BIOL 100 Chapter Notes - Chapter 42: Immunodeficiency, Protozoa, Genital Wart
Textbook Notes
Chapter 42
Infectious Disease
Concept 1: Pathogens
Pathogens
Not all microorganisms are pathogens; only a small fraction cause disease
Only single property that links them is their small size
Bacteria are prokaryotes and their cells lack internal membrane-bound structures
Viruses are acellular, it is only nucleic acid wrap din a coat
Multicellular parasites are multicellular organisms that benefits from a host and typically, the parasite is smaller
than the host
Infectious pathogens - usually qualified as contagious agents because they can be transmitted from one person or
species to another
Once the agent comes in contact with a host, the pathogen can enter and multiply using the host’s
resources, or it can die if the host has a good vigilant immune system
Infectious disease results from the interaction between those few pathogens and the immune system of
the hosts they infect
Infectious microorganisms can be classified as either primary pathogens or as opportunistic pathogens
according to the status of host defenses
Primary pathogens - cause disease as a result of their presence or activity within a healthy host because
of the severity of the disease they cause
Opportunistic pathogens - organisms that cause an infectious disease in an immunocompromised
Typically caused by microbes that are in contact with the host
Transmission
Transmission of an infectious agent can occur through various mediums such as liquids, food, body fluids,
contaminated objects, and airborne inhalation
Mechanical vector - picks up an infectious agent on the outside of its body and transmits it in a passive manner
Biological vector - harbors pathogens within its body and delivers them to new hosts in an active manner
Infection takes place when the mosquito bites the human host, injecting sporozoites
Sporozoites infect liver cells, where they proliferate and become merozoites, which in turn infect red
blood cells
In the red blood cells, the merozoites proliferate, bursting the cell and allowing infection of new cells
It is during this phase that the victims experiences the fever and chills that are associated with
malaria
Gametocytes are produced from the merozoites, and can be transmitted to mosquitoes that bite the
human host
Over the course of 10-14 days, the gametocytes in the mosquito will produce sporozoites, which
can cause a new infection once they localize to the mosquito’s salivary glands
An effective strategy used to control vector transmitted infectious diseases is to kill the vector since the vector is
required in the life cycle of the pathogen
Document Summary
Not all microorganisms are pathogens; only a small fraction cause disease. Only single property that links them is their small size. Bacteria are prokaryotes and their cells lack internal membrane-bound structures. Viruses are acellular, it is only nucleic acid wrap din a coat. Multicellular parasites are multicellular organisms that benefits from a host and typically, the parasite is smaller than the host. Infectious pathogens - usually qualified as contagious agents because they can be transmitted from one person or species to another. Once the agent comes in contact with a host, the pathogen can enter and multiply using the host"s resources, or it can die if the host has a good vigilant immune system. Infectious disease results from the interaction between those few pathogens and the immune system of the hosts they infect. Infectious microorganisms can be classified as either primary pathogens or as opportunistic pathogens according to the status of host defenses.
