IB Biology

 Any microbes (organism or virus) that cause disease
 Including:
 Viruses
 Bacteria
 Fungi
 Protozoa
 Flatworms
 Roundworms

Ebola
 Considered Non-Living
 Two Parts:
 A Capsid: protein coat
 A Nucleic Acid: DNA or RNA
HIV
 Function: Reproduction (
Replication, actually
)
 Method: Hijack a living host cell and use it’s cellular machinery to replicate and build new virus particles.

 HIV: Human Immunodeficiency Virus
 Targets T-Cells (Immune Cells)
 Influenza
 Rhinovirus
 Small Pox
 Polio
 Ebola, Marburg, Hantavirus
 Herpes (different simplexes)

Escherichia coli Staphylococcus aureus
 Most are not pathogenic (major decomposers, major photosynthesizers, critical components for many ecosystems)
 All prokaryotic, unicellular
 Parasitic strains and those that produce toxic byproducts are pathogenic
 Most pathogenic varieties form colonies and can be grown on TSA plates

 Cocci: Staphylococcus (Staph),
Streptococcus (Strep Throat)
 Bacilli: Escherichia coli ( E. coli ; 0157:H7),
Bacillus anthracis (Anthrax), Clostridium botulinum (Botulism Toxin Producer)
 Spirilla: Campylobacter jejuni (causes diarrhea esp. in children), Helicobacter pylori (causes peptic ulcers)


Decomposers that occasionally don’t wait until an organism is dead to feed on it
 Examples: Valley Fever (lung), Ringworm
(skin), Athletes Foot (skin)
 Most are surface/epidermal, some (rarely) become invasive

 Protozoa are unicellular animal-like protists (motile)
 Pathogenic examples include:
 Giardia
 Cryptosporidium
 Trypanosoma
 Many have insect vectors
Giardia

 Flatworms belong to a group called platyhelminthes
 Many are parasitic
 Examples include:
 Tapeworms
 Flukes (liver fluke)
 Schistosoma

 Roundworms are nematodes that range in size from macroscopic to microscopic
 Many parasitic roundworms inhabit the intestines of a host organism
 Examples include:
 Pinworms like Enterobius vermicularis
 Hookworms like Necator and Ancylostoma
 Trichinella spiralis (larvae migrate to muscle)

 Direct Contact: Person to person – communicable (mononucleosis)
 Kissing
 Shaking hands
 Touching open wounds or sores
 Sexual contact – body fluids


 Objects – doorknobs, telephones, ect...
 Air (tuberculosis)
 Food (botulism)
 Water (typhoid fever)
 Vectors
 Animal Bites – disease to organism to humans (rabies, West Nile virus)

 Respiratory Tract – nose, mouth, lungs
 Gastrointestingal Tract – throat, stomach, intestines
 Mucous Membranes – nose, eyes, etc.
 Penetration – bites, cuts, injections

 MDR TB and Staph Infections
 Malaria (hiding in liver cells)
 HIV attacking T-cells and rapid mutation
 Influenza and Rhinovirus rapid mutation rate (flu shots every year)

 Antibiotics
 Attack existing bacterial infections only
 Began with Penicillin (1928 – Fleming)
 Resistance observed rapidly
 Overuse, Incompletion of Prescription, Livestock application
 Vaccinations
 Prepare an immune system in advance of a viral
(usually) or bacterial infection (i.e. tetanus)
 Dead or inactive parts of a pathogen or synthetic

 Blood-born pathogen
 Transmitted via:
 Sexual Contact
 Used Hypodermic Needles
 Early Blood Transfusions (pre-testing)
 Uses only Helper T-Cells for replication
 Compromises Immune Response
 Rapidly mutates differently in each host
 Not a cause of death
 Subsequent infections finish off host

 HIV in Sub-Saharan Africa:
 22.5 million people living with it by 2008
 1.7 million contracted it this year.
 11 million orphans as a direct result
 Varies widely from country to country
 Impacts are widespread and threaten to hold up/roll back decades of progress/economic development
 Causes: poor education system (lack of basic understanding), lack of access to contraceptives, employment situations...
 Insult to Injury: lack of quality health care or testing, lack of funds for ARV drugs, poor sanitation
(additional diseases)