1. Epidemiology

2. COLONIZATION
Colonization is when microbes move in and themselves at home in the host.
For example, the average human body is made up 37 trillion cells, but we have 10 times that many bacterial cells that have colonized our bodies and call our bodies "home"!
So, in addition to our 37 trillion "human" cells, we have what we call our "normal flora."
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3. Normal Flora
Our normal flora consists of all of the many different kinds of microbes that inhabit our body!
Normal Flora Inhabit Our…
Skin
Nose
Eyes
Mouth
Throat
GI Tract (stomach, intestines, etc.)
Respiratory Tract
Urinary Tract
Reproductive Tract

4. NORMAL FLORA
The colonization of our body by normal flora (in the “usual areas” they inhabit) is not considered an "infection".
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5. Infection The other areas of our bodies should remain microbe-free.
When microbes from one part of the body invade another part of the body where they are usually not found, they can be harmful, or even deadly!
An "infection" occurs when a microorganism gets into (or onto) a part of the body where it normally is not found.

6. Staphylococcus aureus
All human skin is colonized by a bacteria called Staphylococcus aureus (sometimes abbreviated as Staph. aureus) about 40% of the time.
This bacteria lives on the surface of the skin and is considered part of the "normal flora" of humans.

7. Staphylococcus aureus
Another way to say this is to say that human skin is "colonized" with Staphylococcus aureus.
It is not considered an infection and does not cause harm... as long as it stays on the surface of the skin. ​
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8. STAPH INFECTIONS
However, if a person were to cut themselves or get some kind of open wound on their skin, the Staphylococcus aureas has a chance of penetrating through the outer layers of skin and entering the blood stream.
At this point, the person is said to have a Staphylococcus aureas infection.
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9. INFECTION AND INFECTIOUS DISEASE
An infection is defined as the presence of a microorganism in a part of the body where it is normally not found.
An infectious disease is defined as an infection that causes harm to the host.

10. Pathogens A pathogen is a microorganism that causes disease.
For Example: Once Staph aureus enters the blood stream it is pathogenic and can then invade internal organs causing more harm to the host in a condition called toxic shock syndrome, which can lead to death.

11. Signs and Symptoms
Doctors use the signs and symptoms of a disease to determine the disease, the pathogen, and the course of treatment.
Since different pathogenic microorganisms have different effects on the human body, knowing the signs and symptoms is vital to the diagnosis.

12. Symptoms are subjective.
Signs vs. Symptoms
Signs are objective.
Symptoms are subjective.

13. Signs can be OBSERVED and MEASURED
Signs are objective.
Easier to measure
Blood cell counts
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14. Signs vs. Symptoms Symptoms are subjective. More difficult to measure
A “10” to one person may be a “8” to another person.
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15. This is called the Wong-Baker Faces pain-rating scale.
Signs vs. Symptoms – Wong-Baker Faces pain-rating scale for attempting to quantify symptoms.
Medical professionals will ask patients to rate their pain (or other symptom) on a scale from 0 to 10.
This is called the Wong-Baker Faces pain-rating scale. 

16. What is epidemiology? Epidemiology is a science that examines...
the patterns
the causes
and the effects
of disease on the health of a specific population.
While epidemiologists study all diseases and not just the diseases caused by microorganisms, we will be focusing our discussion of epidemiology to infectious diseases only.

17. Epidemiologists
Scientists that specialize in the field of epidemiology are called epidemiologists.
Epidemiologists have 3 main goals.
​To identify the factors that cause disease
To identify the factors that transmit disease
To help prevent or reduce future outbreak of disease

18. Epidemiological Studies
There are 4 stages or phases of an epidemiological study.
Disease Etiology - To identify the pathogen causing the outbreak of the disease.
Outbreak Investigation - To determine how, when, where, and why the outbreak occurred.
Disease Screening and Surveillance - To determine patterns and predict future outbreaks based on collected data.
Comparisons of Treatment Effects - Clinical trials are performed in efforts to prevent future outbreaks.

19. ETIOLOGY
ETIOLOGY - The etiology of a disease is defined as the cause of the disease.
ETIOLOGICAL AGENT - An etiological agent is the microorganism that is responsible for causing the disease.

20. Infectious vs Non-infectious diseases
Infectious diseases are diseases that CAN BE SPREAD, either directly or indirectly, from one person to another. 
Casual Contact
Colds
Flu
Ebola
Intimate or Sexual Contact
Hepatitis
Sexually Transmitted Diseases
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21. How Diseases May be Acquired – Person to Person
A disease that is infectious is one that can spread from Person to Person by some means. Some of these means are…
Casual contact
Intimate Contact
Sexual Contact
Healthcare Worker
Child Care
Indirect contact
One person contaminates a surface or item that ano9ther person comes into contact with.
- When a certain outbreak of a disease has been found to be spread from person to person, epidemiologists can potentially find out who that first person was that was infected. ​

22. Infectious vs Non-infectious Diseases
A  noninfectious disease is not contagious
These diseases are not caused by pathogens.
Instead, they are likely to have causes such as
Cancer
Diabetes
Genetic Diseases
Autoimmune Disease
This lovely young lady has a chromosomal abnormality known as trisomy 21 or Downs Syndrome. This is a genetic disease and is not contagious.

23. ZOONOTIC DISEASES
Zoonotic diseases are infectious diseases of animals that can cause disease when transmitted to humans.
Rabies
Anthrax
Lime Disease
Trichinosis
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24. Zoonotic Diseases - RABIES
Rabies – you can contract rabies by being bitten by an infected animal.
Rabies is a viral disease that causes inflammation of the brain in humans and other mammals.
Early symptoms can include fever and tingling at the site of exposure.
Saliva from an infected animal can also transmit rabies if the saliva comes into contact with the eyes, mouth, or nose.
The prognosis – usually DEATH
THE RABIES VIRUS

25. Zoonotic diseases - ANTHRAX
Anthrax – is contracted by handling or consuming anthrax-infected animals (anthrax is found in cows, sheep and goats)
People who handle large amounts of livestock in areas where infections are common, often get vaccinated.
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Patient Wound Photo By Photo Credit: Content Providers(s): CDC - This media comes from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL), with identification number #1934.
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26. Zoonotic diseases - ANTHRAX
Anthrax has been weaponized by various countries as far back as the 1930s.
This including testing the effects of anthrax on prisoners of war.
Anthrax is a favorite because the mode of infection can be inhalation, skin contact or ingestion, which makes it a weapon of choice.
Colin Powell giving a presentation to the United Nations Security Council, holding a model vial of anthrax
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27. Zoonotic diseases - Lime Disease (Lyme Borreli)
Lime Disease – contracted if bitten by an infected tick
Caused by the bacterium Borrelia burgdorferi.
Primarily transmitted by Ixodes ticks, also known as deer ticks or black-legged ticks.
Medication‎: ‎Doxycycline, ‎amoxicilli n‎, ‎cefuroxime
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28. Zoonotic diseases - Lime Disease (Lyme Borreli)
Early Signs and Symptoms
ERYTHEMA MIGRANS – A type of rash associated with lime disease that typically does not itch and is not painful but appears red and grows in size.
Flu-like symptoms (fever, headache, fatigue).
Late Signs and Symptoms (If left untreated)
Joint pain
Heart palpitations
Paralysis to portions of the face
Fatigue
Memory problems
 ERYTHEMA MIGRANS

29. Zoonotic diseases - Trichinosis
Trichinella spiralis.
Zoonotic diseases - Trichinosis
Trichinosis – can be contracted by consuming undercooked pork from a trichinellosis- infected pig.
Trichinosis is caused by an infection by the parasitic worm, trichinella spiralis.

30. How Diseases May be Acquired - Vectors
​ Vectors are living organisms that can transmit infectious diseases either…..
From one human to another human or
From an animal to a human
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How Diseases May be Acquired - Vectors

31. How Diseases May be Acquired - Vectors
Vectors are usually bloodsucking insects.
The process of infection involving blood sucking insects
ingesting the pathogen during a blood meal from an infected host. (human or animal) and
Injecting that pathogen into the next host during their next blood meal.

32. VECTOR-BORN DISEASES - MALARIA
An example of a vector-born disease is MALARIA –
Mosquitoes can carry the pathogenic protozoa, Plasmodium.
When an infected mosquito bites a human, the plasmodium can be transferred to the human host.
THE PATHOGENIC PROTOZOA, PLASMODIUM

33. VECTOR-BORN DISEASES - MALARIA
The Plasmodium travels through the blood stream to the liver and reproduces.
From there the parasite attacks the blood cells of the host.
Begins with flu-like symptoms.
Can be deadly if not treated within the first 24 hours
THE PATHOGENIC PROTOZOA, PLASMODIUM

34. Chronic vs. Acute Diseases
Long-lasting (typically years) or constantly reoccurring.
Sudden onset
Rapid Progression
In Need of Urgent Care
Short Duration
Chronic
Acute
Disease-Causing Virus
Disease-Causing Virus
Chronic vs. Acute Diseases

35. 01 02 03 04 Incidence: # of new cases of disease/total # at risk.
Incidence rate: Incidence/unit of time. 02
Prevalence: # cases (or # with defined condition) existing at one time. 03
Prevalence rate: # of such cases/total # at risk. 04