Typhus

Question 1

What are the pathogens that cause flea borne typhus fever (murine typhus)?

Answer 1

rickettsia typhi, rickettsia felis

Question 2

what is the incubation period of flea borne typhus fever (murine typhus)?

Answer 2

typically 12 days (range 1-2 weeks)

Question 3

how is flea borne typhus fever (murine typhus) transmitted?

Answer 3

Transmitted via flea bites. Infective fleas defecate rickettsiae while taking a blood meal, which contaminates the bite site and other fresh skin wounds.

Question 4

What are the clinical features of flea borne typhus fever (murine typhus)?

Answer 4

• Murine typhus is generally a mild infection.
• Symptoms include fever, headache and myalgia.
• Rash occurs in majority of patients although it is usually not present at onset of illness.
• Other symptoms reported include abdominal pain, nausea and vomiting.

Question 5

what is the investigation required for flea borne typhus fever (murine typhus)?

Answer 5

Serology

• immunofluorescent antibody test
• acute and convalescent samples

The Weil-Felix test is not recommended due to poor sensitivity and specificity

Question 6

how are patients with flea borne typhus fever (murine typhus) managed?

Answer 6

Doxycycline remains the drug of choice (100 mg BD for 5-10 days or for ≥3 days after defervescence occurs)

For select groups of patients in whom doxycycline is not suitable, including pregnant women, children, those with allergy/intolerance to doxycycline or doxycycline resistant typhus: PO azithromycin 500mg as a single dose.

Question 7

What are the pathogens that cause mite borne typhus fever (scrub typhus)?

Answer 7

orientia tsutsugamushi

Question 8

what is the incubation period of mite borne typhus fever (scrub typhus)?

Answer 8

11 days (range 6-21 days)

Question 9

what are the risk factors for mite borne typhus fever (scrub typhus)?

Answer 9

occupational exposure to mite habitats in long grass e.g. hikers, soldoers

Question 10

what are the clinical features of mite borne typhus fever (scrub typhus)?

Answer 10

• A characteristic feature is an eschar corresponding to the site of the chigger bite. Not all patients have the eschar.
• The illness presents with an acute onset of fever, with headache, profuse sweating, conjunctival injection, and lymphadenopathy.

Question 11

What are the complications of mite borne typhus fever (scrub typhus)?

Answer 11

Severe infections may be complicated by pneumonitis, acute respiratory distress syndrome, respiratory failure, and confusion.
Death may occur as a result of these complications, usually late in the second week of the illness.

Question 12

what is the investigation required for mite borne typhus fever (scrub typhus)?

Answer 12

Serology

• immunofluorescent antibody test
• acute and convalescent samples

The Weil-Felix test is not recommended due to poor sensitivity and specificity

Question 13

how are patients with mite borne typhus fever (scrub typhus) managed?

Answer 13

Early treatment should be initiated as soon as the diagnosis is suspected to prevent adverse outcomes. Doxycycline remains the drug of choice. Antibiotic regimen is the same as that for murine typhus.