ANTH-2450 Lecture Summary Notes

Epidemiology

The study of the distribution, dynamics, and determinants of disease.

Distribution of Disease

Demographic and geographic distribution of diseases.

Dynamic of Disease

Mode of transmission of diseases within a population.

Infection

The first step when a microbe enters the body and begins to multiply. The state when a microorganism becomes established in the host and clinically detected.

Disease

The state when cells in the body become damaged as a result of infection and signs and symptoms appear.

Infectivity

The ability of a pathogen to infect a host.

Contagious disease

Any disease that is transmitted from person to person.

Basic Reproduction Number

A mathematical term indicating how contagious an infectious disease is.

Incubation period

The time between exposure to a pathogen and the appearance of the first symptoms.

The incubation period is dependent on:

The specific pathogen and the body’s response systems.

Carrier

A person infected with a microorganism but shows no symptoms and can pass the disease onto others.

Pathogen

Any microorganism that can cause disease.

Bacteria

Single-celled organisms that can cause various diseases and can be classified by shape.

What is an example of a cocci (round) bacteria?

• Streptococcus (A or B)

• Staphylococcus

What is an example of a bacillus (capsule) bacteria?

E. coli.

Viruses

Infectious agents that require a host to reproduce and can cause a variety of diseases.

Structural components of viruses:

• The core contains nucleic acid

• The capsid or protein coat protects the nucleic acid

• The membrane envelope covers the protein coat

Bacteriophage

A virus that infects and replicates within bacteria.

What are the general steps in the reproduction of virus particles?

• Virus attaches to host cell

• Virus penetrates host cell membrane and injects nucleic acid into cell

• Viral nucleic acid replicates using host cell machinery

• New viral nucleic acids are packaged into viral particles and released from the cell

Prion

An infectious agent made of protein that can cause infections leading to neurodegenerative diseases.

Kuru

A disease caused by prions and spread via funerary cannibalism in Papua New Guinea.

Protozoa

Single-celled organisms that can cause diseases like malaria.

What is an example of a protozoa?

Malaria.

Fungi

Organisms that can cause plant and animal diseases, including infections in humans.

A modern day drug derived from fungi.

Penicillin.

How can fungi reproduce and what infections can they cause?

They reproduce through tiny spores in the air, leading to infections on the skin and inhaled into the lungs.

Parasites

Organisms that live within or on a host and use the host's resources to fuel their life cycles.

Symbiotic Relationship

A relationship between two species where both benefit.

Commensal Relationship

A relationship between two species where one benefits and the other remains unaffected.

Parasitic Relationship

A relationship between species where one benefits and the other is being harmed.

Pathogenicity

The ability of a microorganism to cause disease.

Virulence

The degree of pathogenicity of a microorganism.

The degree to which a pathogen causes serious illness or death is dependent on:

• The immune system of the host

• The number of pathogenic microorganisms encountered

• The nature of the pathogen

Direct contact

Transmission of diseases through physical contact; mother to fetus, airborne transmission, skin contact.

Indirect contact

Transmission of diseases through vectors, food, water, or other means.

Horizontal Transmission

Transmission from one individual to another.

Vertical Transmission

Transmission directly from parent to offspring before or directly after birth.

Susceptibility

An individual's risk for infection.

Resistance

The infected individual's capacity to prevent infection from leading to disease and death.

Immunity

Resistance to disease, either innate or acquired.

Innate Immunity

Genetic factors, the first line of defence.

Acquired Immunity

The specific immune response where the microbe gets past the innate immune system.

Herd Immunity

A type of immunity where a significant proportion of a community is immune to a contagious disease, whether through immunization or prior exposure.

The immune system

The body's natural defense system against pathogens.

Paleopathology

The study of past diseases in human remains.

Ethnography

An anthropological study through personal accounts and scientific descriptions of customs.

Sources of information on health and disease:

• Ethnography

• Paleopathology

• Ancient text

• Art

Characteristics of Hunter-gatherer societies:

• A variety of foods (seasonal foods)

• Smaller groups

• Contact between groups is limited

• Lower population density

• Nomadic, highly mobile people

• No class distinctions

Diseases that Plagued Early Hunter-Gatherers:

• Insect bites (Malaria)

• Diseases from other animals (Rabies)

• Chronic infections (acute food poisoning)

• Physical trauma

• Congenital diseases (joint disease)

• Seasonal famines

• External parasites (lice)

Zoonotic Diseases

Diseases that can be transmitted from animals to humans.

Social Stratification

The division of society into different social classes.

Agricultural Practices

The methods and techniques used in farming and agriculture.

Epidemiological Transitions

Shifts in the patterns of diseases and health conditions in populations over time. Agriculture, medical treatments, and re-emergence of infectious diseases.

Noncommunicable Diseases (NCD)

Diseases that are not caused by infectious agents and cannot be transmitted from person to person.

Chronic disease

A disease that cannot be passed from person to person and lasts for a long period of time.

Yersinia Pestis

The bacteria that causes the plague.

Alexandre Yersin

The scientist who discovered the Plague in Hong Kong, 1884.

Bubonic Plague

The most common form of the plague, characterized by swollen lymph nodes and spread through flea bites.

Pneumonic Plague

A more virulent form of the plague that affects the lungs and is spread through inhaling air particles or contact with infected individuals.

Septicaemic Plague

A form of the plague that enters the bloodstream and causes severe symptoms, including internal bleeding and a high fatality rate.

What non-human carriers spread the Plague?

Rats, human fleas, and lice.

Xenopsylla cheopis

The oriental rat flea, responsible for spreading the plague by biting humans and regurgitating infected rat blood into open wounds.

Antibiotics for the Plague

Medications used to treat bacterial infections, including streptomycin, doxycycline, gentamicin, and ciprofloxacin.

Symptoms of the Bubonic Plague:

• Sudden high fever

• Headache

• Body aches and chills

• Swollen, painful lymph nodes causing “bubos” lumps

Incubation period of the Bubonic Plague

2-7 days.

Origin of the Plague

The Bronze Age in Russia.

Plague of Justinian

A plague pandemic that occurred from AD 541-44 and continued intermittently until 750, possibly originating from China and North East India.

The Black Death

The most well-known and devastating plague pandemic that occurred from 1346-1361, spreading across Europe and causing the death of millions of people.

The Great Plague of London

A plague outbreak that occurred in 1665 in London, causing a high number of deaths and leading to significant social and economic transformations.

The fortress of Kaffa

The first possible case of biological warfare between the Italian Christians and the Muslim Mongols.

The origin of quarantines

The Italian word for 40, the number of days Italian ships were isolated upon arrival to new ports.

Third Plague Pandemic/China-California

A plague pandemic that occurred from 1894-1924, originating in China and spreading to other parts of the world, including India and Australia.

Theory of Contagion

Spread of disease between person to person and object to person.

Theory of Miasma

Spread of disease via “bad air”.

Mortality of the Plague

Killed ~30 million people in Europe, 1/3 of the population at the time.

The Flagellants

Travelled through Europe with crosses to appease God and repel the Plague, blamed the Jewish for the Plague.

What event ended the Great Plague of London?

The Great Fire of London.

Influenza Virus

The virus that causes the flu, a contagious respiratory illness characterized by symptoms such as fever, cough, and body aches.

Plague Doctors

Hired to determine if an individual was infected with the Plague, wore a cloak, mask, and carried a poking stick.

Plague Doctor Treatments

• Water and vinegar

• Lancing bubos

• Crushed emeralds

• Bleeding

• “sweating out the disease beside a fire

Pest Houses

Used during the Plague epidemic to contain the disease, the starting of public health efforts to contain and treat disease.

When was the Great Fire of London?

September 1666.

Influenza

A viral infection that enters through the nose and settles in the respiratory tract.

Flu Symptoms

• Headache

• Fever,

• Body aches and chills

• Extreme tiredness,

• Joint aches

• Runny/stuffy nose

• Sore throat

• Coughing

• Vomiting.

What symptom mainly differentiates the Flu from the common Cold?

Vomiting.

Incubation period of the Flu

1-4 days, average of 2.

Influenza Virus Structure

Lipid envelope with hemagglutinin and neuraminidase proteins.

Type A Influenza

Most virulent type found in birds, pigs, and humans. The source of all major pandemics.

Type B Influenza

Found almost exclusively in humans and causes mild symptoms.

Type C Influenza

Found in pigs and humans and causes mild symptoms.

Function of Hemagglutinin

Allows the Flu virus to bind the host cell.

Function of Neuraminidase

Allows the Flu virus to be released from the host cell.

Antigenic drift

Small mutations in hemagglutinin and neuraminidase proteins that produce similar viruses.

Viral Recombination

New strain created when different viral sources mix within a host.

Influenza A subtypes

H1N1, H2N2, H3N2, H5N1.

Neuraminidase inhibition

Antiviral flu drugs like Oseltamivir and Zanamivir that prevent virus release from host cells.

Explain the nomenclature of Influenza viruses

• Antigenic type first (A, B, C)

• Host of origin (Swine, Chicken, Human = no designation)

• Geographical origin (California, Hong Kong)

• Subtype (H1N1, H3N2)

How are vaccines manufactured?

3 strains are selected, inoculated individually in fertilized chicken eggs, and combined to make a vaccine.

Seasonal Influenza Vaccine

Global surveillance system determines strains for the yearly vaccine.

Flu Vaccine Types

Shot (inactivated virus) and nasal spray (live attenuated virus).