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Year : 2022  |  Volume : 8  |  Issue : 1  |  Page : 67-72

A clinico-epidemiological profile of scrub typhus cases admitted in a tertiary hospital in South India

Department of Community Medicine, ESIC-MC and PGIMSR, Bengaluru, Karnataka, India

Date of Submission04-Jul-2021
Date of Decision19-Dec-2021
Date of Acceptance20-Jan-2022
Date of Web Publication30-Jun-2022

Correspondence Address:
Purabi Phukan
Professor, Department of Community Medicine, ESIC-MC and PGIMSR, Bengaluru - 560010, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijcfm.ijcfm_53_21

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Scrub typhus (ST) is a consistently underreported disease. The disease is spreading to newer areas, and an understanding of disease epidemiology is needed in the local Indian and current context. This study describes the demographic characteristics, monthly distribution, clinical and laboratory presentations, and treatment outcome of the ST cases recently identified. Case sheets of 15 ST patients diagnosed from January 2019 to December 2020 were analyzed. The majority of the patients were male. Eighty percent of the patients were from rural or suburban areas. Higher admission was observed from September to December. Fever (100%), skin rash (73.3%), body ache (53.3%), and vomiting (53.3%) were the most common clinical features. The onset of fever till the appearance of skin rash was 3 ± 1.2 days. The mean day from onset of symptoms till diagnosis was 6.8 ± 3.9 days. Eschar was found in only two patients. Nine (60%) patients already had complications at the time of admission. Most patients presented a laboratory picture of thrombocytopenia, neutrophilic leukocytosis, and anemia. Complications such as septic shock, acute kidney injury, and hepatic involvement were observed. All responded to doxycycline within 48 h. No fatalities were observed. Early clinical suspicion of ST among those with high fever, skin rash and thrombocytopenia, and transaminitis showed positive clinical outcome.

Keywords: Doxycycline, febrile illness, scrub typhus, thrombocytopenia, Weil–Felix test

How to cite this article:
Phukan P. A clinico-epidemiological profile of scrub typhus cases admitted in a tertiary hospital in South India. Indian J Community Fam Med 2022;8:67-72

How to cite this URL:
Phukan P. A clinico-epidemiological profile of scrub typhus cases admitted in a tertiary hospital in South India. Indian J Community Fam Med [serial online] 2022 [cited 2023 May 28];8:67-72. Available from: https://www.ijcfm.org/text.asp?2022/8/1/67/349386

  Introduction Top

Scrub typhus (ST) is a re-emerging disease. Although there is an increasing trend in the number of cases and disease outbreaks in India, there is a lack of awareness among clinicians about the disease.[1],[2],[3],[4] Furthermore, there is a lack of awareness about importance of disease surveillance in control of such diseases. Overall, a poor participation of health facilities in disease surveillance activities has been observed.[3],[4] Lack of epidemiological data due to consistent underreporting of ST cases is proving to be an obstacle to effective planning and implementation of appropriate prevention and control measures.

The case fatality rate due to ST is reported to be around 30%–45% and is influenced by a number of patient factors and availability of diagnostic and treatment facilities.[5],[6],[7] Around 50% of those with fever of unknown origin were later found to be positive for ST by serological studies.[8] South India has started to see rise in ST cases.[3],[8],[9],[10] This case series study was undertaken with the objective of describing the demographic characteristics, monthly distribution, clinical presentations, and treatment outcome of the ST cases admitted in a tertiary hospital in South India.

  Methodology Top

A record based case series study was undertaken at a tertiary health facility in Bangalore, South India. The medical records of patients from January 2019 to December 2020 were reviewed for ST cases. A total of 15 patients were treated for ST during that time. The results of the analyzed 15 case sheets are presented here.

Case description of Scrub Typhus

In 2017 the clinical case definition Scrub Typhus surveillance was modified as follows:

A clinical case of scrub typhus is one with acute undifferentiated febrile illness of 5 days or more with or without eschar should be suspected as a case of Rickettsial infection. If eschar is present, fever of less than 5 days should be considered at Scrub Typhus. Other signs and symptoms may be headache, rash, lymphadenopathy, multi-organ involvement like liver, lung and kidney involvement.Other common diseases like dengue, malaria, pneumonia, leptospirosis, and typhoid should be ruled out.[11]

Case series analysis revealed that the confirmation of diagnosis was made either by Weil–Felix test or by strong clinical suspicion after ruling out dengue, typhoid, leptospirosis, and malaria or by observing their response to doxycycline regimen within the first 24–48 h.

The patient blood samples were sent to authorized laboratories for testing. Among those tested with Weil–Felix, a titer of more than 1:80 for OXK was considered diagnostically significant as per the new modified definition for ST by the National Integrated Disease Surveillance Programme (IDSP).[11] Data were analyzed for descriptive statistics using MS Excel and IBM SPSS 23 Chicago, IL. USA.

  Results Top

There was a male preponderance (66.4%) in the case occurrence [Figure 1]. The mean age of the patients was 19.24 ± 18.6 years (range: 2–55 years). Age distribution of the cases showed that there were three (20%) under 5 years, five (33.3%) between 5 and 18 years, and seven (46.6%) above 18 years of age. Comorbid conditions based on investigation reports were found in three cases, with one having alcoholic liver disease (fatty liver signs in ultrasonography [USG] abdomen), one tested positive for typhoid, and one for chikungunya. Only three (20%) gave a history of contact with pets and animals. The majority of the patients came from rural areas (80%) [Table 1].
Table 1: Demographic and clinical profile of the scrub typhus cases (n=15)

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Figure 1: Gender distribution of the scrub typhus cases (n = 15)

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All 15 patients had high grade fever; 7 (46.7%) with and 8 (53.3%) without chills and rigor. Erythematous maculopapular rash (73%), body ache ( 53.3%), and vomiting (53.3%) were the other most common accompanying clinical features. The clinical signs of periorbital puffiness and redness of eyes were observed only among young children. On clinical examination, eschar was found only in two (13.3%) patients who reported insect bite. Location of the eschar was in the ear and thigh region [Table 2].
Table 2: Summary of clinical manifestations of the scrub typhus cases (n=15)

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Time distribution of the cases showed that the majority of the cases (73.3%) were admitted from September to December month in those years [Figure 2].
Figure 2: Scrub typhus case distribution for the years 2019 and 2020 (n = 15)

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Anemia was present in 13 (86.7%) with a mean Hb% of 11.1 ± 2.2 g% (range: 8.6–15 g%), transaminitis was present in 12 (80%), and thrombocytopenia was observed in 9 (60%) cases with a mean platelet count of 98500 ± 54586 lakhs/ml of blood (range: 32000–160000/ml of blood). Five patients (33.3%) developed serious complications. Four of the five patients who developed complications had OXK titer >1:160 [Table 3].
Table 3: Summary of laboratory findings and complications observed among scrub typhus cases (n=15)

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  Discussion Top

Male preponderance (66.4%) of ST was observed in this study. Similar finding was reported by Varghese et al.[12] in the neighboring states of Tamil Nadu and Andhra Pradesh.[13] Fever, rash, and body aches were the most common presenting clinical features. Pain and ulceration on scrotal skin among two (13.3%) male patients were the chief presenting complaints, which has not been reported earlier in any research study. These patients specifically had prominent maculopapular rash with petechial hemorrhage and central necrosis scattered over other parts of their body.

There was no mortality due to ST recorded during the study period even though complications such as sepsis and acute hepatorenal injury occurred in them. All the patients responded to tablet doxycycline. In this study, a dramatic response to doxycycline was observed in all patients. Most of them became afebrile within 24–48 h and symptomatically of improved and could be discharged after around 3–4 days. Similar findings were reported in other studies done in South India.[3],[8],[14]

Eschar was found in only 2 (13.3%) of the 15 patients. Eschar indicates the site of bite by the chigger, the larval stage of the mite. Although the presence of an eschar supports diagnosis, it may not be always found in all cases. Literature review revealed that patients from Southeast Asia rarely present with an eschar. Furthermore, people living in endemic areas rarely develop severe illness, often without rash or eschar.[15],[16]

In this study, those with severe complications were found to have OXK titer >1:160. However, the significance of this titer could not be established statistically in this study. A study did find a correlation between higher titers of Weil–Felix tests to more severe forms of disease.[17]

Even though the Weil–Felix test has a low sensitivity and specificity, it is the cheapest and common test for diagnosis of ST in developing countries.[14],[18] Weil–Felix tests do show false positives in those with urinary infections, leptospirosis, and relapsing fever.[13] Weil–Felix test is usually positive after 5–10 days of onset of fever. We might get false negative test results if the Weil Felix test is done during the first 4 days of illness. So if the early test is negative, clinicians may repeat the test again after 5 days of illness for laboratory confirmation. But symptomatic treatment for suspected Scrub typhus must start. Therefore, timing of the test is crucial.[10],[13] Furthermore, among the immunocompromised, the test might yield false-negative results. Physicians must clinically correlate to come to a diagnosis. In such a situation, response to doxycycline treatment might help. Studies done in India revealed that recombinant IgM ELISA and rapid immunochromatographic test which has excellent specificity and acceptable sensitivity, can be an alternative to Weil–Felix test in a moderate setup.[14],[19] Till better diagnostic techniques are available, low-income countries will have to depend on the Weil–Felix test as a primary screening tool with clinical correlation for disease management. Public health experts in India may review the feasibility and programmatic implementation of IgM test for ST diagnosis and for more accurate reporting of cases.

The monthly distribution pattern of the cases revealed that most of the cases occurred during the relatively cooler and drier months. Mathai et al.[8] and Varghese et al.[12] also found outbreaks of ST to be more common in cooler months in southern states of Tamil Nadu and Andhra Pradesh between August to November and September to January, respectively, in South India. However, another report stated that a high index of suspicion of ST is needed in patients presenting with fever during the monsoon months in India.[1]

Studies have shown that the ST cases mainly belong to rural areas in India.[2],[12],[20] Varghese et al.[12] reported that cases are more likely to be agricultural laborers, not wear a shirt at home, live in houses adjacent bushes or shrubs, and live in a single room home, and the first three of these variables were statistically significant. Since most of the cases in this study belonged to the rural (80%) areas, the same environmental and occupational risks mentioned by Verghese et al.[12] might prevail in this study population as well. Since this was a hospital based retrospective study, these aspects could not be covered in detail. History of abdominal pain was present in five (33.3%) patients, which is considered to be an unusual symptom, observed mostly among people coming from hyperendemic areas.[21],[22] This symptomatology among laboratory-positive cases indicated disease endemicity.[23] Active surveillance of such cases might help to identify the hot spots for taking necessary prevention and control measures.

In this study, there were eight patients below the age of 18 years and three below the age of 5 years. It is observed in this study that the pediatric cases developed periorbital and pedal edema in the early stages suggesting acute kidney injury. A consultative committee of the Indian Academy of Pediatrics in 2016 recommended that pediatricians must be aware of the compatible clinical, laboratory, and demographic features, differential diagnosis to avoid overdiagnosis. They also recommended that once strong clinical suspicion is established, immediate treatment with doxycycline should start without waiting for the laboratory results. This will prevent unnecessary delay and reduce the occurrence of life-threatening complications.[24] Often suspicion of ST occurs only when other treatments fail, and complications develop. Delay in diagnosis is found to be due to time spent in testing for dengue, malaria, typhoid, and leptospirosis. Most of the diagnoses come only after the patients respond to the doxycycline treatment. The clinical observations showed that to properly define cases of ST for surveillance among pediatric and adult populations, more studies on these two population groups are needed which can guide the clinicians better.

It was observed that the rash appeared on the 3rd day of illness (3 ± 1.2 days) and around a week elapsed (6.14 ± 3.2 days) before a diagnosis of ST was made and treatment initiated. Determination of incubation period was not possible as the probable source of infection could not be elicited. A study reported that it takes around 7–10 days from exposure till symptoms manifest. Nine (60%) of the 15 patients already had complications at the time of admission, and many of them were referred from other health facilities. Complications in ST usually appear after a week of illness.[1] They mostly presented with a blood picture of normocytic normochromic anemia, neutrophilic leukocytosis, and thrombocytopenia. ST is an important differential diagnosis in a patient having fever with thrombocytopenia.[19] But endemicity of other thrombocytopenia causing diseases such as dengue and leptospirosis delays the diagnosis of ST due to absence of clinical suspicion.

Even those who had developed complications improved clinically and recovered from acute kidney injury as evident by the laboratory and USG reports after doxycycline treatment was started. It was observed that the Weil–Felix test turnaround time was at least 3 days. Once suspicion of ST is made, treatment should be started without waiting for test results. This might have been the reason for no ST-related mortality in this study. The clinical response with Doxycycline is so fast that often physicians discharge those patients with mild symptoms, without waiting for laboratory confirmation and thereby reduce duration of hospitalisation. Patients were discharged if they remained afebrile for 48 h and blood parameters improved, with advice to continue doxycycline. The current guidelines also state that once suspicion is made, treatment should be initiated without waiting for laboratory confirmation.[25]

Health education and awareness among the general public and health practitioners will play an important role in its prevention and control. Recreational activities such as hiking, camping, or similar activities have become a trend among city dwellers. Before venturing into endemic areas, personal protection measures must be followed.

The following self protection measures are to be followed by people residing in endemic areas and for travellers from non-endemic areas:

  1. Application of repellents such as diethyltoluamide,
  2. Treating garments and hiking boots, socks etc in permethrin solution,
  3. Wear long-sleeved shirts and pants tucked into socks,
  4. C vegetations and shrubs around houses or camping sites,
  5. Avoid walking barefoot, also avoid wearing sandals that do not cover the feet,
  6. Use a mat or tarp when sitting on the ground and
  7. Seek antibiotics from health-care practitioners before entering endemic areas.

There is no vaccine or preventive medication against ST.[6],[26]

Destruction of forest areas for creation of newer human settlements has increased the risk of zoonotic disease in humans. It is thus pertinent that public health professionals, namely the medical fraternity, and the specialists such as entomologists and epidemiologists are sensitized about the enhanced activity of ST pan-India to ensure capacity building and formulation and implementation of strategies to prevent and/or reduce adverse outcomes of ST and associated morbidity.[27]

In 2017, the Integrated Disease Surveillance Programme (IDSP) modified the definition of ST for clinical diagnosis and confirmation of ST.[11] A need is felt for a proper case assessment/survey form for screening fever cases which will help clinicians to diagnose ST early. Furthermore, sufficient evidence is available to consider doxycycline among the essential drugs in rural primary care settings with ST endemicity or for cases of pyrexia of unknown origin (PUO) presenting with fever, rash, and thrombocytopenia, which will save many lives and prevent complications and hospitalizations. Currently, the following regimens are used for treatment of ST irrespective of age:[26]

  1. Doxycycline – drug of choice (4.5 mg/kg/day in two divided doses up to a maximum of 100 mg twice daily for 7–14 days)
  2. Alternative drugs – azithromycin (10 mg/kg/day for 5 days) or chloramphenicol (50–100 mg/kg/day in four divided doses for 7–14 days).

Improved diagnostic methods, improved surveillance mechanisms, public awareness campaigns, and training health-care providers about its treatment and management will determine the success of public health interventions.


The number of cases available for analysis in this study is too small to make a generalizable interpretation of the findings. Other limitations are that most of the inflammatory markers are not done in all the patients to make a comparison. Furthermore, it was not possible to correlate the serological findings with clinical status as patients were admitted at various stages of their illness. Few of the patients were referred to this hospital after receiving initial treatment elsewhere. Their preadmission clinical status was assessed using the available clinical and laboratory investigation report in the discharge summaries. As this data was collected retrospectively using case sheets from medical records, information regarding the socioenvironmental conditions, occupational risk, knowledge, and awareness about the disease could not be elicited. Further, field-level epidemiological studies including all the above factors must be conducted to get a wholesome picture of the ST scenario.

  Conclusions Top

Timely diagnosis and treatment of ST reduces the duration and severity of illness and improves prognosis. Greater awareness among physicians regarding ST as a differential diagnosis for PUO will enhance the testing and diagnosis.

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Conflicts of interest

There are no conflicts of interest.

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  [Table 1], [Table 2], [Table 3]


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