Scrub Typhus (IgM/IgG)

Function

This test detects antibodies (IgM and IgG) against Orientia tsutsugamushi, the causative bacterium of Scrub Typhus. This organism is transmitted to humans through the bite of infected larval mites (chiggers). The test helps identify an immune response to the pathogen.

Why it is Ordered

It is ordered when a patient presents with symptoms common in endemic areas: high fever, severe headache, muscle pain, and especially the presence of an 'eschar' (a dark, scab-like sore at the bite site). It is vital for differentiating Scrub Typhus from other tropical fevers like Malaria, Dengue, or Typhoid.

Associated Conditions

• Scrub Typhus (Tsutsugamushi Disease): The primary condition diagnosed.
• Multi-organ Dysfunction: If left untreated, the infection can lead to respiratory distress, renal failure, or meningoencephalitis.
• Acute Febrile Illness: A broad category for undifferentiated fevers in tropical regions.

Immunology Timing

IgM antibodies usually appear within the first week of symptoms, indicating an acute infection. IgG antibodies appear later and may persist for years, indicating previous exposure. Testing 'paired sera' (two samples taken 2 weeks apart) is the most accurate way to confirm a diagnosis via a four-fold increase in antibody titer.