HEPATITIS. .pptx

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1. General properties, Structure and replication of food borne viruses HEPATITIS

2. VIRUSES Some common characteristics of viruses are that they are (1) ultramicroscopic in size, varying from 10 to 450 nm, (2) able to pass through most bacterial filters (i.e., 0.22 pm), (3) cultivatable only on a susceptible host cell line, (4) incapable of reproduction without a host, (5) able to infect people, animals, plants, or bacteria; however, they have a very specific target host. Viruses consist of a core of nucleic acid, either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), and a protein coat. They actually exist in two different states, the intracellular state and the extracellular state.

3. Classification Classification of viruses include subdivisions based on (1) the host in which the virus multiplies, (2) the types of tissue or organs of primary infection, (3) the mode of transmission. More recent taxonomical approaches include consideration of (1) the nucleic acid present, i.e., RNA or DNA, (2) symmetry, (3) presence or absence of an envelope, (4) diameter of the helical nucleocapsids, and (5) base sequence of the nucleic acid.

4. Numerous viral infections may result in the death of animals or the destruction of plants. In addition, many of the animal viruses can cause disease in humans, e.g., encephalitis, hepatitis, mumps, rabies, smallpox, and yellow fever. Since many cases of food-borne human gastroenteritis are not caused by bacteria ("nonbacterial acute gastroenteritis"), it is widely believed that viruses may be responsible for, or implicated in, these outbreaks of food-borne diseases in humans. Several viruses implicated in food-borne outbreaks, their mode of transmission, and measures to prevent their spread Hepatitis,Norwalk , Astrovirus and Rota viruses are disease causing food borne viruses.

5. HEPATITIS

6. Structure HAV is a tiny virus with a diameter of 27–32 nm . Viruses contain only what's necessary to allow them to hijack the cells they infect. The  nucleocapsid , the core structure of all viruses, contains protein and nucleic acid. The protein portion of the nucleocapsid, called the  capsid , coats and protects the virus genome. In some cases, the capsid is also involved in viral entry. Other viruses contain an envelope that aids in cell entry, but also protects the virus from the host immune system. The nucleic acid contains the genes of the virus and can be RNA or DNA. The genome only has the genes needed to shut down the host cell and make more viruses.

7. Replication HAV replication cycle. At the hepatocyte's basolateral membrane, the HAV virus interacts with host cell receptors, and its uncoated RNA is released into the cytoplasm. The cap-independent, IRES-driven translation of the positive-strand RNA genome produces polyproteins. Nonstructural proteins involved in genome replication (2B, 2C, 3AB, 3Dpol), the protease (3Cpro), and capsid proteins are produced by proteolytic processing of polyprotein. 2BC causes alterations in intracellular membranes, leading to the formation of a membrane-bound replicase complex that guides the production of a matching minus-strand RNA, which is subsequently employed as a template to make numerous new replicas of the RNA genome.

8. Newly generated positive-strand RNAs are instructed to do more translation or RNA biosynthesis, or they can be packed into capsids to produce intracellular viral offspring. These freshly formed viral components are attracted to multivesicular bodies for eventual egress from infected cells into the biliary canaliculus or hepatic sinusoids via the apical plasma membrane and basolateral plasma membranes, respectively. The RNA genome is exposed after entering the cell, and the host ribosomes attach it to create polysomes. A viral RNA polymerase translation synthesizes viral particles that can be assembled and released into the biliary tree.

9. Foods involved Soft fruits and salads, Strawberries, Raspberries Pathogenesis Transmission is through fecal oral route. But primary site of viral replication is liver. Virus reaches liver through blood. Virus excretion begins upto a week before symptoms start. Incubation period:2-6 weeks

10. SYMPTOMS

11. DIAGNOSIS

12. TREATMENT Nutritional Support : Eating a balanced diet can help support recovery. It’s often recommended to avoid alcohol and substances that can stress the liver. Medications : There are no antiviral medications specifically for hepatitis A. Over-the-counter pain relievers, like acetaminophen or ibuprofen, can help with symptoms, but they should be used with caution, especially if liver function is compromised. Prevention : Vaccination is the most effective way to prevent hepatitis A. Good hygiene practices, such as handwashing, are also important.

13. Avoiding Contagion Isolation : Those infected should avoid preparing food for others and limit close contact to prevent transmission.

14. Structure Spherical non enveloped ss RNA virus. Spike proteins are present. Family: Hepaviridae

15. Foods involved By fecal pollution of drinking water-Cause water borne outbreaks. Raw or uncooked pork, shell fish Pathogenesis Affect young to middle aged adults. Low fatality-1% 17-33% death rate in pregnant women in last trimester. Incubation period- 2-9 weeks.

16. Symptoms: Fever, reduced appetite, nausea, vomiting, abdominal pain, slightly enlarged tender liver. Jaundice Cause inflammation of liver.

17. DIAGNOSIS