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Questions and Answers
What is the main organism responsible for the plague?
What is the main organism responsible for the plague?
The mortality rate for pneumonic plague can be 100% if not treated within 12-15 hours.
The mortality rate for pneumonic plague can be 100% if not treated within 12-15 hours.
True
What is the main mode of transmission for the plague?
What is the main mode of transmission for the plague?
rat flea bite
The most common form of plague is __________ plague.
The most common form of plague is __________ plague.
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Match the forms of plague with their symptoms or characteristics:
Match the forms of plague with their symptoms or characteristics:
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What is the mortality rate of endemic typhus if left untreated?
What is the mortality rate of endemic typhus if left untreated?
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Epidemic typhus is called murine-borne typhus.
Epidemic typhus is called murine-borne typhus.
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What organism causes Rocky Mountain spotted fever?
What organism causes Rocky Mountain spotted fever?
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The primary vector for Rocky Mountain spotted fever is the ______.
The primary vector for Rocky Mountain spotted fever is the ______.
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Match the following diseases with their characteristics:
Match the following diseases with their characteristics:
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The mortality rate of Western Equine Encephalitis (WEE) is 30%.
The mortality rate of Western Equine Encephalitis (WEE) is 30%.
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Yersinia pestis is classified as Gram positive bacilli.
Yersinia pestis is classified as Gram positive bacilli.
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What is the causative organism of Lyme disease?
What is the causative organism of Lyme disease?
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The tick that primarily transmits Lyme disease belongs to the ______ species.
The tick that primarily transmits Lyme disease belongs to the ______ species.
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Which is a characteristic symptom of the first stage of Lyme disease?
Which is a characteristic symptom of the first stage of Lyme disease?
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Match the type of typhus with its causative organism:
Match the type of typhus with its causative organism:
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The first stage of Lyme disease can present flu-like symptoms.
The first stage of Lyme disease can present flu-like symptoms.
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What is the recommended antibiotic treatment for Lyme disease?
What is the recommended antibiotic treatment for Lyme disease?
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Which of the following arthropods can transmit diseases through biting?
Which of the following arthropods can transmit diseases through biting?
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All arthropod-borne diseases are caused by viral pathogens.
All arthropod-borne diseases are caused by viral pathogens.
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What is one common symptom of arboviral encephalitis?
What is one common symptom of arboviral encephalitis?
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The mortality rate of Eastern Equine Encephalitis (EEE) is greater than _____%.
The mortality rate of Eastern Equine Encephalitis (EEE) is greater than _____%.
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Which of the following is a vector for Western Equine Encephalitis (WEE)?
Which of the following is a vector for Western Equine Encephalitis (WEE)?
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California Encephalitis primarily affects older adults.
California Encephalitis primarily affects older adults.
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Name one reservoir for St. Louis Encephalitis.
Name one reservoir for St. Louis Encephalitis.
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Match the type of arboviral encephalitis with its pathogen:
Match the type of arboviral encephalitis with its pathogen:
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Study Notes
Arthropod-Borne Infectious Diseases
- Learning Outcomes: Categorize arthropod-borne diseases and suggest appropriate control measures. Key topics covered are in chapters 22 and 23.
Arthropods That Transmit Disease
- Vectors include ticks, mosquitoes, fleas, and biting flies.
- Transmission is typically through biting.
Infections
-
Viral (arboviruses):
- West Nile virus
- Encephalitic viruses (CNS)
-
Bacterial:
- Ricketsia rickettsii
- Borrelia burgdorferi
- Yersinia pestis (CVS)
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Parasites:
- Malaria (CVS)
Arboviral Encephalitis
- Organism: Arbovirus
- Transmission: Mosquito-borne viruses
- Reservoir: Birds, horses, rodents, and mammals
- Seasonality: Summer months
- Symptoms: Fever, headache, and altered mental status (ranging from confusion to coma)
- Control: (Further details needed)
- Types of Arboviral encephalitis: (List of types needed)
Specific Diseases and Characteristics
- Western Equine Encephalitis (WEE): - Pathogen: WEE virus (Togavirus) - Mosquito Vector: Culex and Aedes - Reservoir: Birds, Horses - Epidemiology: Severe disease, frequent neurological damage, especially in infants - Mortality: 5%
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Eastern Equine Encephalitis (EEE):
- Pathogen: EEE virus (Togavirus)
- Mosquito Vector: Culiseta
- Reservoir: Rodents
- Epidemiology: More severe than WEE, effects mostly young children and younger adults
- Mortality: >30%
-
St. Louis Encephalitis (SLE):
- Pathogen: SLE virus (Flavivirus)
- Mosquito Vector: (Not specified)
- Reservoir: Large mammals
- Epidemiology: Mostly urban outbreaks, affects over 40, mainly adults
- Mortality: 20%
-
California Encephalitis (CE):
- Pathogen: CE virus (Bunyavirus)
- Mosquito Vector: (Not specified)
- Reservoir: Large mammals
- Epidemiology: Affects mostly 4-18 year olds in rural/suburban areas. ~10% have neurological damage
- Mortality: 1%
-
West Nile Encephalitis (WN):
- Pathogen: WN virus (Flavivirus)
- Mosquito Vector: (Not specified)
- Reservoir: (Not specified)
- Epidemiology: Most cases are asymptomatic. Symptoms can range from mild to severe
- Mortality: 4-18%
Plague
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Organism: Yersinia pestis, gram-negative bacilli
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Transmission: Rat flea bite (Xenopsylla cheopis)
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Pathogenesis: (Further detail needed)
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Virulence factor: Resistance to phagocytosis
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Forms of Plague:
- Bubonic: Enlargement of lymph nodes (groin, etc.), fever, malaise, headache. Most common form. Mortality rate: 50-75%
- Septicemic: Bacterial endotoxins cause disseminated intravascular coagulation (DIC). Bleeding under skin, blackened skin (nose, fingers, toes), belly pain, diarrhea, vomiting, shock.
- Pneumonic: Highly contagious, spread by airborne droplets. Cough (possibly with blood), shortness of breath. Mortality rate: 100% (unless detected within 12-15 hours of fever onset).
-
Laboratory Diagnosis: Isolation of bacteria, direct detection of capsular antigen (within 15 minutes of blood or other body fluids)
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Treatment: Streptomycin and tetracycline
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Prophylaxis: Vaccine (details needed about target population)
Lyme Disease (Lyme Borreliosis)
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Causative organism: Borrelia burgdorferi
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Spirochete
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Obligate intracellular pathogen.
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Epidemiology
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First diagnosed as rheumatoid arthritis near Lyme, Connecticut
-
Seasonal occurrence: Summer months
-
Mode of transmission: Ixodes species ticks (deer ticks)
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Mammalian reservoir: Mice, deer
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Life Cycle:
- Ticks feed three times: on field mice, field mice, and deer
- Humans become infected by tick nymphs.
- Ticks don't feed for 24 hrs, then 2-3 days before pathogen transmission.
- Occurrence: 1% of tick bites are symptomatic.
-
Stages of Lyme Disease (Symptoms):
- First stage: Erythema migrans (bulls-eye rash), flu-like symptoms. Antibiotic treatment is highly effective in this stage.
- Second stage: Dissemination – Bulls-eye rash spreads to other body sites. Heart palpitations, muscle/joint pain, headaches, neurological symptoms (facial paralysis, memory loss, meningitis, or encephalitis).
- Third stage: Persistent infections lead to chronic arthritis, cognitive impairment, weakness, joint pain (especially in knees), fatigue. Can lead to permanent damage.
-
Diagnosis: Clinical diagnosis (symptoms), laboratory tests (ELISA, IFA, confirmed by Western blot).
-
Treatment: Streptomycin and tetracycline (treats all stages)
Typhus
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Causative organism: Rickettsias (gram-negative, pleomorphic bacteria – obligate intracellular parasites of eukaryotes)
- Spread by arthropod vectors
- Infect endothelial cells of vascular systems and multiply
- Inflammation causes blockage and rupture of small blood vessels
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Types:
- Epidemic typhus: R. prowazekii (Pediculus humanus)
- Endemic typhus: R. typhi (Xenopsylla cheopis)
- Rocky Mountain Spotted Fever: R. rickettsii (Tick-borne)
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Epidemiology (further details needed)
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Symptoms: High prolonged fever, small red spots (caused by subcutaneous hemorrhage)
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Mortality: High (if untreated)
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Treatment: Tetracycline, chloramphenicol
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Control: (details needed for each form)
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Additional characteristics
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Description
Test your knowledge on the plague, its organisms, and related diseases. This quiz covers the forms of plague, their symptoms, modes of transmission, and key characteristics of other diseases such as endemic typhus and Rocky Mountain spotted fever. Challenge yourself and enhance your understanding of these infectious diseases.
