Iatrogenic infection

Acquired as a result of medical procedures such as surgery

Nosocomial infections

Obtained from a hospital environment through any factor.

Zoonotic infections

Acquired from animals, usually vertebrate

non-communicable disease

infectious, but obtained from non-living thing such as soil or contaminated object

Non-infectious diseases

diseases that are not caused by pathogens (diseases caused by genetics)

Infectious diseases

Directly affected by pathogens

Can two disease classifications be present at once?

yes

what is WHO

internal classification of disease

Malaria can be classified as

Communicable, infectious, and zoonotic since its can be spread through an animal bitten by a mosquito which is a (mechanical) vector

what are the five stages of disease

1. Incubation

2. prodromal

3. illness

4. decline

5. convalescence

sickle cell anemia can be classified as

non-communicable, non infectious

what is the first step of disease

Incubation: initial entry of pathogen (through touching a fomite, someone sneezing/ an airborn disease) ; replication begins in this stage

whats the second stage of disease

prodromal stage: replucation continues, signs and symptoms begin to show

what is the third stage of disease

Illness: signs & symptoms are most severe, pathogen is at its highest level

what is the fourth stage of disease?

Decline: pathogen number starts to decreasing, hosts immune system is weak and vulnerable to secondary infection (its harder to fight pathogens 

whats the 5th and final stage of disease?

Host starts to recover, your body starts to develop antibody’s to fight against future infections

convalescent plasmid:

contains antibody’s for certain diseases, is commonly used to treat diseases, popular during covid.

KOCH was the father of

immunology

Koch’s postulates are:

rules for determining an infectious disease

what are Koch’s 4 postulates for determining an infectious disease?

1.The suspected causative agent must be absent from all healthy organisms but present in all diseased individuals.

2.the caustive agent must be isolated from the diseased organism and grown in pure culture.

3. the cultured agent must cause the same disease when innoculated into a healthy susceptible organism.

4. the same caustive agent must then be reisolated from the innoculated diseased organism.

Robert Koch made 3 main wrong assumptions when developing his postulates which are:

1. Pathogens are found only in diseased individuals

2. all subjects are equally susceptible to infections. (there are many factors that determine this, such as age, immune response)

3. All pathogens can be grown in culture

Molecular koch’s postulates :

Focus on a gene in the microbe that is required for a disease to occur

EX of molecular koch’s postulates:

EHEC causes intestinal inflammation and diarrhea, while nonpathogenic strains of e.coli do not

In molecular Koch’s postulates we would isolate the

gene in a pathogen

Pathogenicity is

the ability of a pathogen to cause disease

virulence is

the degree of pathogenicity (how bad the disease is, or how bad of a disease the pathogen can cause)

we can use the terms pathogenicity and virulence to determine:

bio safety level of a lab

examples of virulent pathogens

Bacillus anthracis, becuase it causes severe signs & symptoms

Ex. Low virulent - Rhinovirus (a type of coronavirus) induces low signs & symptoms

What are automatic pathogens?

microbes that always cause infection

What are opportunistic pathogens.

Microbes that can lead to infection in certain cases (ex: normal gut e.coli entering urinary tract can cause infection)

Opportunistic pathogens ex:

Candida albicans (part of normal microbiota)

UTI (caused by e.coli)

Factors that can drive microbes to cause disease

-drugs

-resident microbiota

-age

-genetics

what is the difference between acute and chronic diseases?

-terms used to refer to illness period

what is an acute disease

relatively short diseases (hours, days, weeks)

what is a chronic diseases?

diseases that last for a longer time, (months, years, lifetime)

what is a latent disease?

a disease that comes In episodes, pathogen replicates when disease is active.

virulence curves help:

establish medial infectious dose (ID 50)

and medical LD 50 (lethal dose)

what is the ID 50

the amount of pathogens required to infect 50% of people 

What is LD 50

the amount of pathogen It takes to kill 50% of people

lower ID 50 means:

more infectious

Lower LD 50 means

more lethal infection

Pathogens go through 4 stages to achieve infection:

1. exposure to host

2. Adhesion

3. invasion & colonization

4. Infection

In order to achieve exposure pathogens must be…

exposed to portals of entry to begin adhesion

-some portals are worse than others (mucosa)

examples of portals of entry:

-eye

-nose

-placenta (portal or entry for fetus)

-genitals

-anus

-urethra

-broken skin

-needle 

-gi tract

Listeria can be obtained through:

eating contaminated food (thrives at cold temperatures)

Placenta is portal of entry for :

TORCH pathogens (pathogens that can cross the placental barrier)

T in torch stands for

Toxoplasmosis (toxoplasma gondii), which can come from cat feces 

O in torch stands for

A group of pathogens 

-syphilis

-chicken pox

-Hep B

-HIV

-Fifth disease

R in torch stands for

Rubella (German measles) Pathogen: Togavirus

C in torch stands for :

Cytomegalovirus (pathogen: Human herpes virus 5)

H in TORCH stands for:

Herpres (pathogen: Herpes simplex virus HSV 1 and 2)

Adhesion factors:

Various molecules that allow viruses to latch on to host tissue 

Biofilm is an example of An:

Adhesion factors (helps adhere to infection sight)

Listeria produce a specific protein for adhesion called:

LAP (listeria adhesion protein) helps them latch onto gut tissue

Various virulent factors help with ___

invasion

Helicobactor pylori helps with _____, by producing _____ which breaks down the gel layer on the epithelial tissue of the stomach

invasion

Urease

Urea test would be positive if ____ is present.

H. pylori

_____ can produce specific proteins to help tell the host cell to let them in and allow them to invade.

Listeria

_____ are obligate intracellular.

Listeria (must be in the cell to reproduce and continue their life cycle)

Obligate intracellular pathogens must _____ to survive. 

live inside your cells

Obligate intracellular pathogens enter the cell through ____.

endocytosis

What is endocytosis

when a pathogen is swallowed by the cell.

Obligate intracellular pathogens are also very good at evasion of host immune defenses meaning ______.

they are very good at hiding from your body’s immune system so that it doesnt detect and destroy them quickly.

What are the two invasion mechanisms?

• Effector proteins secreted (special proteins that force their way into cells and inject chemicals into the host cell that tell it to pull them inside. 

• surface proteins ( allow pathogens to stick to and enter host cell, also known as the Trojan horse method)

Examples of pathogens that release Effector proteins:

Salmonella and shigella species 

which mechanism of invasion is known as the Trojan horse method?

Surface proteins

what do surface proteins do?

allow pathogens to attach tightly to host cells, and the host cell unknowingly brings them inside (similar to the Trojan horse sneaking into a city)

Some pathogens are able to survive ____ that engulf them.

lysosomes

what are lysosomes?

the cells stomach, meant to digest and kill invaders. (some pathogens can live through)

Example of pathogen capable of surviving lysosome attack:

Mycobacterium tuberculosis

____ Can break open the phagosome using enzymes called ______. Once they escape into the cells cytoplasm they can grow and reproduce safely.

• Listeria

• Lipases

What are phagosomes?

The bubble the cell uses to trap invaders