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University of Toronto Scarborough
Health Studies
Caroline Barakat

th PLAGUES AND PEOPLE Feb. 13 2012 LEC 5 – Tuberculosis (White Plague) TB epidemics likely from changes in the host population and the environment claims of royal supernatural powers during Middle Ages (scrofula) (AD500-1500) - tapped their head to “cure” disease (1546) Fracastorius describes Modern Theory of Contagion (1629) consumption – leading cause of death in London (1679) Franciscus D Sylvius discovers the lung nodules – “tubercles” 1720 – Benjamin Marten – speculates that TB may be communicable from one individual to another 19 century – TB spread to rest of Europe ad by 1900 reached N America 1839 – term “tuberculosis” first used Sanitariums were used to isolate the diseased (fresh air and nutrition) spread through the air by coughs or sneezes ( each sneeze contains 100,000 nuclei droplets) each droplet nuclei can contain between 1 and 3 bacilli What happens when TB enters the body? Tubercle bacilli can remain viable throughout the host’s lifetime -infection can remain dormant -can cause active disease indefinite and variable incubation period only people who have active TB are infectious Ro – 10-15 people every year Tb in other parts of the body such as the kidneys or spine (Pott’s Disease) cannot easily spread to other people Epidemiology 1/3 of the world’s population is infected with TB bacillus 30 M infected annually; of these, 10 M will develop active disease 2 million TB-related deaths world wide every year Incidence Rates highest incidences – Africa, Asia, Latin America 10 million people get TB every year rates increased since mid-1980s 2007 – WHO announces that epidemic had levelled off Epidemiology of TB in Canada mortality rate declined from 180/100 000 (1900) to less than 1/100 000 (mid-1980’s) incidence rate also declined last sanitaria was closed in the 1970’s improved treatment and drug therapy number of cases have remained relatively constant since 1987 highest rate of cases was in Nunavut 155.9/100,000 (2003) residents and visitors born in countries with high rates of TB accounted for more than two- thirds of all reported cases of TB TB screening for immigration and refugee status Risk Factors host-dependent factors: age, gender, genetics? -younger people more susceptible environmental factors persons most at risk for TB: close contact, countries with high rates of TB, people with weakened immune system (people with HIV/AIDS) HIV and TB form of lethal combination HIV weakens the immune system TB is the leading cause of death among people who are HIV-positive Diagnosis early diagnosis A tuberculin skin test (TST) If TST is positive, it means exposure to TB bacteria but does not mean active TB disease chest x-ray positive sputum smear for bacilli Treatment TB can be cured by MDT people exposed to active TB receive preventive therapy for 6 months to a year to reduce risk of developing disease BCG – Bacille Calmet Guerrin Drug Resistant TB strains resistant to drugs MDR-TB – particularly dangerous form of TB Drug-resistant TB is caused by: -inconsistent or partial treatment -wrong treatment regimes -unreliable drug supply Chapter 13 – Tuberculosis, Phthisis, Consumption In 1800s,epidemic TB reached its peak in western Europe, people will TB were considered beautiful and erotic: extreme thinness, long neck, and hands, shining eyes, pale skin, and red cheeks -a chronic infectious disease Description of consumptive: incessant coughing, making talking and eating almost impossible, breathing painful; weight loss that prevented walking and pain that required opium and whisky to relieve tuberculosis of the lungs called pulmonary TB, giving rise to the slang word “lunger” when localized to the lungs, tuberculosis can run an acute course, causing extensive destruction in a few months-so called galloping consumption -can also wax and wane with periods of remission-spitting up of blood Tuberculosis can affect organs other than the lugs, including the intestine, and larynx; sometimes the lymph nodes in the neck are affected, producing a swelling called scrofula can also produce the fusion of the vertebrae and deformation of the spine called Pott’s disease - may lead to hunchback, and affect the skin and the kidneys TB of the adrenal cortex destroys adrenal function and results to Addison’s disease Miliary TB small tubercles in the lungs look like millet seeds and spread throughout the body via the bloodstream Microbes of TB are called Mycobacteria -free-living inhabit the soil and water -have a protective cell wall -acid-fast bacillus  3 mycobacteria : Mycobacterium tuberculosis, M. Leprae, and M. avium M. Avium is an opportunistic infection found in immunocompromised people with under 50 T4 cells per ml^3 symptoms: weight loss, fever chills, night sweats, abdominal pains, diarrhea, and weakness M. Tuberculosis grows best when oxygen is plentiful and associated with pulmonary TB -spreads from person to person through droplets of saliva and mucus (airborne) History Evidence of TB is found in bony remains that predate human writing afflicted prehistoric men and women in Eurasia and Africa from Neolithic period Pott’s disease and spinal tuberculosis has been described in Egyptian mummies from 3700 BC to 1000 BC suggested that M.Tuberculosis evolved from M. Bovis after cattle were domesticated between 8000 and 4000 BC TB is believed to spread to Middle East, Greece, and India by tribes who were milk-drinking herdsmen who had migrated from the forests of central and eastern Europe ~1500 BC Peaks of Tb occurred in Eastern Europe between 1875 and 1880, and by 1990 it had reached North America Assyrian Kina Ashurbanipla describes the disease: patient coughs frequently, sputum is thick and sometimes contains blood, hard breathing, skin is cold Hippocrates believed the disease was due to evil air, he did not consider it contagious -recommended clean air and sunlight Aristotle suggested that it might be contagious and due to “bad and heavy breath” pulmonary forms were commonly called phthisis or pulmonary consumption infections of lymph glands surrounding the neck were called scrofula skin infections referred to as lupus vulgaris Tuberculosis is of recent vintage and refers to the fact that in the lung were there are characteristics of small knots or nodules called “tubercles” – first described by Franciscus Sylvius in 1679 -however, all other pathologists believed that the disease was due to tumors or abnormal glands rather than infection the cause for the rise in Tb may have been the demographic shift from rural to urban living as well as the creation of “town dairies” -tubercular cows (animal to animal transmission and animal to human transmission of TB -result: sharp rise of scrofula in the 17th century textile industry became mechanized’ which led to rural cottage industry to more urban riverside sites where waterpower was available people were more crowded together people living during Victorian Age (1837-1901), TB was attractive because blood in the sputum blended metaphorically with menstrual blood – sickness and death were blended with eroticism and procreation Evidence of TB in Americas BEFORE European explorers -Incan mummy of boy 700 AD shows evidence of mycobacteria, M. Bovis (source: cattle infection) Factors of spread -urbanization -crowdedness -inadequate ventilation -immigration of infected individuals lack of ventilation in tenement housing for immigrants -higher population densities -poor hygiene 1850, African americans in Baltimore and NYC had higher death rates due to consumption than did whites baltimore – above the age 15, the number of female deaths was twice that of males, but in NYC and London it was the opposite. TB in urban and rural areas In urban areas of New York and Boston, consumption was regarded as “a Jewish Disease” b/c so many jewish young immigrants were in the garment industry (cutting, sewing stitching) -were stigmatized as carriers of tuberculosis Today, there is a higher incidence of TB in US prisons -increase incidence is due to prevalence among close living prisoners and higher incidence of human immunodefiency virus (HIV) infections 1900s, poorer people tended to have higher mortality from TB, greatest number of deaths between ages 15 and 45 American Indians were highly susceptible to TB by being herded together During 19 century, people believed that TB was an act of God, others believed that it was a result of bad air present in crowded and dirty cities Finding the Germ of TB 1865, Jean-Antoine Villemin succeeded in transmitting tuberculosis to rabbits -recovered pus from lung cavity in patient and injected it under the skin of two rabbits -proof of contagious critic named Hermann Pidoux said that consumption in the poor was due to conditions of poverty, overwork, malnutrition, unsanitary housing consumption among the rich was due to overindulgence in their wealth, laziness, flabbiness, overeating, excessive ambition, and habits of luxury Dr. Robert Koch examines carcasses of sheep and was able to isolate anthrax germ, a rod-shaped bacterium he named Bacillus anthracis -microscopic bacillus is colourless and unusually difficult to stain b/c of its waxy cell wall -not easily seen through microscope, requires heating and special aniline dye (methylene blue) -acid-fast Koch also devised a method for growing the bacillus out of the body, by culturing them in test tubes containing coagulated serum as the nutrient source 1890, Koch announced he discovered a protective substance made from an extract
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