BIOL1008 Study Guide - Final Guide: Multi-Drug-Resistant Tuberculosis, Intellectual Disability, Night Sweats
Infectious Diseases
Divergent interests of the pathogen and the host result in a continuous conflict
Interests of pathogen:
oHigh frequency of encounter with host
oHigh survival rate after infection
Interests of host:
oAvoidance and destruction of pathogen
Selection pressures= coevolution or arms’ race
Pathogens
Parasites (e.g. toxoplasmosis)
Fungi (e.g. histoplasmosis)
Bacteria (e.g. tuberculosis)
Virus (e.g. AIDS)
Prions (e.g. spongiform encephalopathy)
Epidemiology
Science dedicated to the understanding and explaining of diseases
It is the study of all ecological aspects of a disease to explain its transmission,
distribution, prevalence and incidence in a population
Disease
Abnormal condition of the body or the mind that causes discomfort, dysfunction or
distress to the person affected
Infectious Disease
A disease caused by transmissible infectious agents
Modes of transmission of pathogens
Direct or indirect contact e.g. smallpox
Consumption e.g. Listeria
Via a vector e.g. malaria via anopheles mosquitoes
Definitions
Epidemic: rapid increase in the levels of an infection
Epizootic: animal equivalent of an endemic
Zoonosis: animal disease transmissible to humans
Endemic: infection with no wide fluctuations, in a defined space
Pandemic: epidemic widely distributed affecting many people
Prevalence: proportion of people, in a population, with a certain disease, at a given
time
Incidence: rate of new cases of infection in a population
Infectious period: time period when infected people can transmit the infection
Incubation period: from time of infection to onset of symptoms
find more resources at oneclass.com
find more resources at oneclass.com
Vectors: vehicles transmitting infections from one host to another
3 lines of defence:
oPhysical and chemical barriers (non-specific)
oE.g. skin, mucosal surfaces, tears, saliva, acid secretions, mucus
oInnate immunity (non-specific)
oQuickly acting non-specific internal response involving:
Cellular defence (e.g. phagocytic cells)
Chemical defence (e.g. cytokines)
Inflammation (to restore homeostasis and allow defensive cells and
chemicals to reach the site of infection/ injury)
Fever (kills some pathogens and speeds up our defences
oAdaptive immunity (specific)
oHighly sophisticated and specialised response against specific pathogen providing
memory (long term protection)
o2 types:
Cell-mediated immune response or cellular immune response
Antibody mediated immune response of humoral immune response
Pathogens- enemy
Antigen: substance recognised as foreign which triggers an immune response
The immune system- defences
Lymphocytes: types of white blood cells (leukocytes) essential in innate and adaptive
immunity- B-lymphocytes and T-lymphocytes
Antibody: protein produced by activated B-lymphocytes (plasma cells) recognising
and binding to a specific antigen
Cytokines: chemical messengers of the immune system produced in response to
infection
Important cells of the immune system
Antigen presenting cells- raise the alarm after engulfing pathogens e.g.
macrophages, dendritic cells
Lymphocytes- upon activation will carry out their effector function and in parallel will
form a pool of specific memory cells
oB-lymphocytes- when activated they call plasma cells which produce specific
antibodies
oT-lymphocytes
Helper T cells- sound out messengers (cytokines) to other cells of the
immune system
Cytotoxic T cells- kill infected and cancerous cells
Regulatory T cells- switch off other immune cells once threat is under
control
find more resources at oneclass.com
find more resources at oneclass.com
Parasites
Organisms that spend part of or all their life either on or in another organism at its
expense
Many different parasites: from single cell eukaryotes (protozoa) to worms,
crustaceans, insects and arachnids (metazoan)
Definitions
Host: organism on or in which parasite lives
Vector: living carrier (often an arthropod) which transports a pathogen from one
host to another
Ectoparasites: live on surface of hosts, mainly arthropods
oExtracellular parasites: live within host body fluids, tissues or organs
oIntracellular parasites: live within host cells
Mesoparasites: live inside host but in organs opening to the outside (i.e. intestine,
urinary and genital tracts)
The host
A parasite might have one host in its life cycle or two or more hosts
Definitive host: If a parasite goes through sexual reproduction, the host in which it
reaches sexual maturity (union of gametes)
Intermediate hosts: other hosts in the parasite life cycle where more development
occurs (but not sexual maturity)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Divergent interests of the pathogen and the host result in a continuous conflict. Interests of pathogen: high frequency of encounter with host, high survival rate after infection. Interests of host: avoidance and destruction of pathogen. Science dedicated to the understanding and explaining of diseases. It is the study of all ecological aspects of a disease to explain its transmission, distribution, prevalence and incidence in a population. Abnormal condition of the body or the mind that causes discomfort, dysfunction or distress to the person affected. A disease caused by transmissible infectious agents. Via a vector e. g. malaria via anopheles mosquitoes. Epidemic: rapid increase in the levels of an infection. Endemic: infection with no wide fluctuations, in a defined space. Prevalence: proportion of people, in a population, with a certain disease, at a given time. Incidence: rate of new cases of infection in a population. Infectious period: time period when infected people can transmit the infection.
