08a bacterial

Misc bacterial infections

Scrub typhus

• Orientia tsutsugamushi – obligate intracellular, Gram negative coccobacillus

• Transmitted by trombiculid mites (aka chiggers)

• Found mainly in Asia Pacific, endemic to some countries in Asia, South East Asia, South Asia, and tropical regions of Australia

• Risk factors: outdoor exposure, summer time, areas known to have chiggers

• S/smx:

  • Incubation period 6-21 days

  • Most commonly asymptomatic and self-resolving, however, can be very severe

  • Initially, fever (lasting around 2 weeks in untreated patients), headache (can be intense), anorexia, malaise

  • Rash – around 50% pts. Nonpruritic, macular/maculopapular rash. Starts on abdomen, spread to extremities.

  • Eschar – painless papule at site of infecting chigger bite, then central necrosis develops.

  • Other smx include lymphadenopathy, nausea, vomiting, diarrhoea, cough, relative bradycardia (up to 2/3), meningitis/meningoencephalitis, seizures, AKI, etc.

• Dx: clinical. Serology (IgG/IgM antibodies), biopsy of eschar, PCR.

• Mx: ☝🏻 doxycycline (7-day course; double dose in severe disease) or azithromycin (can be used in pregnancy).

  • ✌🏻 rifampicin, fluroquinolones, chloramphenicol.

• Reinfection is possible.

• Nice article with pictures – Lee C-S, Hwang J-H. Scrub Typhus. N Engl J Med 2015;373:2455–2455. https://doi.org/10.1056/NEJMicm1503639.