BMS 223 Test 1

Causes of Infectious Disease

Virus, bacteria, protozoa, fungi and helminths

Prehistory of Disease

Early evidence of disease found bacteria, fossil remains of disease, and Egyptian mummies- papyri with case histories. The papyri show early evidence of leprosy, polio, kidney stones, and TB.

Lesions on mummy is evidence of smallpox. TB is the oldest disease.

Egyptian Medicine

Magic

Action of the gods

Demonic Possesion

Used Drugs-some still used today- Used opium, castor oil and olive oil

specialization of physician practice recorded

Diet and cleanliness in lifestyle part of religious practices

Recognized for medical knowledge in ancient world

Medical center for ancient world

First known record to systematically treat disease

Chinese Medicine

Herbal Remedies

Acupuncture

Iron for Anemia

Opium as Narcotic

Magic and superstition plays a big role

Variolation- early form of immunization It takes some sample from diseased individual and giving it to a healthy individual. Some people died but the ones who survived were immune

The Bible and Medicine

Disease cause not researched- caused by God and sin

Plague- recognition of relationship between rats and disease

Mosaic law or code

leprosy- separation from general population

Greece- Hippocrates

460-377 BC

Father of medicine

Humoral cause of disease (4 humors) lead to blood letting

4 humors are in balance disease occurs when they are not balanced

Hippocrates is the first person to follow logical approach and figure out something was wrong. Said superstition was not cause of disease.

Healing Power of Nature

Logical approach and clinical observations

First to work on physiotherapy

Rome

Public Health measures included community sanitation. They had aqueducts, sewers, street cleaning and bath houses.

Bath houses were available everywhere to everyone

Marcus Terentius Varro

116-27 BC part of Roman medicine

“small creatures invisible to the eye”

Thought small creatures cause disease

Galen

130-200 CE

Roman physician

Founder of experimental physiology

Restricted to non-human dissection

Rome not allowed to do autopsies can’t break the body of the dead

Miasma theory

Bad air causes disease

Disease Causes in the Middle Ages

Christianity, Islam and Contagion

Denying body to uplift spirt

Rise of Islam- Mecca

Pilgrims to Mecca carrying and transmitting diseases

Cholera pandemic after pilgrimage

When Rome fell there was a standstill of scientific development. Lost sewers and aqueducts and ignored mind and body now and focus on the spirt.

Crusades spread disease including cholera, leprosy… etc

Black death

Spread of syphilis after Columbus returned from North America

Spread of Smallpox in north and south America

attempt at disease control by isolation and quarantine. It was inconsistently practiced. Not always effective since cause of disease and means of spread unknown.

Most disease pop up because the movement of people

Black plague- mask with herbs because of miasma theory. Oiled gloves and long garments to prevent flea bites. Long stick with claws prevented them from getting close to people.

Typus, dysentery and streptococcus caused diseases were a problem

Leondaro da Vinci (1452-1519) and Andrew Vesalius

Were able to dissect human bodies

Foundation of modern anatomy

Correct the ideas of Galen

Girolamo Fracastoro

1483-1553

Named several diseases including syphilis, tuberculosis, and typus

Suggested an invisible cause

Italian physician

Galileo

Telescope and microscope ideas

First to magnify for scientific investigation

Antonie van Leeuwenhoek

First Microscope

Saw red blood cells

Bacterial identification

beginning of microbiology

Still attributing things to miasma. Some people holding on to old ideas. Made a lens precise enough to see the microbial world.

First to see bacteria but didn’t connect that to disease

Didn’t share information how to make lens, so information dies with him

17th Century Disease

Advances in diagnoses

Vitamin deficiency

Rickets and Beriberi described

Francis Bacon had a large role

Some understanding of excesses and deficiency in the system

Slow process of development of understanding

Thomas Sydenham

1624-1689

Distinguish rheumatism from gout

Distinguish scarlet fever from measles

18th Century Disease Causation

Quackery and enlightenment

Superstition and rationalism

Edward Jenner

1749-1823

Variolation existed previously

Smallpox vaccination

Reported protection of individuals from smallpox by inoculation with cowpox lesion material

Didn’t use needles wasn’t developed until the 1840s

19th Century Disease Causation

Scientific breakthroughs Golden Age of Microbiology

Pasteur

Robert Koch

Ignaz Semmelweis- hand washing

Joseph Lister- clinical observation antiseptics prior to surgrey

John snow- contaminated water

Progress in public health

Miasma theory rejected

Germ theory of disease accepted

Instrumentation progress

Spontaneous Generation Hypothesis

Created by Aristotle

Abiogenesis “vital forces” in nonliving matter produces living things

Biogenesis Hypothesis

Living things arise from preexisting living cells

Redi’s experiment demonstrated life came from life

Louis Pasteur

1822-1895

200 years after Leeuwenhoek

Disproved spontaneous generation (1861)

Swan necked flask experiment shape lets air in but keeps microbes out

Found links between microbes and disease

Developed vaccines anthrax and rabies

His experiments lead to pasteurization

Process of heating liquids just enough to kill most bacteria

Began the field of industrial microbiology

Intentional use of microbes for manufacturing products

Most people didn’t drink water because it made people sick. He wanted to see what spoiled wine. Figured out bacteria ferment, which causes spoilage. Yeast make alcohol which makes it taste good.

Golden Age of Microbiology

Questions Asked


1. Is spontaneous generation possible?
2. What causes fermentation?
3. What causes disease?
4. How do we prevent disease?

Robert Koch

First to link anthrax to a microbe and help outline germ theory

Studied etiology and causative agents of disease

Steps to determine link between microbe and disease experimentally

By 1900 he identified 21 diseases to be caused by microbes

Linked anthrax, cholera, TB

Using deductive reasoning developed postulates

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Koch’s Postulate

1. The microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organism
2. The microorganism must be isolated from a diseased organism and grown in pure culture
3. The cultured microorganism should cause disease when introduced into a healthy organism
4. The microorganism must be reisolated from the inoculated disease experimental host and identified as being identical to the orginal specific causative agent

Exceptions: some cannot be grown in culture. Viruses hard to culture and identify

Ignaz Semmelweis

1818-1865

Hungarian physician who pioneered antiseptic procedures

Deemed the savior of mothers.

Ideas were largely rejected at the time.

Doctors would work on cadavers then deliver a baby. Bacteria still present on cadavers. They picked up streptococcus pyogenes and transferred it to the mother. When handwashing techniques were used saw a dramatic decrease in disease. Mocked for his ideas. Died in a mental hospital from a streptococcus infection.

Joseph Lister

1827-1912

British surgeon who pioneered antiseptic surgery through the use of phenol.

Method was accepted as common practice.

Developed Aseptic techniques

At this time they didn’t wash instruments unless they were being stored. First to start to make connections between the microbial world and cause of disease.

John Snow

1813-1858

British physician attributed as being the father of modern day epidemiology

Linked cholera to poor sanitation and water supply 1840-1855

Carefully mapped incidence of disease occurrence

He was able to map where cholera was popping up

Paul Ehrlich

“the magic bullet”

Chemotherapy for bacterial infections

Made salvarsan and arsenic derivative in 1907, which was effective against syphillis

Take chemical agent get rid of disease while not killing yourself

Alexander Flemming

Discovered penicillin in 1907

Was growing bacteria on plates grew fungal spore. After weekend their was a zone where there was no bacterial growth

Florance Nightengale

Prominent during the Crimean war. People need to have clean linens, clean clothes. Focused on cleaning wounds and patients.

20th century disease causation

The germ theory of disease was the leading epidemiology practice until the mid 20th century when the theory of multiple causation or the web of causation began to be used.

Widespread vaccinations lead to the eradication of some diseases

Emerging infectious disease

20th Century advances and causations

Electron microscope was invented allowed us to see viruses

Antiviral and antibacterial vaccine

Eradication of childhood diseases

Emerging infectious disease: malaria, aids, H1N1 flu, cholera and smallpox

Web of Causation- characterizes the multicausal nature of public health problems

See rise of emerging diseases that were not much of a problem

Tobacco mosaic virus 1892- something causing a disease once electron microscope was invented allowed to see what it was and what it looked like.

1950s Jonas Salk polio vaccine

1970s Restriction Enzymes

1980s PCR

Hypothesis of Disease Causation

Pre-modern era theories: religion often attributed disease outbreaks to divine retribution, disease caused by evil spirts and superstitions

Theory of contagion: Francastoro 1546

The Germ theory: Pasteur, Lister, Koch 19th century

Web of Casuation- epidemiological concept, multiple factors attribute to disease

Microbiome Project

2008-2012

Collection of microbes on body fungi, bacteria and virus

Changing public health focus 21st Century

Death from infectious disease decreasing and rise in non-infectious diseases in developed countries because of longer life expectancy and life changes

Technological advancements include improved cardiac diagnoses and surgery, transplants and cancer, human genome sequencing and immunotherapies.

New challenges: emerging infectious diseases: zika, ebola, mers, SARS-CoV1&2, Dengue

Remerging drug resistant infectious diseases: Measals, TB

Antibiotic resistance

opioid addiction

Normal Microbiota in Hosts

Organisms that colonize the body’s surfaces without normally causing disease

Also termed normal flora and indigenous microbiota

Two types resident and transient

Resident flora

Have on and in you all the time. We have greater than 500 species

Transient flora

Don’t have on you all the time. Pick up from the environment.

Epidemiology

Study of disease occurrence within a population

Public Health

Purpose to keep individuals healthy. Need healthy individuals in order to maintain the economy.

Acquisition of Normal Microbiota

Development in axenic womb (free of microorganisms)

Microbiota develop during the birthing process.

Established during the first months of life

Depending on how you are fed after you are born depends on what normal flora you would get.

Feed solid food right away you get very different microbiota

Opportunistic pathogen

Normal microbiota that cause disease under certain circumstances

An example would be when you use antibiotics to kill bacteria you are at a greater risk to develop a yeast infection.

Conditions that provide opportunities for pathogens

Introducing of normal microbiota into unusual site of body

Immune suppression

Changes in the relative abundance of normal microbiota

Stressful conditions

Reservoirs

Most pathogens can’t survive long without their hosts.

Sites where pathogens are maintained as a source of infection

Three types Animal, human and nonliving

Human- staph, strep

Animal- black plague, leprosy

Nonliving- food, water and soil

Prevalence rate

Number of cases in a population at a specified time

Incidence rate

Number of new cases in a population at a specified time

Attack rate

Number of cases in population divided by total population

Epidemiological case study categories

Observational- descriptive and analytical

Who, when, where, and how many. No manipulation

Be descriptive what has happened. If had a control group analytical aproach and have a comparison group still observational

Experimental- Community trial, randomized controlled trial and other

Manipulating the system for example the treatment group.

How this happened and why

Manipulation

Experimental Study

Community trial vs randomized control trial

both utilize a treatment and control groups

Community- treatment is most easily given to a community

Randomized- clinical trial

Examples include adding fluoride to water and mass educational campaigns

Primary Prevention

Measures taken before the disease occurs to reduce susceptibilty

Ex: vaccines, banning things associated with disease for example cigarettes.

Secondary Prevention

Measures taken to diagnose a disease which is already present

Disease may be present just want to screen for it Ex: pap smear and mammogram

Tertiary Prevention

All measures taken to return the individual to a normal state of health or to keep the person alive.

Bring back to normal state ex: chemotherapy, physical therapy for a person with polio

Theory of Disease Occurrence

If there is equilibrium between the disease agent, host, and enviroment disease will not occur

Viruses

Submicroscopic particles

Smallest disease causing agent

Early 1930s with electron microscope

Made up of either RNA or DNA not both

Borrow cell’s machinery to reproduce and burst out of the cell or may stay in cell to synthesize new viruses without disturbing the cell

May coexist indefinitely in human peacefully

Outside factors may activate virus, leading to presence of actual disease

Not living need to have something living to replicate

Sometimes they have an envelop (lipids)- usually associated with attachment.

Capsid very strong- Can’t be killed with hand sanitizer

Hijacking cells then burst out of cells sometimes they bud off and maintain the cell

A person may be infected and symptoms might not manifest may hang out in our system.

Come in a variety of shapes

Prions

Infectious Proteins

Cause normal host proteins to mis-fold

Can replicate without DNA or RNA

Cause of neurogenerative diseases

Kuru (cannibalism)

Creutzfeld-Jacob disease (CJD)

Chronic Wasting disease in deer

Scrapie in sheep

Mad cow disease in cows

Causes an uneven formation of vacuoles in neurons and gives brain tissue the sponge-like appearance

Own proteins that have misfolded

Naked piece of protein and it is transmissible

All examples same but, seen in different animals

In prion disease get large vacuole spaces get sponge like appearance

Extremely resistant to deactivation

Very resistant to physical and chemical treatment

Cannot be cured it is fatal

usually die within one year of diagnosis

Bacteria

Single cell prokaryote

Most harmless and some beneficial

Disease causing these- secrete toxins/enzymes that destroy cells or interfere with function

Disease examples: pneumonia, septicemia, TB, anthrax, cholera, botulism, tetnus, etc.

Morphology: cocci (strep), bacilli (TB), or spirlla (syphilis)

No nucleus and organization in cell

Genetic information around the cell not housed in 1 area

Have different shapes

Get antibiotics from them

Fungi

Single or multi-celled plant like eukaryotes

Thrive in humid, warm conditions with adequate oxygen supply

Release enzymes (toxins) that digest cells-decomposers

Includes mushrooms, mold and yeast

Disease examples: mycosis, athletes foot, ring worm, vaginitis, jock itch, candidiasis

Can be single or multicelled

Could be microscopic or macroscopic

maintain nutrients through absorption

Rely on high humidity, warmth and adequate oxygen supply

Protozoa

Microscopic single-celled parasitic animal

Release toxins/enzymes that destroy cells or interfere with cell function

Disease examples: malaria-blood parasite, cryptosporidia-intestinal parasite

Small microscopic single celled things

Common in temperate and tropical climates

Metazoa

Multi-cellular parasitic animals

Lodge in various parts of the body and compete for nutrients

Disease examples: tapeworms, roundworms, and flukes

Endemic

Allways naturally there see spikes

Ex blasto mycosis

Common in water ways, banks, small bodies of water.

Sporadic

Pops up all of the sudden infrequent and random

Ex: tetnus and rabies

Epidemic

Occurs in greater frequency than normal, many different areas

ex: flu

Pandemic

More than 1 continent

Ex: HIV, COVID-19, and H1N1 flu

Epidemic and out break similar definitions

Physical Forces cause of disease

Mechanical forces

Temperature: hypothermia and burns

Radiation-sun (ultraviolet rays), X-rays, and nuclear power

(osteomyelitis and hypothermia)

Nutrient causes of disease

Deficiency or excess- disease

Malnutrition- lowers resistance

Other chemical substances cause of disease

alcohol, nicotine, illegal drugs

lead, radon gas, asbestos (environmental)

Excess or deficient secretion of hormones

Excess secretion of uric acid (gout) unnecessary secretion of body chemicals

Host factors

Psychosomatic factors- stress

psychoneuroimmunology- study of the mind effects on body and body effects on mind

Hereditary- sickle cell anemia, cystic fibrosis, etc

Host resistance to non infectious disease- race, gender, heredity- can’t change

drug use and abuse, poor nutrition, lack of excercise stress level

Lifestyle plays a major part- susceptibility to cardiovascular diseases and cancer

Nutrition, weight and health- Individuals inherit traits which give them a higher potential for gaining weight- losing weight is much more difficult

Best way to lose weight and keep it off- a lifetime commitment to changed eating habits and regular exercise

Biological

Clean air, water, food, land

Physical

Climate and geography

Social

eating raw fish, burial practices

Reservoir

Mode of conveyance, sites where pathogen is maintained as a source of infection

Ex: animal, human carrier or non-living

Portal of exit

A way to get out of the host

Same way pathogens got in but often exit in secretions

Transmisson

Direct contact- skin or mucous membrane, kissing or sexual intercourse, droplet spray

Indirect contact- using, touching or ingesting any contaminated object or food

Droplet- airborne transmission

Portal of entry

A way to get into the host

Skin, mucous membranes, placenta (mother to child)

New susceptible host

Modes of transmission

Transmission is from a revisor or a portal of exit to another hosts portal of entry

Three groups of transmission

contact, vechicle and vector

Contact Transmisson

Direct hug, kiss etc

Indirect- touching something that has something on it

Vehicle Transmisson

Some examples include waterways or food

Vector transmisson

Mechanical- cockroach walks on floor then walks on food

vector- ticks, mosquitoes

Signs

Subjective what we are feeling

Symptoms

Can be measured

temperature, is one throws up

Prodromal phase

Start to see some symptoms

Clinical phase

More severe symptoms tend to peak

Decline

Start to feel a little better. Time where you are most likely to relapse

Convalescence

No signs or symptoms left

Amount of time to reach this can vary between individuals.

What advancements in public health occurred during the middle ages?

Attempted to control a disease by isolation and quarantine.

Inconsistently practiced and it was not always effective since cause of disease and means of spread unknown.

What drove the 19th century advancement in understanding microbiology.  

a.      How did the various pioneers in the field contribute to answering these questions?

b.      What are Koch’s postulates and how do we use them.

c.      What is spontaneous generation? How was it disproven?

d.      How do we know what causes disease?

4 questions arose in this century.


1. I spontaneous generation possible?
2. What causes fermentation?
3. What causes disease?
4. How do we prevent disease?

a) Louis pasteur disproved spontaneous generation and answered the questions about fermentation. Koch took steps to link between a microbe and disease and developed Koch’s postulates. Semmelweis and Lister came up with ways to help prevent disease.

b) these were rules that needed to be followed in order to link an infectious organism to a specific disease.


1. The microorganism must be found in abundance in all organisms suffering from disease but should not be found in healthy organisms.
2. The microorganism must be isolated from a disease organism and grown in pure culture.
3. The cultured microorganism should cause disease when introduced in an healthy individual.
4. The microorganism must be reisolated from the inoculated diseased experimental host and identified as being identical to the original specific causative agent.

d) We know the source of the disease by the study of epidemiology, which is the study of the determinants, occurrents, and distribution of the health and disease in a defined population. John snow linked cholera to poor sanitation and water supply. Carefully mapped the incidence of disease occurrence and figured out which well it came from.

Describe the different hypotheses of disease causation

Miasma- disease was caused by bad air

Humoral cause of disease- If the four humors are not in balance disease occurs.

Theory of contagion- There is an invisible cause of disease

Germ theory- certain diseases are caused by an invasion of microorganisms in the body

Web of Causation: multiple factors attribute to disease.

What is epidemiology?

Study if disease occurrence within a population.

Etiology

The study of a disease that has already occurred in the past.

Who were the people most involved in early epidemiology and improving our understanding of public health?

John Snow was the founder of epidemiology and determined where the cholera outbreak in England was coming from.

How has there been a shift in public health focus with our modern understanding of disease?

With new treatments there has been a shift in preventing noninfectious disease because those cause more deaths than infectious diseases. Another thing they do is to maintain the economy. The better the economy the more healthy individuals.

What are the six groups of microorganisms typically studied in the field of microbiology?

1. Viruses
2. Prions
3. Metazoa
4. Protozoa
5. Bacteria
6. Fungi

What is the difference between resident and transient microflora.

Resident is always on you and transient you pick up from your environment and does not remain on you very long.

What is the difference between sign and symptom of disease?

Sign- Subjective what we are feeling.

Symptoms- Can be measured. For example, temperature, if one throws up.

What is the difference between a true pathogen and an opportunistic pathogen?

a. What conditions provide opportunities for infection?

An opportunistic pathogen are normal microbiota that cause disease under certain circumstances. For example, taking antibiotics can cause a yeast infection. Causes disease in an healthy individual.

a) These include burns, hypothermia, radiation, deficiency or excess of nutrients, malnutrition, lead, radon, stress, social practices.

What are the portals of entry and exit?

a) Describe the chain of infection

These are the ways the organism makes it in the body and out of the body to spread to another host.

a) Reservoir- mode of conveyance, sites where pathogen is maintained as source of infection.

Portal of Exit- A way to get out of the host. Usually the same way the pathogen got in, but they often exit as secretions.

Transmisson- movement of agent

Portal of entry- a way to get into a host

New susceptible host

How does the infectious dose and portal of entry influence the course of an infection?

The higher the this the more severe the infection will be. The location of the portal of entry matters to. It could be less severe if it enters in a location where the infection doesn’t infect. EX: flu in the stomach.

What are the stages of an infection?

Incubation Period- no signs or symptoms

Prodromal period- vague, general symptoms. Start to see signs and symptoms.

Illness/ Clinical phase- Most severe signs and symptoms.

Decline- declining signs and symptoms. Start to feel a little better sometimes start to relapse

Convalescence- no signs or symptoms. Amount of time to reach this may vary.