• toxins made by pathogen → toxemia

• incubation period: short (min to hrs)

• s/s happen quickly

  • nausea, vomiting, diarrhea

  • usually NO FEVER (except super Ag) → probably exotoxin (protein toxin; by gram pos. cell)

Staphylococcal Food Intoxication

• cause: Staphylococcus aureus, gram +, cocci, clusters, on skin/many surfaces

• type: bacterial intoxication (eat toxin, NOT bacteria)

• virulence factor: heat-stabile enterotoxin (GI tract)

  • NOT destroyed by boiling

• s/s: N/V, diarrhea, abd cramps, fever (Type I exotoxin)

• incubation period: min to hrs

• reservoir: human skin

• mode of transmission: dirty hands contaminate food

  • bact. produce toxin when food left at improper temp

• prevention: wash hands, safe food handling, refrigerate properly

• tx: oral rehydration, supportive care, abx do NOT work (d/t toxin not bact)

• misc: bact. intoxication, aka “food poisoning”

Staph = skin → toxin in food → fast vomiting

botulism

• cause: Clostridium botulinum, gram +, bacillus, endospore-forming, obligate anaerobe, endospore at end of cell (“drumstick” appearance)

• virulence factor: potent (low LD₅₀), heat-labile neurotoxin (heat can destroy exotoxin), endospores

• s/s: flaccid paralysis, (respiratory/cardiac failure → death)

• reservoir: contaminated food

• mode of transmission: canned food w/ neurotoxins

• prevention: proper commercial canning

  • treat meats w/ nitrites (inhibit germinating)

• tx: respiratory assistance, antitoxins

• dx: drumstick bact. appearance (terminal endospore)

• misc: Clostridium Botulism Intoxication/Foodborne Botulism

infant botulism

• infant ingests C. Botulinum spores (germinate into active cell → produce potent heat labile neurotoxin)

• via honey

• weakened muscle tone (floppiness), trouble feeding

wound botulism

• growth of C. botulinum in DEEP wounds

  • creates anaerobic environment → spore germinates

• common in IV drug users

Clostridium difficile Associated Diarrhea (C.diff)

• cause: Clostridium difficile, gram +, bacillus, endospore-forming, obligate anaerobe

• virulence factor: exotoxins

• s/s: mild diarrhea → colitis,

  • life-threatening colitis: intestinal ulceration/perforation; bloody diarrhea (sometimes)

• reservoir: humans (primary), contaminated medical equipment (secondary)

• mode of transmission: fecal-contaminated water, contaminated medical equipment

• prevention: gowns, gloves, disposable hospital equipment

• tx: antiprotozoal & abx

• predisposing factors: mostly acquired in healthcare settings, extended use of abx

• dx: PCR to detect toxin-producing genes in stool

• misc: aka C.diff Colitis

Salmonellosis (Salmonella Gastroenteritis)

• cause: Salmonella enterica serovar Typhimurium, gram —, bacillus, facultative anaerobe, motile

• virulence factor: invades intestinal mucosa, multiplies in phagocytes (bacteremia)

• s/s: fever (not high), N/V, abd cramps. diarrhea

• incubation period: hours (infection → 1st s/s)

• reservoir: contaminated meat (poultry), raw eggs, fruits/vegetables, pet reptiles

• mode of transmission: contaminated food

• prevention: avoid raw eggs, wash fruits/veg w/ clean water, avoid pet reptiles

• tx: oral rehydration, abx

• dx: PCR to identify serovar/strain in food

• misc: chronic carriers (no s/s → still infectious) can shed bact. in feces for up to 6 mo

Typhoid fever

• cause: Salmonella enterica serovar Typhi, gram —, bacillus, facultative anaerobe, motile

• virulence factor: multiplies in phagocytes → bacteremia

• s/s: prolonged high fever (104 °F), HA, muscle aches, abd cramps, diarrhea, rose spots (skin rash on trunk)

  • severe: intestinal ulceration/perforation → bloody diarrhea (dysentery)

• incubation period: weeks (infection → 1st s/s)

• reservoir: humans

• mode of transmission: fecal-contaminated food or water

• prevention: good personal hygiene (handwashing)

• tx: abx, oral rehydration, chronic → wks tx

• dx: pathogen in blood/stool, rose spots

• misc: 1-3% chronic carriers (asx)/shed bact in feces (ex. Typhoid Mary)

virulence factor: multiply in phagocytes

1. salmonellosis

2. typhoid fever

3. brucellosis

virulence factor: toxins

1. staph. food intoxic

2. botulism

3. c.diff

4. bact. gastroenter

5. hemorrhagic colitis

6. shigellosis