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Week #2 - Sherman Ch. 3, 4; Kiple P. 612-615.docx


Department
Health Studies
Course Code
HLTB21H3
Professor
Caroline Barakat

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(Reading) Week #2 | Sherman Ch. 3, 4; Kiple p. 612-615
Chapter 3
Six Plagues of Antiquity
- diseases of antiquity (5000 BC to AD 7000) were characterized by parasites with long-lived transmission stages as well as those involving person-to-person contact; thus, most
diseases became established only when a small number of infectious individuals could be maintained (when the disease became epidemic), which required population greater than
a few hundred thousand
The Pharaoh’s Plague (Nile Valley of Egypt) (snail fever/blood fluke disease) (endemic hematuria/schistosomiasis)
A look back
- causes blood to appear in the urine (hematuria)
- widespread
- chronic snail fever or blood fluke disease
- water was infested with infected snails, resulting in a high level of disease
- food production spread to other parts of Eurasia and North Africa; plants and domesticated animals also cultivated in the Nile Valley of Egypt, which triggered the rise of Egyptian
civilization; however, also sowed the seeds of Egypt’s decline
- deserts that bordered the Nile discouraged invasion, so people lived in relative security
- all power was invested in the pharaohs, who were both kings and gods
- below the pharaoh was a vast bureaucracy that included workers and peasantry
- early civilizations of Egypt of those of the Fertile Crescent were based on agriculture, which required irrigation and/or natural flooding of rivers; irrigation farming created
conditions favorable for the transmission of snail fever caused by blood fluke
- blood fluke disease: corrosive disease
- rule of pharaohs may have been due to the power of the snail and blood fluke and malaria, which debilitated the populace
- by 660 BC, Egypt became subject to internal political discussion and attack by the Assyrians, and their civilization, based on agriculture and copper weapons, collapsed; Persians
overran in 525 BC
- cause of snail fever was unknown because of the transmission stages of the parasite (eggs, miracidia, and cercariae) are microscopic; as well, the adult worms themselves are tiny
and live within small blood vessels, so they were unnoticed for thousands of years
Search for the destroyer
- blood fluke disease involved feces or urine, water, snails, and flatworm
- soldiers of Napoleon’s army first to experience the disease during invasion of Egypt
- bloody urine high frequency in men
- connection between hematuria and a parasite was not made until Theodor Bilharz made a discovery that worms were found in the blood vessels, a location never encountered;
worms called Distomum (―two mouths‖); in 1858, name changed to Schistosoma; today, called schistosomiasis or bilharzias
- Bilharz reported seeing microscopic eggs in a pointed spine in the female worm; in the following year, he observed these eggs in the bladder, and within the egg he observed a
small, motile embryo; also found that the eggs would hatch to release a small, ciliated larva that swam around for about an hour and disintegrated
- John Harley, examining the blood-tinged urine in a drop of water under the microscope, found schistosome eggs, several of which hatched to give progeny that swam by using
their cilia
- suspicion remained that humans acquired the infection either by eating infected snails or by drinking water containing the ciliated larvae, called miracidia
- Spencer Cobbold found that the eggs hatched in fresh or brackish water
- Japanese physicians found that a related blood fluke, named Schistosoma japonicum, could also infect humans, but this species had eggs without a spine
- Patrick Manson discovered another type of schistosome egg, one with a spine on its side; named Schistosoma mansoni
- miracidia able to penetrate freshwater snails in the rice paddies, and a tailed larva (cercaria) emerged from infected snails and could directly penetrate the skin of mice
- snails Bulinus and Biomphalaria as vectors
- infection acquired by bathing in infested water
- cercariae that hatched from Biomphalaria produced eggs with lateral spines, where those from Bulinus produced eggs with a terminal spine
- S. mansoni remained in the liver and laid its eggs there, whereas S. haematobium early in its development left the liver for the veins surrounding the bladder
- life cycle of snail fever: on reaching fresh water, the discharged eggs releasing a swimming larva, miracidium, which are short-lived, but if they encounter a suitable snail, they
penetrate the soft tissues (usually foot), migrate to liver, and change in form (sporocyst); for 6 to 7 weeks, by asexual reproduction, numbers of parasites increase; snail sheds
thousands of fork-tailed cercariae, which can swim and directly penetrate human skin and in 5 to 8 weeks, they develop into adult worms
Snail fever, the disease
- sexes of schistosomes are separate and inhabit the blood vessels
- adults live in blood vessels close to bladder and small intestine
- pathology of schistosomiasis is due not to the adult worms but to the eggs
- passage of eggs through the bladder wall that results in bleeding and gives the sign of hematuria
- more than two-thirds of eggs fail to work their way out of the body and are washed back in the veins; by bloodstream, they accumulate in the liver and spleen; the piling of eggs
blocks the normal blood flow, and this leads to tissue death
- earliest infection occur within 1 to 2 months and are fever, chills, sweating, headache, and cough
- six months to a year later, the accumulation of eggs produces organ enlargement in the liver and spleen, which causes the abdomen to become bloated, appetite diminishes, blood
loss leads to anemia, and there is dysentery
- schistosomiasis is arithmetic disease: severity of symptoms and damage related to number of worms present, and latter depends on the degree of exposure
- over the centuries the adult inhabitants of areas of endemic disease, such as Africa, developed some immunity, as a result of continuous exposure; Europeans and Americans, with
no immunity, suffer more severe symptoms as a result of higher worm burdens
Where snail fever is found
- wars and human migrations carried blood flukes of East Africa lakes to Nile River, and from there they were distributed along the trade routes to most continents of the world
- estimated 200 million people infected, more than a million deaths annually
- S. japonium found in Southeast Asia and western Pacific as well as China, Philippines, Indonesia
- S. haematobium and S. mansoni found in 43 countries in Africa, but S. mansoni also found in Americas (Brazil, Suriname, Venezuela, Caribbean)
- individuals infected and reinfected almost daily as they paddle through the cercaria-infested waters that they have come to use as their outdoor toilets
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- estimated 50 million cases in Africa; highest in children
- the Aswan High Dam of Egypt, by controlling the level of water in Lake Nasser, has brought electricity to many parts of Egypt as well as making it possible to cultivate four crops
per year through year-round irrigation; but also created favorable conditions for the schistosome-carrying snails
- schistosomiasis first occurred in animals living in rainforests and lakes of East Africa and spread, with vector snails, along the Nile and out into Middle East and Asia via trade
routes
- blood flukes also in birds and mammals
Snail fever today
- preventive measures include education of the population in means to prevent transmission, treatment of infected persons, and control of snail vector using molluscicides
- human exposure can be reduced by safe water supply for bathing and washing as well as sanitary disposal of human wastes
- other measures may be lining irrigation channels with cement to discourage snails, intermittently irrigating rice paddies to disrupt the life cycle, or storing water away from snails
for 2 to 3 days
- earliest treatment required intravenous administration; 1929, intramuscular injections of another antimony compound (tartar emetic), stibophen used, but cure rates were not as
good as those with tartar emetic; both drugs showed severe toxic reactions and sometimes death
- later, an oral drug with low toxicity was developed: praziquantel
- no preventive vaccine or drug for this disease
- failure to control schistosomiasis due to the cost of molluscicides and drugs, as well as infrastructure for providing clean water and sanitary disposal of wastesbut it is the habits
of human population that are critical importance to elimination of this disease
The Plague of Athens (Ethiopia > Egypt > Athens)
- land and climate of Greece were unsuitable for farming grains; as a result, the economy rested on the large-scale movements of goods by ship
- planted vines and olive trees and produced wine and oil
- democratic society: states consisting of a city and its surrounding lands whose inhabitants, citizens, were valued (slaves and women did not have same rights)
- city-states consisted of urban centers dedicated to commercial transactions
- inhabitants were healthy but not immune to diseases that were endemic in Middle East
- at close of Dark Ages, there emerged two powerful city-states that were essentially military garrisons governed by commander and his captains: Athens (in Attica) and Sparta (on
the Peloponnesus); each city-state represented opposing philosophies: stern military discipline in Sparta versus intellectual and political freedom in Athens
- Peloponnesian war began between these two city-states in 431 BC, lasted for 27 years; outcome determined by a disease
- in 430 BC, an epidemic that started in Ethiopia moved into Egypt and from there was brought by ship to Piraeus; raged about 2 years and killed about one-fourth of the Athenians
- typhus is characterized by fever, pustules, and a rash of the extremities; known as ―doctors’ disease‖ from its frequent incidence among caregivers; confers immunity; the rash of
Thucydides’ description does not precisely match that of typhus, nor does the state of mental confusion
- plague of Athens demoralized the citizenry, destroyed the fighting power of the Athenian navy, and prevented the launching of an attack against Sparta
- by 404 BC, Sparta deprived Athens of her navy, and her land defenses were raze
The Roman Fever (Africa via the Nile Valley > Europe) (malaria from air from Pontine marshes)
- malaria probably came to Europe from Africa via the Nile Valley or resulted from closer contact between Europeans and the people of Asia Minor
- Greek physician Hippocrates discussed the two kinds of malaria, one with recurrent fevers every third day (benign tertian), and another with fevers on the fourth day (quartan),
which are today called Plasmodium vivax and Plasmodium malariae; noted those living near marshes had large spleens; believed intermittent fevers were result of an imbalance in
the body’s fluids and brought about by drinking stagnant marsh water
- tertian malaria: rare, speculated that although this kind of malaria was periodically brought into southern Europe from North Africa and Asia Minor, such infections were
infrequent owing to the absence of a suitable mosquito vector in the Mediterranean
- with greater agricultural activities, including deforestation and soil erosion, conditions arose that favored the establishment of a suitable habitat on the shores of Europe for several
Asian and North African species of Anopheles mosquitoes
- highly virulent P. falciparum came to be established in Europe by the second century AD, and from that time onward it plagued the Romans
- flourishing trade with colonies became means by which infectious diseases were transmitted to the naïve populations in distant lands
- regular movement of goods and people to and from Rome made for spread of infections; thus, over time the chances of the Mediterranean population’s contracting an unfamiliar
infection became greater and greater
- malaria not public health problem in Italy, but devastating to the Roman Empire
- recurrent fever occurred during the sickly summer season was believed to be due to vapors emanating from the marshes
- Pontine marshes southwest of Rome lethal source of malaria
- in some unhealthy places, life expectancy was only 20 years of age, whereas in places where malaria was absent, life expectancy could be as high as 40 or 50
- in Roman Empire, malaria was disease of children, but illness also found among immigrants without immunity
- French and German invaders were repelled by the deadly fevers of the Pontine marshes
Plagues and the Rise of Christianity
- early Romans, at first, religion was animism: gods represented the spirits of water, rocks, fire, trees, beasts, sun, moon, stars, and lightning
- cults developed to worship specific gods at specific times (called holy days, or, later, holidays) and those who presided over cult rituals were called priests; these individuals were
neither moral nor spiritual
- Jesus’ preaching in the first century AD took the form of parables and miraculous healings; he encouraged the poor and the oppressed and spoke of forgiveness, detachment of
wealth and property, and special care for the outcasts and sick of society
- early Christians had a moral ideal: they separated themselves from pagan idolatry and espoused universal salvation
- at the outset, Romans regarded Jesus as a minor political rebel whose followers could be used as convenient scapegoats; as a result, the Christians were blamed for all types of
disasters, including plagues, inflation, fires, and even barbarian incursions; reasons: the Christians did not worship the emperor, they did not observe the pagan ritual acts, they
insisted that they alone possessed God’s truth, and Christ’s teachings were critical of the established order
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