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