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Parasitology > RMSF, Ehrlichiosis, Anaplasmosis, Lyme disease, Babesiosis > Flashcards

RMSF, Ehrlichiosis, Anaplasmosis, Lyme disease, Babesiosis Flashcards

1
Q

Rocky Mountain Spotted Fever bacterial pathogen

A

Rickettsia rickettsii (gram -ve, intracellular)

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2
Q

Primary target in RMSF

A

Vascular endothelial cells (symptoms resemble vasculitis)

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3
Q

Tick vectors in RMSF

A

Order: Ixodida - hard tick

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

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4
Q

Risk factors

A

Hiking

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5
Q

Fulminant

A

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

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6
Q

Clinical features

A

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

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7
Q

Antibody titer

A

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

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8
Q

Diagnosis - RMSF

A

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

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9
Q

Treatment

A

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.

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10
Q

Ehrlichiosis pathogen

A

Ehrlichia chafeensis (E. ewingii western US)

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11
Q

Ehrlichiosis Tick Vector

A

Amblyomma americanum - turkey tick

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12
Q

Clinical features of Ehrlichiosis

A

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

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13
Q

Diagnosis - Ehrlichiosis

A

Leukopenia - low wbc
Thrombocytopenia
Pqired IFA
PCR

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14
Q

Treatment - Ehrlichiosis

A

Doxycycline for kids/adults

Chloramphenicol/rifampin for pregnant women

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15
Q

Anaplasmosis - Pathogen

A

Anaplasma phagocytophiia (in wbc)

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16
Q

Anaplasmosis - Tick vector

A

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

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17
Q

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

A

True

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18
Q

Clinical features - Ehrlichiosis

A

Acute febrile illness, headache, myalgia, rash is rare

Paired IFA ordered separate from serology for Ehrlichiosis

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19
Q

Diagnosis

A

Paired IFA ordered separate from serology for Ehrlichiosis

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20
Q

Treatment

A

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

21
Q

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

A

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.

22
Q

Lyme disease - Bacterial agent

A

Spirochete

- Borrelia burgdorferi sensu lato

23
Q

Lyme disease - Insect vector

A
  • Ixodes scapularis
  • I. pacificus, I. ricinus, I. persculatus
    White rodents are natural reservoir
    -White footed mouse - Peromyscus leucopus
24
Q

Early localised symptom - Lyme disease

A

Erythema migrans/ target appearance rash

- Can have central rash/multiple lesions

25
Q

Early disseminated symptom - Lyme disease

A

Meningitis, cranial neuropathy (facial drooping), carditis

26
Q

Late disseminated sequelae - Lyme disease

A

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

27
Q

Coinfection rates - Lyme disease

A

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

28
Q

Most common method of diganosis

A

Two-step serologic test

29
Q

two-step serologic test method

A

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

30
Q

Two step serological test has high sensitivity in late lyme disease

A

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

31
Q

PCR sensitive for lyme disease (T/F)

A

False. PCR not sensitive, high false +ve results

Synovial fluid and CSF use in PCR

32
Q

Subjective symptoms occuring in Lyme disease

A
  • subjective fatigue, CNS complaints but normal CSF, myalgias without muscle inflammation
33
Q

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

A

True

34
Q

Treatment - Lyme disease - Erythema migrans

A

Erythema migrans
Doxycycline for adults
Amoxicillin for kids

35
Q

Treatment - Lyme disease - Neurological disease

A

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

36
Q

Treatment - Lyme disease - Carditis

A

Oral antibiotics for 10-21 days

37
Q

Treatment - Lyme disease - Arthritis

A

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

38
Q

Treatment - Lyme disease - Late Neurologic Lyme (encephalomyelitis)

A

IV Ceftriaxone 2-4wks

39
Q

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

A

True

40
Q

Babesiosis - pathogen

A

Babesia microtii

41
Q

Babesiosis - Tick vector

A

Ixodes scapularis

- Transmitted by blood transfusion and bites

42
Q

Babesiosis type of vector

A

Intraerythrocytic parasite

43
Q

Complications - Babesiosis

A

Hemolytic anemia
RBC destruction occurs
Multiorgan disease - immunocompromised persons

44
Q

Peripheral blood smear

A

A procedure in which a sample ofbloodis viewed under a microscope to count different circulatingbloodcells (redbloodcells, whitebloodcells, platelets, etc.) and see whether the cells look normal.

45
Q

Diagnosis - Babesiosis

A

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

46
Q

Treatment - Babesiosis

A

Atovaquone + Azithro 10 days for mild disease

Quinine + Clinda for severe disease

47
Q

Asplenic

A

Being without a spleen

48
Q

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

A

True

Parasitology (10 decks)

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