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SHORT COMMUNICATION
Year : 2018  |  Volume : 7  |  Issue : 3  |  Page : 201-203

Seroprevalence and clinical manifestations of scrub typhus infection in Chennai city: A cross-sectional study


1 Department of Experimental Medicine, The Tamil Nadu Dr. M.G.R Medical University, Chennai, Tamil Nadu, India
2 The Tamil Nadu Dr. M.G.R Medical University, Chennai, Tamil Nadu, India

Date of Web Publication20-Jul-2018

Correspondence Address:
Dr. Saramma Mini Jacob
Department of Experimental Medicine, Tamil Nadu Dr. M.G.R. Medical University, Guindy, Chennai - 600 032, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijhas.IJHAS_9_18

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  Abstract 


BACKGROUND: Scrub typhus is a zoonotic rickettsial illness caused by Orientia tsutsugamushi and has been reported from Southeast Asia, the Asian Pacific Rim, and Australia. It is an emerging pathogen in Southern India, especially in the urban setting. The objective of this study was to identify scrub typhus infection among febrile patients and to identify clinical manifestations related to the disease.
METHODS: In this prospective cross-sectional study, febrile patients who presented to the Department of Experimental Medicine at the Tamil Nadu Dr. M.G.R. Medical University between November 2015 and February 2016 were enrolled. Demographics and clinical manifestations were recorded using a semi-structured questionnaire. Serum was separated from 2 ml of blood sample for testing. The Scrub Typhus Detect ELISA test was performed as per manufacturer's instructions. Statistical data analysis was done.
RESULTS: A total of 100 patients were enrolled and their age ranged from 4 to 80 years with a mean of 30 years. Nearly 56% were males. Ig M antibodies for O. tsutsugamushi were present in 23% of cases. Most (65%) of the positive patients were females. About 48% positives for scrub typhus were 4–20 years old. Clinical presentations in these patients were fever (100%), myalgia (73.9%), headache (65.2%), nausea (60.9%), cough (60.9%), abdominal pain (52.2%), vomiting (47.8%), breathlessness (39.1%), diarrhea (34.8%), and decreased urine output (26.1%). Eschar was seen in 7 patients of whom 2 were positive for scrub typhus.
CONCLUSIONS: In this study, 23% of febrile patients were positive for scrub typhus infection. Therefore, it needs to be included in the differential diagnosis of febrile illnesses in Chennai city.

Keywords: Chennai, febrile patients, Orientia tsutsugamushi, scrub typhus


How to cite this article:
Jacob SM, Sekkizhar G, Kanagasabai S, Gopal P, Gopal T, Elumalai S. Seroprevalence and clinical manifestations of scrub typhus infection in Chennai city: A cross-sectional study. Int J Health Allied Sci 2018;7:201-3

How to cite this URL:
Jacob SM, Sekkizhar G, Kanagasabai S, Gopal P, Gopal T, Elumalai S. Seroprevalence and clinical manifestations of scrub typhus infection in Chennai city: A cross-sectional study. Int J Health Allied Sci [serial online] 2018 [cited 2020 Jun 1];7:201-3. Available from: http://www.ijhas.in/text.asp?2018/7/3/201/237268




  Introduction Top


Scrub typhus, a zoonotic rickettsial illness, is caused by Orientia tsutsugamushi, an obligate intracellular Gram-negative bacterium. It is transmitted by the bite of larval (chiggers) trombiculid mites and has been reported mainly in the South and Southeast Asia, the Asian Pacific Rim, and Northern Australia.[1] Annually, one million scrub typhus cases have been reported in these regions, and one billion individuals are at risk of contracting the illness.[2] Recent evidence suggest that its range maybe larger with case reports from Africa and Chile and a new related species, Orientia chuto, described from the Middle East.[3] Scrub typhus has been documented as an emerging pathogen in different parts of India, including South India.[4]

Scrub typhus (also known as tsutsugamushi disease) presents as an acute undifferentiated fever. Clinical manifestations range from mild disease to multiple system involvement, acute kidney injury, respiratory complications, and dysfunction of three or more organ systems [2] with the presence or absence of characteristic eschar. The disease is most common in resource-limited settings such as rural areas and is difficult to differentiate clinically from other tropical infections such as malaria, enteric fever, leptospirosis, and dengue.[5] It is grossly underdiagnosed and its awareness among clinicians is limited. Hence, the objective of the present study was to evaluate serological evidence and analyze clinical manifestations of scrub typhus infection in febrile patients in Chennai city.


  Methods Top


This was a cross-sectional, prospective study. Patients with fever who presented to the laboratory in the Department of Experimental Medicine at the Tamil Nadu Dr. M.G.R. Medical University, Chennai, between November 2015 and February 2016 were enrolled. The study was approved by Institutional Ethics Committee. Demographics and clinical features were recorded using a semi-structured questionnaire. Under aseptic precautions, 2 ml of blood was collected, and the sera were tested using detect IgM ELISA kit (InBios International, USA). Data were analyzed using mean, percentages, and Fisher's exact test.


  Results Top


A total of 100 febrile patients were enrolled and their age ranged from 4 to 80 years with a mean of 30 years (SD±21). Fifty-six percent were males. Twenty-three percent (23/100) were positive for IgM antibodies against O. tsutsugamushi. Scrub typhus was significantly higher in females than males (P = 0.03) [Table 1]. Majority (27%) of the scrub typhus-positive patients were in the younger age group (4–20 years) followed by the age group of 21–40, 41–60, and >60 years with 23%, 22%, and 10%, respectively [Table 2]. Among the female patients who were positive for scrub typhus, 73% of them were school and college students.
Table 1: Gender-wise prevalence of scrub typhus

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Table 2: Age-wise prevalence of scrub typhus

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Majority (52%) of febrile patients with scrub typhus infection had fever of <7-day duration and 30% had fever of 2-week duration. The most common presentations were body pain (myalgia, 73.9%), headache (65.2%), nausea (60.9%), cough (60.9%), abdominal pain (52.2%), vomiting (47.8%), breathlessness (39.1%), diarrhea (34.8%), and decreased urine output (26.1%). Unusual clinical signs and symptoms are given in [Table 3]. The pathognomonic feature such as eschar was seen in 7 patients in whom 2 were positive for IgM antibody to scrub typhus.
Table 3: Clinical presentation of scrub typhus (n=23)

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  Discussion Top


The present study reveals that scrub typhus is an important cause of febrile illness in Chennai, South India. The prevalence of scrub typhus varies from 0 - 8% to 60% in different countries.[6] A study from Thailand had documented 59.5% scrub typhus positivity, whereas in Bangladesh, Indonesia, Malaysia, Papua New Guinea, and Sri Lanka, the seroprevalence was found to be 23.7%, 9.3%, 17.9%, 27.9%, and 26.3%, respectively.[2],[6] During the past 10 years, outbreaks of scrub typhus have started to appear in India including parts of South India such as Pondicherry.[4] Neighboring state of Andhra Pradesh recorded 39% seroprevalence, while a recent study from Tamil Nadu observed 31.8% seropositivity.[6],[7] In this study, the prevalence was 23%.

Scrub typhus is known to be a disease prevalent in rural areas. However, our laboratory caters to middle-class urban population. Studies have shown that rodents carrying the mites are transmitting the disease in the urban locales in India.[8] Urbanization, contaminated environment, and rodent population had made it suitable for the transmission of the disease in the urban setting. In this study, scrub typhus infection was seen in the young adults and significantly more in females. Similar results were noticed in Thailand, Japan, and Korea which described the women had higher chances of contacting the infection because they spend more hours on the dry-field farms and tend more to kitchen garden plots in rural regions. In addition, when visiting relatives in rural areas, women are more willing to help in field farming.[9] However, in this study, most of the scrub typhus-infected females were school- and college-going students from the city. There may be a possibility that these students spend their free time in places where bushes or sandy areas are harboring chiggers.

Scrub typhus is an important cause of fever and is to be differentiated from other febrile illnesses.[2],[8] The most common clinical presentations in this study were fever, myalgia, headache, cough, nausea, abdominal pain, vomiting, breathlessness, and diarrhea. Similar clinical presentations were observed in Korean patients and also from various studies conducted in India.[8],[10] These signs and symptoms are also present in other febrile illnesses such as dengue, typhoid, malaria, viral fever, and leptospirosis which should be considered in the differential diagnosis. In this study, eschar was present in 7 patients out of which 2 had scrub typhus infection. Eschar is a pathognomonic sign of scrub typhus. Eschars are painless, punched out ulcers up to 1 cm in width, with a black necrotic center, resembling the mark of a cigarette burn, which is surrounded by an erythematous margin.[11] They maybe single or multiples and is often found in the neck, axilla, chest, abdomen, and groin. It is difficult to identify in dark-skinned people. In this study, eschar was also noticed in patients without scrub typhus infection. Other important differential diagnoses of eschar-forming illness are spider bite, posttrauma, spotted fever rickettsiosis, tularemia, anthrax, and disseminated fungal infection.[12]

The mortality of scrub typhus ranged from 0% to 30% in untreated cases and depends on the age, region, and virulence factor of the strain. Earlier and accurate diagnosis of the disease and appropriate treatment with antirickettsial drugs will reduce the mortality rate. ELISA kit was used for diagnosis in this study. However, indirect fluorescent antibody (IFA) test is the gold standard. However, ELISA was fairly comparable with IFA in terms of sensitivity and specificity.[4]

One of the limitations of this study was that more baseline laboratory investigations were not included. It would have given better profile to the infection along with clinical presentations. Due to financial constraints, the sample size taken was fairly small. A community-based study with a large sample size will give a better understanding of the prevalence and incidence of the disease in the urban setting.


  Conclusions Top


Twenty-three percent of febrile patients had scrub typhus infection. It is an underdiagnosed disease in India and needs to be included in the differential diagnosis of febrile illnesses in Chennai, an urban setting.

Acknowledgment

The authors are grateful to all the patients who took part in the study. The authors acknowledge the Tamil Nadu Dr. M.G.R. Medical University for the financial support.

Financial support and sponsorship

This study was financially supported by the Tamil Nadu Dr. M.G.R. Medical University.

Conflict interest

There are no conflicts of interest.



 
  References Top

1.
Kelly DJ, Fuerst PA, Ching WM, Richards AL. Scrub typhus: The geographic distribution of phenotypic and genotypic variants of Orientia tsutsugamushi. Clin Infect Dis 2009;48 Suppl 3:S203-30.  Back to cited text no. 1
    
2.
Bonell A, Lubell Y, Newton PN, Crump JA, Paris DH. Estimating the burden of scrub typhus: A systematic review. PLoS Negl Trop Dis 2017;11:e0005838.  Back to cited text no. 2
    
3.
Taylor AJ, Paris DH, Newton PN. A systematic review of mortality from untreated scrub typhus (Orientia tsutsugamushi). PLoS Negl Trop Dis 2015;9:e0003971.  Back to cited text no. 3
    
4.
Stephen S, Sangeetha B, Ambroise S, Sarangapani K, Gunasekaran D, Hanifah M, et al. Outbreak of scrub typhus in Puducherry & Tamil Nadu during cooler months. Indian J Med Res 2015;142:591-7.  Back to cited text no. 4
[PUBMED]  [Full text]  
5.
Peter JV, Sudarsan TI, Prakash JA, Varghese GM. Severe scrub typhus infection: Clinical features, diagnostic challenges and management. World J Crit Care Med 2015;4:244-50.  Back to cited text no. 5
    
6.
Ramyasree A, Kalawat U, Rani ND, Chaudhury A. Seroprevalence of scrub typhus at a tertiary care hospital in Andhra Pradesh. Indian J Med Microbiol 2015;33:68-72.  Back to cited text no. 6
[PUBMED]  [Full text]  
7.
Trowbridge P, Divya P, Prasanna S, Varghese GM. Prevalence and risk factors for scrub typhus in South India. Trop Med Int Health 2017;22:576-82.  Back to cited text no. 7
    
8.
Laskar AR, Suri S, Acharya AS. Scrub typhus: Re-emerging public health problem in India. J Commun Dis 2015;47:19-25.  Back to cited text no. 8
    
9.
Jeong MA, Youn SK, Kim YK, Lee H, Kim SJ, Sohn A, et al. Trends in the incidence of scrub typhus: The fastest growing vector-borne disease in Korea. Osong Public Health Res Perspect 2013;4:166-9.  Back to cited text no. 9
    
10.
Lee J, Kim DM, Yun NR, Kim YD, Park CG, Kim MW, et al. The correlation of endoscopic findings and clinical features in Korean patients with scrub typhus: A cohort study. PLoS One 2016;11:e0155810.  Back to cited text no. 10
    
11.
Rahi M, Gupte MD, Bhargava A, Varghese GM, Arora R. DHR-ICMR guidelines for diagnosis & management of Rickettsial diseases in India. Indian J Med Res 2015;141:417-22.  Back to cited text no. 11
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12.
Sundriyal D, Kumar N, Chandrasekharan A, Sharma B. Eschar: An important clue to diagnosis. BMJ Case Rep 2013;2013. pii: bcr2013010105.  Back to cited text no. 12
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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