MICROPARA(LEC) - PRINCIPLES OF DISEASE AND EPIDEMIOLOGY

Koch’s Postulates

1. The same pathogen _________________________ of the disease

2. The pathogen must be ___________ from the diseased host and grown in pure culture

3. The pathogen from the pure culture __________________ when inoculated into a healthy, susceptible laboratory animal

4. The pathogen must be isolated from the inoculated animal and must be shown to be the ____________________

must be present in every case
isolated
must cause the disease
original organism

LIMITATIONS

1. Some pathogens have UNIQUE _________________ (______________)

2. Some infections do not produce specific ________ and _______________

3. Some pathogens can cause __________ disease conditions

4. Ethical considerations

culture requirements
fastidious
signs
symptoms
several

If defenses resist pathogens —> _______________

If pathogens overcome defenses —> ______________

health is maintained
disease may occur

_________________ is the invasion or colonization of the body by pathogenic microorganisms

Infection

_______________ occurs when an infection results in any change from a state of health

Disease

Not all microorganisms cause disease and not every ____________ leads to infection

exposure

A ________________ may be harmless in its normal location but cause disease when it reaches a different body site

microorganism

____________________ is part of normal intestinal microbiota but can cause disease when it infects the urinary tract

Escherichia coli

The outcome of infection depends on several factors:

1. _________________ of the microorganism

2. __________________ and ________ of the host

3. ________ and _________ of exposure

4. _______________ conditions

characteristics
susceptibility
defenses
route
extent
environmental

____________________ is the scientific study and diagnose of disease.

• concerned with the cause(__________), _____________, and ___________/___________ changes caused by the disease

Pathology
etiology
pathogenesis
structural
functional

_____________________- What causes the disease?

Etiology

______________ - How does the disease develop?

Pathogenesis

_______________ - what structural and functional changes occur?

effects

__________________ is the process by which an infectious disease develops and progress in the body. It involves the mechanisms and sequence of events on how the infection is initiated, progresses and factors that influence its severity and outcome

Pathogenesis

Pathogenesis involves the:

1. -

2. -

3. -

4. -

5. -

Portal of entry
Local replication
Invasion of host cell and spread
Damage to the host
Portal of exit

___________________ is the ability of a microbe to cause disease. This is QUALITATIVE. Not all pathogens have the same intrinsic ability to cause disease. We have different immune systems which all reacts differently to microorganisms.

Pathogenicity

_______________ is the intensity of the disease produced by the microbe. QUANTITATIVE ability of an agent to cause disease.

Virulence

___________________ between strains of the microbe may account with the differences on virulence

genetic differences

____________________ are characteristics of the pathogen that ENHANCES its pathogenicity. This is not limited to viruses

Virulence factors

What are the 6 types of virulence factors?

1. -

2. -

3. -

4. -

5. -

6. -

Adhesins
Invasins
Toxins
Capsules
Enzymes
Antigenic variation

_____________ enable pathogen to attach to host cells

adhesins

____________ enable pathogen to invade host cells

invasins

______________ cause damage to host cell

toxins

_______________ protect pathogen from immune cells

capsules

_____________ breaks down host tissue or immune cells

Enzymes

_______________________ enables alteration of surface proteins to avoid detection by the immune system

Antigenic variation

_____________________ is the decrease of virulence of a pathogen. The person may develop immunity.

Attenuation

What are the 3 host-microbiome relationship?

1. -

2. -

3. -

Symbiotic relationship
Microbial antagonism/Competitive exclusion
Opportunistic pathogens

__________________ is where at least one organism is dependent on each other

Symbiotic relationship

____________________ is only one organism benefits; the other is unaffected

Commensalism

__________________ - only one organism benefits; the other is unnafected

Commensalism

________________ - both organism benefits

Mutualism

_______________ - only one organism benefits; the other is affected

Parasitism

_____________________

• symbiotic and parasitism

• able to produce Vitamin b12 wherein it helps with making health red blood cells

Gut microbiome

_____________________/_______________

• prevents overgrowth of harmful microorganisms

• Example: Escherichia coli produce bacteriocins which inhibit pathogenic salmonella and shigella

• may be the reason why sensitive ung gut ng iba

Microbial antagonism
Competitive exclusion

_________________ do not cause disease in their normal habitat in a healthy person but may do so in a different environment or when the host defense is immunocompromised

• taking advantage of the host’s system

opportunistic pathogens

How do microbes cause disease?

1. -

2. -

3. -

4. -

5. -

Transmission
Attachment, invasion, replication
evading host defenses
obtain nutrients from the host
damage to the host

How do microbes cause disease?

Influenced by the ______________/____________ and ________________

pathogenicity
pathogenesis
virulence factors

__________________

• Transfer of pathogens to a host

__________ - organism infected by the pathogen, providing suitable environment for growth and reproduction

Transmission
Host

What are the 5 types of hosts?

1. -

2. -

3. -

4. -

5. -

Susceptible
Definitive
Intermediate
Reservoir
Accidental

_______________ is a host that lacks sufficient resistance to a pathogen and can become infected if exposed

Susceptible

________________ is a host in which the parasite or pathogen reaches sexual maturity and reproduces. Mosquito for plasmodium falciparum(malaria)

Definitive

_________________ is the host that harbors the IMMATURE STAGES of a parasite or pathogen. Humans for plasmodium falciparum (malaria)

Intermediate

_____________ is a host that harbors a parasite or pathogen and can transmit it to human or other animals. Humans for the measles virus (measles)

Reservoir

_________________ is a host that is not normally infected by a parasite or pathogen but can be infected under certain circumstances. Humans for hydatid tapeworm (its definitive hosts are sheep and dogs)

Accidental

Transmission involves the portal of _________, mode of ____________, and portal of _______ of pathogens

Divided into 3 categories:

1. -

2. -

3. -

entry
transmission
exit

contact transmission
vehicle transmission
vector transmission

What are the 4 types of Contact transmission?

1. -

2. -

3. -

4. -

Direct contact
indirect
congenital
droplet

________________

• person-to-perosn; no intermediate object

• direct transmission by PHYSICAL CONTACT between its source and a susceptible host

• common cold, influenza, sexually-transmitted infections, rabies

Direct contact

__________________

• reservoir to host by means of nonliving object

• ________-nonliving object involved in the spread of infection

Indirect
Fomite

___________________

• mother-to-fetus/newborn (pathogen crosses the placenta)

• direct contact with a pathogen during delivery

Congenital

_____________________

• pathogen are spread in droplet nuclei (mucus droplets) that travel only short distances (<1 meter from reservoir to host)

• pneumonia, influenza, pertussis

Droplet

What are the 3 types of Vehicle transmission?

1. -

2. -

3. -

Airborne transmission
Waterborne transmission
Foodborne transmission

_______________ is spread by droplet nuclei that travel >1 meter form the reservoir to host

Ex. Measles and tuberculosis

Airborne transmission

_______________ is spread by water contaminated with untreated or poorly treated sewage

Ex. Cholera and leptospirosis

Waterborne transmission

___________________ is spread by eating food that is incompletely cooked, poorly refrigerated, or prepared under unsanitary conditions

Ex. Food poisoning

Foodborne transmission

What are the 2 types of vector transmission?

1. -

2. -

Mechanical transmission
Biological transmission

_________________ is when the pathogen is not undergoing any part of its life cycle with the vector

Mechanical transmission

________________ is when the vector is part of the pathogen’s life cycle, undergoing replication and development

Biological transmission

_________________ is the initial binding of the pathogen to the host’s surface

Attachment

_____________- pili or fimbriae; viral spike proteins; surface glycoproteins

Adhesins

________________ is the entry of the pathogen inside the host’s cell, then undergoes _______________ causing disease and able to spread to new hosts

Invasion
replication

_______________ is the ability to prevent diseases caused by pathogens relies on the ability of the host immune defense to recognize the pathogens and inhibit their replication

Evading host defenses

__________________

• avoid antibody-mediated immunity of host by changing surface proteins or antigens

antigenic variation

__________________

• avoid detection by host immune system

Latency

______________________

• inhibits phagocytosis

capsule formation

______________________

• prevent access of host defense molecules to bacterial cells by producing a self-produced matrix of extracellular polymeric substances (EPS)

Biofilm formation

______________________

• avoid exposure to host immune system

direct cell-to-cell spread

______________________

• directly absorb nutrients from the host’s cells or body fluids, often using specialized structures or enzymes

• Helminths attach to the intestinal wall and absorb nutrients directly from the host’s digested food

Direct absorption

_________________

• use host cell machinery and nutrients to replicate

intracellular parasitism

_____________________

• produce enzymes to break down host tissues that extracellular matrix, allowing them to access nutrients

digestion of host tissues

________________________

• disrupt the host metabolism to obtain an essential nutrient for its growth

interference of host metabolism

_______________________

• pathogens are able to hijack systems for their own benefit utilizing endocytosis that allows them to be engulfed by the host cells; to manipulate host cell exocytosis to produce the pathogen’s proteins and toxins

Exploitation of host transfer systems

_______________________

• adheres to the intestinal epithelium and produces toxins that disrupt cell function and lead to diarrhea. Produces ENDOTOXIN, stimulating cytokine storm that causes flu-like symptoms

Escherichia coli

_________________________

• produces toxins that damage host cells and tissues, leading to infections like skin abscesses and pneumonia

• EXOTOXINS include leucocidin (kills phagocytic leukocytes) and haemolysin (kkils rbcs)

Staphylococcus aureus

________________________

• colonizes the stomach and produces toxins that damage the gastric mucosa, leading to ulcers and gastric cancer

Helicobacter pylori

____________________

• infects respiratory epithelial cells, causing inflammation and tissue damage, leading to respiratory symptoms

influenza virus

____________________

• opportunistic pathogen that can cause infections of skin, mucous membranes, and internal organs

Candida albicans

_______________________

• intestinal parasite that can cause intestinal obstruction and malnutrition

Ascaris lumbricoides

________________________

• disease in which an infected person transmits an infectious agent, either directly or indirectly, to another person who in turns becomes infected

Communicable disease

____________________ - very communicable; spreads easily and rapidly

Contagious disease

_______________________

• disease that CANNOT BE SPREAD from one host to another

• caused by microorganisms that normally inhabit the body or reside outside the body and produce disease only when introduced into the body

Non-communicable disease

What are the 4 types of infection or disease based on SEVERITY OR DURATION:

1. -

2. -

3. -

4. -

Acute
Subacute
Chronic
Latent

____________

• rapid onset; symptoms maybe severe but resolves quickly

acute

_____________

• slow onset than acute; last longer than acute but not chronic

subacute

_____________________

• develops more slowly with long lasting symptoms that may persist overtime

chronic

________________

• pathogen remains inactive in the body for longer periods with no symptoms until reactivation

Latent

What are the 3 types of infectious diseases based on EXTENT OF SPREAD?

1. -

2. -

3. -

Local
Systemic
Focal

________________ - invading microorganisms are limited to a relatively small area of the body

• localized pain, redness, swelling, tenderness

local

____________ - microorganisms and/or their products are spread through the body by the blood or lymph

• fever, fatigue, loss of appetite, body aches

systemic

_________________ - agents of local infection enter blood/lymphatic vessel and spread to other parts of the body, where they are confined

• may experience both local and systemic symptoms

Focal

What are the 3 types of infectious diseases based on STATE OF HOST RESISTANCE?

1. -

2. -

3. -

Primary
Secondary
Subclinical or inapparent

__________________

• the initial infection caused by a pathogen in a previously healthy host

• caused by direct exposure to pathogen

• often characterized by specific symptoms related to the pathogen

Primary

__________________

• infection that occurs in a host with primary infection whose immunity is weakened

• caused by OPPORTUNISTIC PATHOGENS

• similar to primary infection but more severe or different

secondary

___________________ or _____________

• infection does not produce any noticeable symptoms

• with exposure to pathogen but immune system is able to control the infection

• no noticeable symptoms

• usually for viruses

subclinical
inapparent

_____________________________

• traditionally called ____________________

• infections that patients acquire while receiving treatment for other conditions at a healthcare facility

• most pathogens that cause HAIs are opportunistic

• Some are resistant to commonly used antimicrobial drugs

Healthcare-associated infections

nosocomial infections

HEALTHCARE-ASSOCIATED INFECTIONS

Two principal conditions that can compromise the host:

1. -

2. -

Principal routes of transmission are:

1. -

2. -

Broken skin/mucus membranes

Suppressed immune system
Direct contact from hospital staff to patient/patient to patient

Indirect contact through fomites and the hospital’s ventilation system

_____________________ are basic, minimum practices employed at all levels of healthcare, regardless of whether a patient’s infection status is confirmed, suspected, or unknown

Standard precautions

_______________________ - designed to supplement standard precautions in individuals with known/suspected infections that are highly transmissible or epdemiologically important

Ex. Contact precautions, droplet precautions, airborne precautions

Transmission-based precautions

___________________ is the single cheapest, most important means of preventing the spread of infection

Handwashing

What are the 5 stages of disease?

1. -

2. -

3. -

4. -

5. -

Incubation
Prodromal
Period of illness
Period of decline
Convalescence