VIRUSES PT 2

vertical and horizontal

Transmission can be ___ or ___

Vertical

Transmission through generations.

o From pregnant mother to

embryo.

o From mother to baby via

BREASTMILK.

Horizontal

Transmission from one individual to another of the same species and they are not in a parent child relationship.

via droplet nuclei

via fecal oral route

via sexual intercourse

insect vectors

direct contact with infected patients or contaminated objects

direct introduction into the blood stream

modes of transmission

via droplet nuclei

Particles expelled into the atmosphere during sneezing, coughing, or talking.

o FOR EXAMPLE:

§ Influenza.

§ Common Cold.

§ Measles.

§ Other viruses infecting the resiratory system.

via droplet nuclei

mucus coated droplet easily settles unlike airborne particles

Ease of transmission is dependent on HUMIDITY.

AIRBORNE - mas delikado, easily transmitted.

LOW HUMIDITY

In ____, mucus rapidly dries so the aerosolized particle becomes

lighter and remains suspended in the air for longer.

FECAL-ORAL ROUTE

Common means of transmission for viruses whose primary

infection site is the GASTRO-INTESTINAL TRACT or associated

organs.

o Happens because poor hygiene or sanitation practices.

FECAL-ORAL ROUTE

Mode of transmission of HEPA A & Poliovirus

FECAL-ORAL ROUTE

Mode of transmission of

• HIV or AIDS.

• Hepatitis B.

• HSV 2 - Genital Herpes.

• Human Papilloma Virus (HPV) - Cervical Cancer.

INSECT VECTORS

Mode of transmission of

• Dengue Fever Virus.

• West Nile Disease.

• Tickborne Encephalitis.

DIRECT CONTACT WITH INFECTED PATIENT OR

CONTAMINATED OBJECT

Mode of transmission of

• Introduction onto the SKIN -

o Warts.

o Verrucae.

• Into the BLOODSTREAM by skin damage following scratching -

o Pox Viruses.

DIRECT INTRODUCTION INTO THE BLOOD STREAM

MODE OF TRANSMISISON

• HEPATITIS B and HIV -

o From contaminated syringes and needles.

• RABIES -

o Following animal bites.

• CANNOT reproduce on their own.

• NO metabolism.

• CANNOT synthesize their own proteins, lipids, or nucleic acids.

Things that the viruses cannot do

VIRUSES

TRUE INTRACELLULAR PARASITES -

o That grow within living cells.

o Uses their ENERGY and SYNTHETIC MACHINERY to produce its components.

PRODUCTION and EXCISION from the Host Cell

___ results in CELL DEATH, although not immediate.

VIRUS PROGENY or VIRIONS - the NEW viruses.

REPLICATION of one virus will results to hundred of new viruses which are called ___

VIRAL DISEASE

Propagation from one infected cell to new cells and the

subsequent destruction of tissue or cells.

False. Exception like rabies and influenza that can infectboth animals and humans

T/F. Viruses are always very specific and rarely cross species barriers.

• viruses of bacteria and blue-green algae

• plant viruses

• animal (including insect) viruses

Examples in which viruses can infect

ASYMPTOMATIC

Viruses can also be in certain hosts -

o Host becomes a RESERVOIR and can transmit the virus to a

susceptible recepient.

o EXAMPLE:

Yellow Fever - Virus to humans by mosquitos.

Dengue Fever

-Asymptomatic through its vector - the Aedes spp.

• MULTIPLICATION of the virus.

• DESTRUCTION of the host cell upon release of the Viral Progeny

(Virion).

• MULTIPLICATION of the

virus.

• Release of the Virions WITHOUT the

intermediate destruction of the cell.

• SURVIVAL of the virus in a LATENT stage

WITHOUT noticeable changes to the infected cell.

o Example: Herpes Virus - as they hide

in the immune system of the host.

•SURVIVAL of the Infected Cell in a dramatically ALTERED

or TRANSFORMED state

o Transformation of a Normal Cell to one

having the properties of a Cancerous Cell.

o Examples: HPV, HEPA B, Retrovirus.