Portals of Entry Flashcards
What is virulence?
The characteristics of a micro-organism which favour its survival in or on the host and its ability to cause disease.
What are the sources of infection?
A micro-organism must come from somewhere and enter the human body somehow in order to cause an infection.
Infections can be describe as being either endogenous (from within one’s own body or self-infection)
Or as exogenous (from another person, animal or soil)/ cross- infection.
what are the chronological chain of events for infectious disease
Causative agent
Reservoir
Host
Portal of entry
Mode of transmission
Portal of exit
What are the endogenous infection
The normal, healthy body will have certain micro-organisms in certain areas of the body, living in harmony with the body and often assisting with some function of the body.
These kinds of micro-organisms are called commensals and do not usually cause infection in the host except under certain conditions.
what are the exogenous sources
These types of infections are the most common and are usually from sources such as: other people, animals, soil, water and air.
The most common source of infection is other people
what are the portals of entry
Respiratory tract/ inhalation
Alimentary tract /ingestion
Parenteral/transcutaneous /inoculation
Trans-placental/transplacental
Genitourinary tract- Urinary tract infections
Describe the portal of entry through the respiratory tract and give an example
The air around us contains microorganisms, which are widely spread by coughing, sneezing and talking. By inhalation of the pathogens
Pathogens are airborne or suspended as droplets
E.g. influenza
Describe the portal of entry through the Alimentary tract and give an example
Faecal-oral route
Microorganisms that are in the food we eat enter the body eg typhoid dysentery.
By eating or drinking pathogens
Pathogens are in water and/or food
E.g. Cholera
Describe the portal of entry through the Parenteral/transcutaneous /inoculation and give an example
Pathogens can enter intact skin e.g.
Schistosoma
Pathogens can enter through broken skin e.g. trauma, injections and skin commensals
Pathogens enter blood stream through insect bites e.g. Malaria
Pathogens enter through mucosa by sexual contact e.g. Syphilis
Describe the portal of entry through the Trans-placental and give an example
from infected mother to unborn child/baby eg rubella, gonorrhea, syphilis
Describe the portal of entry through the Genitourinary tract and give an example
Urinary tract infections
How do pathogens exit the body
Body fluids: sweat, tears, saliva, blood, breast milk.
Body secretions: vaginal discharges, penile discharges, semen, mucus, pus.
Body excreta: urine, faeces, vomitus.
Body shedding: dead skin cells, hair.
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What is transmission
Transmission is the passing of a communicable disease from an infected host individual or group to a conspecific individual or group, regardless of whether the other individual was previously infected.
