Midterm 3 Flashcards
Malaria: mentions in history
- 4700 ya: Chinese med texts
- 2nd c BC: Chinese describe Ginghae (artemisia) plant
- New World: quinine, medicinal bark
Malaria: microorganisms
- Multi-cellular protozoa, genus Plasmodium spread by Anopheles mosquitoes
- P. vivax
- P. ovale
- P. malariae
- P. falciparum
P. vivax
- Seldomly fatal
- Most ancient, also affects apes
- Infects young red blood cells
- Dormant liver phase
P. ovale
- Rarest, W Af
- Infects young red blood cells
- Dormant liver phase
P. malariae
- Mild, world wide
- 4 day fever
- Infects old red blood cells
- Can persist sub-clinically for many years
P. falciparum
- Most prevalent and severe
- Infects red blood cells of all ages –> parasitemia
- Rapidly fatal (can -> cerebral hemorrhage/anemia)
Malaria: mosquitoes
- Anopheles gambiae and fenestus
- Flourish in tropical, still, warm water; deforested habitats; ag; irrigation
Malaria: Discoverers
- Charles Laveran: noticed parasites in blood
- Ronald Ross: demonstrated transmission by mosquitoe
Malaria: Symptoms
Classic cyclical presentation:
- Cold stage
- Hot stage
- Sweating stage
- Feel well -> then start over again
- Can have many diff complications: renal failure, hypothermia, etc.
- Characteristic of malaria, allows for historical ID
Malaria: causes of death
- Anemia: destroys red blood cells
- Cerebral: damages brain, other vital organs
Malaria: life cycle
- Inoculation into human, grows in liver cells
- Infects red blood cells (clinical manifestation)
- Differentiates sexually, ingested by mosquito
- Starts over again
- Complex life cycle=long evolution
Malaria: global distribution
- Mostly poor, sub/tropical areas
- 91% of deaths in Af, others in E Med, SE Asia
- 86% of deaths are children (no time to develop immunity)
Af: why most affected by malaria?
- Still slash and burn ag
- Falciparum=most common
- Climate: year round transmission
- Socio-econ instability (can’t afford nets)
Sickle cell anemia
- Long co-ev in Af -> high rates of sickle cell anemia
- Causes blood cells to change shape (can’t inhabit)
- Homozygous: die of anemia
Malaria: who is vulnerable
- Children
- Pregnant women
- Travellers/migrants
NA
- Was endemic, far north as Ottawa valley
- Anopheles mosquito brought w/slave trade
- Elimination: destroying breeding sties, screens, quinine treatment
Malaria Eradication Programs
- WHO, 50/60s
- Drain swamps
- Larvacides
- DDT spraying
- Paris Green
- Domestic mods w/socio econ improvements: screens, AC, safe water, indoor plumbing, nutrition, campaigns
Carson
Silent Spring
- Malaria eradication -> huge enviro probs
- May -> cancer
- Led to worldwide ban but only after eradication in NA
Roadblocks to eradicated malaria
- Cultural trash -> breeding outside natural settings
- Airport malaria
- Politics: civil wars -> hard to treat
- Not well funded by W agencies
Anti-malarial agents
- Chinchona: source of quinine (Peru)
- Chloroquine: artificial quinine (extremely effective)
- Artemisia: source of Artemnisinin (combo therapy for MDR strains)
Origins of malaria
-Gorillas in W Af (Congo, Gabone, etc.)
Cholera: micro organism
- Bacteria Vibrio cholerae
- Diff strains code for diff enterotoxins (-> flushing, fluid loss)
- Biotypes: Classical, El Tor
- Genetics: most pathogenic strains are 01 (^), also 0139
- Evolution through horizontal gene transfer (switching genes, recombo)
Cholera: symptoms
- Abdominal fullness, lack of appetite
- Circulatory collapse (sunken image)
- Vomitting
- Rice water stools
Cholera: recovery and fatality
- Oral rehydration therapy (effective, cheap)
- Healthy carriers: shed back into water
- MR: treated <1%, untreated 50-75%
Cholera: transmission and reservoirs
- Contamination of water/food
- Ppl/water: only major reservoirs
- Disease of social disparity: poverty (drinking water), developing economies (lack of infrastructure)
Cholera: origins
- Unclear, associated w/growing pop density (could have been around before)
- Ancient descriptions: Sanskrit, Chinese, Egyptian
- Hard to distinguish f/other diarrheal diseases
Early sanitation and cholera
- Rome: sewers and aqueducts, latrines well constructed (prob no cholera)
- Medieval Eur: very poor sanitation (tout a la rue, limited access to clean water)
Cholera: early endemic foci
- Late 15th c: Bengal region of India/Bangladesh
- Early 1800s: Ganges and Brahma Rivers (great diversity of vibrio here = origins?)
Initial spread of cholera (outside India)
- Likely began in 1817 near Calcutta
- Associated w/British imperialism, globalization
- Moved to Europe after 1830s
Pandemics of cholera outside India: rough dates, types
- First 4 (starting 1817): unknown biotypes
- 5 and 6: 01 classical
- 7 (1961+): El Tor
- 8: 0139
Second cholera pandemic: background, reached NA
- Industrial rev -> growth of slums, couldn’t manage sanitation
- Reached NA by 1831, Ham by 1832
Role fracturing societies: 2nd pandemic
-Associated w/filthy places, inhabitants -> social unrest (ex: Paris)
Responses to 2nd cholera pandemic:
- Maritime quarantines: opposition
- Pre-mature burial
- Helpless therapies: bloodletting, smoke
- Public health: med journals, sanitary surveillance
Cholera: third pandemic
- Waterborne transmission proposed (John Snow) but not accepted
- Emphasis on sanitary improvements
Cholera, third pandemic, Philadelphia
- Densely populated, between two rivers
- Doesn’t show on skeleton, but museum had gut samples (base of all known classical strains, origins during humidity drop in India, setting on waterways
Cholera, 7th pandemic
- Spread f/Bay of Bengal, several waves
- El Tor
- Less virulent, but can survive longer out of water (fruit, etc.)
- About socio-econ disparity
Cholera: Peru
- 1991 +
- El Tor Biotype
- Relatively low case fatality rate (<1%): info, oral rehydration therapy
Peru: Causative Factors
- Rapid urban growth –> shanti towns (lacked housing, water, sanitation, untreated waste going into water)
- Econ crisis and structural poverty
- Declining public health
- Sewage as fertilizer when water is scarce (-> spread)
- El Nino: warming -> increase in zoo plankton that carry it
Cholera: what does/doesn’t work for treatment
Doesn’t:
- Repressive controls (quarantine) –> hidden cases
- Mass immunization: $, short term
Does:
- Safe water, excreta disposal
- ID, investigation, case reporting (facilitated by good labs, public health systems)
- Access to social, econ resources
Peru: costs of cholera outbreak
- 300k cases that year
- Low case fatality
- Econ loss: $770m (tourism, trade embargoes)
Background to Haiti cholera outbreak
- Structural poverty: 80% below poverty line
- Decades of political violence (no infrastructure)
- Poor sanitation, access to safe water
- Post-earthquake: no cholera
Haiti: type of cholera
- El Tor, sero group 01
- Particularly virulent, higher fatality rate
Haiti: how did it spread
- Traced f/UN base house in Meille, outbreak coincided w/their arrival
- W/in two months, consumed entire country
- Denied by UN, there for imperialist reasons (failed state, security risk)
