Coronavirus disease 2019, shortly called COVID-19 is a respiratory illness caused by a novel coronavirus SARS-CoV-2. COVID-19 transmits from person to person after close contact with an infected patient through cough, sneeze, saliva droplets, or discharge of watery fluids from the nose in hospital and family settings. The SARS-CoV-2 virus has been named by WHO as COVID-19 following best practices for naming new human infectious diseases as of February 11, 2020. It is called a novel coronavirus because it has not been previously identified in humans. According to WHO, a patient with COVID-19 may show the following symptoms:

  • Acute onset of fever & cough
  • Fatigue
  • Sore throat
  • Pain in the muscles
  • Diarrohea
  • Anorexia/nausea/
  • Headache
  • Vomiting
  • Coryza
  • In severe cases, difficulty in breathing

Scrub typhus is a zoonotic disease caused by the gram-negative bacteria Orientia tsutsugamushi belonging to the family Rickettsiaceae. These bacteria are intracellular pathogens carried by mites called Leptotrombidium. Only the larva (chigger) of the mites can transmit the disease to humans and other vertebrates. The bite of the chigger creates a distinctive black eschar that helps the doctor diagnose the condition. Scrub typhus is also called bush typhus because the chiggers are mainly found in the bushes, and humans walking through those bushes get contracted with the scrub typhus disease.
The interesting thing to note is that scrub typhus and COVID-19 have identical symptoms, leading to confusion among patients and physicians. So, first, this article will go through some case studies where people had symptoms highlighting COVID-19 but were later diagnosed with scrub typhus disease. Then, we will see the outcome of such cases was, and finally, we will have a brief overview of diagnostic tests set by the Indian government to distinguish COVID-19 and scrub typhus.

Case studies

Case 1
This case study got published in the 2021 July issue of the Journal of Family Medicine and Primary Care. A 29-year-old lady who was 32-weeks pregnant reported to the hospital with a complaint of sore throat, high-grade fever, abdominal pain, cough, and progressive shortness of breath for the last ten days. The patient also faced difficulty in proper urine output and decreased fetal movement. RT-PCR test to confirm COVID-19 infection came negative. The chest X-ray showed minimal bilateral haziness with prominent interstitial markings. The woman was diagnosed with community-acquired pneumonia with septic shock. The physicians found the prevailing condition of acute hypoxemic respiratory failure and hypotension. She got admitted to the respiratory intensive care unit.
During the 30th week of the pregnancy, the ultrasonography scan results showed the fetus to have normal biometry parameters. However, the ultrasonography showed a single intrauterine fetus with no cardiac activity post-admission to the respiratory intensive care unit. Therefore, after obtaining a high-risk content, the physicians carried out the process for delivery, and a stillborn male fetus of 2 kg was delivered.
Post-delivery, the women continued to remain febrile. Therefore, the physicians carried out tests to rule out the chances of common tropical fevers like dengue and malaria. However, the serology test for scrub typhus came positive. The physicians then carried out a thorough physical examination of the patient and found the presence of Eschar on the right thigh. Thus, the patient was confirmed to have an infection of Scrub-typhus. The patient was then treated with Doxycycline (200 mg/day). Gradually the patient started recovering and was later discharged in stable condition.
Despite the ongoing COVID-19 pandemic, the burden of tropical febrile illnesses mandates the evaluation for all possible causes at the primary healthcare level to ensure early diagnosis and timely intervention to promote the best clinical outcomes in patients.
The article’s authors emphasized the need for primary care physicians to consider India’s most prevalent tropical illnesses while dealing with acute febrile illnesses. The physician should rapidly diagnose tropical fevers, e.g., Scrub typhus, so early treatment is initiated and prevent end-organ damage. However, physicians should not hastily take any decision and carry out a proper physical examination and re-review clinical signs to ensure scrub-typhus.

Case 2
Kiyoshi Shikino et al. published a case study in the 2021 June issue of Journal of General and Family medicine about a 70-year-old man who was initially thought to have COVID-19 but later diagnosed with Scrub-Typhus. The patient visited an outpatient internal medicine clinic with complaints of fever, cough, headache, arthralgia, and a generalized rash. Upon physical examination, it was found that the patient had some scattered papules from the trunk to the extremities. The PCR-test for SARS-CoV 2 was negative. The physician, however, suspected the clinical symptoms to be related to scrub typhus owing to the nature of the occupation of the patient, which was farming. Thus, the physician carried out a detailed physical examination and found the presence of Eschar on the right lateral chest. The serological tests further confirmed the presence of the bacteria responsible for Scrub-Typhus. The patient underwent treatment with 200 mg/day of Minocycline for 14 days and the symptoms resolved entirely. The authors concluded that since COVID-19 and scrub-typhus show similar symptoms, physicians should proceed with differentiation through basic medical history taking and physical examination to rule out chances of any tropical disease. This will also help in beginning the proper treatment as early as possible.

Case 3
In this case, study, published in the 2021 October issue of the APIK Journal of Internal Medicine, a 35-year-old male was reported to have COVID-19 and Scrub Typhus. The patient reported to the hospital with a history of breathlessness and fever from the past five days. The SpO2 level of the patient was low (83%) and was improved to 93% through oxygen supplementation with a venturi mask. RT-PCR test for COVID-19 was positive, and on further evaluation, the patient was found to have leukocytosis (increase in the count of WBC) and thrombocytopenia (decreased blood platelet count). In addition, the laboratory tests for the patient showed a higher level of d-dimer levels, serum ferritin, interleukin-6, and C‑reactive protein.
Upon detailed physical examination, and Eschar mark was present on the right nipple. Serology test (IgM antibody test) confirmed Scrub-Typhus infection. The patient has treated with Doxycycline 100 mg twice a day, and after two days, thrombocytopenia was resolved. The patient stayed for 14 days in the hospital and, upon recovery, was discharged from the hospital.
Laboratory tests by the Government of India for diagnosis of scrub typhus from COVID-19 to prevent confusion and delay in treatment

COVID 19Acute phase: RT PCRNasopharyngeal/ Oropharyngeal swab
Scrub Typhus• Detection of IgM antibodies by Weil-Felix Test (WFT)
• Enzyme-linked immunosorbent assay (ELISA)