Parul*, Barkha Sharma, Udit Jain, Raghavendra P Mishra, Gourab Basak and Shikhar Karan Verma

Department of Veterinary Public Health, DUVASU, Mathura, India

*Corresponding Author: Parul, Department of Veterinary Public Health, DUVASU, Mathura, India.

Received: March 16, 2022; Published: March 29, 2022

Abstract

Scrub typhus, caused by Orientia tsutsugamushi, is an important vector-borne disease that has been classified a neglected tropical zoonosis. The ecology of the disease is complex and less understood thus has more public health implication than other zoonotic diseases. About a million cases of scrub typhus are reported worldwide annually and the disease is associated with high mortality. It is endemic in geographically confined area of the Asia-Pacific termed as the Tsutsugamushi triangle’, which is bound by Siberia and Kamchatka peninsula to the north, Australia to the south, Japan to the east and Afghanistan and India to its west, covering Northern Australia, South and Southeast Asia, the Indian subcontinent and Pacific Ocean. There has been a resurgence of scrub typhus across India in the recent years and the disease has re-emerged as a major cause of acute undifferentiated febrile illnesses (AUFI) in humans with high morbidity and mortality. Thus better understanding of scrub typhus epidemiology is needed to put in place appropriate public health interventions to reduce the burden of the disease globally. This comprehensive review provides summary of work, investigation of this pathogen in vectors and updates for understanding the complexity of scrub typhus.

Keywords:Scrub Typhus; Orientia Tsutsugamushi; Tsutsugamushi Triangle; Vector-Borne Zoonosis

References

1. Jeong YJ., et al. “Scrub Typhus: Clinical, Pathologic, and Imaging Findings”. Radiographics 1 (2007): 161-172.
2. Kelly DJ., et al. “Scrub Typhus: The Geographic Distribution of Phenotypic and Genotypic Variants of Orientia Tsutsugamushi”. Clinical Infectious Diseases 3 (2009): S203-230.
3. Xu G., et al. “A Review of the Global Epidemiology of Scrub Typhus”. PLOS Neglected Tropical Diseases 11 (2017): e0006062.
4. Enatsu T., et al. “Phylogenetic analysis of Orientia tsutsugamushi strains based on the sequence homologies of 56-kDa type-specific antigen genes”. FEMS Microbiology Letters 180 (1999): 163-169.
5. Seong S-Y., et al. “Orientia tsutsugamushi infection: overview and immune responses”. Microbes and Infection 3 (2001): 11-21.
6. Tamura A., et al. “Classification of Rickettsia tsutsugamushi in a New Genus, Orientia gen. nov., as Orientia tsutsugamushi comb”. International Journal of Systematic and Evolutionary Microbiology 45 (1995): 589- 591.
7. Gurung S., et al. “Outbreak of scrub typhus in the northeast Himalayan region-Sikkim: An emerging threat”. Indian Journal of Medical Microbiology 31 (2013): 72-74.
8. Sinha P., et al. “Recent outbreak of scrub typhus in north western part of India”. Indian Journal of Medical Microbiology 32 (2014): 247-250.
9. Lee J-H., et al. “Fibronectin facilitates the invasion of Orientia tsutsugamushi into host cells through interaction with a 56-kDa type-specific antigen”. The Journal of Infectious Diseases 198 (2008): 250-257.
10. Koraluru M., et al. “Diagnostic Validation of Selected Serological Tests for Detecting Scrub Typhus”. Microbiology and Immunology 7 (2015): 371-374.
11. Lim C., et al. “How to Determine the Accuracy of an Alternative Diagnostic Test When It Is Actually Better Than the Reference Tests: A Re-Evaluation of Diagnostic Tests for Scrub Typhus Using Bayesian LCMs”. PloS One5 (2007): e0114930.
12. Ohashi N., et al. “Diversity of Immunodominant 56-kDa Type-Specific Antigen (TSA) of Rickettsia Tsutsugamushi. Sequence and Comparative Analyses of the Genes Encoding TSA Homologues from Four Antigenic Variants”. Journal of Biological Chemistry 18 (1992): 12728-12735.
13. Ruang-areerate T., et al. “Genotype diversity and distribution of Orientia tsutsugamushi causing scrub typhus in Thailand”. Journal of Clinical Microbiology 49 (2011): 2584-2589.
14. Nakayama K., et al. “Genome comparison and phylogenetic analysis of Orientia tsutsugamushi strains”. DNA Research 17 (2010): 281-291.
15. Sonthayanon P., et al. “High rates of homologous recombination in the mite endosymbiont and opportunistic human pathogen Orientia tsutsugamushi”. PLOS Neglected Tropical Diseases 4 (2010): e752.
16. Kweon S-S., et al. “Rapid increase of scrub typhus, South Korea, 2001-2006”. Emerging Infectious Diseases 15 (2009): 1127-1129.
17. Lee J-H., et al. “Fibronectin facilitates the invasion of Orientia tsutsugamushi into host cells through interaction with a 56-kDa type-specific antigen”. The Journal of Infectious Diseases 198 (2008): 250-257.
18. Ogawa M., et al. “Evaluation of a broadranging and convenient enzyme-linked immunosorbent assay using the lysate of infected cells with five serotypes of Orientia tsutsugamushi, a causative agent of scrub typhus”. BMC Microbiology 17 (2017): 1-8.
19. Kim YJ., et al. “Improvement of the diagnostic sensitivity of scrub typhus using a mixture of recombinant antigens derived from Orientia tsutsugamushi serotypes”. Journal of Korean Medical Science 28 (2013): 672-679.
20. Maina AN., et al. “Q fever, scrub typhus, and rickettsial diseases in children, Kenya, 2011-2012”. Emerging Infectious Diseases 22 (2016): 883-886.
21. Manosroi J., et al. “Determination and geographic distribution of Orientia tsutsugamushi serotypes in Thailand by nested polymerase chain reaction”. Diagnostic Microbiology and Infectious Disease 55 (2006): 185-190.
22. Mathai E., et al. “Outbreak of scrub typhus in southern India during the cooler months”. Annals of the New York Academy of Sciences 990 (2003): 359-364.
23. Wang K., et al. “DNA-fueled target recycling-induced two-leg DNA walker for amplified electrochemical detection of nucleic acid”. Talanta 188 (2018): 685-690.
24. Taylor AJ., et al. “A systematic review of mortality from untreated scrub typhus (Orientia tsutsugamushi)”. PLOS Neglected Tropical Diseases 9 (2015): e0003971.
25. Chao CC., et al. “An ELISA Assay Using a Combination of Recombinant Proteins from Multiple Strains of Orientia Tsutsugamushi Offers an Accurate Diagnosis for Scrub Typhus”. BMC Infectious Disease 1 (2017): 413.
26. Vallee J., et al. “Contrasting spatial distribution and risk factors for past infection with scrub typhus and murine typhus in Vientiane City, Lao PDR”. PLOS Neglected Tropical Diseases 4 (2010): e909.
27. Silpasakorn S., et al. “Development of new, broadly reactive, rapid IgG and IgM lateral flow assays for diagnosis of scrub typhus”. American Journal of Tropical Medicine and Hygiene 87 (2012): 148-152.
28. Yang SL., et al. “Evaluation of Enzyme-Linked Immunosorbent Assay Using Recombinant 56-kDa Type-Specific Antigens Derived from Multiple Orientia Tsutsugamushi Strains for Detection of Scrub Typhus Infection”. American Journal of Tropical Medicine and Hygiene (2019) 100.3 (2019): 532-539.
29. Anitharaj V., et al. “Serological diagnosis of acute scrub typhus in southern India: Evaluation of InBios Scrub Typhus Detect IgM rapid test and comparison with other serological tests”. Journal of Clinical and Diagnostic Research 10 (2016): DC07-DC10.
30. Chao CC., et al. “Lateral flow rapid test for accurate and early diagnosis of scrub typhus: A febrile illness of historically military importance in the Pacific Rim”. Military Medicine 182 (2017): 369-375.
31. Koraluru M., et al. “Diagnostic validation of selected serological tests for detecting scrub typhus”. Microbiology and Immunology 59 (2015): 371-374.
32. Paris D., et al. “A highly sensitive quantitative real-time PCR assay based on the groEL gene of contemporary Thai strains of Orientia tsutsugamushi”. Clinical Microbiology and Infection 15 (2009): 488-495.
33. Yamamoto S., et al. “Immunological properties of Rickettsia tsutsugamushi Kawasaki strain, isolated from a patient in Kyushu”. Microbiology and Immunology 30 (1986): 611-620.
34. Kim G., et al. “Diversification of Orientia tsutsugamushi genotypes by intragenic recombination and their potential expansion in endemic areas”. PLOS Neglected Tropical Diseases 11 (2017): e0005408.
35. Wang K., et al. “DNA-fueled target recycling-induced two-leg DNA walker for amplified electrochemical detection of nucleic acid”. Talanta 188 (2018): 685-690.
36. Blacksell SD., et al. “Scrub typhus serologic testing with the indirect immunofluorescence method as a diagnostic gold standard: A lack of consensus leads to a lot of confusion”. Clinical Infectious Diseases 44 (2007): 391-401.
37. Ching WM., et al. “Expression and Refolding of Truncated Recombinant Major Outer Membrane Protein Antigen (R56) of Orientia Tsutsugamushi and Its Use in Enzyme-Linked Immunosorbent Assays”. Clinical and Diagnostic Laboratory Immunology 4 (1989): 519-526.
38. Jeong HW., et al. “Phylogenetic analysis of the 56-kDa type-specific protein genes of Orientia tsutsugamushi in central Korea”. Journal of Korean Medical Science 27 (2012): 1315-1319.
39. Dittrich Sabine., et al. “Survival and Growth of Orientia tsutsugamushi in Conventional Hemocultures”. Emerging Infectious Diseases8 (2016): 1460-1463.
40. Giengkam Suparat., et al. “Improved Quantification, Propagation, Purification and Storage of the Obligate Intracellular Human Pathogen Orientia tsutsugamushi”. PLOS Neglected Tropical Diseases8 (2015): e0004009.
41. Rodkvamtook W., et al. “Isolation and Characterization of Orientia tsutsugamushi from Rodents Captured following a Scrub Typhus Outbreak at a Military Training Base, Bothong District, Chonburi Province, Central Thailand”. American Journal of Tropical Medicine and Hygiene4 (2011): 599-607.
42. Paris D., et al. “A highly sensitive quantitative real-time PCR assay based on the groEL gene of contemporary Thai strains of Orientia tsutsugamushi”. Clinical Microbiology and Infection15 (2009): 488-495.
43. Bora T., et al. “Genetic diversity of Orientia tsutsugamushi strains circulating in Northeast India”. Transactions of the Royal Society of Tropical Medicine and Hygiene 112 (2018): 22-30.
44. Kim D-M., et al. “Comparison of conventional, nested, and real-time quantitative PCR for diagnosis of scrub typhus”. Journal of Clinical Microbiology 49 (2011): 607-612.
45. Jiang J., et al. “Development of a quantitative real-time polymerase chain reaction assay specific for Orientia tsutsugamushi”. American Journal of Tropical Medicine and Hygiene 70 (2004): 351-356.
46. Sonthayanon P., et al. “Association of high Orientia tsutsugamushi DNA loads with disease of greater severity in adults with scrub typhus”. Journal of Clinical Microbiology 47 (2009): 430-434.
47. Tantibhedhyangkul W., et al. “Use of multiplex real-time PCR to diagnose scrub typhus”. Journal of Clinical Microbiology 55 (2017): 1377-1387.
48. Kim D-M., et al. “Clinical usefulness of eschar polymerase chain reaction for the diagnosis of scrub typhus: a prospective study”. Clinical Infectious Diseases 43 (2006): 1296-1300.
49. Paris DH., et al. “Diagnostic accuracy of a loop-mediated isothermal PCR assay for detection of Orientia tsutsugamushi during acute scrub typhus infection”. PLOS Neglected Tropical Diseases 5 (2011): e1307.
50.  

Citation

Citation: Parul. “Scrub Typhus: A Threat to ‘Tsutsugamushi Triangle’".Acta Scientific Veterinary Sciences 4.4 (2022): 165-171.

Copyright

Copyright: © 2022 Parul. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.