SCRUB TYPHUS IgG

An IgG‑positive result in scrub typhus indicates past exposure or a later-stage immune response, since IgG antibodies develop after the acute phase and can persist for months to years. It does not by itself confirm current active infection; acute illness is suggested by IgM, PCR, or a rising IgG titre in paired sera. Clinical symptoms and additional tests are needed for definitive diagnosis.

If scrub typhus is positive, begin antibiotics promptly—doxycycline is first-line; azithromycin is used in pregnancy and young children. Admit if severe and provide supportive care (fluids, antipyretics, oxygen) while monitoring for complications such as respiratory failure, kidney or liver injury, myocarditis, or CNS involvement. Treatment usually lasts 7–14 days with clinical improvement within 48 hours; complete therapy and arrange follow-up.

The other name for scrub typhus IgM is Orientia tsutsugamushi IgM, often called tsutsugamushi IgM antibody or ST IgM. It refers to IgM-class antibodies directed against Orientia tsutsugamushi, the bacterium causing scrub typhus, and is commonly detected by assays such as IgM ELISA for diagnosis of recent infection clinically.

R typhi IgG refers to immunoglobulin G antibodies against Rickettsia typhi, the bacterium that causes murine (endemic) typhus. Detection by serology indicates past or recent exposure; IgG rises after the first week and can persist for months to years. A single high titer or a fourfold rise between acute and convalescent samples supports diagnosis. Results must be interpreted with clinical features due to possible cross‑reactivity.

Typhoid IgG antibodies typically appear after the first week of illness and can remain detectable for months to years. IgG often persists longer than IgM, commonly detectable for 6 months to several years, so a positive IgG may reflect past infection or vaccination rather than active disease. Serology should be interpreted with clinical context and other tests such as blood culture or PCR.

Scrub typhus usually incubates for about 6–21 days. If untreated, fever, rash and systemic symptoms often last 2–3 weeks or more and can progress to serious complications. With timely antibiotic treatment (commonly doxycycline or azithromycin), most people start improving within 48–72 hours, fever subsides in a few days, and full recovery generally occurs within one to two weeks.