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Chapter 13

HLTB21H3 Chapter Notes - Chapter 13: Streptomycin, Mycobacterium, Mycobacterium Tuberculosis


Department
Health Studies
Course Code
HLTB21H3
Professor
Caroline Barakat
Chapter
13

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(Reading) Week #5 | Sherman Ch. 13; Kiple P. 1059-1065
Chapter 13
The People’s Plague: Tuberculosis
Egypt, India, and China as early as 5,000, 3,300, and 2,300 years ago respectively
- consumption was characterized in an 1853 medical text as having the following features: nostalgia, depression, and
excessive sexual indulgence
- another name: ―the White Plague
- in the 1800s, when epidemic TB reached its peak in Western Europe, persons with tuberculosis were considered both
beautiful and erotic: extreme thinness, long neck and hands, shining eyes, pale skin, and red cheeks
- a more accurate and less romantic description of the consumptive includes incessant coughing, which made talking and
eating almost impossible and breathing painful; weight loss that prevented walking; and pain that required opium and
whisky to ameliorate
A Look Back
- tuberculosis of the lungs (called pulmonary TB) is the form of the disease we are most familiar with
- when localized to the lungs, tuberculosis can run an acute course, causing extensive destruction in a few months
galloping consumption
- tuberculosis can affect organs other than the lungs, including the intestine and larynx; sometimes the lymph nodes in
the neck are affected, producing a swelling called scrofula
- tuberculosis can also produce the fusion of the vertebrae and deformation of the spine, called Pott’s disease after Sir
Percival Pott
- this may lead to a hunchback, and it may also affect the skin (lupus vulgaris), and the kidneys
- TB of the adrenal cortex destroys adrenal function and results in Addison’s disease
- microbes that cause TB (also leprosy) are called mycobacteria
- their free-living relatives inhabit soil and water, where they fix nitrogen and degrade organic materials
- mycobacteria have a protective cell wall that is rich in unusual waxy lipids
- three mycobacteria, Mycobacterium tuberculosis, M. leprae, and M. avium, are human pathogens that cause TB, leprosy,
and a pulmonary disease with swollen glands in the neck
- M. avium is an opportunistic infection found in some immunocompromised people; its symptoms can include weight loss,
fevers, chills, night sweats, abdominal pains, diarrhea, and overall weakness
- parasite of cattle, M. bovis
- although M. bovis can infect people, it does so infrequently and with great difficulty
- M. bovis grows under conditions where the oxygen levels are low; when it does infect people, it is not associated with
lung disease
- M. tuberculosis grows best when oxygen is plentiful, and it is associated with pulmonary TB, probably because the lung
has high levels of oxygen
- but TB of the spine is associated with M. bovis and results from a blood infection that spreads to the spine via the
lymph vessels
- it has been hypothesized that M. bovis arose from soil bacteria, and humans first became infected with M. bovis by
drinking milk
- M. tuberculosis is specific to humans and spreads from person to person through droplets of saliva and mucus
- genetically, M. bovis and M. tuberculosis have been shown to be >99.5% identical
- Pott’s disease has been described in Egyptian mummies dating from 3700 BC to 1000 BC
- it has been suggested that M. tuberculosis evolved from M. bovis after cattle were domesticated between 8000 and 4000
BC
- TB, it is believed, then spread to the Middle East, Greece, and India via nomadic tribes (Indo-Europeans) who were
milk-drinking herdsmen who had migrated from the forests of central and eastern Europe ~1500 BC
- Greek physician Hippocrates called the disease phthisis, meaning ―to waste,‖ and noted that the individual was
emaciated and debilitated, and had red cheeks and that it was a cause of great suffering and death
- he did not consider it contagious
- Aristotle suggested that it might be contagious and due to ―bad and heavy breath‖
- during the Middle Ages, a feudal system developed in Europe by which a small elite (nobility) ruled the rest of
society, their subjects
- royalty claimed that their right to rule and their talents were of divine origin, and they publicized this through
claims of royal supernatural powers to heal scrofula
- kings and queens were able to heal those afflicted with scrofula by simple touching
- during the ritual ceremony, the king or queen touched the sufferer, made the sign of the cross, and provided the
afflicted with a gold coin
- in England this practice was known as the Kings Evil or the Royal Touching, and it persisted until the early 18th
century
- the word ―tuberculosis‖ refers to the fact that in the lung there are characteristic small knots or nodules called
―tubercles‖
- these were first described by Franciscus Sylvius in 1679; he also described their evolution into what he called lung
ulcers
- first credible speculation on the infectious nature of TB was Benjamin Marten, who in 1772 proposed that the cause was
an ―animalcule or their seed‖ transmitted by the ―Breath emits from his Lungs that may be caught by a Person‖
- 19th century spread to rest of Europe and N America
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