Download Infection and it`s mode of transmission:

Infection and it’s mode of transmission:
SOURCE OF INFECTION
It is defined as the person, animal, object or substance from which an infectious agent passes or is
disseminated to the host
RESERVOIR:
► It is defined as “any person, animal, arthropod, plant, soil, or substance “(or
combination of these in which an infectious agent lives and multiplies, on which it
depends primarily for survival, and where it reproduces itself in such manner that it
can be transmitted to a susceptible host”
CARRIERS:
A Carrier is defined as an infected person or animal that harbours a specific infectious agent in the
absence of discernible clinical disease and serves as a potential source of infection for others
A) Incubatory
► TYPE
B) Convalescent
C) Healthy
► DURATION
A) Temporary
B) Chronic
PORTAL OF EXIT:
A) Urinary
B) Intestinal
C) Respiratory
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FEATURES OF CARRIER:
Presence of specific microbes in the body
Absence of apparent symptoms and signs
Shedding of micro-organisms in the discharges or excretions
As a source of infection to others
INCUPATION PERIOD:
► The time interval between invasion by an infectious agent and appearance of the first
sign or symptom of the disease in question
FACTORS TO DETERMINE THE INCUBATION PERIOD:
► Infective dose
► Portal of entry
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► Individual susceptibility
COMMUNICABLE PERIOD:
It is defined as the time during which an infectious agent may be transferred directly or
indirectly from an infected person to another person, from an infected animal to man , or
from an infected person to an animal, including arthropods
HERD IMMUNITY:
It is the level of resistance of a community or group of people to a particular disease
BEHAVIOUR OF DISEASE IN THE COMMUNITY:
1. Exotic
2. Sporadic
3. Endemic
4. Epidemic
5. Pandemic
6. Outbreak
EPIDEMIC:
► It is the unusual occurrence in a community or region of cases of an illness, specific
health-related behavior, or other health related events clearly in excess of normal
expectancy (LAST,1995)
OUT BREAK:
► Two or more related cases in infections, suggesting the possibility of a common source
or transmission between cases
EPIDEMIOLOGY OF DISEASE:
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Place
Time
Distribution
Agent determinants
Host determinants
Environmental determinants
Incupation period
Mode of transmission
Portal of entry
Natural history of disease
Secondary attack rate
6 Links to the Chain of Infection:
► Portal of Entry
► Susceptible Host
► Causative Agent
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Reservoir
Portal of Exit
Mode of Transmission
1. Causative Agent:
► Bacteria (includes Richettsia, Chlamydia, and Mycoplasm
► Viruses
► Fungi
► Protozoa
► Helminths
2 Reservoir:
► Humans:
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 Patients
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 Healthcare Workers
► Animals
► Insects
► Rodents
► Shell Fish
► Environment
►  Patient Care Equipment
►  Environmental Surfaces
►  Food
3 Portal of Exit:
The path by which the infectious organism (agent) leaves the reservoir
4 Modes of Transmission:
► Contact (Direct and Indirect)
► Airborne
► Vector-Borne
► Common Vehicle
CONTACT:
► DIRECT: immediate transmission
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Person-to-person
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Actual physical contact between source and patient
► INDIRECT CONTACT:
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Patient to contaminated indirect object (contaminated endoscope)
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Droplets spread (large particles that rapidly settle out on horizontal surfaces –
usually within 3 feet of source)
► AIRBORNE
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Organisms contained within droplet nuclei or dust particles (i.e. droplet
nuclei of tuberculosis
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Suspended in air for extended periods, may be spread through ventilation
systems
► VECTOR-BORN:
► External vector-born transmission; mechanical transfer of microbes on
external
appendages (feet of flies)
► Harbored by Vector
► Harbored by vector, but no biological interaction between vector and agent (i.e. yellow
fever virus
PORTAL OF ENTRY:
The path by which an infectious agent enters the susceptible host
Recommendations isolation precautions:
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Birth of Infectious Disease Hospitals
Patients with infectious disease
process placed in separate facilities
Aseptic techniques used to combat
transmission of diseases
► Barrier Nursing:
►  Hospital personnel wear gowns between patients
► Handwashing between patients with antiseptic solutions after patient contact
►  Disinfection of objects contaminated by patents
7 Categories of Isolation:
► Strict Isolation
► Respiratory Isolation
► Protective Isolation
► Enteric Isolation
► Wound and Skin Precautions
► Discharge Precautions
► Blood Precautions
► Disease were lumped into categories based on epidemiological features of the disease
(resulted in under or over isolation)
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Respiratory
Bone and Joint Infection
Central Nervous System
Gastrointestinal System
Skin and Soft Tissue
Surgical Sites
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Blood Stream
Urinary System (UTI)
Cardiovascular
Eye/Ear/Throat Mouth Infection
Reproductive System
3 Major Modes of Transmission in the Healthcare Setting:
► Skin Contact
► Puncture Wounds
► Mucous Membranes (eye/mouth/nose)
Bloodborne Pathogens:
► Hepatitis B Virus
► Hepatitis C Virus
► Human Immunodeficiency Virus
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