P114 Lec 2 Part 1

How can diseases be classified?

Body system they effect Taxonomic categories Longevity & Severity How they spread to their host Effect on populations

Disease in which symptoms develop rapidly but only lasts for a short time

Acute disease

Disease in which symptoms develop slowly and may last for a prolonged period of time

Chronic disease

Diseases with time course and symptoms between acute and chronic diseases

Subacute disease

Diseases where the causative agent may lie dormant for a period of time and then periodically become active to produce signs and symptoms

Latent disease

Disease without or not producing any symptoms

Asymptomatic Disease

May also be used as classification to describe the extent to which the host's body is infected

Asymptomatic

Infection confined to a particular anatomical region of the body

Local Infection

Infections are widespread and involved many systems

Systemic Infection

Infections that are generally spread by the bloodstream or lymphomatics

Systemic Infection

Infections that remain confined to a particular region of the body and serves as a source of pathogens that spread to other areas of the body

Focal Infection

2 types of disease classification based on the sequence of the infection

Primary infection Secondary infection

Initial infection of the patient

Primary infection

Infection that can weaken the host's immunity, allowing opportunistic pathogens to also cause infections

Primary infection

Follows the primary infection

Secondary infection

T/F: Secondary infections are always more dangerous than primary infections

False. Secondary infections are sometimes more dangerous than primary infections

Diseases classified based on the manner of transmission in the population

Communicable Disease Contagious Disease Noncommunicable Disease

Defintion of Communicable Disease

Disease transmitted from 1 host to another, directly or indirectly

Definition of Contagious Disease

Communicable Disease that is easily spread from 1 person to another

Diseases arising from outside of hosts or from opportunistic pathogens

Noncommunicable Disease

Diseases that do not spread from one host to another, thus infected individual is not a source of infection to others

Noncommunicable Disease

Type of disease where the causative agent typically resides on the body and only occasionally causes the disease, or one residing outside the body and only causes disease when introduced into the body

Noncommunicable Disease

Study of where and when diseases occur and how they are transmittted in populations

Epidemiology

2 measures epidemiologists use to track occurence of diseases

Incidence Prevalence

Difference between Incidence and Prevalence

Incidence is the number of NEW cases of a disease in a given area during a given time Prevalence is the number of TOTAL cases of a disease in a given area during a given period of time

Occurrence is also evaluated in terms of [...] and geographic distribution

Occurrence is also evaluated in terms of frequency and geographic distribution Frequency Geographic Distribution

Occurrence is also evaluated in terms of frequency and [...]

Occurrence is also evaluated in terms of frequency and geographic distribution Frequency Geographic Distribution

Diseases that exhibit relatively steady frequency within a given geographic location in a period of time

Endemic

Diseases that occur only occasionally at irregular intervals and random intervals

Sporadic

When endemic or sporadic disease begins to increase beyond the normally expected numbers for a given area for a short period of time

Epidemic

Epidemic disease occuring in more than 1 continent

Pandemic

\[...] are diseaes acquired in healthcare settings

Nosocomial infections are diseaes acquired in healthcare settings

Nosocomial infections are diseaes acquired in [...]

Nosocomial infections are diseaes acquired in healthcare settings

3 Factors contributing to the development of Nosocomial Infections

Presence of microorganisms in the healthcare setting Weakened/Immunocompromised patients Chain of transmission in the Hospital Environment

4 types of nosocomial infections

Exogenous Endogenous Latrogenic Superinfection

\[...] occurs when pathogens are acquired from the healthcare environment

Exogenous infection occurs when pathogens are acquired from the healthcare environment

Exogenous infection occurs when [...]

Exogenous infection occurs when pathogens are acquired from the healthcare environment

\[...] occur when pathogens arise from normal microbiota due to factors within the healthcare setting

Endogenous infections occur when pathogens arise from normal microbiota due to factors within the healthcare setting

Endogenous infections occur when [...]

Endogenous infections occur when pathogens arise from normal microbiota due to factors within the healthcare setting

\[...] results from modern medical procedures

Latrogenic infection results from modern medical procedures

Latrogenic infection results from [...]

Latrogenic infection results from modern medical procedures

\[...] results from the use of antimicrobial drugs

Superinfection results from the use of antimicrobial drugs

Superinfection results from the use of [...]

Superinfection results from the use of antimicrobial drugs

Arise when an antimicrobial drug kills some microorganisms, but allows others to thrive and cause infection due to the absence of microbial competition

Superinfection

\[...] is composed of 3 main components: Agent, Host, and Environment

Epidemiological triad is composed of 3 main components: Agent, Host, and Environment

Epidemiological triad is composed of 3 main components: [...]

Epidemiological triad is composed of 3 main components: Agent, Host, and Environment

Transmission pathways between the components allow the [...], and can be direct or indirect

Transmission pathways between the components allow the spread of infection, and can be direct or indirect

Transmission pathways between the components allow the spread of infection, and can be [...]

Transmission pathways between the components allow the spread of infection, and can be direct or indirect

6 ways of controlling infectious disease

Behavior Change Vaccines Medication Surveillance Environment Infection control in healthcare facilities

Give examples of behavior change to control infectious disease

Using condoms Regular handwashing Healthy diet Insect repellants

Vaccines not only protect the individual, but also protects others through [...]

Vaccines not only protect the individual, but also protects others through herd immunity

\[...] not only protect the individual, but also protects others through herd immunity

Vaccines not only protect the individual, but also protects others through herd immunity

Is one of the mainstays of managing infectious diseases

Medication

Situations where medications can be used to prevent infections before or after being exposed to the disease

Pre-exposure prophylaxis Post-exposure prophylaxis

Significant issue in the fight against microorganisms

Antimicrobial resistance

Occurs when microorganisms develop resistance to drugs that were once effective

Antimicrobial resistance

Diseases or conditions that are required to be notified by law

Notifiable diseases

3 ways surveillance is used to control infectious diseases

Monitor diseases and their trends Characterize disease patterns Detect outbreaks

May also guide the prioritization, development, and evaluation of disease control programs

Surveillance

Environment related activites in controlling infectious diseases

Vector control Ensuring safe water supply Improving sanitation and hygiene Improving housing and working conditions Ensuring food safety Enhancing air quality

Precautions in healthcare facilities for infection control

Proper sterilization of equipment Wearing of PPE Isolating infectious patients Strict handwashing practices Regular cleaning Good hospital surveillance systems

Broader measures of infection control

Improving social determinants of health (Education and Employment) Strong healthcare system Effective health workforce

Concept that recognizes the human health is closely connected to the health of animals and the environment

One health concept

Organism that shelters and supports the growth of pathogens

Host

A condition in which pathogenic microorganisms penetrate the host defenses, enter the tissues, and multiply

Infection

An abnormal state in which the body is not functioning normally

Disease

Pathology is the study of [...]

Pathology is the study of disease

\[...] is the study of disease

Pathology is the study of disease

Pathogenesis is the [...]

Pathogenesis is the development of disease

\[...] is the development of disease

Pathogenesis is the development of disease

\[...] is the study of the cause of a disease

Etiology is the study of the cause of a disease

Etiology is the study of the [...]

Etiology is the study of the cause of a disease

A situation where an infectious agent may multiply on the surface of the body without invoking tissue or immune response

Colonization

Occurs when there is a disruption of tissue or organ caused by microorganisms

Infectious disease

2 ways where microorganisms can be transmitted

Direct transmission Indirect transmission

Study of the distribution and determinants of health-related states or events in specified populations

Epidemiology

Application of epidemiology

Prevention and control of health problems

2 important aspects of epidemiology

Distribution Determinants

Factors or reasons why the disease is occuring, why there is prevalence or incidence of such disease

Determinants

Focus of Epidemiology

Control or reduce the prevalence or incidence of diseases and their distribution

Basic model developed in order to study health problems

Epidemiological Triangle

Intervention to treat the agent (epidemiological triangle)

Use pharmacological interventions

Intervention to change the host (Epidemiological triangle)

May want to include how can the host improve his/her immunity

Intervention on the environment (Epidemiological triangle)

Facilities or guidelines in place so that even when hosts are close together, transmission can still be prevented

Conditions or activities that can lead to the development of disease within a living organisms or host

Predisposing factors

May depend on on genetic or constitutional factors, specific immunity, and nonspecific factors that affect an individual's ability to resist infection or to limit pathogenicity

Susceptible host

Sum of total influences that are not part of the host

Environment

Components of environment factors that affect host

physical climatologic biologic social economic

Place where infectious agents normally live, grow, and multiply

Reservoir

An infectiojn or infectious agent transmissible under natural conditions from animals to humans

Zoonosis

Major reservoir of diseases

Human reservoirs

Never experience symptoms but can still transmit the disease to other people

Carriers/Asymptomatic people

those who can transmit the agent during the incubation period

Incubating carriers

those who have recovered from the illness but remain capable of transmitting to other people

Convalescent carriers

Harbor the pathogen all throughout the period of infection. May be months or even years after infection

Chronic carriers

4 types of nonliving reservoirs

Soil Parasites from soil Water Food

The way a pathogen enters a susceptible host

Portal of entry

Provides a habitat for further growth and spread of microorganisms

Portal of entry

9 Portals of Entry

Broken skin Insect bite Ears Conjunctiva of eye Mouth Respiratory (Nose) Urogenital (vagina, penis, urethra) Anus Placenta

4 Direct modes of transmission

Contact Droplets Vertical Biological vector