foodborne & waterborne disease viruses

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Foodborne & Waterborne Disease Viruses

Suphachai Nuanualsuw

anDVM, MPVM,

PhD

3. Hepatitis viruses

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Hepatitis-causing viruses

Suphachai DVM, MPVM, PhD

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Hepatitis-causing viruses

Type Nucleic acid Alias Transmission

HAV (+)ssRNA Infectious hepatitis Fecal-oral

HBV dsRNA Serum hepatitis Parental

HCV (+)ssRNA Non-A Non-B Parental

HDV (-)ssRNA Hepatitis delta Parental

HEV (+)ssRNA Non-A Non-B Fecal-oral

Suphachai DVM, MPVM, PhD

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Hepatitis A virus(HAV)1. Virus particle

• hepatovirus, picornaviridae• single serotype• 28 nm• (+)ssRNA

Suphachai DVM, MPVM, PhD

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Hepatitis A virus(HAV)2. Implicated food

• shellfish• water• strawberry, lettuce

Suphachai DVM, MPVM, PhD

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Hepatitis A virus(HAV) 3. Disease pattern• asymptomatic : kid < 5 yr.• hhhhhhhhh h hhhhh : > 14 yr.• mild gastrointestinal illness• incubation period ~ 28 days(4 weeks) virus from GI -> liver -> immune response• liver inflammation(hepatitis) -> jaundice -> liver enzyme(ALT) increaseSuphachai

DVM, MPVM, PhD

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Hepatitis virus migrating to liver

intestine

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Hepatitis virus shedding to intestine

Suphachai DVM, MPVM, PhD

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Hepatitis A virus(HAV) 3. Disease pattern

Suphachai DVM, MPVM, PhD

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Hepatitis A virus(HAV)3. Disease pattern

• HAV shedding in stool before onset of illness• Immunoglobulin M rises as ALT enzyme rises• IgM falls while IgG rises• IgM represents recent infection• IgG represents previous infection(permanent)• HAV shedding ~ 2 weeks after onset of illness

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Hepatitis A virus(HAV)3. Disease pattern

Suphachai DVM, MPVM, PhD

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Hepatitis A virus(HAV)4. Transmission/Control

• fecal-oral• indirect transmission associated with sanitation

• food(shellfish) and water• fomite• secondary infection : household• food handlers

Suphachai DVM, MPVM, PhD

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Discharge untreated sewage straight into the sea

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Hepatitis A virus(HAV)5. Epidemiology

• Worldwide epidemic

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Hepatitis A virus(HAV)5. Epidemiology

• > 90% got infected < 6 years • children are carrier & asymptomatic• Shanghai China outbreak associated with raw sewage contaminated shellfish in the coastal water -> 300,000 cases over months • homosexual, drug users• sanitation, institutional • visit endemic area should get vaccinated

16EstuarineSeashore

Sewage discharge Beach

Suphachai DVM, MPVM, PhD

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Hepatitis A virus(HAV)• hhhhhhhhh hhh h hhhhhhhhh hhhhhhh hhhhh• shellfish and sanitation• children < 5 yr are carrier and asymptoma

t i c• incubation period ~ 4 8 days(long)• virus shedding in stool before onset of illnesh

Suphachai DVM, MPVM, PhD

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Hepatitis E virus(HEV) 1 . Virus particle• - - enterically Non A Non B(ENANB) hepatitis virus• - - - enterically transmitted Non A Non B(ET NANB)• hhh hhhh hh hhhhhhhhhhh

• diameter 3 2 nm• hhhhh(+ ) 7 ,2 0 0

Suphachai DVM, MPVM, PhD

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Hepatitis E virus(HEV)2. Implicated food

• mostly drinking water

Suphachai DVM, MPVM, PhD

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Hepatitis E virus(HEV) 3. Disease pattern• - liver inflammation > icterus, Hepatomegaly• cannot distinguish from other viral Hepatithh• hhh hhhhh h hh: , , +

adache, fever• incubation period ~ 4 0 days (longer than that of HAV)

• illness duration ~ 4 weeks• - illness of middle aged adults (1 4 4 0 yhhh

Suphachai DVM, MPVM, PhD

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Hepatitis E virus(HEV)3. Disease Pattern

Week after exposure

Virus in stool

Clinical illness

Tite

r

ALT

-IgM anti HEV

-IgG anti HEV

Suphachai DVM, MPVM, PhD

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Hepatitis E virus(HEV) 3. Disease pattern• h hh hhhhhhhh hh hhhhh hhhhhh hhhhh hh hhhhhhh

• IgM rises as ALT rises• IgG rises just soon after IgM• IgM represents recent infection• - IgG represents previous infection last 2 14 yr.• HAV shedding ~ 2 weeks after onset of illness

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Hepatitis E virus(HEV)4. Transmission/ Control

• Fecal-oral route• water supplies• sanitation

Suphachai DVM, MPVM, PhD

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Hepatitis E virus(HEV)5. Epidemiology

• mortality rate 0.1-1.0% • mortality rate up to 20% in pregnant • swine HEV and human HEV are closely related• endemic in southeast Asia(SEA), middle Asia, middle east, northern Africa, and Mexico

Suphachai DVM, MPVM, PhD

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Phylogenetic relationships between HEV isolates

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Geographic distribution of Hepatitis E

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Hepatitis E virus(HEV)• - fecal oral route• longer incubation period than that of HAV• illness of adult with hepatomegaly• serious in pregnant women• temporary immunity

Suphachai DVM, MPVM, PhD

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Foodborne and Waterborne Disease Viruses• Noroviruses is most prevalent• Rotaviruses in kid & HAV, HEV in adult• Fecal oral route• Food: shellfish & Water: sanitation• preventing virus transmission

• Preventing contamination• Inactivation e.g. heat, chlorine, UV

Suphachai DVM, MPVM, PhD

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