Microbiology, Chapter 20
1. Plague – Yersinia pestis – caused the black
death of the middle ages - pandemics
a. Small gram negative rod, rodent
reservoir, and insect vector
b. Rats, small rodents, ground squirrels
c. Humans acquire it from fleas
Microbiology, Chapter 20
Microbiology, Chapter 20
d. Disease starts at site of bite, and the organisms enter
blood stream where the bacteria are phagocytized,
grow in phagocyte and the organisms proliferate to
infect lymph nodes (form bulbous swellings – buboes
(619) – thus bubonic plague)
e. Can spread to lungs – pneumonic form and can be spread
by respiratory droplets – very serious form of disease
and can often be fatal
f. Septicemia is also seen
g. Now found in the us west and seem to be more cases
(people and rodents are coming together more often) –
endemic in rodents
h. Antibiotics – streptomycin and tetracycline are effective if
caught early enough – vaccine is available
Microbiology, Chapter 20
2. Tularemia – Francisella tularensis – 90% acquired by handling wild
rabbits (skinning), can be transmitted by ticks, even infected wild
meat – streptomycin, gentamycin drugs of choice – so infective in
such small doses that researchers have to be extra careful
Microbiology, Chapter 20
3. Brucellosis – Brucella species – undulant fever –
small gram (-) rod, fastidious, cattle, sheep,
goats, wild animals like elk
a. Brucellosis usually mild, self limiting
disease, fever rises and peaks at night – thus
undulant fever
b. Used to be passed to humans through
unpasteurized milk
c. With current vaccination programs and
pasteurization occurs infrequently
Microbiology, Chapter 20
Microbiology, Chapter 20
Brucella
Microbiology, Chapter 20
4. Lyme’s disease – Borrelia burgdorferi – (pg. 625
life cycle) spirochete transmitted by tick bite, deer
tick in Texas - probably the most common tick borne
disease in the us
a. Circular rash (bulls eye) at site of bite (pg 624)
b. Systemic progression of disease – aches, pains,
fever, fatigue, chronic arthritis symptoms
c. Caught early, antibiotics are useful, in later
stages, large doses are required
d. Lyme county Conn. – first described in 1970’s
Microbiology, Chapter 20
Microbiology, Chapter 20
Microbiology, Chapter 20
5. Rickettsial diseases – small gram – obligate intracellular
parasites
a. Rocky mountain spotted fever – tick borne
b. Typhus – lice or fleas
c. Systemic diseases, caught early then antibiotics are
effective
Microbiology, Chapter 20
Rocky mountain spotted fever, microbe in
cells, rash on child’s hand
Microbiology, Chapter 20
6. Yellow and dengue fever – hemorrhagic viral diseases, spread by
mosquitos
a. Panama canal was halted because of yellow fever – a serious
infection with a high mortality rate
b. US finished it after Walter Reed discovered a vaccine for
yellow fever
c. Dengue fever similar to yellow fever, break bone fever – so
painful, person feels bones are breaking
Microbiology, Chapter 20, Walter
Reed and Yellow fever vaccine
Microbiology, Chapter 20
Oh, so much more, too little time
Microbiology, Chapter 20
7. Epstein-Barr virus: Infectious mononucleosis – large
enveloped DNA virus that can survive outside host. Infects
the lymphatic system and can last for weeks
Microbiology, Chapter 20
8. Plasmodium species – Malaria – mosquito bornlook at our lab manual – complex life cycle (see
page 633 for life cycle) chloraquinone is drug used
to treat it, now have resistant strains, old quinine
treatment had lots of side effects
Fig. 20.18
Microbiology, Chapter 20, Malaria: sexual and
asexual phase
Microbiology, Chapter 20
9. Emerging viral hemorrhagic diseases See page 627,
checkpoint 20.7
a. Marburg – filament virus, from monkeys imported
from Africa to Marburg germany
b. Ebola – another filo virus, 90% mortality rate,
shepherds crook
c. Lassa fever African disease, rodents involved see
pg 641 these bugs make good thriller movies
Microbiology, Chapter 20
Microbiology, Chapter 20
10. Toxoplasma – protozoan with complex life cycle.
Transmitted to humans usually by cats. Particularly a problem
with fetus, organism can cross placenta. HIV patients are at
higher risk
Toxoplasma; cycle and CNS cytopathology
Microbiology, Chapter 20
11. Schistosoma species – Flukes – Trematode helminth.
Not a problem in us, but fairly wide spread in the orient.
Complicated life cycle with an intermediate host like a snail.
Could be eliminated with proper sanitation.
Schistosoma; egg, symptoms
Schistosoma, free swimming larvae
Microbiology, Chapter 20
12. Filarial diseases – oh there is so much more but so little time.
– another course – PARASITOLOGY
Microbiology, Chapter 20
HIV handout – on line
Separate power point on HIV
virion
Sarcoma