|Year : 2020 | Volume
| Issue : 1 | Page : 41-43
Serological prevalence of scrub typhus among febrile patients from a tertiary care hospital in South Kerala
Swetha Sivaraman, Ivy Viswamohanan, Ganga Raju Krishna, Ashish Jithendranath, Ramani Bai
Department of Microbiology, Sree Gokulam Medical College and Research Foundation, Thiruvananthapuram, Kerala, India
|Date of Submission||16-Mar-2020|
|Date of Decision||15-May-2020|
|Date of Acceptance||25-May-2020|
|Date of Web Publication||13-Aug-2020|
Dr. Swetha Sivaraman
Department of Microbiology, Sree Gokulam Medical College and Research Foundation, Thiruvananthapuram, Kerala
Source of Support: None, Conflict of Interest: None
Scrub typhus, a potentially fatal rickettsial infection, is common in India. As the clinical features include fever, vomiting, headache, respiratory infection and rashes the differential diagnosis includes Enteric fever, Dengue, Leptospirosis and Malaria. Though many methods are available for diagnosis, IgM ELISA is the most sensitive method. A prospective study was carried out at the Sree Gokulam Medical College Thiruvananthapuram from January 2019 to December 31 2019. A total of 178 samples were screened for scrub typhus. Commercially available IgM ELISA was used. Out of 178 samples 28 samples were positive for scrub typhus(15.7%). 20-40 years age groups showed maximum number of cases and cases were more from June to September. Males were more commonly affected (57%). Scrub typhus is considered one of the important differential diagnoses of pyrexia of unknown origin in this area.
Keywords: Scub typhus, ELISA, rickettsia
|How to cite this article:|
Sivaraman S, Viswamohanan I, Krishna GR, Jithendranath A, Bai R. Serological prevalence of scrub typhus among febrile patients from a tertiary care hospital in South Kerala. J Acad Clin Microbiol 2020;22:41-3
|How to cite this URL:|
Sivaraman S, Viswamohanan I, Krishna GR, Jithendranath A, Bai R. Serological prevalence of scrub typhus among febrile patients from a tertiary care hospital in South Kerala. J Acad Clin Microbiol [serial online] 2020 [cited 2020 Oct 29];22:41-3. Available from: https://www.jacmjournal.org/text.asp?2020/22/1/41/291895
| Introduction|| |
Scrub typhus is a type of Rickettsial disease caused by Orientia tsusugamushi. It is transmitted by the bite of larval form of trombiculid mite of genus leptotrombidium. The name is derived from the prevalence of mites in the areas of heavy scrub vegetations. The larval forms or chiggers transmit the disease to humans accidentally the following bite, so the disease is also known as Chigger borne disease or chiggerosis. Scrub typhus is the most important rickettsial disease in the world. Its endemic areas are Australia, Asia and islands in the Indian and Pacific Oceans, and the area is called as tsusugamushi triangle. In India, the first case of scrub typhus was reported in 2009 from Kerala. In recent years, outbreaks have been reported in the Sub-Himalayan belt, Maharashtra, Rajasthan, Tamil Nadu and Kerala.
The incubation period of scrub typhus is one–three weeks. Clinical features include the triad of eschar, regional lymphadenopathy and maculopapular rash. Non-specific features include fever, headache, myalgia, cough and gastrointestinal features. The differential diagnosis of scrub typhus in our hospital includes dengue, leptospirosis, malaria and enteric fever. Even though the presence of eschar is diagnostic, it is not seen commonly. The methods used for diagnosis are Weil Felix test, indirect immunofluorescence assay, enzyme-linked immunosorbent assay (ELISA), rapid test like immunochromatographic tests, culture, polymerase chain reaction (PCR) and LAMP. Weil Felix test is the oldest test, which is cheap, easy to perform, but it lacks sensitivity. Indirect Immunofluorescence Assay is the gold standard test, but the cost and technical expertise limit the use. Culture requires Biosafety Level-3 and is, therefore difficult. PCR, although sensitive and specific, is expensive. So ELISA is the currently preferred method.
| Materials and Methods|| |
A prospective study was conducted on serum samples of 178 patients who presented with acute febrile illness for 12 months from January 2019 to December 2019 in Sree Gokulam Medical College, Thiruvananthapuram. The patients were in the age group of 1–80. The samples were subjected to immunoglobulin M (IgM) capture ELISA for the detection of IgM antibodies in the patient sera. The samples reported positive for malaria, dengue, leptospirosis or enteric fever were excluded from the study. The patients were diagnosed to have scrub typhus if the IgM ELISA test is positive. The detection of IgM antibodies to Orientia tsutsugamushi derived recombinant antigen by ELISA was done using InBios International TM IgM ELISA kit.
| Results|| |
Out of 178 samples, 28 samples were positive for scrub typhus (15.7%). Sixteen (57%) of them were males and 12 (33%) were females [Figure 1]. Out of 178 samples, 15 (54%) were in the age group 20–40 [Figure 2]. More number of cases were seen in June-September. Headache was the most common clinical feature in this area (79%), followed by nausea and vomiting, abdominal pain, myalgia and rashes. The clinical signs were thrombocytopenia, lymphadenopathy, hepatomegaly and rashes.
| Discussion|| |
Out of 178 febrile patients that were screened 28 were positive for scrub typhus. In our study, 16 of the patients were male and 12 were female. Males were more commonly affected due to occupational exposure. Age profile showed that a maximum number of cases (54%) were in the age group 20–40 followed by 22% in the age group 40–60. In our study, younger age groups were more affected due to their occupational exposure to scrub vegetation where the mites are more seen. In a study by Rajagopal et al., the highest percentage was in 16–25 years. In a study from Thiruvananthapuram, more number of cases were in the 40 above age group. Ragini et al., found maximum cases in the 31–40 age group in a study on febrile illness in Uttarakhand. In this study, more cases were seen in August. The prevalence of scrub typhus is more in monsoon and post-monsoon season than summer. This may be due to the breeding of mites during rainy days. Studies from Thiruvananthapuram Medical College (Kerala), Tamil Nadu and Uttarakhand found more cases during September to December and maximum cases in October.,, Headache was the most common clinical feature in this area (79%), followed by nausea and vomiting, abdominal pain, myalgia and rashes. The clinical signs were thrombocytopenia, lymphadenopathy, hepatomegaly and eschar. Eschar was seen in only one patient. Headache and vomiting were common symptoms found in a study from the North Eastern region of India. Vomiting, myalgia and respiratory infections were commonly reported from many studies, including different states of India and Northern China.
| Conclusion|| |
Scrub typhus is one of the re-emerging diseases in Kerala. All the 28 patients were treated with Doxycycline and all of them were cured, and there was no mortality. It is known that it existed in the past but went unnoticed as many doctors might have been treating their patients with the commonly used antibiotics such as Doxycycline and Azithromycin, to which scrub typhus responds, without considering it in their differential diagnosis. Primary care doctors must include scrub typhus as an important differential diagnosis in patients presenting with fever, cough, myalgia, headache, rashes, anorexia, vomiting or abdominal pain and should start Doxycycline early in the course of illness. It must be included in the panel of serological tests ordered in such patients.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]