lecture 8: gibraltar case study 1804

the perfect urban mosquito life: (4)

• warm temperature - more blood meals

• clean/still water for breeding

• absence of predators in their breeding spaces (ex: goldfish love to eat mossie larvae)

• humans for biting

mosquito control measure types:

either direct control of mosquitoes or individual level control through reducing human contact with mosquitoes

direct control of mosquitoes: (3)

• larvicide or insecticide

• eliminate water or add oil to standing water (dirty water = no more breeding)

• top down - community based

reducing human contact with mosquitoes: (3)

• screening buildings (homes)

• mosquito repellent

• protective clothing

gibraltar: (5)

• british colony in 1830 (with civillian population)

• british ‘found it’ in 1704 - took it from spain; wanted to set up a garrison post (soldiers/navy) where they can guard the gates to the mediterranean or the atlantic ocean

• originally a fortified garrison post

• tension between spain and britain (i.e. give gibraltar back) - currently still belongs to the UK

• gibraltar important relationship with morocco - large population in a locale where you cannot produce any food

gibraltarians meaning:

refers to the civilian population of gibraltar

gibraltarians: (3)

• fusion: european, north african, mediterranean peoples (spanish residents were booted out)

• 19th century: ‘motley’ population; including seedy adventurers and fortune hunters - very dynamic place with lively people

• religious diversity: anglican, catholic and jewish

gibraltar economics: (4)

• commercial centre - became a tax free zone which attracted more for trades

• naval port and garrison (location is still to this day an important strategic position)

• coaling station - major part of economy

• all features enhancing the introduction and transmission of disease (people coming from all walks of life

interconnectedness of gibraltar:

long distance communication (via trade, colonialism, military activity) facilitating the movement of people and disease

history of yellow fever epidemics in nearby spain - since the disease was not endemic in spain - how/why was yellow fever periodically introduced?

interconnectedness of gibraltar and spain - ex; santo (1st reported victim and known ‘vector’) brought yellow fever from spain back into gibraltar, on his way back from a trip to spain he returned hastily to gibraltar right as it was closing its gates to spain due to hearing of the epidemics there…

1804 was the 1st time…

YFV was introduced to the new-ish civilians of gibraltar (the established british settlers)

an epidemic of YFV in spain did not always indicate…

an epidemic in gibraltar

how did authorities suspect yellow fever entered gibraltar in 1804:

through boyd’s building - 1st case identified in boyd’s building - Santo got it first ; as gibraltar was about to close the gates between it and spain where yellow fever was spreading - santo rushed home before the gates closed

• obviously was probably more than just santo himself who did this

was the arrival of an infected individual (or, more likely, individuals) enough to cause a yellow fever epidemic?

no! however gibraltar fit the delicate balance perfectly (all needed factors)

a delicate balance:

• must have aedes aegypti (vector)

• everyone in gibraltar at this time was vulnerable to the virus

YFV origins:

virus analyzed - Africa origins (through genetic analyses): aedes aegypti moved abroad/via shipboard travel

is YFV in canada?

no it was never established in canada

• eradication & vaccination programs

travel & trade routes:

• facilitated the movement of vectors and viruses

• ex: linkage between africa and the americas in the colonial slave trade

aedes aegypti aboard ships: (3)

• tolerates brackish and water - but higher salt concentrations = lethal

• aedes found barrels (of clean drinking water) - ideal location for breeding

• additionally the bilge (area at the bottom of the ship) can be potentially quite dirty water but may also serve as a breeding area as long as water wasnt too salty

when aedes aegypti finished their sailing…

they were first established in sylvatic cycles (with indigenous ‘forest mosquitoes’ - genus haemagogus)

• where sylvatic is natural area/rainforest area

how much did aedes aegypti manage to spread?

insanely widespread with it being in established in 134 countries atleast but not in canada notably

contagionist vs. noncontagionist (miasmatic) perspectives: how did beliegs about disease transmission/prevention differ?

• miasmatic perspectives interpreted dead fish or open sewers (other gross/dirty/rotting/smells) caused the virus (pre-germ theory thoughts)

• contagionist perspectives viewed the disease as derivative of contact with an infected individual

who were nooth and pym and how did their actions viz. yellow fever differ?

• nooth was gibraltars original medical officer of health and one of the garrison’s leading supporters of thr noncontagionist theory of yellow fever causation - he visited all of the worst cases of yellow fever not backing down from his conviction that the disease was not spread by personal contact - nooth contracted yellow fever early on in the 1804 epidemic and died shortly after

• pym succeeded nooth as medical officer of gibraltar and had the opposite contagionist view of contraction; any contact with individuals from infected spanish cities and as a threat to gibraltar

what local factors increased the risk of disease transmission in gibraltar? (3)

• water in gibraltar: access to potable water depended entirely on the civilians ability to collect rainfall (only clean water native there) - poorer classes relied on smaller less expensive means of capturing rain (buckets, tinajas, earthen jugs) - this dependence on water storage in containers contributed heavily to the epidemic (suitable vector breeding)

• very overcrowded - patio living

• government ordered door and window open policy allowing mosquitoes even more reign over the population

what became a central concern thereafter? (3)

uncontrolled immigration

• ex: committee for the preservation of public health

• led to reforms on immigration policies; gibraltar intended to be the jewel in england’s crown but quickly became her greatest curse

at all costs gibraltar wanted to avoid what…

quarantine!

why did gibraltar wish to avoid quarantine? (3)

• they have no food source for themselves (ex; bartering on the neutral ground, everything traded from spain was dipped in vinegar)

• they are an economy based on ships coming and going

• everyone suffers (if quarantine occurs)

who was scapegoated in gibraltar’s yellow fever epidemics and why?

the british committee (of 5 white men) said the cause of the 1804 epidemic was the jewish immigrants

• gibraltar was very expensive - the poor/immigrants were made to be scapegoats from their ‘filth’: cost of potable water escalated (in summer droughts) making some of the poor consume well water which was contaminated to the point that it was intended only for washing cooking utensils and clothing

juan pena 1828:

granted a fever pass - social significance of ‘acquired immunity’ (even before germ theory)

• if you had yellow fever previously and survived it you were exempt from quarantine and such because you will not get sick again

how bad was the 1804 epidemic?

it was particularly devastating - approximately 5000-6000 deaths (many more in civilian relative to military polulation)

why did more civilians die than soldiers in gibraltar?

• probably due to educated immune systems because soldiers would move between many posts - therefore they were exposed to yellow fever in another locale (basically a fever pass)

• stationary civilian population did not have educated immune systems

story of the ‘population pyramid’:

describes the demographic of 30 and over folks being lost to the population after YFV in 1804 - irony of the community not being able to function without (immigration) constant influx of new people, as they blamed immigration as the cause…

despite local attempts to curb the epidemic… what was most critical in marking the end of the 1804 YFV epidemic?

the temperature drop!

• ‘waiting for the frost’ - cold temperatures; below 15*C/59*F - Aedes aegypti become lethargic/nonfunctional

• observed that the disease waned and left with the arrival of frost