Finding the right tests…
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Finding the right tests…
Serology
Scrub typhus is a bacterial infection called Orientia tsutsugamushi, spread by the bite of infected chigger mites found in scrubby or overgrown vegetation. This test checks your blood for antibodies your immune system makes against the bacteria, most often using an ELISA method that looks for IgM. A dark, scab-like mark at the bite site, called an eschar, is a strong clinical clue your doctor may look for alongside this test, though not everyone develops one. Antibody levels take time to build, so laboratory confirmation can lag behind how sick you feel — which is why doctors often start treatment for suspected scrub typhus before this result comes back.
A positive or negative reading for antibodies against Orientia tsutsugamushi is what this test returns, most often using an ELISA method that targets IgM. According to CDC guidance, detectable antibody levels generally don't appear until 7 to 10 days after your illness starts, so a sample taken very early in a fever can come back negative even in a genuine infection. Confirming the diagnosis with paired testing means a second sample taken weeks after the first, checking for a rising antibody level. A single blood draw is enough for each sample, with no special preparation needed.
Scrub typhus is caused by Orientia tsutsugamushi bacteria, carried by the larval stage of certain mites, commonly called chiggers, found in scrub vegetation across rural parts of India and other parts of Asia and northern Australia. After a bite, it typically takes up to 10 days for symptoms — fever, headache, body aches, and often a dark scab called an eschar at the bite site — to appear.
Your immune system needs time to build a detectable antibody response, and CDC guidance notes that detectable antibody levels generally don't appear until 7 to 10 days after illness begins. This means a blood test done in the first few days of fever can come back negative even when scrub typhus is the actual cause, which is one reason doctors don't wait for a confirmed result before starting treatment if the clinical picture, including an eschar, points strongly toward it.
A single antibody test supports a probable diagnosis, but a fully confirmed one usually needs a second, convalescent sample taken some weeks later, showing a clear rise in antibody level compared to the first sample. Because a fluorescent antibody test considered the reference standard isn't widely available outside specialised labs, ELISA-based antibody testing is the practical option used in most settings, including India.
An eschar is a dark, scab-like mark that forms at the site of the chigger bite that spreads scrub typhus. It's a strong clinical clue, though not everyone who's infected develops one.
According to CDC guidance, detectable antibody levels generally don't appear until 7 to 10 days after your illness starts, so testing very early in a fever can come back negative.
Yes. CDC guidance notes treatment should never be withheld while waiting for diagnostic confirmation, since laboratory results, especially a fully confirmed one, can take weeks.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
A confirmed diagnosis usually needs a convalescent sample taken 2 to 10 weeks after the first, showing a clear rise in antibody level, since a single early sample can miss the infection.
Yes. Scrub typhus occurs across rural parts of the Indian subcontinent, along with other areas of Southeast Asia, Indonesia, China, Japan, and northern Australia, according to CDC information.
It's spread through the bite of infected chigger mites, the larval stage of certain mites found in scrub vegetation, rather than person to person.
The indirect fluorescent antibody test is considered the reference standard, but CDC guidance notes it's usually not available in developing countries where scrub typhus is common, which is why ELISA-based antibody testing is used more widely in practice.