Hum Bio 217 Week 4 Transcript

Commonly referred to as bubonic plague, Black Death, etc.
Importance of precise terminology discussed; generally referred to as 'the plague'.

Plague: A bacterial disease caused by the bacterium Yersinia pestis.
- Shape: between sphere and rod; described as short, stout rod shapes.
- Type: gram-negative bacteria (lacks a protective cell wall).
- Significance of being gram-negative in treatment and targeting discussed.
- Highly pathogenic, evades immune system, especially the second line of defense.

Yersinia pestis possesses an ability to evade phagocytosis, a key immune response mechanism mediated by immune cells like macrophages and neutrophils.
Maintains presence in soil and animal reservoirs; still exists today.
Natural reservoirs for Yersinia pestis:
- Primarily rodents (chipmunks, ground squirrels, prairie dogs).
- Susceptible species include felines (mountain lions, bobcats).
- Can also survive in the soil for approximately 24 days.

Bubonic Plague:
- Transmission via flea bite from an infected animal (e.g., rat); bacteria enter skin and infect lymph nodes.
- Symptoms: swollen lymph nodes (buboes), high fever, body aches, malaise.
- Untreated mortality rate: approximately 60%. Individuals typically die 3 days to a week post-infection.
- Cardinal signs: swollen lymph nodes in the groin (inguinal), armpit (axillary), or neck (cervical).
Septicemic Plague:
- Result of flea bite or progression from bubonic plague to bloodstream.
- Symptoms: absence of lymph node swelling, high fever, widespread organ failure, DIC (disseminated intravascular coagulation), internal bleeding, necrosis of tissues.
- Untreated mortality rate: nearly 100%. Can kill within 24-72 hours; prognosis depends on treatment timing.
Pneumonic Plague:
- Contact via respiratory droplets or spread from another infected body part to lungs.
- Symptoms: high fever, cough, respiratory distress, chest pain, potential blood in cough.
- Highly contagious, nearly 100% untreated mortality rate; can kill within 24 hours.

Evolved from Yersinia pseudotuberculosis; origins debated, estimated around 5,000 years ago.
Historical documentation of plague:
- First documented outbreak around 540 AD, likely originated in India; reached Constantinople.
- Fatalities estimated at 1/3 of affected populations; post-outbreak social upheaval noted.

Justinian Plague (540 AD):
- Limited documentation; likely caused numerous deaths, historically significant for its societal impacts.
Black Death (1347-1351):
- Most famous plague outbreak; significant primarily for its mix of bubonic and pneumonic plagues.
- Spread by trade routes via infected rats and fleas.
- Initial spread described through the siege of Caffa.
- Panic due to ignorance of transmission; various conspiracy theories about caused but mostly incorrect.
- Resulted in population decline and socio-economic ramifications, increasing labor demand led to wage increases.
- Cultural and political influence of the church diminished due to clergy losses during the outbreaks.
Third Plague Pandemic (Mid 1800s - 1900s):
- Originated in China, related to wild rodent reservoirs; widespread via trade routes and steamships.
- Estimated to kill 15 million over the century, including major effects on regions like Hong Kong.
- Key scientific discoveries (e.g., isolation of Yersinia pestis by Alexandre Yersin).

Historical treatments: ineffectiveness of bloodletting and herbal remedies.
Introduction of quarantine measures and lazarettos; early public health responses.
Discussion of plague doctor outfits and their significance established.

Plague remains a treatable disease with antibiotics:
- First antibiotics tested included sulfanilamide and later streptomycin (1947).
- Gentamicin (1980s) recognized for its effectiveness with lower toxicity.

Historical attempts at vaccinations; no widespread effective vaccine yet developed, focus remained on antibiotics.
Surveillance for antibiotic-resistant strains remains critical due to historical impact.

Plague cases reported globally between 1,000 to 2,000 per year; concentrated in regions of Africa and some parts of the USA.
Presence in animal reservoirs remains a concern; monitoring protocols are in place for potential bio-warfare.

Comparison of smallpox to plague: distinct causative virus (variola virus) encountered by the human population with massive mortality rates;
- Estimated deaths ranged between 300-500 million in the 20th century alone.

Variola virus: double-stranded DNA virus with specific replication mechanisms.
Transmission: respiratory droplets and contaminated objects; can spread from mother to fetus.
Characteristic symptoms progression identified across six stages of the disease.

Antonine Plague (165 AD):
- Documented symptoms attributed to smallpox; substantial impacts on the Roman Empire.
- Persecution of Christians due to association with outbreak theorized.
Spread and Effects on Society:
- Overview of smallpox's dissemination and its ties to military and economic upheavals.
Impact on Indigenous Peoples of the Americas:
- Introduction by European colonizers; many indigenous populations decimated due to lack of prior exposure to the virus.

Inoculation practices: early variolation methods of introducing mild smallpox to confer immunity noted through history, particularly in China and India.
Edward Jenner’s contributions: pivotal advancement through cowpox vaccination — the foundation of modern vaccination protocols.

Global vaccination campaigns led by WHO: eradication success by 1980; stockpiling of virus remains a concern.
Classification of smallpox as a biological threat, necessitating continued vigilance and preparedness for potential re-emergence.

Ethical considerations surrounding the historical and present-day implications of emerging infectious diseases as potential bioweapons. Reflect on the balance between advancing medical research and ensuring societal safety against potential misuse of knowledge.