Rickettsia

Question 1

What are the 3 main groups of rickettsial disease?

Answer 1

Spotted Fever Group
Typhus group
Scrub typhus group

Question 2

Epidemology:

What is the main source of infection?

How is the infection transmitted?

What area is it most common in?

Answer 2

Rats carry

Ticks transmit - fall of and then bit another animal or person

SE Asia - Tsutsugamushi triangle

Question 3

4 stages:

(1) What are the symptoms and signs in the inoculation phase?
(2) What happens when it spreads to the lymph nodes?
(3) What happens when it reaches the blood stream?
(4) If it invades vascular endothelium - fever, systemic lymphadenopathy

Answer 3

Inoculation - papule, maculopapular rash
Eschar
Ulcer

Invade lymph nodes - lymphadenopathy

General symptoms of sepsis

Question 4

Clinical manifestations:

Inoculation period 4-21 days.

What happens in the first wk?

What about in the second wk?

3rd wk - Convalesce - recover one’s health and strength over a period of time after an illness or medical treatment.

Answer 4

Systemic toxic symptoms

Worse/complications

Question 5

Specific features:

Eschar:

• What does it look like?
• Where is it typically found?
• Which type is it most specific to?

Maculopapular rash - 1 wk - appears anywhere

Regional lymphadenopathy also

Answer 5

Ulcer surrounded by red areola + dark scab in centre

Axillary fossa
Inguinal region 
Perianal 
Scrotum 
Buttocls 

Scrub typhus

Question 6

Lab exams:

Bloods - what is the main thing seen?

Serological tests:

Weil-Felix - what is it? ****

IFA (Indirect Fluorescent antibody) - positive at the end of the 1st wk

What does PCR detect?

Answer 6

Also see some raised LFTs

Leukopenia - normal WBC

Weil-Felix is a nonspecific agglutination test which detects anti-rickettsial antibodies in patient’s serum.

Orientia DNA

Question 7

Diagnosis:

Travel to endemic area 3 wks before.

What activities should you ask about?

Answer 7

Working
Camping
Sitting on grass

TICK BITES

Question 8

Treatment:

Sensitive ABs used
IV fluids
Intensive nursing care and prevent complications

What 3 ABs are used?

Answer 8

Chloramphenicol
Doxycyline
Azithromycin

Question 9

Prevention:

Source of infection - how to deal with?

How to reduce risk of transmission?

Answer 9

Rat eradication or control

Avoid ticks - long sleeve clothing
Use repellent
Avoid tick-infested areas