1. Foodborne & Waterborne
23/04/60
Foodborne & Waterborne
Disease Viruses
2. Norovirus & Rotavirus
Suphachai Nuanualsuwan
DVM, MPVM, PhD

2. Noroviruses 1. Virus particle
formerly Norwalk-like viruses since first outbreak in Norwalk, Ohio, U.S.A.
gastroenteritis virus
one of 2 human Calicivirus genera
small round, structured viruses (SRSV)
~ nm
single structural protein
ssRNA(+) of 7,500 bases
Suphachai
DVM, MPVM, PhD

3. Electronmicrographs and model of Caliciviruses
Norovirus
Suphachai
DVM, MPVM, PhD

4. Noroviruses 2. Disease gastroenteritis mild and self-limiting
“winter vomiting disease”
projectile vomiting
incubation period is dose-dependent
incubation period & illness duration hr.
Suphachai
DVM, MPVM, PhD

5. Noroviruses 3. Transmission and Control
major virus shedding in 1.vomitus and 2.stool
infection
primary infection : food or water
secondary infection : infected patients
aerosol droplet can shed virus on the fomite
Suphachai
DVM, MPVM, PhD

6. Suphachai
DVM, MPVM, PhD

7. Noroviruses 4. Epidemiology
person-to-person by fecal-oral is main route through food handlers
institutional outbreak : the poor sanitation
food & water contaminated with virus particles
shellfish e.g. oyster
recreational water
no age specific
Suphachai
DVM, MPVM, PhD

8. Noroviruses 5. Stability in case of prevention broke
need to inactivate virus in food or water
nature of FB-WB disease viruses are resistant to the environment
inactivation (data usually from epidemics)
drying on the fomite surface pH
heating
Ultraviolet(UV) and chlorine
Suphachai
DVM, MPVM, PhD

9. Noroviruses 6. Food and Risk factors A safe food handler Suphachai
DVM, MPVM, PhD

10. Shellfish bivalve mollusk found in shallow coastal, estuarine water
feeding by filtration
accumulate virus particles
eating raw or undercooked shellfish?
oyster mussel clam cockle
Suphachai
DVM, MPVM, PhD

11. Shellfish thoroughly cooking to inactivate viruses Suphachai
DVM, MPVM, PhD

12. Relaying and Depuration not standard for viruses
Shellfish
Relaying and Depuration
not standard for viruses
Suphachai
DVM, MPVM, PhD

13. Personal sanitation of food handlers
A safe food handler
Suphachai
DVM, MPVM, PhD

14. Noroviruses formerly Norwalk-like viruses Caliciviridae family
incubation and illness ~ Hr.
gastroenteritis virus
distinctive symptom: vomiting
virus shedding in vomitus and stool
transmission: fecal-oral route
diagnosis: epidemiology, symptom, RT-PCR

15. Rotavirus infection
Suphachai
DVM, MPVM, PhD

16. double coat protein & icosahedral symmetry diameter of 70-80 nm
Rotavirus
1. Virus particles
Reoviridae family
double coat protein & icosahedral symmetry
diameter of nm
11 dsRNAs -> re-assortment
diverse serotypes
Group A rotaviruses (7 serotypes)
mostly found in children < 5 years
Suphachai
DVM, MPVM, PhD

17. food and water contaminated with viruses pre-harvest and post-harvest
Rotavirus
2. Implicated food
Shellfish
food and water contaminated with viruses
pre-harvest and post-harvest
Suphachai
DVM, MPVM, PhD

18. gastroenteritis -> acute diarrhea
Rotavirus
3. Disease
gastroenteritis -> acute diarrhea
vomiting, fever, and respiratory illness
water and electrolyte loss
malnutrition as aggravating factor
serious in children, mild for adult
incubation period ~ 1-3 days
illness duration ~ 4-6 days
Suphachai
DVM, MPVM, PhD

19. shedding virus ~ 8 days after disease onset institutional outbreak
Rotavirus
4. Epidemiology
shedding virus ~ 8 days after disease onset
institutional outbreak
very low infective dose
children < 5 years ~ 6-24 %
diverse serotypes -> re-infection
short-term IgG(<2 wk) -> re-infection
non-seasonal
associated with sanitation
Suphachai
DVM, MPVM, PhD

20. Rotavirus
5. Transmission/Control
food & water
fertilizer, sewage
water treatment, supplies, distribution
fomites and environmental surface
relative humidity, porous surface
sediment
hands and fingers
63 % of transmission
polyvalent vaccine

21. fecal-oral route <- sanitation gastroenteritis, vomiting, fever
Rotavirus
fecal-oral route <- sanitation
gastroenteritis, vomiting, fever
children < 5 years got serious illness
short-term immunity 2-4 weeks
Suphachai
DVM, MPVM, PhD

22. 23/04/60