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PLAGUES AND PEOPLE LEC 2 - CHAPTER 3 & 4 - Plagues of Antiquity Bubonic Plague (Black Death).docx

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Health Studies
Caroline Barakat

PLAGUES AND PEOPLE CHAPTER 3 – SIX PLAGUES OF ANTIQUITY (5000 BC to 700 AD) 2 million years ago, human populations were not exposed to infection because of small-group hunter gatherers -only diseases with very high transmission rates that induced little to none immunity, & macro parasitic diseases not involving vectors for transmission and STD’s were able to establish themselves in groups of hunter-gatherers malaria and yellow fever came more existent after human populations settled down agriculture provided increased amounts of food for the people, but it also contributed to the conditions that would result in a decline in human health -urban life enhanced the transmission of certain diseases through the air and water, by direct contact, and by vectors such as snails, mosquitoes, and flies. The diseases of antiquity (5000 BC to AD 700) were characterized by parasites with long-lived transmission stages (ex: eggs) as well as those involving person-to-person contact THE PHAROAHS’ PLAGUE (snail fever/blood fluke/ endemic hematuria) 1900 BC: Hematuria – a disease that causes blood to appear in the urine -was described by the father of Arabian medicine, Avicenna disease undergoes transmission stages Tomb of Ptah-Hetep I and Mehou of the VIth Dynasty at Sakarrah - figures of fisherman and bargemen with enlarged abdomens, representing the pathology of chronic snail fever or blood fluke disease -found the calcified eggs of the blood fluke in the kidneys of mummies Fossil snails capable of transmitting blood fluke disease have been found in the well water of Jericho -people of Jericho defeated by Joshua’s army b/c of disease and inability to repair the decaying walls -Joshua destroyed Jericho to prevent disease and remained deserted for 500 years Snail Fever – existed in tropical and subtropical parts of the world, especially in Egypt Blood Fluke disease– not a fatal disease, (unlike malaria and yellow fever), but it is a corrosive disease Early civilizations of Egypt were based on agriculture (required irrigation and/or flooding by rivers) -caused conditions favourable for the transmission of snail fever caused by the blood fluke - Cause of snail fever : set Egyptian civilization on its inexorable downward spiral, was unknown to ancient Egyptians because the transmission stages of the parasite (eggs, miracidia, and cercariae) are microscopic. (adult worms are tiny and live within the small blood vessels, so they were unnoticed) Blood Fluke – also known as snail fever, endemic hematuria, involves feces or urine, water, snails, and a flatworm symptom: bloody urine (worms were found in blood vessels by Theodor Bilharz, a German physician working in Egypt Theodor named the worm Distomum Haematobium but later changed to Schistosoma (split-body) Today, Blood Fluke is calledSchistomiasis or bilharzia Bilharz reported seeing microscopic eggs with a pointed spine in the female worm - he observed eggs found in the bladder and within egg, he observed a small, motile embryo. -eggs would hatch to release small ciliated larva that swam for an hour and disintegrate -infected by eating infected snails or by drinking water containing the ciliated larvae called miracidia -eggs did not hatch in urine, but they did in fresh or brackish water Schistosoma japonicum – eggs without a spine (found in Southeast Asia and the Western Pacific) Schistosoma mansoni – eggs with spine on the side (found in Africa, Brazil, Venezuela, and the Caribbean) tailed larva called a cercaria emerged from infected snails and could directly penetrate the skin of mice -suggested that the infection was acquired by bathing in infested water Leiper identified the snails Bulinius and Biomphalaria as the vectors -he showed that when cercariae was placed in hydrochloric acid, they were killed -also showed that the adult S. mansoni and S haematobium were different from each other and that cercariae that hatched from Biomphalaria produced eggs with lateral spines -cercariae hatched from Bulinus produced eggs with terminal spine S. Mansoni remained in the liver and laid its eggs there S. Haematobium early in development left the liver for the veins surrounding the bladder Life cycle: -reach fresh water -discharge eggs releasing swimming larva called Miracidia -Miracidia are short-lived, penetrate the soft-tissues, migrate to the liver, a change form (sporocyst) -6-7 weeks, by asexual reproduction, parasites increase -during that time, snail sheds thousands of fork-tailed cercariae, which can swim and directly penetrate human skin -5-8 weeks, develop into adult worms Snail Fever, the disease schistosomes: sexes are separate and they inhabit the blood vessels -adult worms are ~10mm in length, stouter males have groove running lengthwise, called the gynecophoric canal where female resides -adults live in blood vessels close to the bladder and small intestine -mating occurs in the gynecophoric canal, then paired worms move “upstream” into smaller veins where female lays eggs -each day, 100s of embryo-containing eggs move across the walls of the veins into the bladder or intestine, aided by the hosts inflammatory response, then eggs become enclosed in a small tumor called a granuloma it is the passage of eggs through the bladder wall that results in bleeding and gives the signal of hematuria -once in the bladder/intestine, egg becomes freed of granuloma and is eliminated from the body through urine/feces more than 2/3 of eggs are washed back in the veins by bloodstream and scattered throughout the body -accumulation is greatest in liver and spleen -piling up of eggs block blood flow leading to tissue death Earliest signs of infection occur within 1-2 months: -fever, chills, sweating, headache, and cough Six months- 1 year: -accumulation of eggs increased, especially in liver and spleen. (enlarged liver causes the abdomen to become bloated, appetite diminishes, blood loss Origins Schistosomiasis probably first occurred in animals living in the rainforests and lakes of East Africa and then spread along the Nile and out into Middle East and Asia Blood Flukes occur in birds and mammals other than humans ”swimmer’s itch” or “cercarial dermatitis” is found in lakes and along the seashore in Michigan, Minnesota, Wisconsin, New Jersey, and New England that normally infect aquatic birds and mammals -skin rash are the result of their failure to continue their migration past human skin tartar emetic (treatment for schistosomiasis) The Plague of Athens Athenians defeated by Spartans high death rates including ‘’pericles’’ identity of this plague – unknown to this day Some suggested that it seems like typhus because it had symptoms include: fever, rash on extremities, pustules. The Roman Fever mosquito vector 0 malaria became prevalent thought to results from “bad air” epidemics every 5-8 years enlarged spleens due to malaria have been found in Egyptian mummies more than 3000 years old -malaria has been detected in lung and kin samples from mummies dating from 3204-1304 BC malaria probably came to Europe from Africa via the Nile Valley or from close contact between Europeans and people of Asia Minor symptoms: enlarged spleens, headaches, periodic chills, and fever Greek physician Hippocrates discussed in “Of the Epidemics,” two kinds of malaria, one with recurrent fevers every third day (Benign tertian) and another with fevers on the fourth day (Quartan) - today, they care called Plasmodium vivax and Plasmodium malariae Hippocrates believed that the intermittent fevers were the result of an imbalance in the body’s fluids (bile, blood, phlegm) brought by drinking stagnant marsh water Hippocrates did not mention the deadly tertian malaria (Plasmodium Falciparum), so we suspect that it did not exist or was rare -overtime, mosquito vector competence increased, the highly virulent P. Falciparum came to be established in Europe by the second century AD, and from that time onward it plagued the Romans Plagues and The Rise of Christianity Epidemic – smallpox struck the city in AD 65  believed to be brought by Roman troops campaigning in Mesopotamia role of religion was to appease the multitude of gods so that the worshippers would receive some benefit The early Christians had a moral ideal: they separated themselves from pagan idolatry and espoused universal salvation. -however, the Romans simply regarded Jesus as a minor political rebel whose followers could be used as convenient scapegoats as a results, Christians were blamed for all types of disasters, including plagues, inflation,
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