RMSF, Ehrlichiosis, Anaplasmosis, Lyme disease, Babesiosis Flashcards Preview

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

Flashcards in RMSF, Ehrlichiosis, Anaplasmosis, Lyme disease, Babesiosis Deck (48)
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1

Rocky Mountain Spotted Fever bacterial pathogen

Rickettsia rickettsii (gram -ve, intracellular)

2

Primary target in RMSF

Vascular endothelial cells (symptoms resemble vasculitis)

3

Tick vectors in RMSF

Order: Ixodida - hard tick

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

4

Risk factors

Hiking

5

Fulminant

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

6

Clinical features

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

7

Antibody titer

How much antibody an organism has produced, expressed in a serial dilution that still gives a positive result. ELISA is a common means of determining antibody titers.

8

Diagnosis - RMSF

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

9

Treatment

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.

10

Ehrlichiosis pathogen

Ehrlichia chafeensis (E. ewingii western US)

11

Ehrlichiosis Tick Vector

Amblyomma americanum - turkey tick

12

Clinical features of Ehrlichiosis

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

13

Diagnosis - Ehrlichiosis

Leukopenia - low wbc
Thrombocytopenia
Pqired IFA
PCR

14

Treatment - Ehrlichiosis

Doxycycline for kids/adults
Chloramphenicol/rifampin for pregnant women

15

Anaplasmosis - Pathogen

Anaplasma phagocytophiia (in wbc)

16

Anaplasmosis - Tick vector

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

17

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

True

18

Clinical features - Ehrlichiosis

Acute febrile illness, headache, myalgia, rash is rare
Paired IFA ordered separate from serology for Ehrlichiosis

19

Diagnosis

Paired IFA ordered separate from serology for Ehrlichiosis

20

Treatment

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

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

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

Lyme disease - Bacterial agent

Spirochete
- Borrelia burgdorferi sensu lato

23

Lyme disease - Insect vector

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

24

Early localised symptom - Lyme disease

Erythema migrans/ target appearance rash
- Can have central rash/multiple lesions

25

Early disseminated symptom - Lyme disease

Meningitis, cranial neuropathy (facial drooping), carditis

26

Late disseminated sequelae - Lyme disease

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

27

Coinfection rates - Lyme disease

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

28

Most common method of diganosis

Two-step serologic test

29

two-step serologic test method

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

Two step serological test has high sensitivity in late lyme disease

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