Inflammatory Cytokines in Scrub Typhus and COVID-19 : Indian Journal of Public Health

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Letter to Editor

Inflammatory Cytokines in Scrub Typhus and COVID-19

Farhat, S. K.1; Srivastava, Pradeep Kumar2; Baskar, P3; Krishnan, Jayalakshmi4,

Author Information
Indian Journal of Public Health 67(1):p 184, Jan–Mar 2023. | DOI: 10.4103/ijph.ijph_873_22
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Dear Editor,

Scrub typhus is an underreported, underdiagnosed, and neglected topic till today, compared to other targeted vector-borne diseases such as malaria, where the national programs since 1953 are conscious for their elimination. Scrub typhus threatens one billion people worldwide and infects one million people every year.[1] Scrub typhus has now been noted as an intense public health concern, especially in India where the disease epidemic is re-emerging.[1] This letter highlights the importance of differential diagnosis of scrub typhus during the pandemic and checking for the possibilities of other hidden viral, bacterial coinfections and inflammatory illnesses, since the mistreatment of the illness may sometimes lead to fatality.

Amid this COVID-19 pandemic, the geographical areas endemic to scrub typhus such as South-Eastern and Eastern Asia, Northern Australia, Pakistan, Maldives, Indonesia, Myanmar, India, Nepal, Sri Lanka, Thailand, and other islands in the region[2] have to be much more cautious when diagnosing the cases of fever of unknown origin (FUO), especially during the disease outbreaks. The blooming of COVID cases has suppressed the screening and diagnosing of scrub typhus cases.[3] Since cytokine elevation is a key factor in all inflammatory diseases, such as COVID-19, rheumatoid arthritis, scrub typhus, Ebola, and dengue virus infection, their importance to public health has to be recognized.[4]

Probing into the case reports from various hooks and corners of India showed how the scrub typhus-positive patients were initially mistreated for COVID-19 with considering the common symptoms such as fever, headache, and myalgia. Upon thorough re-evaluation of fever cases through serological tests, they revealed a hidden Eschar and confirmed the case to be scrub typhus positive.[5] The vulnerable group such as pregnant women has to be very carefully diagnosed for scrub typhus and treated accordingly during the pandemics and also by considering the case history to elude the cases of intrauterine fetal deaths.

Scrub typhus has made it difficult for the physicians to identify cases, particularly during the pandemics like COVID19, due to its widespread symptoms of Dengue, Leptospirosis, Acute Encephalitis Syndrome, and other inflammatory disorders. Although the literature shows evidence of cytokine elevation in both scrub typhus cases and COVID-19 patients, these cytokines act as an intermittent fuel for inflammatory diseases. Advancement in the detailed differential diagnosing of patients with FUO has to be made and the results have to be recorded and submitted to the National Vector Borne Disease Control Programme for the implementation of new program strategies. Therefore, the disease surveillance program can track the prevalence and incidence rate of the disease and the disease burden can be controlled.

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1. Xu G, Walker DH, Jupiter D, Melby PC, Arcari CM A review of the global epidemiology of scrub typhus. PLoS Negl Trop Dis 2017; 11: e0006062.
2. Sharma P, Kakkar R, Kaore SN, Yadav VK, Sharma R Geographical distribution, effect of season &life cycle of scrub typhus. JK Science 2010; 12: 63–4 Available from: http://www.jkscience.org63 Last accessed on 2020 Mar 19.
3. Ihara S, Shikino K, Ikusaka M A case of availability bias for COVID-19 causing scrub typhus diagnostic errors. J Gen Fam Med 2022; 23: 52–3.
4. Teijaro JR Cytokine storms in infectious diseases. Semin Immunopathol 2017; 39: 501–3.
5. Jesrani G, Chhabra A, Garg A, Kaur A, Gupta M Co-infection of scrub typhus and COVID-19:A diagnostic challenge. APIK J Intern Med 2021; 9: 268.
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