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Chapter 1

Study Notes -- the Power of Plagues, Chapter 1

Health Studies
Course Code
Caroline Barakat

of 4
The Power of Plagues
Chapter 1
The Nature of Plagues:
- Legionnaires disease: respiratory infection resulting from aspiration of bacteria (called
Legionella) in aerosolized water.
TSS (Toxic Shock
- Gender-specific
- tampons which contained cross-
linked carboxylmethyl cellulose
with polyester foam, which
allowed toxin-producing S. aureus
to grow.
- nausea, chills, diarrhea, headache,
and sore throat
- high temperature & heart rate
- red rash on thighs, face, abdomen,
and arms
- brownish discharge from pelvic
SARS (severe
acute respiratory
- Chinese physician who traveled
to Hong Kong who was ill
- Disease traveled around the
world through, transmitted from
- fever, dry cough, sore throat,
Measles - caused by virus
- transmitted through air through
coughing, sneezing, and talk
- infection multiplies, reaching
lymph nodes and released viruses
that invade white blood cells all
of which are essential to
- fever, weakness, loss of appetite,
coughing, runny nose, and tearing
of the eyes
- rash later appears on ears,
forehead, face, neck, trunk, and feet
- Immunization for children, treating illness with effective drugs and antibiotics, and good
nourishment help minimize the effects of an epidemic.
- New and old diseases can erupt and spread throughout the world more quickly due to
increased and rapid movements of people and goods, as well as advances in technology (as
in the case of TSS)
Living Off Others:
- derived from the Latin word parasitus meaning food.
- Entities that are unable to survive on their own and require another living being for their
- Parasitism is the intimate association of two different kinds of organisms wherein one
benefits (the parasite) at the expense of the other (the host)
- Found in many different sizes, shapes, and body forms rods (bacilli), spheres (cocci), or
- determining the kind of parasite will allow for selective treatment
Types of Parasites:
1)Fragment of genetic material wrapped in protein, such as a virus
2)Single cellular, such as bacteria, fungi, protozoa
3) Multi-cellular, such as roundworms, flatworms, etc
- Some parasites live inside the body, whereas others live on the surface
- All parasites cause harm to their host, some deathly
- The more the offspring of the parasite, the greater probability of reaching a host, therefore
enhancing its chances for survival
- Malaria: - virus transmitted through salivary glands (containing thousands of parasites)
of a mosquito to a host
- AIDS: cause by HIV virus, invades a specific kind of white blood cell (T-helper
lymphocyte), where it replicates and spreads throughout the body
- The movement of a parasite from host to hostwhether direct or indirect
- Vectors: living organisms (such as fleas, ticks, etc) that are involved in the transmission of
- Mechanical transmission: bite wound of a mosquito or fly
- Developmental transmission: parasites that grow and reproduce
- microparasites
- Contain genetic code (DNA & RNA), however, do not replicate on their own viruses enter
living organisms and use cellular mechanisms to reproduce
- referred to as infectious microbes, or germs
- Macroparasites do not reproduce within an infected individual; they produce infective
stages that usually pass out of the body of one host before transmission to another
Plagues and Parasites
- plague comes from the Latin word plaga meaning to strike a blow that wounds
- Carriers: infectious but asymptomatic individuals
- Typhoid: disease which causes headache, loss of energy, diarrhea, high fever, and in 10% of
cases, death
Forecasting Storms, Predicting Plagues
Three factors required for a parasite to spread from host-to-host:
1) Must be infectious individuals
2) Must be susceptible individuals
3) Must be a means for transmission between the two
- Epidemiologists: disease forecasters who study the occurrence, spread, and control of a
disease in a population by using statistical data and mathematical modeling to:
1) Identify the causes and modes of disease transmission
2) Predict the likelihood of an epidemic
3) Identify risk factors
4) Help plan control programs such as quarantine and vaccination
- R0 value: basic reproductive ratio of the disease. > 1, infection will spread rapidly, to more
people, and more often. If R0 value is less than 1, each infection produces fewer than one
transmission stage
Three Types of Epidemics:
Type I) large population and regular series of outbreaks, but disease never disappears
endemic (R0 >1)
Type II) midsized population, peaks of infection are discontinuous, but regular pattern of
occurrence of case no endemic
Type III) small population or isolated, pattern of cases at irregular intervals, and long
periods of no disease (R0 <1)
Factors affecting the spread of a parasite:
- Size of the population, activities which bring contact among infected individuals and
susceptible individuals, countermeasures (quarantine, hospitalization, immunization) and
seasonal patterns