Brock Midterm

Spontaneous Generation vs. Biogenesis

Competing beliefs: life from nonliving matter vs. life only from life. No scientific method used at first

Robert Hooke

Coined the term cell; built compound microscope.Observed cork, molds, insects - but couldn't see disease link.

Anton van Leeuwenhoek

Made 500+ microscopes; observed "animalcules" (microbes). First descriptions of microorganisms.\Did not connect microbes with disease.

Why it matters:

Students see how scientific observation precedes explanation. Tools existed before understanding.

Crimean War (1853-1856)

Poor sanitation, lack of training, high infection. Florence Nightingale: sanitation, ventilation, nutrition → reduced deaths.Wrote Notes on Nursing.

American Civil War (1861-1865)

Initially ignored Nightingale's lessons.Innovations: ambulance corps, field hospitals, bromine bandages, handwashing withchlorinated soda, boiling sponges.Birth of modern nursing in the U.S.

Angel's Glow

mysterious survival advantage from glowing wounds (bioluminescent bacteria).

Hospitalism

Belief in "bad air" (miasmas).

Dr. James Simpson

restructure hospitals, improve ventilation.

Ignaz Semmelweis

Linked handwashing to lower death rates in maternity wards. Mortality dropped to 2%.

Joseph Lister

Used antiseptics (carbolic acid). Transformed surgery into a safer procedure.

Jean-Antoine Villemin

Showed tuberculosis contagious in rabbits.

Carl Crede

Prevented newborn blindness with silver nitrate drops.

John Snow

Mapped cholera outbreaks in London (Broad Street pump). Laid foundations for epidemiology.

Edward Jenner (1796)

Used cowpox to protect against smallpox, creating the first successful vaccine. Laid foundation for modern vaccination and immunology.

Debate (1865-1900)

Some believed disease caused by miasmas, poisons, or damaged cells.

Louis Pasteur

Disproved spontaneous generation; developed pasteurization; proved microbes cause diseases like anthrax and rabies.

Robert Koch

Proved tuberculosis caused by Mycobacterium tuberculosis; developed Koch's Postulates.

Major discoveries (1800s)

microbes cause disease, not bad air.

New tools

microscopes, Gram staining, aseptic technique, pure cultures.

Applications

fermentation, pasteurization, disinfection, vaccines.

Alexandre Yersin (1894)

Identified Yersinia pestis as the cause of bubonic plague.

Phage Biology

Viruses that infect bacteria (bacteriophages) discovered by Twort & d'Herelle.

Discovery of Antibiotics

Fleming's penicillin (1928) marked start of antibiotic era.

DNA discovered as hereditary material

Watson & Crick identified double helix (1953).

Poliovirus vaccine

developed through cell culture techniques.

3 PCR (Polymerase Chain Reaction)

revolutionized DNA study, sequencing, and forensics.

Decline of Infectious Diseases

Reduced prominence due to sanitation, clean water, and antibiotics. Public health initiatives transformed disease prevention.

Sanitation & Germ Theory

Louis Pasteur, Robert Koch → linked microbes to disease.Germ theory (1880s) → foundation of modern public health.Rise of sanitary engineers & bacteriologists.

Birth of Public Health Systems

1887: Marine Hospital Service established to monitor cholera in immigrants.By 1900: 40 states had health departments. 1920s-1950s: major progress (plague, malaria, TB greatly reduced).

Public Health as "Early Emergency Management"

USPHS evolved from Marine Hospital Service. Centralized prevention, mitigation, response, recovery. First use of quarantine, surveillance, sanitation policy.

Safe disposal of human waste

prevents food & water contamination.

Global sanitation challenges

2.6B people lack toilets. 200M tons untreated waste annually. 500,000 child deaths/year from diarrhea-related dehydration.

1993 Milwaukee outbreak

Cryptosporidium parvum in water supply = largest U.S. waterborne outbreak.

Hurricane Katrina (2005)

exposed Gulf Coast residents to unsafe water.The Jungle (1906) by Upton Sinclair: exposed unsafe meatpacking practices.

Meat Inspection Act (1906)

Public outrage and modern food safety laws.

Microbes

Microscopic, usually single-celled organisms. Most are beneficial or essential (nutrient cycling, health).

pathogens

cause disease or death.

Six types of Microbes:

Bacteria, Viruses, Protozoa, Fungi, Algae (unicellular), and Prions

Emerging

New, previously unknown diseases or spread to new areas.

Reemerging

Once under control but now returning (e.g., TB, measles).

Causes

Global travel, population growth, ecological disruption, misuse of antibiotics.

By 2050

>9 billion people; 80% in developing nations.

Overpopulation

increases all modes of transmission.

Aging populations

= more reservoirs for infection.

Person-to-person (Direct Transmission)

Touching, kissing, and sexual contact.

Droplets (direct transmission)

Coughing/sneezing onto someone.

Vertical(direct transmission)

Mother → Baby (birth or breastfeeding).

Fomites(indirect)

Objects (doorknobs, towels, needles).

Vehicle-borne(indirect)

Food, water, soil.

Foodborne(indirect)

Contaminated or undercooked food.

Waterborne(indirect)

Contaminated water (cholera, leptospirosis).

Airborne(indirect)

Pathogen remains suspended in air (TB, measles).

Fecal-Oral Route(indirect)

Poor sanitation/hygiene → contaminated hands, food, or water.

Vector-Borne

Disease carried by an insect or animal (mosquito → malaria, tick → Lyme).

Zoonotic

Infection passes from animals → humans (rabies, influenza, Ebola).

Reservoirs

Where a pathogen lives and multiplies.

Deforestation, urbanization, and climate change

bring humans closer to animal hosts.

Natural disasters (floods, droughts, hurricanes)

increase outbreaks (cholera, malaria).

Climate change

expands vector ranges (e.g., mosquitoes).

Jet travel

Rapid global spread, before symptoms appear.

Hospital-acquired (nosocomial) infections

through blood, equipment, or transplants.

Antibiotic resistance

from overuse/misuse.

Human behavior

Complacency, migration, crowded living, and globalized food systems.

Cell Theory

All living things are made of cells; cells arise from pre-existing cells (life begets life).

Spontaneous Generation

Disproved; replaced by the principle that life originates from existing life.

Metabolism & ATP

Cells capture energy in ATP.

Heterotrophs

Require organic molecules.

Autotrophs

Use CO₂; can be photosynthetic (sunlight) or chemosynthetic (inorganic compounds).

Aerobes

Require oxygen.

Anaerobes

Killed by oxygen.

Facultative anaerobes

Can grow with or without oxygen.

Prokaryotes vs. Eukaryotes

Prokaryotes (no nucleus/organelles); Eukaryotes (have both).

Bacteria

First life forms (~3.5 billion years ago).

Photosynthetic microbes

Produced oxygen ~2 billion years ago.

Classification Systems

Linnaeus: 2 kingdoms,Haeckel: 3 kingdoms,Whittaker: 5 kingdoms

Woese (1990): 3 domains

Bacteria, Archaea, Eucarya

Extremophiles

Thrive in extreme conditions:

Hyperthermophiles

Heat

Psychrophiles

Cold

Halophiles

Salinity

Prions

Protein particles (~27-30 kDa)

Viruses

20-400 nm

Bacteria

1-15 µm

Protozoa

1 µm-3 mm

Fungi

2-200 µm

Prions

Acellular, no DNA/RNA, infectious protein particles. Reproduce by converting normal proteins into prions. Human diseases: CJD, FFI, kuru. Animal diseases: Scrapie, Mad Cow, Chronic Wasting Disease

Viruses

Acellular, RNA or DNA genome. Obligate intracellular parasites. Require host cell to replicate. Diseases: Smallpox, flu, measles, rabies, Ebola

Bacteria

unicellular, prokaryotic, and replicate by binary fission. Some motile (flagella), autotrophic or heterotrophic. Diseases: Cholera, TB, Plague, Syphilis, Anthrax

Fungi

Eukaryotic; unicellular (yeasts) or multicellular (molds). Heterotrophic, non-motile, reproduce sexually/asexually. Diseases: Yeast infections, Ringworm, Aspergillus, PCP

Protozoans

Unicellular, eukaryotic, no cell wall. Motility by flagella, cilia, or pseudopods. Diseases: Malaria, Amebiasis, Giardia, Leishmaniasis, Sleeping sickness Algae. Uni- or multicellular, eukaryotic, photosynthetic. Not infectious, but can produce harmful neurotoxins (red tide).

Influenza (Flu)

1918 Spanish Flu killed 50-100 million. H1N1 virus has H (entry) & N (exit) genes.

Avian Flu (Bird Flu)

H5N1 and related strains (H7N3, H7N9, etc.) — few infect humans.

Polio

Affects the nervous system; can be eradicated by vaccination.

HIV/AIDS

Began in 1980s; global pandemic still affecting millions.

Smallpox

Eradicated; first disease eliminated by vaccination.

Ebola / Marburg / Dengue

Hemorrhagic fevers; can cause multi-organ failure and death.

COVID-19, SARS, MERS

Caused by coronaviruses; respiratory illnesses of varying severity.

Enteroviruses

Infect through the GI tract (e.g., Polio, Hepatitis A/E, Norovirus).

CNS Viruses

Attack the brain and nerves (e.g., West Nile, St. Louis Encephalitis).