Scrub typhus is among the common causes of febrile illnesses, noted globally. It should be included in the differential diagnosis of febrile illness along with more common conditions such as malaria, typhoid, leptospirosis, etc. In addition to fever, patients with scrub typhus may have headache, skin rash, joint pains, lymphadenopathy and an eschar.
Eschar is caused by the chigger mite bite. The bite as well as the eschar may be painless, and hence, is often not noted by the patients. The clinicians should carefully look for eschar. In the picture above, it was noted near right axilla. Other sites of eschar include scrotum, abdominal wall, etc. The patient had features of scrub typhus meningitis and he responded well to the treatment. To learn more about evolution of eschar in scrub typhus, please read the following article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5154431/
Scrub typhus needs to be differentiated from bacterial meningitis. Factors favouring a diagnosis of scrub typhus meningitis over bacterial meningitis include: 1. Longer duration of fever: 8 days versus 3 days, 2. Elevated liver enzymes (ALT) , 3. CSF pleocytosis: 80 cells in scrub typhus versus 690 in bacterial meningitis, 4. Lymphocytic predominance (in CSF) in scrub typhus as compared to neutrophilic predominance in bacterial meningitis cases, 5. Relatively lower CSF glucose and higher CSF protein in bacterial meningitis cases. For more details, please read one of the papers co-authored by me. The link is: http://www.neurologyindia.com/temp/ni61117-3661825_101018.pdf