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HLTB21H3 (100)
Chapter 7

Chapters 7, 8, 9


Department
Health Studies
Course Code
HLTB21H3
Professor
Caroline Barakat
Chapter
7

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Small pox – variola vera
Origin-old world disease and an indiscriminate disease, 10000BC first agricultural settlements in NE Africa and spread to
India by means of ancient Egyptian merchants, earliest evidence on mummies (1570-1085BC)pharaoh ramses v died
1156BC – pockmarks,
1122BC in China mentioned in ancient text of India, 100ADplague of Antonine, Europe: frequent epidemic during middle
ages,
16th century became a serious disease in England and Europe
Effects-new world 16th century – fall of the empires of the Aztecs and the Incas, contributed to the settlement of N America
by the French & English (1617), biological warfareFrench Indian War (1754-1767) deliberate use of smallpox, slave trade
Etiology-virus: genusOrthopoxvirus(also includes: monkeypox, cowpox, camelpox virus etc.), family Poxviridae, at least
two strains exist: variola major and variola minor, variola minormortality rate is less than 2% in unvaccinated persons,
mortality rate for variola major3% in vaccinated individuals and 30%-50% in unvaccinated, hemorrhagic smallpox
(blackpox) 1.malignant and hemorrhagic forms of variola major develop in approximately 5-10% of infected people 2.almost
always fatal; mortality rate of 95%
Transmission-continuously transmission required, only short term carriers, animals reservoirs do not exist, direct contact
inhalation of aerosols or contaminated fomites, virus multiples in the mucous membranes of the mouth and nose then moves
to the lymph nodes and then to internal organs and there it re-enters the bloodstream, infectious virus – oronasal secretions
and in skin scabs, potential for long distances aerosol spread is controversial , transmission on fomites possible for short
periods of time, virus only remains viable for up to 2 days outside human host, average incubation period of 12-14 days
Clinical Manifestation-acute onset-fever, malaise, rigors, vomiting, headache, backache, and occasionally delirium
-2-3 days later skin lesion appear, 8-14 days after symptoms appear the pustules develop scabs and heal (can lead to severe
scarring), infectious – day prior to the appearance of the rash and until the time the scab have separated, secondary
infections, distributions - most on the face, hands and feet
Epidemiology-18th century-60 million Europeans, case fatality rate varied from 20-60%, 1/3 of survivor became blind,
acquired immunity – disease of childhood, epidemic every 5-15 years
Variolationinoculation-earlier treatment-prayer and quack remedies, instillations of smallpox virus into non immune
individuals, practiced initially in Africa, India and China, 1670 – introduce to Turkish Ottoman Empire, Europeat the
beginning of the 18th century , simultaneous practices in Boston 1721
-Lady Mary Wortley Montague (1689-1762)
-contracted sp in 1715, 18 months later brother died of illness, 1717 husband was appointed ambassador, learned about the
variolation practiced at the Ottoman court, inoculated 5 year old son in 1718, 4 year old daughter inoculated in the presence of
physicians of the royal court (London,1721), royal experiment, repeat of experiment on orphaned children, variolation
gained acceptance in the Royal family, 2-3% of variolated persons died from the disease, case fatality rate associated with
variolation is 10 times lower than that associated with naturally occurring sp, 1721 Boston epidemic which lead to regular
practice of variolation in N America it was a controversy 14% compared to 2% amond variolated individuals
-Edward Jenner (1749-1823)
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-variolation led to the practice of vaccination, controversy over who started vaccination, he planned the experiments, 1796
Jenner found a young dairymaid Sarah Nelms who had fresh cowpox lesions, inoculated an 8 year old boy James Phipps,
inoculated boy again this time with matter from a fresh sp lesion, no disease developed, gradually variolation became
prohibited in England
SpCanada-1796 Dr.John Clinch forwarded a letter to Dr.Edward Jenner in Gloucestershire requesting info about using
cowpox pustule matter; -1799 vaccinating people in Newfoundland
Development in the 20th century
-late 19th century realized that subsequent revaccination was necessary
-1950s sp was eradicated in many areas in Europe and N America
-1958 report of sp in 63 countries
-program of eradication began in 1967, global campaign succeeded sp eradicated in 1977, May 8 1980 World Health Assembly
announced that world was free of sp
-August 1978 Janet Parker (1938-1978), university of Birnimgham Medical School, her mom contracted the disease but
survived, radical changes in how dangerous pathogens are studied, debate over stocks of vaccine, transmitted via aerosol
through vents under her apartment was a lab, owner of lab committed suicide
Measles (rubeola, hard measles, red measles, morbilli, hasbah)
Historical perspective-earliest description attributed to Rhazes(900AD)-clinically separated sp and measles-believed that
both proceeded from the same cause, prevailing theory-red rash came represented moms menstrual blood, measles was a way
for child to rid himself of the so called poison”, origin of term measles misellus or misella” ie. Miserable
Modern history
-1670 Thomas Syenham observed clinical features; description of sons attack, clearly separated measles from sp and
recognized complications such as cancrum oris and encephalitis
-scientists rejected the mother’s blood theory
-1757 Francis Home demonstrated the infective nature, he succeeded in transmitting measles using blood from an infected
child
-Peter Ludwig Panum (1820-1885), sent by Danish government to investigate an epidemic in Faeroe Isles in 1846, conducted
the first epidemiology study, geographic location ideal for an epidemiology study, approx. 7800 inhabitants – 102 died of
measles , arrival of
boats noted in the local calendar, visits from the Danish mainland were rare, epidemic originated in a single seaman from
Copenhagen, on arrival he had not recovered completely, followed the course of the epidemic, was able to establish 4
important facts
1.rash appears 12-14 days after contact with an infectious person 2.infectivity is greatest 3-4 days before the rash appears
3.contagious nature of diseaserespiratory route of transmission 4.life lone immunity
Recent history 20th century
-1910 Hektoen(1863-1951)
-1963 Enders(1897-1985) isolated virus and produced vaccine, 1969 discovery of relationship between measles and a rare
degenerative diseasesub-acute sclerosing panencephalitis, occurs 1 in 100000, develops 5-10 years after acute measles
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