The Epidemiology of viruses. Epidemiology versus Pathogenesis. Pathogenesis: Concerns the processes by which viruses infect individuals . Epidemiology: Studies the transfer and persistence of viruses in populations. Routs of virus transmission. Mother. Individuals. Individuals.
Concerns the processes by which viruses infect individuals.
Studies the transfer and persistence of viruses in populations.
- Minor surgical procedures (tattooing, dentistry, ear piercing)
- Arm to arm vaccination
1. Local infection in respiratory tract
(cause ifluenza, colds, pharyngitis, bronchiolitis, and pneumonia. e.g. Influenza A and B viruses; Parainfluenza virus, respiratory syncytial virus; Rhinoviruses, many Corona- and Adenoviruses).
2. Initiation of infection via the respiratory tract but can also produce generalized infection usually without respiratory symptoms.
(Herpesviruses: EBV, Cytomegalovirus; some enteroviruses; Paramyxoviridae: mumps, measles; rubella virus from Togaviridae)
- Bile salts
(HSV, EBV, Cytomegalovirus)
(Rotaviruses, several Adenoviruses, Narwalk virus from Calciviridae)
Virus shedding in urine: Cytomegalovirus, Rubella virus, measles virus, mumps virus, HBV
Arena virus in rodent urine
Inhalation of dust containing viruses in dried urine
Human infection: e.g. hemorrhagic fever
(e.g. measles and Newcastle disease virus from Paramyxoviridae)
So, to control or eradicate viral infections, we must manipulate these variables
Prepared in the tissues of an inoculated animal.
(e.g. small-pox vaccine from the skin of a calf).
Products from the inoculation of embryonated eggs (e.g. inactivated influenza virus vaccine)
Tissue culture-propagated vaccines
(e.g. poliomyelitis, measles, mumps, and rubella vaccines)
Using nucleic acid recombinant technology (e.g. HBV Subunit vaccine)
(Recombinant vaccines is a help!)
_ Percentage of recipients protected.
_ The duration of protection.
_ The degree of protection.
Immunoglobulins: Gama globulin
- Exposure has occurred and time does not allow for vaccination.
- No effective vaccine exists.
DNA virus, double strand, circular, Icosahedral nucleocapsid, small size (45-55nm).
Oncogenic in some animals (e.g. in rodents)
Causing mucocutaneous lesions
cervical cancer which starts with a flat area of dysplasia (visible as a white plaque).
HPV viral genes, “E6and E7”
Tumor suppressor genes
(e.g. P53 )
Uncontrolled DNA duplication and cell division
- Nonenveloped, icosahedral particle, Single and Positive DNA strand.
- Very small viruses (18-26 nm in diameter) and ubiquitous.
- Infect many species of animals.
- unusual requirements for replication: either a helper virus (a helper adenovirus)or rapidly dividing cells.
Two types of these viruses:
Dependovirus and parvovirus. B19 virus is a parvovirus replicating in erythroid precursor cells.
7-8 days after infection, a prodromal influenza-like illness, characterized by headache, malaise, chills.
17 to 18 days after infection, the development of a mild feverish illness and a maculopapular rash. It starts with erythema of the cheeks followed by a rash (resembling the rash of rubella) on the trunk and limbs. These symptoms disappeared 1-3 weeks.
(e.g. in Sickel cell anemia, Leukemia or hemolytic anemia)