1 Foodborne & Waterborne Disease Viruses Suphachai Nuanualsuwan DVM, MPVM, PhD 1. Introduction.
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Transcript of 1 Foodborne & Waterborne Disease Viruses Suphachai Nuanualsuwan DVM, MPVM, PhD 1. Introduction.
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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 Suphachai DVM, MPVM, PhD
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Etiology % Outbreak
Bacteria 28
Chemicals 5.6
Parasites 0.7
Viruses 1.9
Known etiology 36.6
Unknown etiology 63.7
Outbreak by etiology 1988-1997
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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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
Estimated cases by etiology
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
Suphachai DVM, MPVM, PhD
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Common properties among FB-WB viruses
• inert transmissible particles
• fecal-oral route
• human specific
• non-cytopathic effect
• non-enveloped viruses
Suphachai DVM, MPVM, PhD
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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
Suphachai DVM, MPVM, PhD
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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
Suphachai DVM, MPVM, PhD
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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 Hepatitis A virus ~ 28 nmDiameter of Calicivirus ~ 30 nm
diameter of < 30 nanometers (mostly)
Suphachai DVM, MPVM, PhD
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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
• fomiteSuphachai DVM, MPVM, PhD
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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 meatSuphachai DVM, MPVM, PhD
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- Common properties of FB WB disease viru
ses
4. Difficult to culture in laboratory
• hhh hh hhhhhhhh
• 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 virusesSuphachai DVM, MPVM, PhD
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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
Suphachai DVM, MPVM, PhD
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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
• CoronavirusSuphachai DVM, MPVM, PhD