Schaechter: Chapter 1 Establishment of Infectious Disease

What are the events that take place in all infectious diseases

* **Encounter:**the agent meets the host
* **Entry**: the agent enters the host
* **Spread**: the agent spreads from the site of the entry
* **Multiplication**: the agent multiplies in the host
* **Damage**: the agent or the host response, or both, causes tissue damage.
* **Outcome**: the agent or the host wins out, or they learn to coexist.

definition of encounter

=def.: the agent meets the host

def. Entry

= def.: the agent enters the host

def. spread

= def.: the agent spreads from the site of the entry

Def. multiplication

= def.: the agent multiplies in the host

def. damge

= def.: the agent or the host response, or both, causes tissue damage.

**def. Outcome**

= def.: the agent or the host wins out, or they learn to coexist.

How is a baby protected from the outside environment before and after birth?

And how does come in contact with microorganism

* uterine enviromnet is sterile
* first contcat to enviormnet : birth
* after birth abay has antibody from moms blood in the circulation
* mothers milk( colostrum) contains maternal antibodies

difference between Endogenous and Exogenous Encounters with diseases ?

* @@**Exogenously acquired diseases**@@: from encounters with agents in the environment
* @@**Endogenously acquired diseases:**@@ caused by misbalanced agents already present in or on the body

types of entries for exogenously aquired diseases?

* ingestion
* inhalation
* sexual contact
* wound
* insect bite

what are the two types of entry of pathogens?

* @@**Ingress**:@@ entry without crossing Epithelial barries
* via swallowing( contaminated food) , inhalation( aerosol droplets or dust particles)
* @@**Penetration**@@: entry by crossing(penetrating) an epithelial layers
* via single-cell mucus layers
* penetrate the skin… insect bites; hookworms
* penetration from cuts or wounds
* organ transplant and blood transfusion
* active transport through a membrane with macrophages via phagocytosis

What is the def. of **inoculum size** what is its association with disease development

=def.: the number of invading organisms

* key factor in the development of infection potential

def. of **lateral propagation**

= def.: the spread of microorganism form original site of entry to contiguous tissues

def. **dissemination**

= def.: the spread from contiguous tissue to distant sites(organs)

what is the **active participation** by microbes?

= def.: microbes move, wiggle, swim, or secrete products to contribute the spreading

how do **fluid dynamic** infleunce spreading of microbes?

Depending where the microbe enter the body, fluids like **blood** determine the pathway in which the microbe spread

Draw the microbial multiplication and clincal manifestation of diseases

def. incubation period

= def.: the time needed for infectious agents to overcome early defense and grow to a certain population size

what are the two defence strategies that we have against unwanted microbes?

* @@**complement and phagocytosis**@@
* The complement system functions to kill microbes via lysis or phagocytosis, to clear immune complexes and apoptotic debris from the circulation, to promote inflammation, and to stimulate humoral immunity (Chapter 37. Humoral Immunity and Complement)
* @@**humoral and cellular immunity**@@
* Humoral immunity, mediated by antibodies produced by B lymphocytes, is a form of specific immunity directed primarily toward extracellular antigens

what causes damage to cells during an infection?

* harmful activities by the **invading agent** ( for example necrosis)
* consequences of the **hosts response**( for example: apoptosis)

Whta are the two diffrnet immon repsonses towrads infcetoins

* **innate immune response**: first line of immune responses which are always present and available for action
* does not require previous exposure to microbe
* **adaptive immune response:** an alternative immune response that targets specific infected cells due to production of specific antibodies
* requires previous encounter with microbe
* causes **antigen-antibody complexes**