MRS. ASHLEYMEDICAL ASSISTANT

Microbes and Human Health

Types of Disease Causing Organisms

BacteriaVirusProtozoaWormFungusPrions

Microbes

Are very small, usually need microscope to see.

Only a small number cause disease, most are helpful

Microbes Maintain a healthy digestive system- Example: Normal

Flora Breakdown dead plant and animal matter Produce foods and medicines

Normal Flora

Varies in different body sitesMay Protect the host by competing with

pathogensThey may cause disease if

Immunocompromised host After being introduced to different body sites May overgrow in favorable conditions

Mode of Transmission of Pathogens

Airborne Transmission (influenza, tuberculosis)

Food and Waterborne Transmission (botulism, typhoid fever, hepatitis A

Vector Transmission (Lyme Disease, Malaria)Sexually Transmitted (Syphilis, Gonorrhea,

AIDS)Direct Skin Contact (Leprosy)

3 Forms of Bacteria

Cocci- SphericalBacilli- rod shapedSpirilli- spiral shapedCocci can be diplococci (in pairs),

streptococci (in chains) or staphlococci (in clusters)

Bacilli may be single or in chains (streptobacilli) or may lay side by side in pairs

DescriptionStaphylococcus aureus VISA 2.jpg

g/ml.

Date 2001

Source

Author Content Providers(s): CDC/ Matthew J. Arduino, DRPHPhoto Credit: Janice Haney Carr

Permission(Reusing this file)

f this image.

Public domainPublic domainfalsefalse

Viruses

Are true parasites, require host to replicateAre either DNA or RNA but not both

Fungus

Of 50,000 known species, only about 300 are known to be human pathogens

Cause diseases from skin infections (athletes foot) to serious, systemic infections (yeast infection)

Protozoans

One celled organisms that may cause diseaseOften spread by water or vectors, or

ingestion of some part of life stageExamples: malaria shownat right

Prions

Protein that is not considered “alive” except when in the presence of nerve tissue

Causes Bovine spongiform encephalopathy disease in cows

Causes Creutzfeldt–Jakob disease in humans

Examples of Diseases

Viruses PrionsHIV virus “Mad Cow

Disease Disease”Flu virusPolio virusProtozoans BacteriaAmebic dysentery Lyme DiseaseMalaria Strep ThroatFungi HelminthsAthlete’s foot TapewormsRingworm Round wormsYeast infections