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Foodborne & Waterborne
Disease Viruses
1. Introduction
Suphachai Nuanualsuwan
DVM, MPVM, PhD
1
Foodborne and waterborne disease viruses
• Top 3 foodborne disease outbreak during
1988-1997(10 years) following bacteria and
chemical
• Data from CDC most updated
• unknown etiology was ~ 64%
• passive record
2
Suphachai
DVM, MPVM, PhD
Outbreak by etiology 1988-1997
Etiology
% Outbreak
Bacteria
28
Chemicals
5.6
Parasites
0.7
Viruses
1.9
Known etiology
36.6
Unknown etiology
63.7
Source : CDC 1996 Surveillance for foodborne disease outbreaks-US 1988-1992 MMWR 45(ss-5): 1-71
CDC 2000 Surveillance for foodborne disease outbreaks-US 1993-1997 MMWR 49(ss-1): 1-62
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Estimated cases by etiology
Etiology
% Cases
Bacteria
13.47
Parasites
6.58
Viruses
79.95
• Noroviruses
59.54
• Rotavirus
10.10
• Astrovirus
10.10
• Hepatitis A virus
0.22
Source : Mead, et al 1999. Food related illness and death in the United Stated Emerging Infectious
diseases 5(5) 607-625
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Foodborne and waterborne viruses
• Estimated Top 1 of food-related illness
• Higher than bacteria & parasites combined
5
Suphachai
DVM, MPVM, PhD
Common properties among FB-WB viruses
• inert transmissible particles
• fecal-oral route
• human specific
• non-cytopathic effect
• non-enveloped viruses
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Suphachai
DVM, MPVM, PhD
Common properties of FB-WB disease viruses
1. inert transmissible particles
• viruses are not a living organism
• diameter of < 30 nanometers (mostly)
• icosahedral symmetry
• single stranded RNA (+)
(mostly)
• RNA-dependent RNA polymerase(RdRp)
• intracellular parasites
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Suphachai
DVM, MPVM, PhD
What is VIRUS ?
A group of infectious agents characterized by their
inability to reproduce outside of a living host cell.
Viruses may subvert the host cells' normal functions,
causing the cell to behave in a manner determined by
the virus.
Virion: Virus particle – Infectious (native) or noninfectious
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Suphachai
DVM, MPVM, PhD
Icosahedral symmetry
Noroviruses
Poliovirus type 1
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Nonenveloped enteric viruses in human
Diameter
Nucleic acid
(nm)
Stranded
RNA
DNA
25-38
single
Astrovirus
Parvovirus
Calicivirus
Coronavirus
Picornavirus
70-85
double
Reovirus
Adenovirus
Rotavirus
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diameter of < 30 nanometers (mostly)
Diameter of Hepatitis A virus ~ 28 nm
Diameter of Calicivirus ~ 30 nm
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Suphachai
DVM, MPVM, PhD
Common properties of FB-WB disease viruses
2. Fecal oral route transmission
• virus ingestion -> virus shedding
• direct transmission
• fecal-oral route
• person-to-person route
• indirect transmission
• food & water
• fomite
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Suphachai
DVM, MPVM, PhD
Common properties of FB-WB disease viruses
3. Human adaptation
• all FB-WB disease viruses are human specific
except Hepatitis E virus(HEV) and Tick-borne
encephalitis virus
• associated with sanitation rather than
undercooked meat
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Suphachai
DVM, MPVM, PhD
Common properties of FB-WB disease viruses
4. Difficult to culture in laboratory
• human specific
• no lab host cells or no cytopathic effect(CPE)
renders infectivity test difficult
• RT-PCR is a leading diagnostic tool yet cannot
differentiate infectious and inactivated viruses
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Suphachai
DVM, MPVM, PhD
Common properties of FB-WB disease viruses
5. Non-enveloped viruses
• all FB-WB disease viruses are non-enveloped
• resistant to environmental condition e.g. pH,
heating, UV
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Suphachai
DVM, MPVM, PhD
Foodborne and Waterborne Disease Viruses
1. Noroviruses(NV) formerly Norwalk-like viruses
2. Rotaviruses
3. Hepatitis A virus(HAV)
4. Hepatitis E virus(HEV)
5. Other viruses
• Astrovirus
• Parvovirus
• Tick-borne encephalitis virus
• Enteroviruses
• Adenovirus
• Coronavirus
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Suphachai
DVM, MPVM, PhD
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