Week 1- Plague Flashcards
What is the infectious agent that causes the plague?
Gram negative bacterium Yersinia pestis
How is the plague transmitted?
Through the bite of fleas that have fed on infected animals like mice, rats, rabbits. squirrels, chipmunks, and prairie dogs, or on infected humans. It also spreads through direct contact with an infected person or animal, or by eating an infected animal that hasn’t been cooked properly
Why is the plague considered a nationally notifiable disease?
Because it’s very dangerous- infected people need to notify the CDC
The plague is endemic to rural areas in (4)
- Central and southern Africa (especially eastern 2. Democratic Republic of Congo, northwestern Uganda, and Madagascar)
- Central Asia and the Indian subcontinent
- The northeastern part of South America
- Parts of the southwestern United States
Endemic
An endemic disease is naturally occurring in that environment
Incubation period definition
Time between infection and onset of symptoms
What is the incubation period of the plague?
1-6 days
Types of plague (3)
- Bubonic (most common)
- Pneumonic- spreads through aerosols
- Septicemic- blood infection
Bubonic plague signs and symptoms
Rapid onset of fever, painful and swollen lymph nodes (usually inguinal, axillary, or cervical), headache, nausea and vomiting, joint pain. The swollen lymph nodes can break and release pus that contains Yersinia pestis
Pneumonic plague signs and symptoms
High fever, overwhelming pneumonia, cough, bloody sputum, chills, muscle weakness. Bloody sputum typically does not occur with regular pneumonia
Septicemic plague signs and symptoms
Fever, prostration, hemorrhagic or thrombotic phenomena, progresses to acral gangrene (extremities turn black and discharge liquid)
Why is the plague also called the black death?
Called black death due to dead tissue (tissue becomes necrotic)
What is the most deadly form of plague?
Septicemic is the most deadly form- it takes a while to realize that you have the septicemic form and by then it’s too late
What is the most contagious form of plague?
Pneumonic is most contagious because it’s airborne
What samples are collected to diagnose plague?
Isolation of bacteria from bubo aspirates, blood cultures, or sputum culture (if pneumonic). Need blood cultures for septicemia, but you can do it for all forms
How is Y. pestis identified in collected samples?
Culture, serologic tests for the Y. pestis F1 antigen
Antibiotics used to treat plague (4)
gentamicin, doxycycline, ciprofloxacin, and levofloxacin
Parental antibiotics (3)
Moxifloxacin, streptomycin (alternative), and chloramphenicol (alternative). These antibiotics are given by IV when people are very sick
Why is plague considered a re-emerging disease?
The black death is re-emerging due to antibiotic resistance. Also, you would normally find Y. pestis is a wild environment, but we are starting to invade wild areas and being exposed to infected animals
Ways to prevent plague (5)
- Keep rodent population under control in your home, workplace, and recreation area
- Keep the home free from stacks of cluttered firewood or piles of rock, brush, or other debris that could attract rodents
- Protect pets from fleas using flea control products. Pets that roam freely outdoors may be more likely to come into contact with plague-infested fleas or animals
- Use insect repellent products
- Vaccines- no licensed vaccines- the ones that are available aren’t effective for a long period of time
Types of vaccines (4)
- Killed whole cell vaccine
- Live attenuated vaccine
- Subunit vaccines are under development
- Monoclonal antibodies are used as a therapeutic vaccine
Killed whole cell vaccine
Kill the bacteria and introduce the entire killed bacteria to the body. The body recognizes the threat and produces antibodies
Live attenuated vaccine
Bacteria has been attenuated (missing certain components so it’s not infectious anymore)
Subunit vaccine
Has certain products of the bacteria- difficult to develop this type of vaccine against a whole bacteria
Monoclonal antibodies
Used as a therapeutic vaccine. Antibodies can be created in a lab, or plasma can be isolated from a plague patient that contains antibodies and introduce it to another patient. Allows the body to create its own antibodies for a certain period of time
When did the medieval plague occur?
Over a span of 7 years in the mid 14th century. Half of Europe’s population died
How did the plague influence European culture?
It drove the intensification of Christian belief and practice. It manifested as extremist cults that questioned the authority of the clergy and in Christian pogroms against European Jews. Heightened religiosity inspired the founding of new universities- this decreased the unity of medieval Christianity and enhanced the rise of stronger national identities. It also contributed to the rise of the Reformation that split Christianity in the 16th century
How did the plague shape the medical field?
Doctors had firsthand experience with plague patients and began to rebel against ancient medical doctrine, like the causes of disease. People began to realize that diseases were contagious, and doctors prioritized a new empirical approach- this was the basis for the scientific revolution. In the 15th century, quarantines became routine- new outbreaks were due to breaks in the quarantine. This resulted in the emergence of state power in Europe
How did the plague shape the European economy?
Wage rates rose rapidly in Europe- people were willing to pay more for scarce labor- rising autonomy of the poor contributed to peasant uprisings. The plague also ended the medieval trade system between Europe and Asia. There was a new economic globalization involving the Americas- stimulated new pandemics of other diseases like measles and smallpox
Why are modern plague infections less severe than infections in the medieval period?
Modern plague infections are much less severe than medieval plague infections, but this isn’t due to differences in the genome- the genomes of the medieval strains of the plague and the modern strains are very similar. Could be due to climate changes or social changes, but also due to modern immunity since we have been exposed to different pathogens
