GI Acute Non-Inflammatory: Viruses + Cryptosporidium

Question 1

describe the classification of rotavirus

Answer 1

11 segments of dsRNA non-enveloped

Question 2

if a child is infected with rotavirus and is < ___ months or > ___ years, they are asymptomatic

Answer 2

if a child is infected with rotavirus and is < 6 months or > 5 years, they are asymptomatic; protection against diarrheal infectiono

Question 3

describe how rotavirus is acquired and the incubation period

Answer 3

fecal-oral route or water-borne or air-borne

incubation: <48 hours (1-3 days)

Question 4

desribe the pathogenesis of rotavirus

Answer 4

• acquired via: fecal-oral route, water-borne, or air-borne
• replication: epithelial cells of SI
  
  • shortening and blunting of villi, patchy irregularly intact mucosa, mononuclear cell infiltration of lamina propria
  • diarrhea results from the loss of absorptive area and the flux of water/fluid across the damaged surface
• shed in feces
  
  • shedding may persist for 10 days or more
  • peak within 8 days

Question 5

the replication of rotavirus takes place in ____

Answer 5

the replication of rotavirus takes place in epithelial cells of SI

Question 6

the diarrhea caused by rotavirus results from _____

Answer 6

the diarrhea caused by rotavirus results from the loss of absorptive area and the flux of water/fluid across damaged surface

Question 7

describe the clinical manifestations of rotavirus

Answer 7

• sudden onset watery diarrhea with or without vomiting
• up to 6 days
  
  • longer = immunocompromised
• complications: dehydration could be severe and life-threatening

Question 8

describe the detection of rotavirus

Answer 8

• virus in stool peaks at day 3/4 of diarrhea
  
  • latex agglutination

Question 9

describe the Sketchy

Answer 9

Question 10

describe the Norwalk virus (Norovirus) classification

Answer 10

small, non-enveloped (+) ssRNA

Question 11

most cases of norovirus occur during ____ (season)

Answer 11

most cases of norovirus occur during the winter

“winter vomiting disease”

Question 12

describe the transmission of norovirus and the main vector for food-borne illness

Answer 12

• transmission via:
  
  • primary = fecal-oral route
  • water-borne
  • food-borne
    
    • raw-shellfish

Question 13

describe the pathogenesis of norovirus

Answer 13

1. transmission via fecal-oral route, water-borne route, food-borne route (raw shellfish)
2. virus multiplies in SI
3. produces transient lesions of intestinal mucosa
4. spares large intestine (NO fecal leukocytes)
5. shed in feces

Question 14

norovirus spares the ____ and therefore there are NO ____

Answer 14

norovirus spares the large intestine and therefore there are NO fecal leukocytes

Question 15

describe the duration of clinical manifestations of norovirus infections

Answer 15

mild and brief: 24-48 hours following ingestions; lasts 24-60 hours

characterized by: abdominal cramps, myalgias, malaise, headache, nausea, low-grade fever & 1-2 days diarrhea

Question 16

norovirus is commonly associated with outbreaks on _____

Answer 16

norovirus is commonly associated with outbreaks on cruise ships

Question 17

describe the Sketchy

Answer 17

Question 18

describe the classification of adenovirus

Answer 18

non-enveloped dsDNA

icosahedral protein shell

Question 19

the main target of adenovirus is the ____

Answer 19

the main target of adenovirus is the respiratory tract

Question 20

describe the classification of astrovirus

Answer 20

(+) ssRNA, non-enveloped

Question 21

describe the 3 different types of diarrhea that Cryptosporidium spp. causes

Answer 21

• self-limiting diarrhea (most common)
  
  • stomach cramps or pain, dehydration, nausea, vomiting, fever, weight loss
• persistent diarrhea in endemic developing countries
  
  • persistent diarrhea in children
• chronic diarrhea in immunocompromised

Question 22

Cryptosporidium spp. is a frequent cause of ____ disease

Answer 22

Cryptosporidium spp. is a frequent cause of waterborne disease

• drinking and recreational water

Question 23

infection by Cryptosporidium occurs after ingestion of ____

Answer 23

infection by Cryptosporidium occurs after ingestion of thick-walled oocysts

Question 24

after ingestion of oocysts, the ____ attach to and invade the epithelial cells of the SI where they develop into the ____

Answer 24

after ingestion of oocysts, the sporozoites attach to and invade the epithelial cells of the SI where they develop into the trophozoites

Question 25

the ___ are the diagnostic stage of Cryptosporidium spp.

Answer 25

the thick-walled oocysts (also the infective form) are the diagnostic stage of Cryptosporidium spp.

Question 26

describe the diagnosis of Cryptosporidium spp.

Answer 26

• not routine O&P; must request
• microscopic stool examination:
  
  • multiple stools collection on separate days
  • wet mounts
  • thick walled oocysts
• differential staining = modified Ziehl-Neelsen

Question 27

describe the Sketchy

Answer 27