M5: Infectious/Communicable Diseases (MS)

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Control

it refers to measures that are applied to prevent transmission after the disease has occurred.

Amoebic Dysentery / Amoebiasis

Is a protozoal infection of human beings initially involving the colon, but may spread to soft tissues, most commonly the liver and lungs by contiguity or hematogenous or lymphatic dissemination

Pathogen

can be anything you can imagine, such as a virus, bacterium, fungus, parasite, or even a prion

Prion

an abnormally shaped protein that causes disease

Metazoa

are multicellular animals, many of which are parasites.

Protozoa

are single-cell organisms with a well-defined nucleus. Some of these are human parasites.

Fungi

are nonmotile, filamentous organisms that cause diseases that can be very difficult to treat.

Etiologic agent: Bacteria

are single-celled organisms that lack a nucleus.

Virus

• are very small, consisting of an RNA or DNA core and an outer coat of protein.

• They can reproduce and grow only inside living cells.

Portal of Exit

the route by which the disease agent may escape from the human or animal reservoir.

• Respiratory

• Genitourinary

• Alimentary - mouth/bites

• Skin

• Transplacental - mother to fetus

Enteric Isolation

• They control diseases transmitted through direct or indirect oral contact with infected feces or contaminated articles.

• Transmission of infection depends on the ingestion of the pathogens. E.g. Hepatitis, Dysentery

Disinfection

destruction of pathogenic organisms excluding spores.

Measles / 7 Day Measles /Morbili / Red Measles / English Measles

Pathognomic sign:

• Enanthem sign (Koplik's spot, Stimson's line) followed by Maculopapular rash

Hepatitis C

• A blood-borne infectious disease caused by a virus originally known as "non-A, non-B hepatitis"

• The infection is often asymptomatic, but once established can cause scarring of the liver (fibrosis) and eventually, cirrhosis (advanced scarring)

Gonorrhea

Etiologic agent:

• Neisseria gonorrhea

AIDS

• Most most advanced stages of HIV infection.

• It is defined by the occurrence of any of more than 20 opportunistic infections or HIV-related cancers.

Communicable disease

• A disease caused by an infectious agent that is acquired/transferred from an infected source and is transmitted to a susceptible host either through direct contact, indirect contact, or direct inoculation into the skin.

• Can be either infectious, contagious, or both.

Infectious diseases

this disease is caused by pathogenic microbial agents, such as viruses, bacteria or other microorganisms.

Contagious diseases

a disease is _______ when it spreads through direct, bodily contact with an infected person, their discharges, or an object or surface they have contaminated.

Epidemiologic Triangle Model / Triad of Disease Causation

The interaction and interdependence of agent, host, environment, and time are used in the investigation of diseases and epidemics.

Pathogenicity

ability to cause disease

Virulence

potency of organism which influence course of the disease

Dose

the number of causative agents

Infectivity

ability to enter the body and move to tissues

Antigenicity

ability to stimulate antibody response

Infection

When a pathogen enters its host and multiplies inside of it, we term that process ___________

Disease state

When tissues /organs are damaged as a result of infection and the body failed to function normally

then the client enters a ________________

The Infection Cycle/ Chain of Infection

• A chain consisting of six links.

• To produce disease, each link of the infectious process must be present in a logical sequence.

• Removing one link in the chain will control the cycle of infection.

Rickettsia

• Are a genus of bacteria usually found in the cells of lice, ticks, fleas, and mites.

• They are smaller than most bacteria and share some characteristics of viruses.

Prions

are infectious agents that do not have any genes. They seem to consist of a protein with an aberrant structure, which somehow replicates in animal or human tissue. Can cause severe damage to the brain.

Reservoir

- The place where the infectious agent is normally present before infecting a new human

- It is the place where infectious agent derived its

nourishment and multiplies.

- Without it, infectious agents could not survive and hence could not be transmitted to other people.

- Can be human, animals, and environment

Frank or Typical

patients who are obviously ill and manifest signs and symptoms of the disease.

Subclinical

has mild or inapparent signs and symptoms.

Classification of Human Reservoir: Carriers

Infected individuals that do not manifest signs and symptoms.

Contact

in close association with a case (an individual who has a particular disease).

Suspect

person who displays signs and symptoms of the disease

Zoonoses

Diseases such as rabies, where the

infectious agents can be transmitted from animal hosts to susceptible humans

Vehicles

Non-living things like water, food and soil can also be reservoirs for infectious agents, but they are called ___________ because they are non-living things.

Mode of transmission

the means by which an organism transfers from one carrier to another by either direct transmission or indirect transmission.

Direct transmission

refers to the transfer of an infectious agent from an infected host to a new host, without the need for intermediates such as air, food, water or other animals.

Direct contact

transmission requires physical contact with an infected person through kissing, sexual contact, oral secretions, blood or contact with body lesions

Perinatal

Similar to contact infection; however, the contact may occur in utero during pregnancy or at the time of delivery

Indirect transmission

when infectious agents are transmitted to new hosts through intermediates such as air, food, water, objects, or substances in the environment, or other animals.

Indirect transmission

when infectious agents are transmitted to new hosts through intermediates such as air, food, water, objects or substances in the environment, or other animals.

Airborne transmission

The infectious agent may be transmitted in dried secretions from the respiratory tract, which can remain suspended in the air for some time.

Vehicle-borne transmission

any non-living substance or object that can be contaminated by an infectious agent, which then transmits it to a new host.

Vector-borne transmission

an organism, usually an arthropod, which transmits an infectious agent to a new host. Arthropods

which act as vectors include houseflies,

mosquitoes, lice and ticks.

Contamination

refers to the presence of an infectious agent in or on the vehicle.

Indirect contact

a person is infected from contact with a contaminated surface. Some organisms are capable of surviving on surfaces for an extended period of time through touching contaminated surfaces then putting contaminated skin in mouth, eyes, nose, etc.

Portal of Entry

Successful transmission of the infectious agent

requires it to enter the host through a specific part

of the body before it can cause disease.

Routes of Entry: Penetration

into the bloodstream,

exemplified by Hepatitis B Virus and HIV

Routes of Entry: Inhalation

of airborne organisms, illustrated by Mycobacteria

Routes of Entry: Ingestion

of organisms, demonstrated by salmonella

Susceptible Host

Individuals who are likely to develop a communicable disease after exposure to the infectious agents

Risk factors

Factors that increase the susceptibility of a host to the development of a communicable

disease

Immunity

Refers to the resistance of an individual to communicable diseases, because their white blood cells and antibodies (defensive proteins) are able to fight the infectious agents successfully.

Defense Mechanism Against Infection: First line of Defense

- External and Physical Barriers

- Chemical substances

- Normal Flora

Defense Mechanism Against Infection: Second line of Defense

include the inflammatory processes provided by the white blood cells

Defense Mechanism Against Infection: Third line of Defense

- Immune response:

a. Cell mediated

b. Antibody mediated

Natural History of Communicable Disease

refers to the sequence of events that happen one after another, over a period of time, in a person who is not receiving treatment.

Stage of Exposure

Stage wherein the susceptible host has come into close contact with the infectious agent, but it has not yet entered the host's body cells.

Natural History of Communicable Disease: Stage of Infection

the infectious agent has entered the host's body and has begun multiplying

Stage of Infectious Disease

Stage wherein the clinical manifestations of the disease are present in the infected host.

Natural History of Communicable Disease: Stage of Outcome

at this stage the disease may

result in recovery, disability or death of the patient.

Incubation period

The time interval between the

onset (start) of infection and the first appearance

of clinical manifestations of a disease

Active cases

Infected hosts who have clinical manifestations of the disease

Carriers

Individuals who are infected, but who do not have clinical manifestations

Prevention

it refers to measures that are applied to prevent the occurrence of a disease

Level of Prevention: Primary Prevention

• Increasing the resistance of the host

• Inactivating the agent

• Interrupt the chain of infection

• Restricting spread of infection

  • isolation

  • quarantine

  • segregation

  • personal surveillance

Level of Prevention: Secondary Prevention

- Activities targeted at detecting disease at earliest

possible time to:

§ begin treatment

§ stop progression

§ protect others in the community

Level of Prevention: Tertiary Prevention

• Limits the progression of disability

• Treatment of symptoms and rehabilitation vary with each specific disease

Control of Communicable Disease

1. Notification - early reporting of a case

2. Epidemiological investigation

3. Case finding, early diagnosis and treatment

4. Isolation

Isolation

the process of separating patients from others to

prevent transmission to healthy people, the period

of isolation is based on the longest period of

communicability.

Strict Isolation

Used to prevent the transmission of all highly communicable disease that are spread by both contact and airborne routes of transmission. Eg. Chickenpox, Rabies.

Modes of Isolation: Respiratory Isolation

Used to prevent transmission of organisms by means of droplets that are sneezed or breathed into the environment. Eg. Influenza and tuberculosis.

Modes of Isolation: Protective Isolation

Used to prevent contact between potentially pathogenic micro-morganisms and uninfected persons who have seriously impaired resistance. Eg. Leukemia, who are on certain therapeutic regimens.

Wound and Skin Isolation

• Used to prevent the spread of microorganisms found in infected wounds (including burns and open sores) and heavily contaminated articles.

• Diseases that required precautions include e.g., Herpes, Impetigo, and ringworm

Modes of Isolation: Blood Isolation

Used to prevent acquisition of infection

by patients and personnel from contact

with blood or items contaminated with

blood. E.g. Hepatitis B virus, H.I.V./A.I.D.S

Discharge Isolation

a. Secretion Precautions Lesions

b. Secretion Precautions Oral

c. Excretion Precautions

Standard Precaution

• A primary strategy for reducing the risk of and controlling nosocomial infections.

• - Applies to blood, all body fluids, secretions and excretions except sweat, skin that is not intact, and mucous membrane.

Transmission-Based Precautions

applies to those who are known to be or suspected of being infected with highly transmissible infection

a. Airborne Precautions

b. Droplet Precautions

c. Contact Precautions

d. Enteric Precautions

Quarantine

limitation in the freedom of movement exposed individual, animal, or contact with a case of communicable disease based on the longest incubation period of the disease.

Sterilization

destruction of pathogenic organisms including spores

Ø Example: Autoclaving

Control of Communicable Disease: Disinfestation

• is the procedure of destroying or removing small animal pests, particularly arthropods and rodents, present upon the person, the clothing, or in the environment of an individual, or on domestic animals.

• Achieved by using chemical or physical agents, e.g., spraying insecticides to destroy mosquitoes, and removing lice from the body and clothing.

Medical Asepsis

• Concurrent disinfection

• Destruction of organisms after they leave the body

• Washing hands

• Use of disposable equipment

• Wearing gloves helps

Control of Communicable Disease: Barrier cards/ Placarding

placing signage in patient's unit

Terminal disinfection

done after the patient left the room

Concurrent disinfection

done at the bedside of the patient

Measles / 7 Day Measles /Morbili / Red Measles / English Measles

• An acute, contagious, exanthematous disease that usually affects children who are susceptible to upper respiratory tract infection (URTI).

• One of the most common and most serious of all childhood diseases.

Measles / 7 Day Measles /Morbili / Red Measles / English Measles

Etiologic Agent:

• Measles virus (Rubeola virus) which belongs to the genus Morbili virus

Measles / 7 Day Measles /Morbili / Red Measles / English Measles

Treatment:

- Anti-viral drugs (isoprinosine)

- Antibiotics if with complications

Rubella/ German Measles / 3 Day Measles

An acute contagious disease characterized by mild constitutional symptoms and a rose-colored macular eruption. It has a teratogenic effect on the fetus.

Rubella/ German Measles / 3 Day Measles

Causative Agent: Rubella virus

Rubella/ German Measles / 3 Day Measles

A mild febrile (fever-causing) infectious disease resembling both scarlet fever and measles but differing from these in its short course; characterized by a rash of both macules and papules that fades and disappears in three days.

Rubella/ German Measles / 3 Day Measles

Causative agent:

Rubella virus

Rubella/ German Measles / 3 Day Measles

Pathognomonic sign:

- Forscheimer's spot (pinkish rash on the soft palate)

- Petechiae (red spots on the soft palate)

Rubella/ German Measles / 3 Day Measles

Treatment:

• Treatment is supportive - there is no specific antiviral agent that can be used.

  • Simple analgesics and anti-inflammatory agents (NSAIDs) may be used.

• Prophylaxis with immunoglobulin (antibodies) may be considered in pregnant women who are exposed and termination is unacceptable.

Chicken Pox (Varicella)

- also known as Varicella

- An acute and highly contagious disease of viral etiology that is characterized by vesicular eruptions on the skin and mucous membrane with mild constitutional symptoms.

Chicken Pox (Varicella)

Infectious agent:

Herpes virus varicella/ Varicella zoster virus

Chicken Pox (Varicella)

Pathognomonic sign:

A rash that turns into itchy, fluid-filled blisters that eventually turn into scabs.