lesson 10 Flashcards
Infectious diseases
Infectious diseases = caused by pathogenic
microorganisms such as bacteria, viruses,
parasites, fungi
- Spread between people, via environment
Immune system
Immune system = cells, tissues, and molecules
that mediate resistance to infections
immunity
Immunity = resistance of a host to pathogens
and their toxic effects
immune response
Immune response = collective and coordinated
response to the introduction of foreign
substances in an individual mediated by the
cells and molecules of the immune system
Homeostasis
Homeostasis – destruction of abnormal or
dead cells
(e.g. dead red or white blood
cells, antigen-antibody complex)
Innate immunity (non-adaptive)
Innate immunity (non-adaptive): Rapid, nonspecific, no memory.
first line of defense
Skin, enzymes, complement proteins, phagocytes.
based on genetic makeup
Adaptive immunity (acquired)
Adaptive immunity (acquired): Slower, specific, develops memory.
secnd line of defence
T-cells (cell-mediated) and B-cells (antibody production).
immune system physilogical systems
- Organs
* Tonsils and adenoids, Thymus
* Spleen
* Appendix
* Bone marrow
* Lymphatic system - nodes, vessels
* Peyer’s patches (lymph nodules in intestines) - Cells
* Lymphocytes
* T-lymphocytes * B-Lymphocytes, plasma cells * natural killer lymphocytes* Monocytes, Macrophage* - Molecules
* Antibodies
* Complement
* Cytokines
* Interleukines
* Interferons
natural adaptive immunity
occurs when a person is
infected by a pathogen, body
develops immune memory for the
virus, conferring immunity against the
disease so if they encounter it again,
they are able to fight it off swiftly
cultura adaptive immunity
(vaccine-Induced) - artificial
active immunity, body builds
resistance to a disease following an
immunization. Vaccine designed to
mimic/ilicit ‘natural’ response without
infection
Types of Immunity
- Active Immunity: Created by the host.; Natural (infection) or cultural (vaccination).
- Passive Immunity: Antibodies received externally; Natural (maternal antibodies) or cultural (immune serum injections).
naturral passive immunity
– the direct transfer of
antibodies through breast milk, placenta, can
be influenced by culture, diet, ecology
cultural passive immunity
through direct injection of immune serum or cells
evoution of immune systems and pathogens
- Immunity is shaped by:
Deep evolutionary time (species-level adaptation).
Early-life exposures (immune programming).
Recent environmental changes (e.g., diet, hygiene).
- Pathogens evolve rapidly through mutation and selection:
Can become more transmissible or virulent.
Evolve resistance to treatments (e.g., antibiotics, vaccines).
heritablee replicators
favurable variation increases copy numbers
co-evolution and arms races
Host-pathogen relationships reflect antagonistic co-evolution.
Hosts evolve defense mechanisms.
Pathogens evolve to evade or overcome them.
Examples:
HIV: High mutation rate and diversity.
CCR5Δ32 allele: Confers HIV resistance; evolved from past pathogen pressures.
human dispersal and disease
More Infectious disease and parasites
in Tropics
* Phylogenetic analyses of viruses track
human dispersals
* Tuberculosis moved with humans out
of Africa – originated with cattle, now
spreads in places of crowding, poor air
quality
cultuer and infectioous disease
Cultural changes (domestication, urbanization, globalization) shape disease environments.
Agriculture:
Created conditions for zoonotic and crowd diseases (e.g., TB, leprosy, malaria).
Globalization:
Accelerated disease spread (e.g., plague, influenza).
Introduced diseases to naïve populations (e.g., syphilis, smallpox).
Evolutionary mismatch: Cultural innovations outpace biological adaptation (e.g., antibiotic resistance).
sickle cell disease
a red blood cell disorder that affect hemoglobin,
the protein that carries oxygen through the body
* normally, red blood cells are disc shaped and
flexible to move easily through the blood vessels. * Among those with sickle cell disease, red blood
cells are crescent or “sickle” shaped. * Sickle cells do not bend and move easily and can
block blood flow to the rest of your body, causing
anemia
Heterozygous advantage – when having one
of each copy of a genetic variant confers
advantages over being homozygous
sickle cell carriers are more resistant to malaria
as the P. falciparum- blood produces carbon
monoxide – harder for malaria to take hold
Higher frequencies are - found in regions of
endemic malaria
leprosy
Infecious disease of the skin and nervous system,
caused by Mycobacterium leprae
- genetic convergence of M. leprae strains, 3600 BP- demonstrates that it was spread by human migration
genetic analysis suggests African origin with dispersal to
Near East, Europe by trade routes, China by Silk Road
* Widespread in Europe 12th to 14th Centuries
* Strains brought to Americas by Europeans, and from Philippines
syphilis
disease first identified in Europe (1495)
* Strains appeared in Africa and Southeast Asia as non venereal
infection
* Spread to Middle East Later spread to the Americas as YawsColumbian Exchange Theory
- first brought to Europe by Columbus?
- Epidemic three years after first voyage
- BUT – Epidemics occur in both
Americas and Europe around this time
- Exchange of strains?
SARS-CoV-2 and Modern Pathogen Evolution
SARS-CoV-2 originated from coronaviruses in bats and pangolins.
Cultural and ecological factors (wildlife markets, habitat destruction) enabled zoonotic spillover.
Virus mutates rapidly; widespread infection allows for the emergence of new variants.
Emphasizes the role of human behavior and global systems in disease dynamics.
immunity theft
suggests that coincident resulting health outcomes are
related to:
* Immune Exhaustion – temporary immunodeficiency that happens after
you get an infection
* Long term damage to cellular / organ function
immunity debt
is the notion that current illnesses are due to ‘coddling’ our
immune systems through mask use and lockdowns
* Builds on pop-culture ideas of the ‘hygiene hypothesis’
* Advocates for a ‘let it rip’ model of public health policy (remember UK)
* Spreads disinformation about dangers
* Used by anti-science, anti-intervention, and anti-government advocates
