Lecture 17: Viral Enteric Pathogens Flashcards
Enteric Pathogens: Bacteria
Salmonella spp.
Shigella spp.
E. coli
Campylobacter spp.
Yersinia spp.
Clostridium difficile
Enteric Pathogens: Viruses
Rotavirus
Norovirus
Astrovirus
Adenovirus
Enterovirus
Enteric Pathogens: Parasites
Entamoeba histolytica
Giardia lamblia
Cryptosporidium
Viral Gastroenteritis
- Nov-Feb in Canada
- 1-3 days of duration
- Acute nausea and vomiting
- 2nd to upper resp infections
- Most common in 1-10yrs
Viral Gastroenteritis Syndromes
Biggest issue = dehydration
- Make sure to eat electrolytes
- Mild afebrile illness with watery diarrhea
- More severe febrile illness with watery diarrhea, vomiting, headache, and constitutional symptoms
Established Pathogens
- Norovirus
- Rotavirus (Infantile gastroenteritis)
- Astrovirus - can give you conjunctivitis, pharyngitis, gastroenteritis all at the same time (enteric types)
- Caliciviruses (other than noro)
Likely and emerging pathogens
- Coronaviruses
- Enteroviruses - can lead to meningitis
- Torovirus
- Picornaviruses
- Pestiviruses
Norovirus
- Nonenveloped
- SS positive-sense RNA genome
- Member of Caliciviridae family
- Airborne and vomitus transmission
- 18-72 hrs of incubation
- Virus shedding in stool
Noro Epidemiology
- Outbreaks common in closed settings (Hospitals, nursing homes, ships, military, uni res)
- Outbreaks terminate spontaneously after 1-2 weeks
- Transmission also from food that have been in contact with contaminated water
Noro signs and symptoms
- Gradual or abrupt onset of illness
- 1st complain of ab cramps and/or nausea
- Usually vomiting and diarrhea occurs with vomiting being the prominent feature
- Fever with 4-8 non-bloody stools/day
What is significance of blood in stool
Invasion of GI mucosa } viruses usually don’t do this -> bacteria does
Treatment/Hospital Control Measures for Noro
- Oral fluid replacement with isotonic liquids
- Symptomatic treatment
- No antibiotics!!
- Stabilize + rehydrate patient!!
Rota
- Reoviridae family
- ONLY double stranded RNA genome
- Non-enveloped
- Not deadly but vaccine is given bc country loses billions a year w employees being sick
Rota Serogroups
A, B, C - human and non-human disease
a= most important clinically; endemic gastroenteritis in kids
b+c= associated w epidemic gastroenteritis affecting all ages
d->g= non-human disease
Rota epidemiology
- Cause severe, dehydrating gastroenteritis in < 5 yr olds in all socioeconomic groups worldwide
- Peak severe disease 6 months - 2yrs
- Kids acquire serum antibody in first 2-3 yrs of life
- Africa, SE Asia, S America
Rota Transmission
- Fecal-oral transmission
- Virus detected in still 4-10 days after sympt.
- Outbreaks in daycare, playgroups, families, nursing homes, and hospitals
Rota Pathogenesis
- Not understood
Potential roles of: malabsorption related mucosal damages and depression of disaccharides, shortened and blunted villi in duodenum with crypt hypertrophy and mononuclear infiltration
Comes in, infects, lytic, replicates, then your over it
Rota signs and symptoms
DEHYDRATION = biggest risk
- Begin w vomiting and fever 2-3 days
- Progress to profuse watery diarrhea for 4-5 days
- Sympt range
- Most severe symptom w dehydration compared to other enteric pathogens and infants and young children
Rota Treatment
- Rehydration, restoration of electrolytes
- Oral rehydration solutions preferred for mild or moderate cases
- IV for severe cases
- NO antibiotics
Rota Control of transmission
- Hardy virus - non enveloped virus
- able to survive on fomites for up to 2 days at RT 85% humidity
- 10 days at 4oC at 25-50% humidity
- Handwashing, contact precautions till symptoms resolve
- Sick employees should NOT come to work
Lab Diagnosis for Enteric Viruses
- Neither virus can be propagated in vitro
- High viral loads in stool enables - Electron-microscopy for virus diagnosis
- PCR is the mainstay of diagnosis now
- Antigen detection is also available
