RMSF, Ehrlichiosis, Anaplasmosis, Lyme disease, Babesiosis

Question 1

Rocky Mountain Spotted Fever bacterial pathogen

Answer 1

Rickettsia rickettsii (gram -ve, intracellular)

Question 2

Primary target in RMSF

Answer 2

Vascular endothelial cells (symptoms resemble vasculitis)

Question 3

Tick vectors in RMSF

Answer 3

Order: Ixodida - hard tick

Dermacentor variabilis - Dog tick
Dermacentor andersoni - Wood tick
Rhipicephalus sanguineus - Brown dog tick

Question 4

Risk factors

Answer 4

Hiking

Question 5

Fulminant

Answer 5

(of a disease or symptom) severe and sudden in onset.

Question 6

Clinical features

Answer 6

Fever, headache, confusion, abdominal pain
Can be fulminant with encephalitis, ARDS, myocarditis
Spotted rash - 50% persons in first 72 hrs of illness; 10% with no rash at all;
ankles/wrists spread centrally, also palms/soles

Question 7

Antibody titer

Answer 7

How muchantibodyan organism has produced, expressed in a serial dilution that still gives a positive result. ELISA is a common means of determiningantibody titers.

Question 8

Diagnosis - RMSF

Answer 8

Mostly clinical
Thrombocytopenia - low platelets
Elevated LFTs -
Hyponatremia - low Na+
Confirmatory acute + convalescent antibody titers
Immunohistochemical staining on skin biopsy of rash

Question 9

Treatment

Answer 9

Carefully removing tick
Doxycline for kids/adults
Chloramphenicol for pregnant women (slightly less effective)

Because far fewer than 1% of ticks carry this infection, antibiotics are not usually given after a tick bite.

Question 10

Ehrlichiosis pathogen

Answer 10

Ehrlichia chafeensis (E. ewingii western US)

Question 11

Ehrlichiosis Tick Vector

Answer 11

Amblyomma americanum - turkey tick

Question 12

Clinical features of Ehrlichiosis

Answer 12

Acute febrile illness, headache, myalgia, flu like symptoms
30% of adults have petechial rash
Fever persists for mths if untreated

Question 13

Diagnosis - Ehrlichiosis

Answer 13

Leukopenia - low wbc
Thrombocytopenia
Pqired IFA
PCR

Question 14

Treatment - Ehrlichiosis

Answer 14

Doxycycline for kids/adults

Chloramphenicol/rifampin for pregnant women

Question 15

Anaplasmosis - Pathogen

Answer 15

Anaplasma phagocytophiia (in wbc)

Question 16

Anaplasmosis - Tick vector

Answer 16

Ixodes scapularis/ I. pacificus (same tick carrying lyme disease)

Question 17

Anaplasmosis + Lyme disease can be transmitted at the same time (T/F)

Answer 17

True

Question 18

Clinical features - Ehrlichiosis

Answer 18

Acute febrile illness, headache, myalgia, rash is rare

Paired IFA ordered separate from serology for Ehrlichiosis

Question 19

Diagnosis

Answer 19

Paired IFA ordered separate from serology for Ehrlichiosis

Question 20

Treatment

Answer 20

Doxycycline for kids/adults ; Chloramphenicol/ rifampin for pregnant women

Question 21

Clinical case:
34 yo WF presents in August with 2 days of high fever (38.9C), myalgias and headache but not neck stiffness.
She reports that she was backpacking in North Carolina mountains 5 days ago but doesn’t recall any insect bites or any other unusual animal/water exposures. She does not have a rash and rest of her exam is unremarkable.
Screening labs show WBC 5.2, plt 98. Which of the following is most likely?
RMSF
Ehrlichiosis
Anaplasmosis

Answer 21

RMSF seems most likely due to location of hiking however based on symptoms it can be any one. Treatment should be Doxycycline which will treat any of the three infections.

Question 22

Lyme disease - Bacterial agent

Answer 22

Spirochete

- Borrelia burgdorferi sensu lato

Question 23

Lyme disease - Insect vector

Answer 23

• Ixodes scapularis
• I. pacificus, I. ricinus, I. persculatus
  White rodents are natural reservoir
  -White footed mouse - Peromyscus leucopus

Question 24

Early localised symptom - Lyme disease

Answer 24

Erythema migrans/ target appearance rash

- Can have central rash/multiple lesions

Question 25

Early disseminated symptom - Lyme disease

Answer 25

Meningitis, cranial neuropathy (facial drooping), carditis

Question 26

Late disseminated sequelae - Lyme disease

Answer 26

Arthritis - single large joint like the knee -swelling in joint with minor pain at first Chronic encephalomyelitis Mononeuritis multiplex

Question 27

Coinfection rates - Lyme disease

Answer 27

Can have coinfection in 10% of cases -with Babesia or Anaplasma (Need clinical suspicion of these diseases)

Question 28

Most common method of diganosis

Answer 28

Two-step serologic test

Question 29

two-step serologic test method

Answer 29

Two-step serologic test - ELISA - Western Blot The first required test is the Enzyme Immunoassay (EIA) or Immunofluorescence Assay (IFA). Negative test result: -Consider alternative diagnosis -If had symptoms for <30 days treat with convalescent serum Positive test result: 1) Symptoms <30 days, IgM Western blot performed 2) Symptoms >30 days, IgG Western blot is performed

Question 30

Two step serological test has high sensitivity in late lyme disease

Answer 30

True - however false positive do occur. Due to serological testing being insensitive thereby missing cases of disease, clinical testing is sufficient.

Question 31

PCR sensitive for lyme disease (T/F)

Answer 31

False. PCR not sensitive, high false +ve results | Synovial fluid and CSF use in PCR

Question 32

Subjective symptoms occuring in Lyme disease

Answer 32

- subjective fatigue, CNS complaints but normal CSF, myalgias without muscle inflammation

Question 33

The use of serological testing on populations with subjective symptoms result in greater likelihood of false positives (T/F)

Answer 33

True

Question 34

Treatment - Lyme disease - Erythema migrans

Answer 34

Erythema migrans Doxycycline for adults Amoxicillin for kids

Question 35

Treatment - Lyme disease - Neurological disease

Answer 35

IV Ceftriaxone for 14 days (except for facial nerve palsy) OR Oral doxycycline for 14 days

Question 36

Treatment - Lyme disease - Carditis

Answer 36

Oral antibiotics for 10-21 days

Question 37

Treatment - Lyme disease - Arthritis

Answer 37

28 days of Doxycycline Adjunct therapy in rare cases -Hydrochloroquine, Methotrexate Long term inflammatories - Anthroscopic synovectomy

Question 38

Treatment - Lyme disease - Late Neurologic Lyme (encephalomyelitis)

Answer 38

IV Ceftriaxone 2-4wks

Question 39

Persistent infection is rare in Lyme disease (T/F)

Answer 39

True

Question 40

Babesiosis - pathogen

Answer 40

Babesia microtii

Question 41

Babesiosis - Tick vector

Answer 41

Ixodes scapularis | - Transmitted by blood transfusion and bites

Question 42

Babesiosis type of vector

Answer 42

Intraerythrocytic parasite

Question 43

Complications - Babesiosis

Answer 43

Hemolytic anemia RBC destruction occurs Multiorgan disease - immunocompromised persons

Question 44

Peripheral blood smear

Answer 44

A procedure in which a sample of blood is viewed under a microscope to count different circulating blood cells (red blood cells, white blood cells, platelets, etc.) and see whether the cells look normal.

Question 45

Diagnosis - Babesiosis

Answer 45

Peripheral smear has "Maltese Cross" - resembles a star with 4 points Serological less informative PCR reasinable alternative with high suspicions

Question 46

Treatment - Babesiosis

Answer 46

Atovaquone + Azithro 10 days for mild disease | Quinine + Clinda for severe disease

Question 47

Asplenic

Answer 47

Being without a spleen

Question 48

Asplenic persons can have recurrence of disease (T/F)

Answer 48

True