Arthropod Bites

Question 1

Lyme Disease Pathogen

Answer 1

•Borrelia burgdorferi: Spirochetes, Highly Motile (cork screw), Gram negative (unusual for spirochete)

Question 2

Lyme Disease Transmission

Answer 2

•Tick Bite:Lxodes sp.

Question 3

Lyme Disease Lab Identification

Answer 3

•Blood, CSF, joint fluid: Detection of Abs (serology),Molecular ID

Question 4

Lyme Disease Clinical manifestations

Answer 4

•Erythema chronicum migrans
–Characteristic skin lesion
–Bulls Eye Rash
•Joint Pain, Fatigue, Neurologic Manifestations, Cardiac Manifestations

Question 5

Tularemia Pathogen

Answer 5

•Francisella tularensis:Gram neg small coccobacilli,Nonmotile, Intracellular, parasitize reticuloendothelial system

Question 6

Tularemia Transmission

Answer 6

•Vectors:Ticks (dermacenter tick), mite, lice, flies
•Contact with infected animal (usually rabbits) from skinning them
•Ingestion
-Endemic areas: Northern hemisphere: AK & MO, Russia, Scandinavia, Spain

Question 7

Tularemia Lab Identification

Answer 7

• Flourescents, serology

* NO CULTURE—high risk of infection

Question 8

Tularemia Clinical Manifestations

Answer 8

• Variable depending on route of transmission
• Ulceroglandular is MC form
• Lymphatic spread
• Painful regional lymph nodes
• Blood invasion
• +/- lungs, GI involvement
• Formation of granulomatous nodules around reticuloendothelial cells
• +/- rash

Question 9

Tularemia resivor

Answer 9

Rodents

Question 10

Rocky Mountain Spotted Fever Pathogen

Answer 10

•Rickettsia rickettsii: Small gram-negative,Must live inside of another cell, Requirement for co-enzyme A, NAD, ATP,Non-motile,Obligate intracellular parasite.

Question 11

Rocky Mountain Spotted Fever Pathogenisis

Answer 11

• Attachment of tick to host—inject in host blood–uses membrane proteins OMPA and OMPB to gain entry
• Survives in cystol and nucleus of host cell (unusual)
• Disseminate through lymph and blood
• Enter vascular endothelial cells—foci of infection
• Spread to distant endothelial and smooth m. cells→ increased vascular perm.–> edema, hypoproteinemia and dec perfusion to organs

Question 12

Rocky Mountain Spotted Fever Lab identification

Answer 12

• Serology, direct florescence, PCR

- Dont culture, won’t grow.

Question 13

Rocky Mountain Spotted Fever Clinical Manifestations

Answer 13

• Fever, headache, rash
• Lymphadenopathy
• Anemia, atypical lymphocyte

Question 14

Rocky Mountain Spotted Fever demographic

Answer 14

•South Atlantic & Midwestern states

Question 15

Rock Mountain Spotted Fever Transmission

Answer 15

• Dog Tick: Dermacentor variabilis-Eastern US
• Wood tick: D. androsoni-West
• Lone Star tick: Amblyomma americanum-South West

Question 16

Rickettsia Prowazekii Clinical Manifestations

Answer 16

• Sudden onset of fever, chills, headache, arthralgia/myalgia
• Rash 7 d later on trunk that spreads to extremities
• Complictions: Myocarditis, stupor, delirium, mortality 70%
• Some typhus connection?

Question 17

Rickettsia Prowazekii Diagnosis and control

Answer 17

Diagnosis: Clinical, serology
Control: Killed typhus vaccine

Question 18

Human Ehrlichiosis & Anaplasmosis Pathogen

Answer 18

• Infect leukocytes
• E. chaffeensis
• E. ewingii:Vector: Lone Star tick,Reservoir: White tailed deer,SE, Mid‐Atlantic, South Central US
• A. phagocytophilum:Vector: Deer and dog ticks,Reservoir: small mammals,Wisconsin, Minnesota, Connecticut

Question 19

Human Ehrlichiosis & Anaplasmosis Features

Answer 19

• Tick‐borne: peak infection May‐August obligate intracellular
• Obligate intracellular, Gram negative( but No LPS or PG, weird!)
• Replicate in membrane‐bound compartments inside host cells
• 2 forms: DC (dense‐cored) (infectious form) and RC (reticulte cells)

Question 20

Human Ehrlichiosis & Anaplasmosis Clinical Manifestations

Answer 20

• Resembles Rocky Mountain Spotted Fever, but rash is rare
• Symptoms 5‐10 days after tick bite:Fever,headache, malaise, confusion,Nausea & vomiting, abdominal cramps, myalgia
• 20% of cases: rash

Question 21

Human Ehrlichiosis & Anaplasmosis Lab ID

Answer 21

Direct exam of Giemsa‐stained peripheral blood, Serologic testing,
-Culture is possible, but rarely attempted

Question 22

Dengue Virus Genome and structure

Answer 22

Flaviviridae; enveloped ss(+)RNA virus

Question 23

Dengue Virus Vector

Answer 23

• Aedes aegypti mosquito

- tropics worldwide, spreading to the US

Question 24

Dengue Virus resivor

Answer 24

humans and primates

Question 25

Dengue Virus Clinical features

Answer 25

Incubation period: <1 week
 Symptoms: High fever + two or more of the following:
o Severe headache, eye/joint/muscle pain (“break‐bone” fever)
o Non‐pruritic rash, low white cell count
o Mild bleeding (e.g., nose, gum bleed, petechiae, easy bruising)
o Lifelong immunity is generated in the host

Question 26

Dengue Virus Control

Answer 26

Vector control only; no vaccine is currently available

Question 27

Dengue Hemorrhagic Fever

Answer 27

-4 Sterotypes (DV1 through 4): Get sick with Dengue fever 2–recover–get sick with DF 4–at risk for hemorrhage

Question 28

Dengue Hemorrhagic Fever Test

Answer 28

Serology, PCR, blood work

Question 29

Dengue Hemorrhagic Fever Clinical Manifestations

Answer 29

-1) 2‐7 d fever; 2) Hemorrhages; 3) Thrombocytopenia (low platelet); 4) Increased vascular permeability
-Dengue Shock Syndrome (DSS: rapid pulse, cold, clammy skin, hypotension,
circulatory failure)
 Up to a 10% fatality rate

Question 30

Yellow fever Genome/Structure

Answer 30

-Flaviviridae (Dengue, West Nile), (+)ssRNA enveloped viruses

Question 31

Yellow fever vector and risk groups

Answer 31

• Aedes aegypti mosquito

- infants and elderly

Question 32

Yellow fever Prevention

Answer 32

Live, attenuated vaccine

Question 33

Yellow fever diagnosis

Answer 33

-Clinically: Fever, followed by possible signs
of jaundice within 2 weeks
-Labs: Elevated bilirubin; urinalysis
(proteinuria/albuminuria)

Question 34

Yellow fever Test

Answer 34

PCR, viral antigen detection