Transcript UNIT 9: DISEASES AND DISORDERS:

UNIT 9: DISEASES AND
DISORDERS:
An infection occurs when living
agents enter tissue, multiply there
and damage the tissue.
The General causative agents for
disease include:
1.
2.
3.
4.
5.
6.
7.
bacteria
viruses
fungus
Rickettsia
protozoan
arthropods (acting as vectors)
vermiform (various invertebrate
worms)
STAPHYLOCCOCCAL
INFECTIONS: (bacteria)
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Staphyloccocci are spherical gram positive
bacteria about .5 to 1.5 miccrometers in diameter.

They tend to form in irregular clusters like grapes
Staphylococcus aureus is the most pathogenic of
the staphylococci (forms golden yellow colonies,
almost all pathogenic and produces coagulase for blood
clotting)
S. Aureus common problem in hospital s due to
being carried on the skin of patients, visitors and
the danger of infection of surgical wounds or skin
breaks is high .
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S. aureus is difficult to treat and is very
resistant to many antibiotics…..mainly due
to resistance to penicillinase.
S aureous often enters the body via
natural openings in the skin barrier, hair
follicles ect…, if through mouth (food
poisoning)
Antibiotics do not penetrate abscesses well, thus
making the infection more difficult to treat, often
draining pus from abscess is one of the first
steps of treatment…treat with penicillin or
erythromycin.
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Staph infections on newborns includes impetigo
(vesicles on the skin rupture and crust over), or
scalded skin syndrome ( lesions on the nose
and mouth, then bright red area appears, within
48 hr the skin of palms and soles peels off in
sheet when touched…serious illness)
30 to 50% health adults carry staph in
their nose and 20% carry staph on their
skin.. and the human immune system is good at
combating staph infections ( most susceptible
include infants, elderly drug users and immune
impaired)
scalded skin syndrome
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The boils that Job scraped with
broken pottery (Job 2:7-8) could only
have been caused by staph
STREPTOCCOCAL INFECTION:
including flesh-eating bacteria
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Streptococci are gram positive spherical bacteria
with cells growing in chains.
They are facultative anaerobes
Many are nonpathogenic and occupy the mouth,
gastrointestinal tract and upper respiratory systems.
Some Streptococci are responsible for skin infections and
secrete several enzymes including hemolysins (damages
RBCs)
Impetigo is one disease caused by Strep
infections (symptoms include: superficial skin infection,
isolated pustules( round elevations full of pus) that
become crusted and rupture
Impetigo is one disease caused
by Strep infections
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Strep also causes scarlet fever, infections
of the throat
Steptococcus pneumonia most common
cause of bacterial pneumonia…and also
the cause of flesh-eating bacteria
(necrotizing fasciitis )
S. pneumonia is highly resistant and emits an
enzyme able to destroy the fascia, or tissue that
binds skin to muscle at a rate of an inch an
hour…about 1500-2000 cases in USA per year
with fatality rate of 30% in otherwise healthy
adults.
necrotizing fasciitis

Jim Henson from
muppets died of
this bacteria in
1990 from a
splinter cut on his
finger (duration
from time of
splinter to death—6
weeks)
PSEUDOMONADS (bacteria)
Aerobic gram negative rods, widespread in
soil and water, able to survive in any moist
environment.
 Cause otitis externa (swimmers ear)
 Pseudomonas dermatitis causes rash
outbreaks and is associated with
swimming pools
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Pseudomonas aeruginosa common and
serious opportunistic pathogen in burn
patients (esp 2nd and 3rd degrees), it is
carried on flowers or plants sent by wellwishers, thus reason hospitals do not
permit these patients to receive flowers.
Treatment with antibiotics gentamicin and
carbenicillin, (Silver sulfadiazine used in burn
victims)
WARTS: viral
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Caused by Viruses that stimulate an uncontrolled
but benign growth of skin cells, they can be
transmitted from one person to another by
contact.
Medical treatment includes applying extremely
cold liquid nitrogen to them, drying them with
electric current, or burning them off with acid.
Some skin or cervical cancers associated
with this papillomarivius.
SMALL POX (VARIOLA VIRUS)
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During middle ages 80% of population
expected to contract small pox
Two basic forms of this disease: variola
major (mortality rate 20%), and variola
minor (mortality rate 1%)
Transmission and progression is via respiratory
route, the virus infect many internal organs
before eventually moving into the blood
(viremia)…this leads to infection of the skin and
the production of more recognizable symptoms (
virus in epidermal layers causes skin lesions that
house the virus) .

Rameses V
(1156B.C.) showed
evidence of small
pox rash,
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Pocahontas (1617)
died of small pox
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Last outbreak in the USA was in 1947,
routine vaccinations for small pox were
discontinued in the United States in 1971
when it was deemed that the vaccination
posed a greater threat that did contracting
Ali Maow Maalin
HERPES SIMPLEX: (VIRUS)

Greek meaning to “creep”
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both types of herpes simplex viruses may spread to the
brain and cause herpes encephalitis, type 2 = 70%
mortality if untreated
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About 90% of the population of the United States has been
infected with the herpes simplex virus…initial infection
usually during infancy, and often subclinical.
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About 15% of the cases develop lesions known as cold sores or
fever blisters (usually occurring in oral or nasal mucous
membranes)… these lesions heal and the infection subsides but
recur when the infection strengthens again ( due to hormonal,
emotional stress or drop in immune system)
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Between recurrences, herpes simplex type
1 viruses are latent in the trigeminal nerve
ganglia communication between the face
and the central nervous system.
Herpes simplex 2 virus is transmitted via
sexual contact (lesions appear after incubation
period of 1 week and cause a burning sensation,
after which vesicles appear) urination can be
painful, and walking uncomfortable. ( vesicles
heal in a couple of weeks and contain the virus)(
location of vesicles in female: external genitals,
males: base of penis)
Herpes simplex 2 has latent periods and
active periods…varying per person…it can
cross placental barriers and affect
fetus…birth is via c section to prevent
spread of disease to baby if the disease
has not spread thru placenta
 There is no cure for genital herpes,
however Acyclovir can be
administered topically or orally.
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Shakespeare wrote of this unsightly curse
in Romeo and Juliet: “ O’er ladies’ lips,
who straight on kisses dream/Which oft
the angry Mab with blisters
plagues,/Because their breaths with
sweetmeats tainted are”
MEASLES (RUBEOLA VIRUS)
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Extremely contagious disease that spread
by the respiratory route.
Person with measles is infectious before
symptoms appear, thus quarantines not
effective
Humans are the only reservoir for measles,
although monkeys are also susceptible.
Law requires immunization for
school…vaccines being 95% effective.
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Development and progression of rubeola begins in the
upper respiratory system…incubation period of 10-12
days, symptoms develop including sore throat,
headache, and cough, followed by a papular rash
appearing on the skin, lesions of the oral cavity include
Koplik spots ( tiny red patches with central white
specks (helpful for diagnostics) on the oral
mucosa opposite the molars
Measles is extremely dangerous disease, especially in
very young or elderly. …(1 in 3000 cases fatal in infants,
complications such as encephalitis occur, if at all, about a
week after the rash appears) and can cause severe birth
defects if an expecting mother contracts german
measles
SCABIES: arthropod
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Infection of the human skin caused by the mite
Sarcoptes scabiei, a parasitic arthropod.
The disease is most common among school
children and is also found in adults…sometimes
occurring as a nosocomial infection.
The fingers, wrist, and elbows are the most
frequent sites of infection.
The mite burrow into the skin and fill the tunnel
with their eggs and feces.
The eggs hatch, and new mites mature, mate and
lay more eggs, perpetuating the life cycle.
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Symptoms are the result of hypersensitivity reactions to
the mites, and first occur 2 to 6 weeks after the initial
infection….
main symptom is itching especially when the skin is
warm (ex in bed at night), a red raised lesions
(erythematous papules) develop, which may become
infected with bacteria through scratching.
Diagnosis is made by examination of the skin with a 10X
hand lens to id burrows, sometimes the mites can be
picked out with a needle for microscopic examination.
Treatment is by a topical application of gamma benzene
hexachloride (kwell) , with bedding and other personal
objects sanitized.
CUTANEOUS MYCOSES: (fungal)
ringworms and athletes foot
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Fungi that colonized the hair, nails and
outer layer of the epidermis are called
dermatophytes and their infection are
called dermatomycoses.
Dermatophytes grow on the karatin
present in those locations, causing
ringworms ( most being asymptomatic and
removed for cosmetic reasons, named from
Greek time period who believed the infection to
be caused by worms)
Dogs and cats are frequently infected with
ringworms, as well as humans, if ring
worms are in the groin region it is called
jock itch, if on the feet it is athlete’s foot
 Treatment is of a variety of topical
medications including: miconazole, or
clotrimazole, or with oral medication such
as griseofulvin.
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Ring worms
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Athletes foot
CANDIDIASIS: Fungi
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The infection of the mouth with the fungi Candida
albicans, which is not affected by antibacterial drugs,
and will sometimes overgrow the mucosal tissue when
normal bacterial flora are suppressed.
Newborns infants, whose normal flora have not
yet established are often afflicted with
candidiasis of the oral cavity called thrush
Elderly, diabetics, and cancer patients can be
afflicted with candida in the mucosal tissues of the
vaginitis.
Treatment is usually with a topical application of
miconazole, clotrimazole, or nystiatin.
Thrush
CONTATGIOUS CONJUNCTIVITIS: pinkeye bacteria
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Caused by
Hemophilus
aegytius, and is
transmitted by
hand contact or by
flies.
Treatment topical
application of
antibiotics (vary)
BACTERIAL MENINGITIS:
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An inflammation of the meninges caused
by gram negative bacteria.
Most patients suffering from any type of
meningitis complain of headache and have
symptoms of nausea and vomiting,
convulsions and coma accompany the
infection in many cases.
Mortality rate varies with pathogen but is
generally high for an infectious disease
today…many survivors suffer from various
neurological damage.
Meningitis caused by different types of
pathogens (viruses, bacteria, fungi,
protozoan)
 There are 3 major types of bacterial
meningitis:
1.
2.
3.
meningococcal meningitis: caused by Neisseria
meningitides mortality rate 27%
pneumococcal meningitis caused by
Streptococcus pneumonia mortality rate 11%
Hemophilus influenza mortality rate 43% most
common
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Diagnosis is via analysis of cerebral spinal fluid and
blood.
Treatment is though a strengic regime of various
antibiotics including Rifampin, penicillin and ampicillin
TETANUS: bacteria
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Causitive agent is Clostridium tetani, an obligate,
anaerobic,endospore-forming, gram positive rod
that is common in soil contaminated with animal
feces.
Symptoms are caused by an extremely potent
neurotoxin (tetanospasmin) that is released
upon the dath and lysis of the growing bacteria.(
potent enough that the amount of toxin in the
ink of one . could kill 30 people)
In normal muscle operations, one muscle
contracts and the opposing muscle relaxes
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This neurotoxin blocks the relaxation pathway so
that both the muscles contract, resulting in
characteristic muscle spasms (if in the jaw…lock
jaw)
Mode of transmission is improperly cleaned deep
puncture wounds, especially those with little or
no bleeding, immunization is 100% effective and
boosters of every 10 years maintains
immunity..(DPT: diphtheria, pertussis, tetanus)
Recovery does not confer immunity, an d about 560,000
babies die each year in Asia and Africa because their
umbilical cords are cut with filthy instruments or the
stump is packed with dirt.
Tetanus
BOTULISM: Bacteria
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Caused by Clostridium botulinum, an
obligately anaerobic, endospore-forming,
gram-positive rod that is found in soil and
many freshwater sediments.
Ingesting the endospore usually does no
harm, however in anaerobic environments,
ex sealed cans, the microorganisms
produces an exotoxin that is highly potent.
Persons suffering from botulism undergo
progressive flaccid paralysis for 1-10 days and
may die from respiratory and cardiac failure.
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Symptoms include nausea, but no fever, varying
neurological safe) , difficulty swallowing ,general
weakness, blurred Recovery does not confer immunity
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First described 1800s with blood sausage (blood and
ground meat tied in pig stomach and incubated)
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Botulin toxin not formed in foods with acidity below ph
4.7 ( ex tomatoes
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Mortality rate 25 to 40%
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Treatment relies heavily on supportive care, antibiotics of
no use because toxin is preformed
Diagnosis by inoculation of mice with samples from
patients serum, stool, or vomitus
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LEPROSY: BACTERIA
Causitive agent Mycobacterium leprae, an
acid-fast rod, with an optimum growth
temperature of 30 C
 first isolated and identified about 1870.
 Sometimes called Hansen’s disease
(avoid term leprosy)
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Two main forms:
tuberculoid (neural) form characterized by
regions of skin that have lost sensation and are
surrounded by a boreer of nodules…. Recovery
sometimes spontaneously
2. lepromatous (progressive) form: skin cells are
infected and disfiguring nodules form all over
body…mucous membrane of nose affected,
deformation of hand into clawed form and
necrosis of tissue
1.
 Both
forms are spread by transfer of bacteria
from lesions or inanimate objects exposed to
lesion discharge
 Patients can be made noncommunicable
within 4-5 days by administration of sulfone
drugs
 National leprosy hospital in Carville Lousiana
reports about 200 cases a year.
 No vaccine for leprosy currently exists
POLIOMYELITIS: Virus
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Causitive agent: poliomyelitis virus
Best known as a cause of paralysis, however, only
about 10% of infected people develop identifiable
symptoms, and the paralytic form probably
affects less that 1% of those infected.
Symptoms often asymptomatic or mild and may include
headache, sore throat, fever and nausea.
Humans only known natural host
Primary mode of transmission is ingestion of
water that is contaminated with feces containing
virus
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Occurrence more often in summer months in
temperate regions
Predilection sites: tonsils, lymph nodes of neck
and ileum
Diagnosis based on isolation of virus from feces
and throat secretions
Preventives: Salk vaccine and Sabin
vaccine (more common in USA, less
expensive and oral medication of orange
flavored medicine)
RABIES: virus
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An acute infectious disease that usually results
in fatal encephalitis.
Causative agent is rabies virus (rhabdovirus)
with a characteristic bullet shape
Mode of transmission: bite of an infected
animal, even the lick of such an animal
can transmit the virus
Bats probably transmit the disease among
themselves via inhalation of virus in guano (
documented cases of aerosol transmission to
human who spelunker)
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Initially the virus multiplies in skeletal muscles
and connective tissue then enters the peripheral
nerves to the central nervous system where it
causes encephalitis
Symptoms: spasms of muscles of mouth and
pharynx when liquid is swallowed, later stages
just the sight of water causes spasms
(hydrophobia), final stages result from extensive
damage to the nerve cells of the brain and
spinal cord….Death inevitable
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1.
2.
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2 forms of the disease
furious rabies: dogs highly excitable and snap at
anything within reach
Dumb (paralytic) rabies: common in cats, only
minimal excitability
Treatment: Pasteur treatment (14-21
inoculations) and more recent human diploid cell
vaccine (HDCV) (5-6 inoculations)
Carriers: skunks 46%, bats 19%, foxes 10%,
raccoons 10%,domestic animals 6%, dogs
6%….seldom in rabbits, squirrels or mice
AFRICAN TRYPANOSOMIASIS:
protozoan
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Causes African sleeping sickness..
Causative agent Trypanosoma brucei gambiense,
a flagellate that is injected by the bite of the
tsetse fly (arthropod vector)
Predilection site: blood
Symptoms: decreased physical activity and mental
acuity, if untreated, the host enters a coma and death is
inevitable.
Treatment: drugs only affective when central nervous
system is not affected,, drugs kill 99% but the remaining
1% becomes immune and multiply in the blood, new
antibiotics are used and 99% are killed and the 1%
become immune and rebuild the numbers…making this a
difficult condition to treat.
NAEGLERIA FOWLERI:
protozoan (amoeba)
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A protozoan known to cause neurological disease.
Symptoms: flu-like and death within one weak
Etiology: the spore enters a broken mucous
membrane, usually oral or nasal and the
protozoan migrates to the brain where it causes
encephalitis like conditions and death.
Most common victims are children who swim in
ponds or streams.
Only a few cases per year are reported, bur
fatality rate is nearly 100%
ANTHRAX: Bacteria
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Common names include splenic fever, mrrian ( biblical
term for anthrax), and charbon to name a few
Anthrax is an acute infectious febrile disease of virtually
all animals caused by Bacillus anthracis and is generally
septicemia in nature but may be localized.
Clinically characterized in a very short course (10-12 hrs)
Generally appears in late spring and summer
It is an aerobic, encapsulated rod, gram positive, not
acid fast and oxygen is necessary for sporulation.
Vegetative form is easy to kill with disinfectant, 12oF
also kills this bacteria
Mode of transmission is: ingestion,
inhalation, biting insect,
 Incubation period 1-14 days usually 36Prognosis: unfavorable
 Symptoms: increased pulse rate (rapid but
weak), temp 104F, spleen enlarged,
edema of lungs, Post mortal findings: rigor
mortis is incomplete or completely absent

3 types of Anthrax:
cutaneous anthrax: characterized as
pustular infection of skin, danger of
septicemia
2. Inhalation anthrax: endospores are
inhaled, high fever, difficulty breathing
and chest pain, septicemia and high
mortality rate
3. Ingestion anthrax: ingest endospores
and enters gastrointestinal tract
1.
KURU AND MAD COW DISEASE:
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Kuru occurs in
isolated groups of
cannibals who eat
brains.
TAPEWORMS:
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Often asymptomatic
Includes Taenia saginata: beef tapeworm,
infestations begin with the consumption of
undercooked beef, pork, or fish, adult worms
can live in the intestines for up to 25 years and
reach lengths of 6 meters (18 feet)
Symptoms abdominal discomfort, psychological
distress, when several feet pass through anus,
flatulence
Drug of choice to eliminate the infection is
niclosamide
NEMATODES:
Round worm infections including the
following:
1. pinworms: Enterobius
vermicularis…. Which migrates out anus of
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human host to lay eggs, causing local
itching…treat entire house with pyrantel
pamoate, or mebendazole… contraction is oral
fecal …generally children putting dirty fingers in
mouth.
1.
hookworms: Necator
americanus….
Attaches to intestinal
wall and feeds on
blood and tissue, can
lead to anemia, or
craving unusual food
such as soil or
laundry starch,
contact is bare skin
in soil, treat with
mebendazole.
1.
2.
Ascariasis: Ascaris
lumbricoides…can grow
up to one foot in length,
live in intestinal tract and
often diagnosed when
adult worm emerge from
anus, may be coughed up
and swallowed allowing
for migration to throat,
lungs, or abdominal
cavity.
Effectively treated with
mebendazole
CHINESE RESTRANT DISEASE:
bacterial

Aka Monosodium
glutamate (MSG) which
can cause chest pain,
burning sensations, and
feeling that your face is
blowing up like a balloon.
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The effects depend on how
much MSG and vary from
person to person but is a
reminder that MSG is
manufactured by
Corynebacterium
glutamicum, a cousin to
the diphtheria germ
TUBERCULOSIS: bacteria

A chronic bacterial disease caused by
Mycrobacterium tuberculosis, characterized
clinically by wasting of the body and
granulomatous tubuncles.

Often called white death, it is referred to in the
Bible…It was the “plague of the pharaoh’s”
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Mode of transmission: picked up by injection,
inhalation, wound contamination
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Etiology: it is a slender, rod shaped obligate aerobe,
stains gram positive, is acid fast, moderate resistance to
heat, may stay alive under moderate conditions 2-4
years
Symptoms: gradual lose of weight , coughing, apnea,
partial loss of appetite, unusual signs or symptoms
depending on where the lesion is located, if body has
enough resistance to the first tubercle, it may become
walled off by scar tissue and never do any other damage
to the body or spread further ( occurred with Marie
Currie)
Prognosis: unfavorable
Incubation time: not
definite time

By law cattle must me branded on the left jaw with a T
to indicate TB positive animals and a reactor tag is
placed in left ear ( red tag)
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Charles Dickens character David Copperfield died of
tuberculosis…. Well known personalities that suffered
from TB included: King Tut, Edgar Allan Poe, Chopin,
Robert Louis Stevenson, Adolph Hitler, Nelson Mandela
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Treatment: today various drugs are used to treat TB
including streptomycin, isoniazid (INH) and rifampin
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Charles Dickens
character David
Copperfield died of
tuberculosis….
Well known personalities
that suffered from TB
included: King Tut, Edgar
Allan Poe, Chopin, Robert
Louis Stevenson, Adolph
Hitler, Nelson Mandela
YELLOW FEVER: arthropod borne
virus
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Historically important because it was the
first such virus discovered and provide the
first conformation that an insect could
transmit a virus.
The virus is injected into the skin by the
mosquito ( Aedes aegypti is the vector)
Symptoms: fever, chills, headache, backache,
nausea, jaundice
Treatment: none
Incubation period: 4-18 days
Vaccine: good for 6 years
DENGI: virus
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Acute but rarely fatal viral disease transmitted
by the mosquito Aedes aegypti.
Sometimes called breakbone fever,
characterized by acutely high fever ,followed by
a rash 2-4 days later (mainly on trunk, never on
palms of hands or soles of feet)
Generally will occur between Sept and
November
No specific treatment against the virus
HOT VIRUS;
ONE THAT SPREADS EASILY,
KILLS QUICKLY, WITH HIGH
MORTALITY RATE, AND HAS NOT
CURE OR PREVENTIVE VACCINE
VIRAL HEMORRAGIC FEVERS
(MARBURG/EBOLA
Marburg (city in Germany):
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1967 3 factory workers became nauseated and began to
vomit.
Diarrhea set in eyes became severely bloodshot and a
painful rash occurred ( due to blood clotting in
thousands of capillaries), their throats became so raw
they could not swallow and had to be fed intravenously…
within 10 days they began vomiting and defecating
blood…blood and Marburg virus gush in all directions…
If the virus lands on another human, the horrid cycle of
infection begins again, killing about 25% of the people
infected…
very lethal virus (only 3 documented outbreaks
1967,1976,1990
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The virus looked like a short piece of yarn ( thus
called filovirus) unlike the spherical shape of
most viruses.
Many scientist believe that this was an emerging
virus ( one that had jumped into a new animal
species….
reason it was uncommonly deadly and the new
host has never been exposed to the virus, and the
hosts immune system has no defense against the
virus.
both Marburg,and Ebola are Biosafety level 4
agents, kept under constant negative air pressure
to ensure no escape of the virus… as compared to
HIV with is only a level 2 virus
Ebola (river in Zaire)
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First appearance 1976 (325 of 358 dead),
kills 90% of its victims,
it can attack and amplify itself in virtually any body tissue except
bone and perhaps skeletal muscle.
Characterized by seering headache, fever and muscle pain, then the
bleeding starts (internal hemorrhaging and the body’s clotting
factors begin, organs such as liver and spleen are transformed into
hardened masses of coagulated blood and tissue, kidneys become
so clogged with blood that they cease to function, blood flows into
lungs, stomach and intestines… death soon follows often from shock
, heart failure or lung congestion
Ebola does in 10 days what it takes AIDs ten years to do…
it is a filovirus( shaped like a question mark), transmitted
by air, but luckily not easily transmitted from human to human
through casual contact…hospitals where greatest miniepidemics
occur.
Antibodies have been collected and used
to treat victims of hot virus diseases.
 The blood of one nun, a survivor of Ebola,
was repeatedly tapped for its Ebola
antibodies…when injected into a person
during the early stages of Ebola fever, it
sometimes proved beneficial
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CHAGAS: protozoan
A protozoan disease of the cardiovascular
system
 Causitive agent is Trypanosoma cruzi , a
flagellated protozoan
 Affects 40 to 50% of population in rural
areas of S. America
 Reservoir include rodents, opossums, and
armadillos
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Arthropod vector is the reduviid bug (kissing
bug)that bites humans or animals around the
lips… the wound is scratched and the
trypanosome enters the would
Most damage is due to inflammation around the
wound but the nervous system can be affected (
loss of involuntary muscle contraction in
esophagus and gastrointestinal tract
Treatment is difficult in chronic progressive
stage… Nifurtimix drug of choice for
treatment…no cure
Some believe that
Charles Darwin
contracted chagas on
his voyage on the
H.M.S. beagle
 He was known to
have been bitten by
the kissing bug
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MALARIA: protozoan
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Characterized by chills, fever and often vomiting
and severe headache… Causitive agent is
Plasmodium falciparum, carried by the mosquito
vector Anopheles
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The sporozoite enters the bloodstream of bitten human
within 30 minutes of bite, reproducing and moving to the
bloodstream where it causes RBCs to rupture and the
release of the mature merozoites….fever reaches
104F, sweating begins, fever subsides and patient feels
normal until cycle begins again ( if 1% RBC infected then
over 100,000,000,000 parasites in circula

Treatment is with
quinine, or quinine
derived
antibiotics…no
effective control of
malaria in sight
LYME DISEASE: spirochete
Named after location identified
(Lyme Connecticut)
 Number 1 tic-borne disease in USA
Causitive agent is the spirochete
Borrelia burgdorferi and the vector
being a tic Ixodes pacificus
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Symptoms usually a rash appearing near bite
site that expands out to about 15 cm ( bullseye
appearance) followed by flu like symptoms….if
untreated the heart can become affected
(possible requiring a pacemaker) and
neurological symptoms can occur (face paralysis,
meningitis, encephalitis) other symptoms include
chills, headache, and muscle pain
Treat with antibiotics… but the later diagnosed
the more difficult the treatment
ROCKY MOUNTAIN SPOTTED
FEVER: rickettsia
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The number 2 tic-borne disease in USA
This rickettsia is a parasitic Tick borne disease
that is passed form one generation of ticks to
another through their eggs (transovarian
passage)
Causitive agent is Rickettsia rickettsia , major tic
vectors are Dermacentor andersoni (west) and
D. variabilis (east)
Symptoms: About one week after bite a
rash appears (often on palms and
soles...which does not occur with viral
rashes) resulting in leakage of blood into
surrounding tissues, fever and headache
follow,, death in about 3% cases
 Treat with Antibiotics such as testracycline
and chloramphenicol …very effective

TICK PARALYSIS
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Called ascending flaccid paralysis
Possibly due to a toxin in the tic saliva, usually
affects children
Incubation period is 4-7 days, most cases in May
and June
Host wakes up paralyzed …removal of tic
results in full recovery…like a miracle
Severity of case is according to how close
to the brain the tic is…death is rare
Causitve agent: Dermacentor andersoni
WHOOPING COUGH: bacteria
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Causitive agent Bordetella pertussis, a
small, nonmotile, gram negative
coccobacillus, it is an obligate aerobe.
The organisms does not invade tissues, but
rather attaches to the cilia in the trachea and
impedes their action, allowing mucus to
accumulate.
It primarily affects children and is quite
severe
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Symptoms: initial stage (catarrhal stage)
similar to common cold, the paraoxysmal stage
is characterized with persistent coughs so
violent that it can break ribs, gasping for air
between coughs causes a whooping sound, and
occurs several times a day for 1-6 weeks.
The Covalescence stage may last for
months.
This is a very long duration for a
respiratory infection, symptoms include high
white blood cell count with diagnosis made from
cultured throat swabs.
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Transmission is by inhaling pathogens expelled
by coughing of infected patient…Mild case
requires no specific treatment…
Severe cases are treated with Tetracyclines and
chloramphenicol…..but only render the patient
uncontagious
Vaccines exist but have considerable safety
concerns (3.2 in 1 million result in
neurological damage)
INFLUENZA: virus

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Caused one of the worst plagues ever to
afflict humankind in 1918 (Spanish flu
also called Swine flu 40 million dead
within months)….It is pandemic
So desperate the situation that Chicago
police arrested people for sneezing in
public and San Francisco required people
to wear surgical masks over their mouths
and noses in pubic… violators were
arrested
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1957 and 1968 had milder epidemics… but
Virologist are scared that before long
another “superflu” will emerge saying we
are already overdue
Influenza does keep reemerging (reason
for flu shot each year)( only AIDS virus
mutates faster that the Influenza
virus…both being classified as RNA
viruses)
If the same flu strain appeared each
year we would develop an immunity
to it…
 thus it mutates by changing its viral
coat ever so slightly… under a
microscope it looks like a pasta salad
with twists of macaroni entwined
with one another ( 8 twisted
segments in all)
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Mutation is due to its ability to enter
humans, pigs and ducks ( thriving in the
digestive tract and allowing a mixing and
blending of different strains….what
emerges is a new strain each year)
If the recombinant strain that is made is
capable of infecting and causing illness in
humans, a new pandemic looms over the
horizon

Solution: keep ducks and pigs and humans away from
one another as much as possible… If different strains are
not given the opportunity to co-infect a host, no superflu
can emerge

However in Asian countries: hens are hung in cages
above pigs, which feed on the hen droppings, the pig
feces are used to fertilize fish ponds where ducks swim
drink and release their waste … the last few flu strains
have been Hong Kong flu, Shanghai flu and Singapore
flu… Luckily there has been no epidemic strain since
1968.
HANTAVIRUS:
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1950s It was known as Korean hemorrhagic
fever, later renamed hemorrhagic fever with
renal syndrome
Was first discovered in the lung tissue of its
natural host, the striped field mouse, in which it
causes no illness
Kidney involvement seemed to be a hallmark of
the disease.
When rats were tested in Baltimore,
Philadelphia, New Orleans, New York and San
Francisco the Seoul Korea
Hantavirus turned up everywhere
(1980 due to importing goods)
 The American variety of hantavirus is
a more deadly and silent killer, taking
its toll unnoticed until late 1980s.
 It has been confirmed in cases of
hypertension and chronic kidney failure at
a frequency 5X greater than the general
public.
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1993 a hot hantavirus struck a Navajo
reservation in New Mexico… a Navajo Indian
passed away 5 days after his bride to be died
both suffered mild flulike symptoms, then
suffered severe respiratory distress…Over a
dozen more cases followed.
One patient sat up in bed in the morning
talking and eating breakfast was on a
respirator by afternoon and was dead that
night.
Prevention: Control of rodent population,
wear mask when doing spring cleaning in
garages or attics if mouse droppings are
present….birds possible are carriers of
hanta as well
 Treatment: poor but a vaccine against
certain strains does exist

PLAGUE: BACTERIAL

Also called Black Death due to the
characteristic blackish areas of skin
caused by hemorrhages
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14th century ¼ total population in Europe
died of Plague
Causitive agent is Yersinia pestis, a gram
negative rod shaped bacteria transmitted
from one rat to another by the rat flea
Xenopsylla cheopis
Is endemic in wild rodents especially
ground squirrels, prairie dogs and
chipmunks… with the number of plague
cases reported in the USA increasing
If the host dies, the rat flea seeks a
replacement…another rodent or a human
Virulence is due to the ability of the
bacteria to survive and proliferate inside
phagocytic cells rather than being
destroyed.
 Symptoms: lymph nodes in groin and
armpit become enlarged (swellings called
buboes reason for name bubonic plague),
fever develops… mortality rate 50-75% if
untreated… death within one week
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Particular danger is if the bacteria enters the
blood and lungs (pneumonic plague)… mortality
rate 100%, even today this disease can rarely be
controlled if not identified within 12-15 hours of
onset of fever….death usually within 3 days…
high likelihood of airborne infections from
infected person
Diagnosis is by a fluorescent-antibody test…no
vaccines are available except for persons likely
to come in contact with infected fleas
Prevention: control rat-based population via
sanitation
IN CONCLUSION:
“A wise man should consider that health
is the greatest of human blessings, and
learn how by his own thought to derive
benefit from his illness” Hippocrates
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Fifty million people drink unfiltered water
in America.
Not surprisingly, waterborne microbes
such as rotavirus, the world’s leading
cause of diarrhea continue to infect, sicken
and kill.
Each year thousands of people die in the
USA from infections by the familiar
foodborne bacteria, salmonella and
shigella.
Tuberculosis and AIDs are also on the rise
in the USA, Canada and Europe.
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Jet travel has brought the human
population(all 6 million +) together.
It creates a melting pot for pathogens and
for disease transmission.
The extremely virulent viruses emerging
from the rain forests (Ebola, Marburg,
Lassa) are no longer isolated from the
population.
The resurgence of tuberculosis has
reminded us that diseases once
vanquished can return with a vengeance
To this point we have been blessed.
 The most common yet potentially
dangerous bacterial infections (Step
and Staph)remain susceptible to at
least one antibiotic (vancomycin) and
the most virulent or most lethal
infections (Ebola, AIDS, and
Marburg) are not easily transmitted.

But what if common
pathogens become
resistant to all antibiotics?
What if AIDS or Ebola
become airborne and
easily spread as the flue or
common cold?
Given the conditions that
exist today, it is a scary
thought.
There is little doubt that the fourth
horseman—pestilence—has saddled
up and is charging at us.
The fight against
pathogens is never over.
To quote one epidemiologist “
We are all in it together”
AND THE BATTLE
CONTINUES!!!!!!