Mode Of Transmission Flashcards
Transmission of infection involves a triad of
Infectious agents
Environment
Susceptible host
Infectious agent generally referred to as
Microbes
Infectious agent
Traditional infectious agents are:
Bacteria,
Fungi,
Parasites
Viruses
Other agents like some insects may be considered as parasitic (ectoparasites) and infectious protein like Prions
______contain the largest number of species that are pathogenic for humans.
Bacteria
List the characteristics of bacteria
They are single-celled and contain both DNA and RNA genome.
Their DNA, is not contained within a nucleus
they are prokaryotic and reproduce by binary fission.
Fungi:
List their characteristics
single and multicellular organisms
contain a defined nucleus and cytoplasm
they are eukaryotic microorganisms
They can exist as either Yeasts or Moulds (Molds) or dimorphic
Characteristics of yeast & molds?
Yeasts are single-celled fungi most of which reproduce by budding
Molds or moulds are more complex multicellular organisms that reproduce by both sexual and asexual means
List the characteristics of Parasites
They are a large and very complex group of microbes.
single-celled animals such as the protozoa and very complex, multi-celled organisms e.g helminths
Macroscopic or microscopic
Characteristics of Viruses
comprise a large number of infectious agents
that lack organelles to sustain their propagation.
They must infect another life including humans, animals, plants, bacteria, and even other viruses.
Viruses contain either DNA or RNA, but not both.
READ WELL
Let’s simplify and explain the different ways infectious agents can enter the body, along with examples:
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Aerosol (Breathing in tiny particles from the air)
- Portal of Entry: Respiratory system (lungs, airways)
- Example: Influenza virus (flu)
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Direct Contact (Touching infected skin or surfaces)
- Portal of Entry: Cutaneous (skin)
- Example: Herpes simplex (cold sores or genital herpes)
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Sexual Intercourse
- Portal of Entry: Genital
- Example: Syphilis, Gonorrhea
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Oral or Nasopharyngeal to Eye (Transferring germs from mouth or nose to eyes)
- Portal of Entry: Ocular (eyes)
- Example: Bacterial or viral conjunctivitis (eye infection)
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Transfusion of Blood Products
- Portal of Entry: Intravascular (into the bloodstream)
- Example: Hepatitis (liver infection)
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Cooling Tower Drift (Tiny water droplets in the air)
- Portal of Entry: Respiratory system
- Example: Legionnaires’ disease (lung infection)
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Food or Water
- Portal of Entry: Gastrointestinal tract (stomach and intestines)
- Example: Enteric pathogens (bacteria or viruses causing stomach/intestinal infection)
-
Bite
- Portal of Entry: Cutaneous (skin)
- Example: Rabies (virus affecting the nervous system)
-
Tick Bite
- Portal of Entry: Cutaneous (skin)
- Example: Lyme disease (bacterial infection)
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Aspiration of Endogenous Flora (Breathing in bacteria from one’s own mouth or throat)
- Portal of Entry: Respiratory system
- Example: Bacterial pneumonia (lung infection)
-
Perforated Viscus (A hole in the stomach or intestines)
- Portal of Entry: Gastrointestinal tract
- Example: Bacterial peritonitis (infection of the lining of the abdominal cavity)
-
Oropharynx to Middle Ear (Germs from mouth/throat to ear)
- Portal of Entry: Ear
- Example: Bacterial otitis media (middle ear infection)
- Infected humans can transmit diseases through various routes like breathing, touching, sexual contact, and blood transfusions.
- Contaminated environments can spread infections through air, food, and water.
- Animals and ticks can transmit diseases through bites.
- Patients can self-infect by spreading bacteria from one part of their body to another.
Understanding these routes helps in taking preventive measures to avoid infections.
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Host Responses to Infection
- Once an individual (host) is infected, the body elicits various responses to fight off the infection.
- These responses can be:
- Localized (at the site of infection): The body’s response is concentrated where the infection is located.
- Generalized (systemic): The response affects the entire body.
-
Local Reaction: Inflammation
- Inflammation: The body’s local reaction to infection.
- Inflammation can be caused by both immunologic components (like white blood cells attacking the invader) and nonimmunologic components (like swelling and increased blood flow to the area).
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Types of Defense Mechanisms
- The body’s defenses against infection can be:
- Cellular: Involves cells like white blood cells (e.g., neutrophils, macrophages) that directly attack and destroy the pathogens.
- Noncellular (humoral): Involves molecules in body fluids (like antibodies and complement proteins) that help neutralize or eliminate pathogens.
- The body’s defenses against infection can be:
What are the Categories of Infectious Diseases
Here’s an explanation of each term related to infectious diseases:
-
Communicable Disease
- Definition: An illness that can be transmitted from an external source (animate or inanimate) to a person.
- Example: Tuberculosis, influenza, COVID-19.
-
Contagious Disease
- Definition: An illness that can be transmitted from person to person.
- Example: Measles, chickenpox, COVID-19.
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Iatrogenic Infection
- Definition: An infection that is produced by medical interventions or procedures.
- Example: Surgical site infections, infections from catheters or ventilators.
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Infectious Disease
- Definition: An illness caused by a replicating or multiplying external agent (such as bacteria, viruses, fungi, or parasites).
- Example: Malaria, HIV/AIDS, bacterial pneumonia.
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Nosocomial Infection (Healthcare-Associated Infection - HCAI)
- Definition: An infection that is acquired in a healthcare facility, not present or incubating at the time of admission.
- Example: Urinary tract infections from catheters, surgical site infections.
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Opportunistic Infection
- Definition: An infection that occurs in a patient with compromised defenses (e.g., immunosuppression) by an agent of low virulence that would not normally cause infection in a person with a competent immune system.
- Example: Pneumocystis pneumonia (in HIV/AIDS patients), fungal infections in immunocompromised individuals.
-
Subclinical Infection
- Definition: An infection that triggers an immune response in the body but produces minimal-to-no clinical symptoms.
- Example: Asymptomatic carriers of pathogens, such as certain viral infections.
These terms help classify different aspects of infectious diseases based on how they are transmitted, where they originate, their impact on the host, and the nature of their symptoms.
How do you Control microbial agents
1, Preventing Transmission
2, Controlling Microbial Reservoirs
- control of pests and insect vector populations
3, inimizing Risk Before or Shortly After Exposure
- Immunization or vaccination, Cleansing and use of antiseptics
Infection prevention & control(IPC)
These are a Set of policies guideline and practices performed primarily in healthcare setting to prevent spread of pathogens
What are the Component of IPC
Standard precaution
Additional precaution
Transmission based precaution
