According to Chilean scientist Katia Abarca the disease in Chile corresponds to an endemic variety of the bacteria and has thus not arrived from the "Tsutsugamushi Triangle". The fact that the disease was first reported in 2006 in Chile is likely the result of underdiagnosis and underreporting. In January 2020 the disease was for the first time reported in Chile's southernmost region. The main symptom of "O. tsutsugamushi" infection is high (febrile) fever; however, the symptom is similar to other vector-borne tropical diseases such as malaria, leptospirosis, typhoid, murine typhus, chikungunya, and dengue fever. This makes precise clinical diagnosis difficult, which often leads to misdiagnosis. The initial indications are fever with chills, associated with headache, muscle pain (myalgia), sweating and vomiting. The appearance of symptoms (the incubation period) takes between 6 and 21 days. A simple visual diagnosis is the presence of an inflamed scar-like scab called eschar, which is regarded as "the most useful diagnostic clue in patients with acute febrile illness". Eschar is formed on the skin where an infected mite bit, usually seen in the armpit, groin or any abdominal area (Figure 7). In rare cases, it can be seen on the cheek, ear lobe and dorsum of the feet. But, the problem is that eschar is not always present; at the highest record, only 55% of scrub typhus patients had eschar during an outbreak in south India. Also, eschar is not specific to scrub typhus, occurring in other rickettsial diseases such as Rocky Mountain spotted fever, Brazilian spotted fever, and Indian tick typhus. Using DNA analysis by advanced polymerase chain reaction, different rickettsial infections can be identified from eschars. Suspected infections are confirmed with serological tests. "O. tsutsugamushi" is most often detected from blood serum using the Weil–Felix test. Weil–Felix is the simplest and most rapid test, but it is not sensitive or specific, as it detects any kind of rickettsial infection. More sensitive tests such as rapid immunochromatographic test (RICT), immunofluorescence assays (IFA), ELISA, and DNA analysis using polymerase chain reaction (PCR) are used. IFA is regarded as the gold standard test, as it gives a reliable result; however, it is expensive and not specific for different rickettsial bacteria.