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FoodBorne Virus

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Viruses require a host for multiplication. Original source of all foodborne virus is the human intestine. ... It passed in the urine and faeces of infected persons. ... – PowerPoint PPT presentation

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Title: FoodBorne Virus


1
FoodBorne Virus
  • Ms.Worrawalan P.
  • I.D. 441-8716

2
Foodborne Virus
  • Types of foodborne virus involves in two main
    groups
  • Norwalk-like virus
  • Heptatitis A virus
  • Other types of viruses are astrovirus and
    rotavirus, but foodborne transmission of these
    viruses is rare

3
Genaral characteristic of viruses
  • Viruses require a host for multiplication.
  • Original source of all foodborne virus is the
    human intestine.
  • The virus attaches to the outside of cells lining
    human intesine, then it transfers its genetic
    material into that cell.
  • Finally, killing the human cell to release new
    copies of it that attach to more cells of human
    intestines lining.

4
Norwalk-like viruses (NLV)
  • Round blue ball, surrounding the virus genetic
    material.
  • It is also called small round strucutre virus.
  • It is a part of calicivirus.
  • It is named from the place where the outbreak
    occured.
  • Other viruses with similar features were
    described as Norwalk-like viruses.

5
  • Nature of Disease
  • Common names of the illness are viral
    gastroenteritis, acute nonbacterial
    gastroentertitis, food poisoning, and foodborne
    infection.
  • Humans are the only known hosts. It passed in the
    stool of infected persons.
  • Humans infection can occur either by the
    consumption of contaminated food, or from person
    to person.

6
  • Symptoms and Risk
  • Nausea, vomiting, diarrhea, and abdominal pain
  • Headache and low fever may also found.
  • Mild and brief illness will develop 24-48 hours
    after contaminated food or water is eaten, and
    lasts 24-60 hours.
  • Severe illness or hospitslization is very rare.
  • Usually recover in 2-3 days.

7
  • Target Populations
  • People who ingest the virus and had infection
    with the same or related strain.
  • More frequent in adults and older childern than
    in the very young.

8
  • Sources
  • Food may occur either during preparation and
    serving by infected food handlers, or by contact
    with sewage sludge or polluted water.
  • Mainly found in molluscan shellfish, especially
    oysters, which found in shallow coastal commonly
    near sewage outlet.
  • Molluscs are either eaten raw or after a mild
    heat process, it may not inactivate virus
    particles.

9
  • Sources (cont.)
  • Fruit and vegetables may act as vehicles of
    infection if fertilized with sewage slidge or
    irrigated with sewage-contamination water.
  • WHO states that fruit and vegetables to be eaten
    raw should not be fertilized with sewage or
    irrigated with contaminated water.

10
  • Sources (cont.)
  • Infection from person to person
  • Human infection can occur through body contact or
    release of aerosol.

11
  • Diagnosis of Human Illness
  • Laboratory diagnosis is difficult. Diagnosis is
    often based on the combination of symptoms,
    particularly the prominance of vomiting, slight
    fever, and the short duration of illness.
  • Identification of virus can be made by electron
    microscopy and various immunoassays from samples
    of stool or vomitus.
  • Confirmation requires demonstration of
    seroconversion, the presence of specific IgM
    antibody.

12
  • Food Analysis
  • Virus has been identified in food by
    radioimmunoassay.
  • Because less amount of viruses can cause illness,
    the genome of Norwalk virus has been cloned and
    development of gene probes and PCR amplification
    techniques to detect the virus in clinical
    specimens.

13
Heptatitis A
  • Heptatitis A is classified in the Picornaviridae
    family.
  • It has a single molecule of RNA suurouned by a
    small protein capsid

14
  • Nature of Disease
  • The disease from Heptatitis A called heptatitis.
  • Humans are only known host. It passed in the
    urine and faeces of infected persons.
  • It can be infected via food contamination or from
    person to person.

15
  • Symptoms
  • Heptatitis is usually mild illness, and usually
    lasts a few weeks but may several months.
  • The symptom include loss of appetite,
    malaise,fever, and vomitimg. Follwed in several
    days by jaundice.
  • Death may occur, particularly in elderly, but is
    very rare.

16
  • Target Population
  • People who ingest the virus and are
    immunologically unprotrcted are susceptible to
    infection.
  • More common in adults than children.

17
  • Sources
  • Food human infection occurs when susceptible
    people consumed contaminated food or water.
  • Cold cuts and sandwhiches, fruits, especially
    soft fruits, and fruit juices, milk and milk
    products, vegetables, salads, shellfish, and iced
    drinks.
  • Water, shellfish, and salads are most frequent
    sources.

18
  • Sources (cont.)
  • Infection by person to person HAV is transmitted
    by contact through fecal contamination.

19
  • Diagnosis of Human Illness
  • Heptatitis A is diagnosed by finding IgM-class
    anti-HAV in serum collected during the acute or
    early convalescent phase of disease.
  • Diagnosis is based on detection of specific IgM
    and IgG antibodies in the blood serum or saliva.
  • Heptatitis A virus in fecae cannot be detected by
    elctron microscopy.

20
  • Food analysis
  • Because of the long incubation period, the
    suspected food is often no longer available for
    analysis.
  • Sensitive molecular methods used to detect HAV in
    water and clinical specimens, should prove
    usedful to detect virus in foods.
  • PCR amplification method seems particularly
    promising.

21
Control of Foodborne Virus
  • Heptatitis A and Norwalk-like virus is rapidly
    destroyed by heating at temperatures aboves 85?C.
  • Inactivation of virusses occurs at temperature
    above 65?C and also depends upon the composition
    of medium.
  • They are resistant to acidic conditions (pH3),
    and alcohol or high sugar concentrations

22
Control of Foodborne Virus
  • Shellfish are an important cause of viral
    gastroenteritis. Cultivation in clean water is
    very improtant.
  • Heat treatment to an internal temperature of
    85-90?C maintained for 90 seonds is required to
    destroy virusses in molluscs.
  • Uncooked raw oysters can cause cross contamonated
    to other foods in the kitchen.

23
Control of Foodborne Virus
  • Other foods will normally contaminated on the
    surface of the food, more susceptible 70?C for 2
    minutes will reduce amount of them.
  • Wash raw vegetables throughly before eating or
    prepareing salads.
  • It is suggested to drink only boiled drinks or
    carbonated bottled beverages without ice in the
    area that appears to have polutted water.

24
Control of Foodborne Virus
  • Immunity to viruses is not permanent and
    reinfection can occur and infection may also
    spread from person-to-person, especially in
    heptatitis A.
  • If there are infected person , then
  • Wash hand with soap and warm water after toilet
    visits, before preparing or eating food, and
    after caring for the sick and drying with
    disposal towel or drying machine.

25
Control of Foodborne Virus
  • Exclude infected person from the kitchen and the
    factory.
  • Always diapose of sewage in the saniary manner.
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