Scrub typhus is transmitted by –
**Core Concept**
Scrub typhus is a zoonotic disease caused by the bacterium *Orientia tsutsugamushi*, transmitted through the bite of an infected chigger (larval mite) of the genus *Leptotrombidium*.
**Why the Correct Answer is Right**
The chigger injects the bacteria into the host's skin while feeding, leading to a characteristic eschar formation at the site of the bite. The bacteria then multiply and spread through the bloodstream, causing fever, headache, and rash. This transmission route is unique among the scrub typhus-causing bacteria, as it relies on the chigger's feeding behavior rather than direct contact with an infected vector.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as scrub typhus is not transmitted through the bite of a tick, which is the vector for diseases like Lyme disease and Rocky Mountain spotted fever.
* **Option B:** This option is incorrect as scrub typhus is not transmitted through the bite of a mosquito, which is the vector for diseases like malaria and dengue fever.
* **Option C:** This option is incorrect as scrub typhus is not transmitted through direct contact with an infected animal, although the bacteria can be found in rodents and other small mammals.
**Clinical Pearl / High-Yield Fact**
Scrub typhus is often misdiagnosed as dengue fever or leptospirosis due to similar clinical presentations, making it essential to consider the epidemiological context and perform specific serological tests to confirm the diagnosis.
**Correct Answer:** A.