HLTA01H3 Chapter 1 The Nature of Plagues 1/19/2012 11:24:00 AM
Disease can be a personal affair.
pneumonia 肺炎== Legionnaires’ disease== air was implicated as the
probable pathway of spread of the disease, and the most popular theory was
that infection resulted from aspiration of bacteria (called Legionella) in
aerosolized water from either cooling towers or evaporative condensers (冷凝
--Unlike infections caused by inhalation (inhalation means entry of disease
during respiratory), aspiration is produced by choking. Secretions in the
mouth get past the choking reflex and instead of going into the esophagus
(食道) and stomach, mistakenly enter the lungs.
--The outbreak of Legionnaires’ disease have been traced to water heaters,
whirlpool baths, respiratory therapy equipment and ultrasonic misters used
in grocery stores.
Toxic shock syndrome TSS= the source of Mary’s infection and the
possibility that it might be spread thru the population as a sexually
transmitted disease (STD).
--TSS is a gender specific disease.
--However, TSS was note an STD, it linked to the use of certain types of
tampons, especially those containing cross-linked carboxymethyl cellulose
with polyester foam, which provided a favorable environment for the toxin-
producing S. aureus.
--The symptoms of TSS are begin with vomiting and high fever followed by
lightheadedness and fainting, the throat felt sore, and the muscles ached. A
day later, a sunburn-like rash（红疹） appeared, and the eyes became
bloodshot. Within 3-4days, victims suffered confusion, fatigue, weakness,
thirst and a rapid pulse, the sin became cool and moist, and breathing
became rapid. This was followed by a sudden drop in blood pressure, if it
remained low enough for a long enough period, circulatory collapse produced
The effects of disease at the personal level can be tragic, but when illness
occurs in many people, it may produce another emotion-fear- for now the
disease might spread rapidly.
Our world is much more vulnerable than it was in the past. New and old
diseases can erupt and spread throughout the world more quickly because of the increased and rapid movements of people and goods.
E.g. the efficiencies in transportation, fast moving ships, trains, and planes.
New diseases may be related to advances in technology, e.g. TSS resulted
from the improved menstrual tampons. Legionnaires’ disease was the result
of the growth and spread of ―germ‖ thru the hotel’s air-conditioning system.
Incubation period: interval of time required for development of a disease
Latent period: seemingly inactive period between exposure to an infection
and subsequent illness
Parasite virulence: capacity of a parasite to cause disease
Zoonotic infections: animal infections that can be transmitted to humans
The germs that caused SARS, Legionnaires’ disease and TSS are parasites.
Parasites: some entities are unable to survive on their own and require
another living being for their nourishment. These life-dependent entities that
―feed at the table of the rich‖ , from the Latin word parasitus, meaning
--Some parasites, such as tapeworms, hookworms the malaria parasite HIV
live inside the body, whereas others (ticks and chiggers) live on the surface.
--Parasites are invariably smaller in mass than their host.
--Parasites often harm their host. However, they will not always kill their
host, this is because resistance may develop in any population of hosts, and
not every potential host will be infected-some individuals may be immune or
not susceptible because of a genetic abnormality or the absence of some
critical dietary factor.
--Some parasites have complex life cycles and may have several hosts. e.g
malaria, the hosts are mosquitoes and humans.
--Parasites produce lots of offspring, thereby increasing the odds that some
will reach new hosts, More offspring will have a greater probability o
reaching a host and setting up an infection. Then m the parasite enhances
its chances for survival. e.g. malaria parasite, the red blood cell-destroying
hookworms and the white blood cell killer HIV.
The movement of a parasite from host to host-whether by direct or indirect
means- is called transmission. When the transmission of parasites involves living organisms such as flies,
mosquitoes, fleas, lice or snails, these animate intermediaries are called
Transmission by a vector may mechanical or developmental or
contamination of eating utensils (用具), drinking cups, food ,bedclothes,
towels or clothing or in droplet secretions (小滴分泌物).
Parasite and their free-living relatives come in a variety of sizes,
shapes and kinds or species. e.g. bacteria and virus are called micro
parasites. Larger parasites that can be seen without the use of a microscope
are referred to as macro parasites, they are composed of many cells.
Virus: although a virus’s genetic code contains all the info needed for
assembling a new virus, it lacks that which is necessary for reproduction. So
for a virus to reproduce, it must enter a living cell and use the cellular
machinery to replicate itself. Viruses are not completely independent,
they are not alive, and yet they can be killed if their DNA or RNA is
destroyed. Virus are neither cells nor organisms, they are called infectious
microbes or ―germs‖.
Bacteria: are independent existence. Bacteria do not need a host to
reproduce, they can be either free living or parasitic.
Plagues- all diseases outbreaks, irrespective of their cause. When a parasite
invades a host, it establishes an infection and wounds the body.
Contagious: are contagious before symptoms appear, has a short
incubation period, and infrequently requires hospitalization. e.g normal flu.
infectious: infectious only after symptoms appear, longer incubation period
and hospitalization required. e.g SARS
-- infectiousness, may persist even after disease symptoms have
disappeared, the person who are infectious but asymptomatic are called
Forecasting Storms, prediction Plagues
Three factors are required for a parasite to spread from host to host:
1. there must be infectious individuals; 2. there must a susceptible
individuals, and there must be a means for transmission between the two. Epidemiologists are disease forecasters who study the occurrence, spread,
and control of a disease in a population by using statistical data and
mathematical modeling to identify the causes and modes of disease
transmission, to predict the likelihood of an epidemic, to identify the risk
factors, and to help plan control programs such as quarantine and
R0 is the basic reproductive ratio of the disease or called the multiplier of
the disease, which help to predict how fast a disease will spread thru the
The longer a person is infectious, and the greater the number of contacts
that the infectious individual has with those who are uninfected, the greater
the value of R0 and the faster the disease will spread. An increase in the
population size or in the rate of transmission increases R0. The increase in
parasite mortality or a decrease in transmission will reduce the spread of
disease in a population, so reduce the R0.
If the value of R0 larger than 1, the ―seeds‖ of infection will lead to an ever
expanding spread of the disease- an epidemic or a plague.
If the value of R0 smaller than 1, each infection produces fewer than one
transmission stage and the parasite cannot establish itself.
Epidemic or plagues can be classified into three types:
1. type I epidemic patter: found in pop of about 300000 to 500000 people,
shows regular series of outbreaks, the disease never completely disappears.
very epidemic; R0 greater than 1.(because the number of susceptible
individual is large enough for the chain of transmission of infection to remain
2. type II epidemic: pop found about 10000 to 100000; peaks of infection
are discontinuous, but there is a regular pattern of occurrence of cases; not
epidemic, there are temporary absence of the disease, R0 smaller than 1.
(there are not enough susceptible individuals to maintain the chain of virus
3. Type III epidemic: found in pop less than 10000 people, cases occur at
irregular intervals, there are long periods when there is no disease. R0 is a
number much smaller than 1. (because the chain of transmission of infection
is interrupted) When an infectious disease becomes world wide or widespread, R0
is large enough, then the epidemic(传染病，流行病) is called a
pandemic (全世界流行). e.g. SARS, AIDS, influenza, cholera, bubonic
Factors affecting the spread of infection include the size of the
population, those communal activities , the countermeasures used and
seasonal patterns. or the changes in travel patterns or other sociological
Immunization (接种疫苗) is effective to control the infections. And may
convert a type I epidemic to type II, or even convert a type II epidemic to
The earlier the individual received immunization, the better the
transmission will be blocked. So if transmission is intense, R0 is very
large, mass immunization must take place at the earliest age feasible.
Herd immunity: resistance of a group to an disease attack due to
immunity Chapter 3 Six plagues of Antiquity (古迹) 2012/1/19 11:24:00
Plagues are present only after human populations settled down and adopted
an agriculture life. So plagues came to be more recorded only in our
recent past, in a time when we became farmer.
Agricultural revolution, with the cultivation of crops and animal husbandry,
that provided the driving force for the growth of cities (urbanization), but it
also contributed to the conditions that would result in a decline in human
health. Urban life also enhanced the transmission of certain diseases thru
the air and water, by direct contact, and by vectors such as snails,
mosquitoes, and flies. The disease of antiquity were characterized by
parasites with long-lived transmission stages as well as those involving
The Pharaohs’ Plague
disease that causes blood to appear in the urine (hematuria)
the pathology of chronic snail fever or blood fluke disease
Transmission stages: water was infested with infected snails, resulting in
a high level of disease. lakes, water, rainforests
The rise of Egyptian civilization, Nile Valley of Egypt rises due to agriculture
and irrigation was suffered from snail fever, because irrigation farming,
especially in the tropics, created conditions favorable for the transmission of
snail fever caused by the blood fluke.
Blood fluke disease- the plague of the pharaohs is not a fatal disease as
malaria and yellow fever, are, however, it is a corrosive (腐蚀性的) disease
Blood fluke disease, also known as snail fever or endemic hematuria. The
symptom of the disease is bloody urine. High frequency in the men,
especially the soldiers. Worms were found in the blood vessels. Today, blood
fluke disease is called schistosomiasis (血吸虫病) or bilharzia (住血吸虫).
Snail fever/schistosomes resulted from the worms and eggs. The
schistosome adults, live in blood vessels/ veins close to the bladder and
small intestine. Female worm deposits the fertilized eggs. The pathology of
schistosomiasis is due not to the adult worms themselves but to the
eggs. Eggs move across the walls of the veins into the bladder or intestine,
some are eliminated from the body, either with the urine or in the feces.
However, more than two-thirds of the eggs, fail to work their way out of the body and are washed back in the veins, so lead to the organ enlargement,
especially the liver and spleen (脾).
Prevention of the snail fever:1. education of the population in means to
prevent transmission, treatment of infected persons, and control of the snail
vector using molluscicides. 2. Human exposure can be reduced by providing
a safe water supply for bathing and washing as well as sanitary disposal of
human wastes. 3. discourage snail, intermittently irrigating rice paddies to
disrupt the life cycle.
The Plague of Athens
Route: Ethiopia, into Egypt, then Athens
¼ OF Athenian killed by an unknown plague.
High death rates including ―Pericles‖
The Roman Fever
Roman Empire established in 27BC
Malaria being devastating to the Roman Empire. The disease was so
prevalent in the marshland (沼泽地) of the Roman Campagna, near Ostia,
that the condition was called the ―Roman fever‖.
Malaria, is Italian name, which means ―bad air‖.
Epidemics every 5 to 8 years.
In the Roman Empire, malaria was a disease of children, but severe illness
was also found among immigrants without acquired immunity. It reduced
the life expectancy. In some particular unhealthy places, life expectancy was
only 20 years of age, whereas in place where malaria was absent, life
expectancy could be as high as 40 or 50.
The Antonine Plague
The epidemic of Antoniuns, called the Antonine plague, spread to other parts
of Europe, causing so many deaths that cartloads of bodies were removed
from Rome and other cities.
The symptoms of the plague are: high fever, inflammation of the mouth and
throat, thirst, diarrhea, and a telltale sign, pustules （脓包） on the skin that
appeared after 9 days. Even today, precisely what this plague was remains a mystery, but most suspect that this was the first record of a smallpox
The Cyprian Plague
The Cyprian Plague appeared to have originated in Ethiopia, move into
Egypt, and eventually come to the Roman colonies of North Africa.
The symptoms of plague are: vomiting, diarrhea, gangrene (坏死)of the
hands and feet, a burning fever and a sore throat.
Cyprian plague became a pandemic, advancing quickly thru direct
person-to-person contact as well as by contaminated clothing, it is
suspected that the disease was smallpox or measles. Mortality rate is very
high, the number of deaths exceeded the number of survivors.
Roman empire collapsed due to the disease (Antonine, Cyprian and others),
famine, war and death.
The Justinian plague
First pandemic of the Bubonic plague.
The plague raged (肆虐) in the city of Constantinople, the capital of the
Roman Empire in the East. CHAPTER 4 An Ancient Plague, the Black Death 1/19/2012 11:24:00 AM
The first bubonic plague pandemic is in Constantinople, the capital of the
Roman Empire in the East, contributed to Justinian’s failure to restore
The second pandemic began in 1346.
The rat-borne bubonic plague, spread quickly by rats or plague-infected
rodents, thru steamships and railways.
Port cities were most affected, then trade routes, both sea and land. (silk
Public Health to help controlling the spread of Black Death Plague
1. quarantine- isolation of the sick people
2. infected individuals were removed from their homes and families and
isolated in special hospitals called pest houses.
3. The dead were removed and quickly buried.
4. The burning of the clothing and bedding of the infected may also
5.Towns closed gates to travelers.
6. Restricting the long-distance movement of people and baggage from
Theory of Contagion, by Fracastoro, the transmitted by semanaria
(―germs‖) in three ways, direct contact, thru carriers such as dirty linen, and
thru airborne transmission.
The number of learned individual decreases as the mortality of plague
increases. As the number of university students declined, so too did the
number of universities.
Because of the restriction on long-distant movement, the local universities
This not only diminished the dominance of certain centers of learning, but it
also led to curriculum (全部课程) reform (改革).
Economy and social order Trade ceased. The economic effect of the Black Death was inflation and a
sharp rise in the cost of food.
The nature of farming was altered.
Bigger ships with smaller crews could remain at sea for longer periods of
time and would be able to sail directly from port to port.
The new economy became more diversified. There was a more intensive use
of capital, technological innovations become more and more important, and
there was a greater redistribution of wealth.
Finding the Killer
Bubonic plague, caused by a rod-shaped, gram-negative bacterium, was
named Yersinia pestis .
The intermediary between a dead rat and a human, might be the flea. So
The disease of Plague
Types of plague
1. bubonic plague: resulted from the bite of a rat flea. Three days after the
buboes appear, there is a high fever, the individual becomes delirious （神志
昏迷）, and hemorrhages (出血) in the skin result in black splotches. The
buboes continue to enlarge, sometimes reaching the size of a hen’s egg;
when these buboes burst, there is agonizing pain. Death can come 2 to 4
days after the onset of symptoms.
2. Septicemic plague: when the bacteria enter the bloodstream. The
second form of the disease, which may occur without the development of
buboes. Septicemic plague is characterized by fever, chills, headache,
malaise, massive hemorrhaging, and death. Higher death rate than
3. Pneumonia or pneumonic plague, when bacteria move via the
bloodstream to the alveolar spaces of the lungs. The only form of the
disease that allows for human-to-human transmission thru coughing and
spitting produce airborne droplets laden with the highly infectious bacteria,
an by inhalation others may become infected. Rapid fatal from of the
disease, and death can occur within 24 hours of exposure. The lesson the Black Death teaches us is that ignorance of the contagious
agent can lead to misunderstanding, discrimination, persecution, and
profound social and medical outcomes. Chapter 14 Leprosy, the striking hand of God 1/19/2012 11:24:00 AM
There is a morbid interest in and dread of leprosy, largely stemming from
frequent references in the Bible.
Leprosy probably arose in the Far East. (Hindu, Chinese literature described
In the Middle Age, leprosy was considered a disease of soul. The
association of the disease with sinfulness stigmatized the leper.
The belief that venereal (性交的) disease was due to immorality was
―logically‖ extended to leprosy; in this way, leprosy became accepted as
divine punishment for the sins of the flesh (肉体). (punishment from the
In 1179, the Third Lateran Council issued a decree urging the segregation
of lepers from society: the leper was told not mix with crowds, to use his
own container in drawing water, and not to touch anything unless he paid for
There are almshouses or refuges for lepers, which called ―leper house‖, or
―Lazar houses‖ or ―lazarets‖.
By the 16 thcentury most of the lazarets has been closed ,and by the 18 th
century they had all but disappeared.
When Father Damien died and suspected to be contracted leprosy during his
residency, his death caused much fear and reinforced the belief that the
disease was highly infectious. Although Hawaii became a territory of the US
in 1900, the involuntary isolation of those with leprosy on Molokai
continued until 1974.
The Disease of Leprosy
The first objective and scientific appraisal of leprosy came in 1873 with the
discovery of the leprosy bacillus, Mycobacterium leprae, by Gerhard Armauer
Hansen in Norway.
M. leprae like its cousin M. tuberculosis, is an acid-fast bacillus, but it differs
in several significant ways—it cannot be grown in tissue culture and it grows
very slowly (slow multiplying bacillus) and only in humans, mice ad nine-
banded armadillos, taking about 2 weeks to divide (Tuberculosis bacilli divide
every 12 hours).
Where Leprosy is
Leprosy was found mostly in the tropics. Even today, leprosy leads to a lifetime of social ostracism (排斥) and misery
The higher the standard of living, the less the incidence of leprosy.
Leprosy is often an endemic (地方病) disease. It is usually acquired in
childhood, but infection can occur even at age 70.
In many parts of the world, males are more frequently infected than females,
but the reasons for this remain unclear as well.
The diagnosis of leprosy, has not changed substantially in 100 years: it
relies on microscopic examination and evaluation of the response of the
patient to a pinprick or heat.
Leprosy can be treated by using multiple drug therapy (MDT) including
dapsone, rifampicin and clofazimine) or leprosy vaccine.
The bacilli are shed with the skin, but most bacilli are found in the nasal (鼻
子的) secretion. Thought to be transmitted via droplets, from the nose
during close and frequent contact.
Leprosy is considered a disease of low virulence (有毒性).
Not very infectious—may be related to genetic susceptibility
Leprosy patients have no greater susceptibility （敏感性） to tuberculosis
than do those without infections.
The leprosy transmission routes and how nerves are destroyed are
Mainly affects the skin, nerves and mucous membranes.
Leprosy Reader (834-839)
Leprosy occurs naturally only in humans and is caused by infection with
Skin and systemic afflictions （痛苦） are only resembled leprosy symptoms.
The leprosy bacillus multiplies quite slowly, usually in the sheaths （末梢）of
peripheral (外围的) nerves.
At the very beginning, losing sensation in some areas of the skin, but people
will ignore the symptom of infection in this stage because sometimes the
affected dermis （真皮） can be damaged without evoking a pain. Secondary infection and inflammation of an involved area are common,
leading to scarring and callusing (老茧) of surviving tissues. This long
process can result in the loss of fingers, toes, nasal tissue or other parts of
Leprosy will also influence one’s facial nerves.
Distribution and incidence
Leprosy occurs commonly only in tropical and subtropical regions. Most of
the lepers residing in Africa, South and Southeast Asia and South America.
The distribution of the leprosy reflects the poverty of these regions that it
does the possibility that elevated temperatures and humidity facilitate
The poor sanitation system, high social costs of early identification and
treatment, as well as the poverty contribute the slow spread leprosy inland.
For despite cross-immunity, the most common associated cause of death in
leprosaria is tuberculosis, illustrating how long-sufferers of leprosy lose the
ability to combat other chronic infections.
Increased population density in urban areas facilitates the spread of
tuberculosis infection, which may have contributed to a declining incidence
of leprosy as cities and large towns appeared.
caused by Mycobacterium leprae
Slow multiplying bacillus
Incubation period of 3-5 years after infection.
Thought to be transmitted via droplets, form the nose during close and
Not highly infectious=maybe related to genetic susceptibility
mainly affects the skin, nerves and mucous membranes.
Indeterminate leprosy (IL)
---earliest and mildest form, usually few lesions （损伤）. and loss of
sensation is rare. Tuberculoid leprosy (TT)
--1-2 years after exposure, large lesions. loss of sensation, affected nerves
become thick (nerves can damaged), progression can occur resulting in
Borderline tuberculoid leprosy (BT)
--lesions are smaller, but more visible and more in numbers than TT. Can go
back and forth.
Borderline lepromatous leprosy (BL)
--lesions are numerous, but they may also consist of papules （丘疹）,
plaques and nodules, punched-out-appearing lesions that look like inverted
（反向的）saucers (茶托) are common, the disease may remain in this stage.
Lepromatous leprosy (LL)
--never reverts to a less sever form
--early symptoms- nasal stuffiness, discharge and bleeding, and swelling of
the legs and ankles
--following problems may occur: skin thickens, eyebrows and eyelashes are
lost, nose deformation or collapses, ear lobes thicken, photophobia
blindness, enlarged liver and lymph nodes, hoarseness （嘶哑的）of voice
and fingers and toes become deformed (畸形).
Risk of leprosy
leprosy can affect people of all races all around the world.
most common in warm, wet areas in the tropics and subtropics
most common between the ages of 0 and 14 and in those aged 35-44 years
rarely seen in infants.
Leprosy is caused by an intracellular pathogen, production of circulating
humoral antibodies is of little use in combatting the infection of cells an the
multiplication o the organism in human tissues.
Some ways to prevent leprosy: 1. hand washing; 2. disinfection (消毒) of
fomites (污染物), handkerchiefs（手帕） and nasal secretion; 3. household
contacts (examination in every five years); 4. young household contact
should be treated with drugs; 5. vaccine. Possible causal factors for the disappearance of Hansen’s disease
1. selective mortality of leprosy patients during plague pandemic.
2. cross-immunity with other mycobacteria
3. loss of pathogenicity (the bacillus no longer strong).
4. genetic selection of the population
5. improved quarantine
6. improved socio-economic conditions
7. better housing and sanitation
8. climate Chapter 13 The people’s plague: tuberculosis 1/19/2012 11:24:00 AM
A disease called consumption from the Latin con meaning ―completely‖ and
sumere meaning ― to take up‖. Consumption was characterized in an 1853
medical text as having the following features: nostalgia, depression and
excessive sexual indulgence (纵欲).
Today, consumption is more common called tuberculosis or TB, also
called ―White Plague‖.
Tuberculosis is an ancient disease. Tuberculosis of the lungs
(pulmonary TB) is the form of the disease we are most familiar with, giving
rise to the slang world ―lunger‖. When localized to the lungs, tuberculosis
can run an acute course ,causing extensive destruction in a few months- so
called galloping (急性的) consumption.
Tuberculosis can affect organs other than lungs, including the intestine
and larynx (喉咙); sometimes the lymph （淋巴） nodes in the neck are
affected, producing a swelling called scrofula (淋巴结核).
The microbes that cause TB are called mycobacteria.
Mycobacteria have a protective cell wall that is rich in unusual waxy lipids,
such as mycolic acid, and polysaccharides such as lipoarabomanan and
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（脊柱） is associated with M. bovis and results from a
blood infection that spreads to the spine via the lymph vessels.
M. tuberculosis is specific to humans and spreads from person to person thru
droplets of saliva and mucus.
Transmission of TB:
1. the rise in TB may have been the demographic shift from rural to urban
living as well as the creation of ―town dairies‖.
2. The tubercular cows were within the town, which provided ideal
circumstances for animal-to-animal transmission as well as animal-to-human
(zoonotic) transmission of TB.
3. Towns grew in population size to become cities; as peasants streamed
into these urban centers, people were more and more crowded together.
4. The practice in England of taxing a building partly based on its number of
windows ended to affect building design to minimize the number of windows. This enhanced the rebreathing of exhaled air of those living and working in
the crowded, airless rooms.
5. The increased density of people provided ideal conditions for the aerial
transmission of M. tuberculosis and pulmonary TB.
6. TB was brought to the America, with urbanization, immigration of infected
individuals, higher population density, and poor hygiene. Inefficient heating
of the home usually led to a sealing of the windows and doors in winter to
keep out the cold, so transmission was enhanced. In addition, behavioral
patterns also contributed to the spread of pulmonary TB: caretakers of the
sick slept in the same bed as their patients.
In NY, TB was known as ―Jewish disease‖/tailors disease‖
7. Inadequate ventilation was also a contributing factor in the spread of
8. Between 1829 and 1845, the annual mortality due to TB in eastern cities
of the US was less than half a percent. Even today, there is a higher
incidence of TB is US prisons. The increased incidence is due to several
factors: prevalence is higher among new prisoners than in the general
population because there is a preponderance (多数) of prisoners from the
lower end of the socioeconomic scale; close living arrangements make
transmission more likely, and prisoners are at a higher risk for TB owing to
the higher incidence of HIV infections.
Poor people tended to have a higher mortality from TB, the greatest number
of deaths occurred between the ages of 15 and 45, but there was also a
minor peak between 5 and 10 years of age. The American Indians, were
highly susceptible to TB.
Finding the Germs of TB
--In 1865, French military physician, Jean-Antoine Villemin- succeeded to
transmitting TB to rabbits—proof the contagious nature of TB
--In 1882—Robert Koch—isolated and characterize the germ of anthrax, a
rod-shaped bacterium he named Bacillus anthracis.—Developed ―tuberculin‖
test. This is a skin test, this test remains one of the most useful methods for
determining previous exposure to TB. --He determined to find the microbe
that cause TB.
--In 1895, Whilhelm Konrad von Rontgen-use of radiation The Disease of TB.
Person with pulmonary TB may infect others thru airborne
transmission: coughing, sneezing and speaking. Each droplet nuclei can
contain between 1 and 3 bacilli and each sneeze contains 100000 nuclei
Inhalation is the major route of infection. Oral infection, thru eating or
drinking, is less efficient because the bacteria rarely survive passage thru
the acid in the stomach.
3 main types of human bacillus: 1. Type 1: found in India, least virulent; 2.
type A-Africa, China, Japan, Europe, and North America; 3. Type B-
exclusively in Europe and North America.
Forms of TB
-several animal forms of the bacillus- could be infectious for human via milk,
e.g. infectious cows.
--Bovine type which caused by M.bovis lead to pulmonary TB or Military TB—
spreads thru the body via blood stream.
What happened when TB entered the body?
--tubercle bacilli can remain viable thruout the host’s lifetime.
--infections can remain dormant (潜伏的) or can cause active disease.
--only people who have active TB are infectious.
--R0=10-15 people every year
--people with TB in their lungs are infectious, TB in other pars of the body
such as the kidneys or spine cannot be easily spread to other people.
-- if one person got TB and cured, he still has equal chance to get a new TB.
--When a person contract pulmonary TB from inhaling droplets from a cough
or sneeze by an infected person, we will see a granuloma (肉芽瘤) in lung
tissue. Granulomas is from M. tuberculosis.
The epidemiological trait: needs three factors: host, agent and
environment --Host-dependent factors are age, gender and genetics—which means
younger people are more susceptible, females under 30 have higher morality
Environment factors: overcrowding, low protein intake, bad working and
living conditions (the physical exertion and stress of exhausting work also
magnify an individual’s risk of developing TB as does smoking.
socioeconomic status, also affect a population’s tuberculosis mortality rates.
Low income levels suffer the most from the disease. Crowded and
impoverished living conditions prevail for numerous people and lead to
increased TB mortality.)
Persons most at risk for TB: 1. close contacts of a person with TB; 2. from a
country with high rates of TB; 3. those with weakened immune systems; 4.
people with HIV/AIDS.
HIV and TB
HIV and TB form a lethal combination.
HIV weakens the immune system.
TB is the leading cause of death among people who are HIV-positive because
of weakened immune system.
Today’s diagnosis of TB
1. Tuberculin, discovered by Koch in 1890, not cure TB but control of TB thru
tuberculin test, a small amount of tuberculin or PPD is injected under the
skin of the forearm, within 48-72 hours after injection, an inflamed area
develops if the person has been exposed to TB. A positive skin test does no
indicate an active infectious case of TB but merely that the person has been
2. method of staining-red fuchsin followed by treatment with nitric acid – by
3. Wilhelm Roentgen discovered X rays photography.
4. stethoscope, by Rene Laennac- a hallow wooden tube about a foot long.
Although this scope cannot identify the specific cause of the abnormal chest
sounds, Laennac theorized that phthisis （肺结核）and scrofula (淋巴结核), as
well as military TB were different forms of the same disease.
Controlling of Consumption Open-air hospital-sanitaria. Sanitaria were considered to be indispensable
for cure, and patients were provided with brilliant sunshine, fresh air, quiet,
rest and good nutrition, but no anti-TB medicine. Also sanitaria was able to
isolate the contagious individuals and physicians could maintain complete
control of their patients.
How to prevent the spread of consumption:
1. an education campaign using newspaper s and circulars to call attention
to the dangers of TB, possibilities for treatment and precautions to prevent
2. compulsory reporting of TB by all public institutions;
3.assignment of inspectors to visit the homes of patients in order to enforce
sanitary regulations regarding the disposal of sputum and to arrange for
4. provision of separate wards in hospitals for TB patients with pulmonary
5. provision of special consumptive hospitals to be used exclusively for the
treatment of TB
6. provision of laboratory facilities for the bacterial examination of sputum
1. Streptomyces—discovered by Dr. Selman a. Waksman and his graduated
students-- inhibited the growth of tubercle bacilli both in the body and in
2. Multi-drug therapy is possible to delay or prevent the emergence of
drug resistance. The first combination of therapy are isoniazid and rifampin
administered for 9 months is curative for TB. If rifampin is not used, 18
months is the minimum duration of therapy for cure.
Vaccination against TB
--BCG (Bacillus Calmette Guerin)
--Injection of BCG produces a mild infection, induces immunity and has
never resulted in a virulent infection. However, it produces some adverse
reactions and is not 100% effective, efficacy range from 30%-80%.
BCG uses as a vaccine would be of little benefit to those already infected.
--Canada-pioneer in using BCG as protection against further spread of
tuberculosis to uninfected people. Chapter 12 The Great Pox Syphilis 1/19/2012 11:24:00 AM
Tuskegee Syphilis Study: many men enrolled in this study but were
denied access to treatment for syphilis even after penicillin came into use in
1947. They were left to degenerate under the ravages of tertiary (最严重的
stage) syphilis. The Tuskegee study was designed to document the natural
history of syphilis, but it came to symbolize racism in medicine, ethnical
misconduct in medical research, paternalism by physicians and government
abuse of society’s most vulnerable-the poor and uneducated.
History of Syphilis- the Great Pox
--Syphilis was brought to Naples by the Spanish troops sent to support
Alphonso II of Naples against the French king Charles VIII. Charles VIII
launched an invasion of Italy in 1494 and besieged (被包围) Naples in 1495.
During the siege, his troops fell ill with the Great Pox. Many Neapolitan
women also get syphilis, the pox spread rapidly thru Europe. The Pox was
evident in the invading troops, within 5 years of its arrival in Europe, the
disease was epidemic.
How did the army of Charles VIII contract this disease? (Two
There are two main theories, called Columbian and the pre-Columbian
Columbian theory (American disease)—Christopher Columbus visited the
Americas and set sail for home 3 months later and carrying with him several
natives of the West Indies, and then some of them joined the army of
Charles VIII. So syphilis had been imported into Europe from the Americas.
By the 1600s, the Great Pox was an extremely dangerous infection. By the
end of 1800s, both the virulence of the pathogen and the number of cases
Pre Columbian theory (European disease)—theory suggests that human
treponemes may have come from animals and that an infection similar to
pinta, localized in the skin, arose about 15000 BC in Africa and then with
human migration passed across the Bering Straits to become isolated in the
tropics of the Americas, places where the humidity is high.
--According to the pre-columbian theory, true venereal transmission from
spirochetes in the vagina and the penis occurred as a result of a third
mutation, coinciding with the emergence of cities about 3000 BC in the Middle East. From this region it spread thru the Mediterranean and into
--Many populations of native Americans themselves were decimated by
syphilis in the 16 century after the arrival of the Europeans.
What produced this dramatic outbreak of syphilis?
--Some have suggested that it was a new disease introduced into a naïve
population and that the increased rate of transmission by sexual means
transformed what once had been a milder disease in to a highly virulent one
HIV. Another hypothesis was the European syphilis was derived from yaws,
the initially infection was by direct contact, such as mouth-to-mouth kissing,
using same drinking cups.
Origin of the term Syphilis
--Early observers believed that syphilis was God’s punishment for human
--In 1530, Girolamo Gracastoro recognized that the disease was contagious,
and he called it syphilis after a fictitious shepherd, named Syphilis, who got
it by cursing the gods. He wrote a poem called Syphilis sive morbus gallicus
--In 1905 Fritz Schaudinn and Erich Hoffmann in Germany identified a
slender, spiral-shaped (螺旋) bacterium, a spirochete (螺旋菌) in the syphilitic
chancres. Because of its shape, Schaudinn and Hoffmann called the microbe
Treponema, and because it stained so poorly, they named its species
pallidum. Human beings are the only natural host for T.pallidum. It divides
slowly and is quite fragile, requiring a moist env’t.
The disease Syphilis
--Caused by Treponema pallidum
--extremely fragile spirochete surviving only briefly outside the host
--only natural host is human being
In the past, diseases such as syphilis were called venereal (性交的) diseases
or VD. Venereal refers to the Roman goddess of Love, Venus. However,
since love and sex are not equivalent, HIV and syphilis are now referred to
as STDs (sexually transmitted diseases).
Clinical Manifestations 1. Primary Stage, also called chancre stage— (contagious)
--earliest clinical sign of disease. Infection ~21 days after initial contact, a
painless pea-sized ulcer called a chancre (下疳).
--Chancre is a local tissue reaction and occur on the lips, fingers, or genitals.
--Spread via kissing or touching a person with active lesions on the lips,
genitalia or breasts and thru breast milk.
--If untreated, chancre will disappear within 4-8 weeks, leaving a small scar.
The presence of a lesion larger than that of small pox gives the disease the
name the Great Pox.
2. Secondary stage (contagious)
--develops 2 – 12 week after the chancre stage.
--T. pallidum is present in all the tissues but especially in the blood. Results
of serological (血清学的) test are positive.
--Skin rash and mucous membrane lesions, rough, red or reddish brown
spots on the palms of the hands and bottoms of the feet.
--Then patients enters the early latent stage, in which he or she appears to
be disease-free and no clinical signs. However, the most dangerous times is
during the early latent stage, because the infected individual can still
transmit to others.
3. Late latent or tertiary stage (not contagious)
-still spirochetes present in the body but the individual is no longer
infectious. The disease becomes chronic.
-- With destructive ulcers called gummas （梅毒瘤）appear in the skin,
muscles, liver, lungs, and eyes.
-- without treatment, the disease may damage the internal organs, including
the heart, joints, bones, brain and nerves. causing incomplete paralysis,
complete paralysis or insanity. Many untreated patients dies within 5 years
after showing the first signs of paralysis and insanity (精神错乱).
--Syphilis can be transmitted from the mother to the developing fetus via
the placental blood supply, resulting in congenital (先天性的) syphilis, this is
more likely to occur when the mother is in an active stage of infection.
--If the mother is treated during the first 4 months of pregnancy, the fetus
will note become infected. --A diseased surviving child may have the same symptoms as the mother, or
there may be deformities (牙齿畸形), deafness (聋子), or blindness.
--First described in 1862 by the London physician Jonathan Hutchinson.
--Hutchinson’s triad: deafness, impaired vision and a telltale groove across
--The Wassermann test is a serological reaction that originally used extracts
of tissues infected with T. pallidum, however it was found that uninfected
tissues reacted positively with syphilitic sera, these antibodies were
-- most commonly used tests are the VDRL and the RPR tests.
--Paul Ehrlich developed an arsenical (含坤的) derivative, salvarsan (撒尔佛散
), that was effective in reducing the severity of the disease. However, it was
toxic, required years of treatment and was difficult to administer.
--Penicillin (青霉素) remains the drug of choice in the treatment of syphilis.
--By 1497, George Sommariva tried mercury as treatment , called salivation
--Another treatment was guaiacum (愈创树脂) (holy wood) resin from trees
indigenous to the West Indies and South America.
Syphilis and the social reformers (改革)
A great deal of the failure can be attributed to social attitudes toward
syphilis in particular and sexually transmitted disease in general.
Social reformer focused on the a man or a woman who had strayed from the
path of moral virtue and consorted with prostitutes or people of ill repute.
The moral code at the time in the Victorian era held that only sex within
Distribution and Incidence of Syphilis
The highest syphilis rates were in the American South, which accounted for
44% of all cases
Syphilis primarily in males aged 35 to 39 and in women aged 20 to 24 years.
The incidence among men was five times that in women. Poverty, inadequate access to health care, drug use, prostitution, lack of
education and male homosexuality remain associated with disproportionately
high levels of syphilis in certain populations.
Vaccine against Syphilis
Syphilis and AIDS in the social Context
Some important similarities of social attitudes, 1. the moral approach—best
way to prevent infection is to advocate a social and sexual ethic that makes
it possible to acquire an infection—sexual abstinence until marriage. This can
be achieved thru education and the suppression of prostitution.2. attempts
to divorce itself from any particular judgement about sexual behavior and
suggests that individuals should be provided with the means for protecting
themselves from infection should they choose to engage in sexual behavior,
and treatment should be nonpunitive so as to encourage infected individuals
to seek help.
Famous people give contribution to syphilis
John Hunter- founder of scientific surgery, he developed th signs of syphilis
and concluded the two infections (syphilis and gonorrhea 淋病) were the
same, he died of heart problems –tertiary syphilis.
Philippe Ricord—demonstrated that gonorrhoea and syphilis were different
disease, determined the three stages- primary, secondary and tertiary of
Rudolph Virchow—established that syphilis was spread thru the body by
Shaudinn and Hoffman—discovered the germ that causes syphilis, which
call T. pallidum. Chapter 9 Smallpox, the Spotted Plague, Variola vera 1/19/2012 11:24:00 AM
In 1520, Hernan Cortes with fewer than 600 troops, conquer the Aztecs
which with militaristic and wealthy troops. Because Cortes’s ally (伙伴) was a
very efficient killer—smallpox. Smallpox spread from village to village
thruout the Yucatan. So great was the die-off that there were not enough
people to farm the land or protect the cities.
Smallpox was a devastatingly selective disease, only the Aztecs died, the
Spaniards were left unharmed.
Twelve years later 1532, another Spanish conquistador, Francisco Pizarro
captured Atahualpa, the leader of the Inca Empire. Again, smallpox had
made Pizarro’s success in South America possible.
Smallpox was an Old World disease to which the New world Amerindians had
never been expose, and against which they had no immunity.
Smallpox leads to death, devastation, and demoralizations.
Smallpox has been involved not only with war but also with exploration and
Smallpox is indiscriminate, with no respect for social class, occupation, or
age; it killed or disfigured princes and paupers, kings, and queens, children
and adults, farmers and city dwellers, generals and their enemies ,rich and
A Look Back
It is suspected that humans acquired the infectious agent from one of the
pox-like diseases of domesticated animals.
The best evidence of smallpox in humans is found in three Egyptian
mummies, dating from 1570 to 1085BC. (mummies name Pharaoh
Ramses V, who died as a young man in 1155BC).The mummified face, neck
and shoulders of the Pharaoh bear the telltale scars of the disease:
Described 1122BC in China and is mentioned in ancient texts of India.
Smallpox was apparently known in Greece and Rome, but it does not seem
to have been a major health threat until about AD 100, when there was a
catastrophic epidemic called the Plague of Antonius. This plague led to the
decline of the Roman Empire.
By AD 1000, smallpox was probably endemic in the more densely populated
parts of Eurasia, from Spain to Japan, ,as well as in the African countries
bordering on the Mediterranean Sea. The spread of smallpox was assisted by the caravans (商队) that crossed the
Sahara to the more densely populated kingdoms of West Africa, and the
disease was repeatedly i