Viral Foodborne Diseases Flashcards
true/false: viruses are the most common cause of foodborne illness
true
true/false: testing for viral etiologies of diarrheal disease is commonly done
false
pathologic viruses
Hepatitis A virus
Norovirus group
Rotavirus
Other viral agents (astroviruses, adenoviruses, parvoviruses)
Hepatitis A
accounts for 90% of viral hepatitis infections worldwide
shed into bile → Exits via feces
Majority of infections are asymptomatic
Infection in infancy or childhood is asymptomatic
true/false: true number of Hepatitis a infections is unknown
true
Hepatitis A reservoir
People: most important
possible non human primates
Hepatitis A: high endemicity
In least developed countries
poor socioeconomic conditions
Entire population is infected as children minimal clinical disease
Hepatitis A: low endemicity
developed countries, better sanitation reduces transmission
Seroprevalence is lower
Often see more outbreaks: adults susceptible
Hepatitis A: transmission
direct: fecal-oral (most important)
vehicle: food, water contaminated with feces
Hepatitis A: clinical signs
Related to hepatitis
Diarrhea, dark urine, jaundice, and flu‐like
symptoms
Nausea, anorexia, fever, malaise, or abdominal pain
Hepatitis A: Case Definition/Diagnosis (CDC)
- Discrete onset of clinical signs
- Jaundice or elevated serum aminotransferase
AND
Either: Positive serologic test for IgM antibody to Hep A
OR: An epidemiological link to a lab confirmed case Household or sexual contact
Hepatitis A: treatment
supportive
post exposure prophylaxis
Hepatitis A: prevention
Target the host: vaccination
Target the vehicle
Block transmission
what is the most common cause of foodborne illness worldwide
Norovirus
percent of known foodborne illnesses caused by Norovirus
58%
Norovirus: reservoir
people
Norovirus: transmission
direct: fecal-oral
vehicle: food and water contaminated with feces, fomites
Norovirus: clinical signs
nausea
acute onset vomiting
watery non-bloody diarrhea with abdominal cramps
Norovirus: case definition/diagnosis
- Kaplan Criteria used to determine if an outbreak was caused by Norovirus:
- Mean(median) illness duration: 12 – 60hrs
- Mean (median) incubation period: 24 – 48hrs
- More than 50% of people with vomiting
- No bacterial agent found - RT PCR of stool, vomit or environmental samples
Norovirus: treatment
supportive
Norovirus: prevention
Target the vehicle: Proper preparation, cooking and handling of food: MOST IMPORTANT
Block transmission: Personal hygiene and hand washing
true/false: Norovirus outbreaks are generally small
false: Multiple potential modes of transmission Prolonged asymptomatic shedding Environmental stability of the virus Lack of persistent cross‐protective immunity
restaurant workers
Low paid
No or poor benefits
Have to work when sick
Norovirus, Influenza
Noroviruses and cruise ships
The increase in gastroenteritis on cruise ships is primarily attributed to noroviruses
Noroviruses have caused large consecutive cruise ship outbreaks
Prompt implementation of disease control measures are key to controlling norovirus outbreaks
what is the most common cause of severe diarrhea in children around the world
rotovirus
Rotovirus: reservoir
people
many species of animals (livestock, monkeys)
Rotovirus: transmission
direct: fecal-oral
vehicle: contaminated food and water, fomites (virus is hardy-lasts for weeks in environment)
Rotovirus: hight risk for transmission
Children attending day care centres
Children in hospital wards
Parents or workers in day care or hospitals
Immunodeficient people
Rotovirus: clinical signs
In children 3 to 36 months of age First infection after 3 months of age is most severe up until about 36 months Diarrhea, in most cases is self limiting May see temporary lactose intolerance Dehydration, electrolyte imbalances
Rotovirus: case definition/diagnosis
no definitive case definition
Rotavirus antigen in stool detected with enzyme immunoassay (EIA)
Rotovirus: treatment
supportive
Rotovirus: prevention
target host
target vehicle
block transmission
Rotovirus: vaccination
children get infected very young
- 2 vaccines available (2-3 oral doses at 2 months of age)
by contrast bacterial illness:
Usually have a moderate incubation period, lack of vomiting, and somewhat longer duration of illness
by contrast parasitic illness:
Usually have a longer incubation period (1 to 2 weeks) and a longer duration of illness (>2 to 3 weeks)
other viral agents include
Astroviruses, adenoviruses, parvoviruses
