Viral Gastroenteritis Flashcards
Viruses that cause gastroenteritis
- Poliovirus (and all other enteroviruses)
- all replicate in gut
- enteroviruses can cause meningitis (throat swab and faeces sample)
- Adenoviruses OTHER THAN types 40 and 41
- Hepatitis A
How to diagnosie viral gastroenteritis
Faecal sample
NB most viruses do not cause D and V
Adenovirus replicates in the gut but causes
conjunctivitis
Hep A replicates in the gut but causes
Jaundice
2 Groups of viruses associated with gastroenteritis
- Norovirus
- Related viruses e.g sapoviruses (Both family calciviridae)
- Affect all ages and the previously healthy
- Most common gastroenteritis causing organsism
- Rotaviruses(Wheel like, significant cause), adenovirus types 40 & 41 astroviruses (Star)
- Affects mainly
- Children under age 2
- Elderly
- Immunocompromised
- Affects mainly
Norovirus infection microbiology
- Family: Caliciviridae
- Non-enveloped, single stranded RNA
- Six norovirus genogroups
- Three of the genogroups affect humans
- GI, GII, and GIV (genogroup)
Norovirus Pathogeneis
- Lack of RNA polymerise to transcribe
- Infectious dose very small (10-100 virions)
- Tough – ie survives well in environment – not enveloped
- Transmission through a variety of routes
- Person to Person (faecal-oral and aerosolised formites)
- Food-borne
- Water
- Infectious period from onset till 48 hours after symptoms stop
- Immunity lasts less than a year
- Continuing antigenic variation
- All ages at risk
Symptoms of norovirus
Some are asymptomatic
- Projectile Vomiting
- Diarrhoea
- Nausea
- Abdominal cramps
- Headache, muscle aches
- Fever (minority)
- Dehydration in young and elderly
Complications of norovirus
- Significant proportion of childhood hospitalisation
- Illness in hospital outbreaks lasts longer with an increased risk of mortality (underlying illness)
- In elderly increased post infection complications
- Chronic diarrhoea & virus shedding in both solid organ transplant patients and bone marrow transplant patients
- shedding for up to 2 years
AIRBOURNE TRANSMISSION RATES HIGH
Treatment of norovirus
No direct antivirals
Symptomatic therapy
- Oral &/or IV fluids
- Antispasmodics
- Analgesics
- Antipyretics
Food contamination of norovirus
- Source
- Shellfish from contaminated water
- Contaminated water used for irrigation
- Human faeces used as fertilizer
- Processing
- Preparation
- Food handlers
- Customers
- Insects
Norovirus laboratory diagnosis
Norovirus infection control
- Isolation or cohorting
- Exclude symptomatic staff until symptom free for 48 hours
- Do not move patients
- Do not admit new patients
- Throrough cleaning of ward/ hotel/ cruise ship/ bus
- 48 hours after last case symptomatic
- Dilute hypochlorite or hot soapy water
- Patient/ visitor/ passenger/ guest awareness
Rotavirus microbiology
Family: Reoviridae
Double stranded RNA virus
11 strands of RNA so potential for much antigenic variation
Low infectious dose (10–100 virus particles)
Who does rotavirus infect
Infection occurs throughout lifetime
Illness common only under age 2 (Usually only first infection after maternal antibody lost)
Elderly and immunocompromised can have severe and persistent symptoms
most infectious when have D and V
Hospital outbreaks in paediatric wards common
Symptoms of rotavirus
Symptoms of rotavirus infection usually begin within 2 days of exposure and last 3-8 days
Anorexia, Low-grade fever
Watery, bloodless diarrhoea
Vomiting
Abdominal cramps
Treatment of rotavirus
No antivirals available
Rehydration
Rotavirus vaccine
Rotarix (live attenuated vaccine) for children under 2
Adenovirus features
Tend to behave like rotavirus infections – hard to clinically differentiate
ie occur throughout life
Only first infection symptomatic except in elderly and immunocompromised
Although nearly everyone has been infected by age 5, only a few have had symptomatic infection
Outbreaks rare
Diagnosis of rotavirus, adenovirus and astrovirus
Rota, adeno, astrovirus infection control
Isolation or cohorting
Do not move patients
Do not admit new patients
Through cleaning of ward
48 hours after last case symptomatic
Dilute hypochlorite solution
Parent / visitor awareness
Summary of gastroenteritis causing viruses
- Many viruses replicate in gut
- Most do not cause GI symptoms
- Norovirus causes outbreaks of D&V in all age groups
- Rotavirus causes D&V in under 2s
- Common in winter
- Adeno 40 & 41 and astrovirus behave like rotavirus but much rarer
