Smallpox

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Department
Health Studies
Course
HLTB21H3
Professor
Caroline Barakat
Semester
Fall

Description
LEC06 SMALLPOX 11/4/2012 6:02:00 AM Origins Etiology Clinical manifestations Epidemiology Variolation Vaccination Disease origins  Old world disease and an indiscriminate disease o Has no relations to social class, economic status age o Anyone is susceptible to small pox o Human got this from fox like diseases  10,000 BC - first agricultural settlements in NE Africa and spread to India by means of ancient Egyptian merchants  Earliest evidence on Egyptian mummies (1570–1085 BC)  Pharaoh Ramses V (died 1156 BC) – pockmarks o Bears evidence of the disease o Pock marks, the lesions from the disease o Due to skin elasticity  Described1122 BC in China and is mentioned in ancient texts of India  100AD – Plague of Antonine o first epidemic of small pox, not confirmed o smallpox and malaria had contributed to the decline of the roman empire  Europe - frequent epidemic during the Middle Ages th  16 century became a serious disease in England and Europe Effects of smallpox  Plague of Antonine (1 episode) o Decline of the roman empire is a result of this o Started in Mesopotamia  New world in the 16 thcentury - fall of the empires of the Aztecs and nd the Incas (2 episode) o With intro of Spanish and Portuguese and had an impact on the aboriginals o Many people were susceptible and many people got infected  Contributed to the settlement of N America by the French & English (1617) (3 rd episode) o Introduced by early settlers o Led to the decline of natives o Epidemic amongst the Indians and made it easier for people to make a colony of their own Biological warfare (the first biological warfare)  French-Indian War (1754–1767) - deliberate use of smallpox o Hostile against British groups o Small pox infected blankets were used  Slave trade o A lot of Indians provided labor essential for colonization in America and a lot of them died cause of small pox o Supplementary slave trade came into north America’ o That increased the spread as well  " '... Captain Simeon Ecuyer had bought time by sending smallpox- infected blankets and handkerchiefs to the Indians surrounding the fort -- an early example of biological warfare -- which started an epidemic among them. Amherst himself had encouraged this tactic in a letter to Ecuyer.' "  Carl Waldman's Atlas of the North American Indian [NY: Facts on File, 1985]. Etiology  Virus : Genus - Orthopoxvirus, family Poxviridae  Common name - variola virus o 200 genses o its one of the largest can be seen with a light microscope o one can see that virus is present  At least two strains exist: variola major and variola minor o Major is more virulent and has mortality of 30% o Minor is the leaset virulent and mortality rate is 2%  Orthopoxvirus genus also includes the monkeypox, cowpox, camelpox, chickenpox, and ectromelia (mousepox) viruses o Monkey pox is indistinguishable in humans  Variola virus  Variola minor - mortality rate is less than 2% in unvaccinated persons  Mortality rate for variola major - 3% in vaccinated individuals and 30% - 50% in unvaccinated  Hemorrhagic smallpox or black pox o Very serious  Malignant and hemorrhagic forms of variola major develop in approximately 5 to 10% of infected people  Almost always fatal; mortality rate of 95% Transmission  Continuously transmission required o Has to be continuously transmitted from person to person  Only short-term carriers  Animal reservoirs do not exist  Direct contact - inhalation of aerosols or contaminated fomites  Virus multiplies in the mucous membranes of the mouth and nose then moves to the lymph nodes and then to internal organs, there it re-enters the bloodstream o No signs of illness in the first week of illness but then moves on to lymph o Present continiiouslt in oral nasal secretions or skin scabs  Infectious virus - oronasal secretions and in skin scabs  Potential for long–distance 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 o Symptoms slowly start to develop Clinical manifestation  Acute onset - fever, malaise, rigors, vomiting, headache, backache and occasionally delirium o 9 thday o depends on how the virus impacts the host o how susceptible different symptoms  2 to 3 days later skin lesions appear  8 to 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 scabs have separated  Secondary infections  Not chronic  Has lead to blindness  R0>1 Epidemiology th  18 -century - 60 million Europeans  Case-fatality rate varied from 20% to 60% o Children are less susceptible to it o Indian population was decimated
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