Page 87 - MNU-PM503 Parasitology practical book

Pharm D- Clinical Pharmacy Program Third Level Parasitology and virology (PM503)

Viral infection

This laboratory section will define and discuss the basic principles of viral

infection, the entire process by which viruses cause disease. Viral disease is a sum

of the effects on the host of virus replication and of the immune response.

Viral Entry

• Three requirements must be satisfied to ensure successful infection in an individual

host:

• Sufficient virus must be available to initiate infection

• Cells at the site of infection must be accessible, susceptible, and

permissive for the virus

• Local host anti-viral defense systems must be absent or initially ineffective.

- To infect its host, a virus must first enter cells at a body surface.

- Common sites of entry include the mucosal

linings of the respiratory, alimentary, and

urogenital tracts, the outer surface of the eye

(conjunctival membranes or cornea), and the

skin.There are many ways that you can become

infected with a virus, including

1. Inhalation. If someone with a viral infection

sneezes or coughs near you, you can breathe in
droplets containing the virus. Examples of viral

infections from inhalation include the flu or

common cold.

2. Ingestion. Food and drinks can be contaminated with viruses. If you eat them, you
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