Flashcards in Foodborne Dz: Viral Deck (45)
T/F: Viruses are the most common cause of foodborne illness
T/F: Testing for viral etiologies of diarrheal dz is routinely done
Hepatitis __ virus accounts for about 90% of viral hepatitis infections worldwide
T/F: Majority of Hepatitis A infections are asymptomatic
****infection in infancy or childhood is asymptomatic
Where does hepatitis A replicate? How is it shed?
replicates in the liver and causes hepatitis
then the virus is shed into bile and is excreted in the feces
Many cases of hepatitis A are acquired when _______
Who is the most important reservoir of Hepatitis A?
The virus is shed 1-3 weeks before illness and up to several weeks after recovery ***long shedding period
T/F: In areas with high endemicity of Hepatitis A there are numerous clinical cases reported
*in these areas the majority of the population are infected as children - therefore there is minimal clinical dz
*occurs in least developed countries with poor socioeconomic status
In more developed countries where there is a low endemicity of Hepatitis A, is there a high or low clinical disease?
There are more outbreaks of clinical disease
In these countries, the average age of infection goes up. More adults are susceptible
*remember in children/young people - they tend to be asymptomatic
What are the modes of transmission of Hepatitis A and which is most important?
Direct: Fecal-oral = most important (close personal contact, poor personal hygiene, infected food handlers)
Vehicle: food, water contaminated with feces (improper sewage tx)
*associated foods = shellfish from contaminated waters, raw produce, Contaminated drinking water, Uncooked foods and cooked foods that are not reheated after contact with an infected handler
What is the incubation period of hepatitis A?
average is 28 days
Can range from 15-50 days
What is the duration of illness associated with Hepatitis A?
varies from 2 weeks to 3 months
What clinical signs will be associated with a Hepatitis A infection?
fatigue, dark urine, jaundice, flu-like symptoms
Nausea/vomiting, anorexia, fever, malaise, or abdominal pain
What is described as a positive case definition of hepatitis A according to the CDC?
1. discrete onset of clinical signs: nausea, anorexia, fever, malaise, or abd pain
2. Jaundice or elevated serum aminotransferase
Either positive serologicatl test for IgM to Hep A
An epidemiological link to a lab confirmed case (within the household/sexual partner)
How can Hep A be prevented?
1. Target the host: Vaccination (this will reduce the reservoir)
2. Target the vehicle: proper sewage/water tx, proper preparation, cooking, and handling of food - wash veggies and fruit, ***good sanitation
3. Block transmission: personal hygiene and hand washing
What is the group of related single stranded RNA, non-enveloped viruses, that cause acute gastroenteritis in humans, and are also known as "winter vomiting disease"?
6 recognized groups
What is the most common cause of foorborne illness around the world?
Noroviruses account for ____% of all KNOWN foorborne illnesses in the US
(only 20% of all domestically acquired foodborne illness)
Who is the reservoir of Noroviruses?
How is it shed?
Feces** and vomit
Shedding begins 18 hours post infection - usually lasts for about 28 days (ranges from 13-56d)
**95 billion viral particles per gram of feces
T/F: Once infected with a norovirus, you will gain immunity and likely not be infected again
*there are multiple strains with little cross protection
What are the modes of transmission of noroviruses?
1. Direct: fecal oral route (close personal contact, poor personal hygiene)
a- food/water contamination with feces (Infected food handlers = MOST IMPORTANT) Also improper sewage tx
--> associated foods: shellfish harvest from contaminated waters, raw produce, uncooked or cooked foods that are not reheated after contact with infected handler
b- FOMITES: surfaces contaminated with fecal material (virus can survive at least one week on counters/surfaces)
What is the incubation period and duration of illness of noroviruses?
Incubation= 12 to 48 hours
Duration of illness = 24 - 72 hours
What clinical signs are associated with noroviruses?
Nausea, acute onset of vomiting, watery non-bloody dhr with abdominal cramping
What are the Kaplan Criteria used to determine if an outbreak was caused by a norovirus? (there are four requirements)
1. Mean (median) illness duration = 12-60 hours
2. Mean (median) incubation period = 24-48 hours
3. More than 50% of people affected --> vomiting
4. No bacterial agent found
(other diagnosis done by Real time PCR of stool/vomit/environmental samples)
Who is norovirus treatment most important for?
Supportive care: fluids/electrolytes
How can norovirus be prevented?
1. Target vehicle: proper preparation, cooking, handling of food (MOST IMPORTANT), good sanitation
2. Block transmission: personal hygiene, and hand washing
T/F: Outbreaks of norovirus are often smaller scale
Often larger due to: multiple potential modes of transmission, prolonged asymptomatic shedding, virus stability in environment, lack of cross protective immunity
The increase in gastroenteritis on cruise ships is primarily attributed to ______
What shellfish has norovirus been known to be transmitted through?