Pathology - the scientific study of the nature of disease and its causes. A PATHOGEN is any disease causing agent. Quick Exercise: How many diseases can you think of? Now watch " The A to Z of Germs... ". S ome diseases are communicable, such as:
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Pathology - the scientific study of the nature of disease and its causes
A PATHOGEN is any disease causing agent.
Quick Exercise: How many diseases can you think of?
Now watch "The A to Z of Germs..."
Some diseases are communicable, such as:
anthrax, swine flu, herpes, common cold, malaria, salmonella, AIDS
Other diseases are not contagious:
cancer, lupus, arthritis, allergies
This unit will focus on the first type: the disease, its agents, treatment and history and will cover three main areas of pathology
1. Viruses (virology)2. Bacteria (bacteriology)3. Parasites (parasitology)
Host - organism which provides nutrients, etc. to another organism
Parasite - organism which lives at the expense of (and may even harm) its host; the parasite is generally smaller than the host and is metabolically dependent upon it
Disease - an upset in the homeostasis of the host, resulting in generation of observable changes
Symptom - evidence of damage to the host (headache)
Infectious disease - one in which detrimental changes in health of the host occur as a result of damage caused by a parasite, can be transmitted
Virulence - a measure of pathogenicity, which is the ability to cause disease (a microorganism that causes disease is virulent)
Epidemic - when a disease affects a community
Pandemic - when a disease affects the world
1. Food and Water borne - pathogen is in a food or water source
2. Blood Borne - carried in blood or other bodily fluids
Sexually Transmitted - transmitted by sexual contact
3. Zoonotic- carried by animals
4. Airborne - carried by the air, often affect respiratory tract
Organizations Dealing with Health -
Centers for Disease Control (CDC)
World Health Organization (WHO)
U.S. Department of Health and Human Services (HHS)
U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID)
If a microorganism is the causative agent of an infectious disease, it must be:
Steps in Pathogenesis
To cause disease, a pathogen must:
[Image: An emergency hospital ward in Kansas during the 1918 flu]
Edward Jenner (1796)
Noting the common observation that milkmaids did not generally get smallpox, Jenner theorized that the pus in the blisters which milkmaids received from cowpox (a disease similar to smallpox, but much less virulent) protected the milkmaids from smallpox.
Jenner tested his hypothesis by inoculating James Phipps, a young boy of 8 years (the son of Jenner's gardener), with material from the cowpox blisters of the hand of Sarah Nelmes, a milkmaid who had caught cowpox from a cow called Blossom
Observed that women in the maternity wards died of childbed fever. He proposed that it was caused by doctors doing autopsies on the deceased women and then carrying the disease causing agent to healthy women who were in labor.
His solution: Wash your hands before delivering babies!
*The Germ Theory did not exist at this time
Cholera is an infection of the small intestine caused by the bacteriumVibrio cholerae.
The main symptoms are watery diarrhea and vomiting. Transmission occurs primarily by drinking water or eating food that has been contaminated by the feces (waste product) of an infected person, including one with no apparent symptoms.
Overview of issue
It was discovered later that this public well had been dug only three feet from an old cesspit that had begun to leak fecal bacteria. A baby who had contracted cholera from another source had its nappies (diapers) washed into this cesspit, the opening of which was under a nearby house that had been rebuilt farther away after a fire had destroyed the previous structure, and the street was widened by the city. It was common at the time to have a cesspit under most homes. Most families tried to have their raw sewage collected and dumped in the Thames to prevent their cesspit from filling faster than the sewage could decompose into the soil.
After the cholera epidemic had subsided, government officials replaced the Broad Street Pump Handle. They had responded only to the urgent threat posed to the population, and afterward they rejected Snow's theory. To accept his proposal would have meant indirectly accepting the oral-fecal method transmission of disease, which was too unpleasant for most of the public to contemplate.
Louis Pasteur - developed the germ theory and disproved spontaneous generation, in 1885 he developed the rabies vaccine
Robert Koch - Koch's postulates
Alexander Fleming - discovered penicillin, though it wasn't until much later that it was produced as an antibiotic.
Antibiotics are used to treat bacterial infections.
1980 - WHO declared smallpox eradicated
1983 - Discovering and identification of the AIDS virus (HIV)
1985 - First vaccine for Haemophilus influenzae type b (HiB)2006 - First vaccine for human papillomavirus
Check out http://www.bt.cdc.gov/socialmedia/zombies_blog.asp
The Germ Theory (around 1860)
*Why is this a theory and not a fact?
Malaria is an infectious disease caused by a parasite plasmodium (a one-celled parasite),that's transmitted by mosquitoes. The illness results in recurrent attacks of chills and fever, and it can be deadly.
Malaria has been virtually eradicated in countries with temperate climates, but it's still prevalent in tropical and subtropical countries in Africa, Asia, the Middle East, South America and Central America. Malaria remains one of the world's leading infectious killers, particularly of children in sub-Saharan Africa.
Evolving strains of drug-resistant parasites and insecticide-resistant mosquitoes continue to make malaria a global health problem.
Most American cases of malaria develop in travelers who have recently returned from parts of the world where malaria is widespread, particularly Africa and India. If you're traveling to malaria-endemic places, take precautions before, during and after your trip.
Treatment for malaria is with antimalarial drugs.
How do you prevent this disease?
There are actually three parallel routes, any or all of which could transform the current situation into a deadly pandemic.