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  Table of Contents  
Year : 2016  |  Volume : 34  |  Issue : 1  |  Page : 88-91

Co-infection of scrub typhus and leptospirosis in patients with pyrexia of unknown origin in Longding district of Arunachal Pradesh in 2013

Department of Microbiology, Regional Medical Research Center, NE-Region, Dibrugarh, Assam, India

Date of Submission24-Feb-2015
Date of Acceptance14-Jul-2015
Date of Web Publication15-Jan-2016

Correspondence Address:
Dipankar Biswas
Department of Microbiology, Regional Medical Research Center, NE-Region, Dibrugarh, Assam
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0255-0857.174116

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 ~ Abstract 

Background: Scrub typhus and leptospirosis are bacterial zoonotic disease causing high morbidity and mortality. The seasonal outbreak of pyrexia is common in Arunachal Pradesh (AP); many times the disease remains undiagnosed. Objective: An outbreak of pyrexia of unknown origin (PUO) occurred in Longding district of Arunachal Pradesh in 2013, with 108 deaths, which was investigated to elucidate the cause of illness. Methodology: Blood samples from the affected region with acute pyrexia were collected, and screened for the malaria parasite, scrub typhus IgM and leptospira IgM. Results: Scrub typhus IgM was reactive in 97% (30/31), and 25% (8/31) cases were co-infected with leptospira. Incidentally, scrub typhus reactive (67%) and leptospira co-infection (62.7%) were higher in females. Record of previous 3 years (2011–2013) from Longding, Community Health Centre showed an increase in indoor pyrexia cases by 2-fold or more during October and November. Conclusion: The present study is the first report of co-infection of scrub typhus with leptospirosis from Northeast India. Medical officers in this region should take scrub typhus and leptospirosis in their differential diagnosis of patients with PUO for early diagnosis and effective treatment.

Keywords: Arunachal Pradesh, co-infection, leptospirosis, pyrexia of unknown origin, scrub typhus

How to cite this article:
Borkakoty B, Jakharia A, Biswas D, Mahanta J. Co-infection of scrub typhus and leptospirosis in patients with pyrexia of unknown origin in Longding district of Arunachal Pradesh in 2013. Indian J Med Microbiol 2016;34:88-91

How to cite this URL:
Borkakoty B, Jakharia A, Biswas D, Mahanta J. Co-infection of scrub typhus and leptospirosis in patients with pyrexia of unknown origin in Longding district of Arunachal Pradesh in 2013. Indian J Med Microbiol [serial online] 2016 [cited 2021 Mar 3];34:88-91. Available from:

 ~ Introduction Top

Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi and leptospirosis is a common spirochetal zoonosis caused by pathogenic strains of Leptospira interrogans.[1],[2] The mortality rate for both scrub typhus and leptospirosis is up to 30%, if effective treatment is not given timely and appropriately.[3],[4]

Although, the seasonal outbreak of pyrexia is being reported continuously from different regions of Arunachal Pradesh, at times the disease remains undiagnosed. During October and November 2013, it was brought to the notice by the state health authorities that 108 people died in Longding district of Arunachal Pradesh. Longding (Longitude: 95.32E and Latitude: 26.86N) situated at an altitude of 886 m is the 17th district of Arunachal Pradesh, with a total population of ~60,125. Six people died in hospital due to pyrexia of unknown origin and several died at home from similar symptoms during the period. State health authority of Arunachal Pradesh requested Regional Medical Research Center (RMRC), Dibrugarh, to investigate and diagnose the cause of death. A rapid response team of scientists and technicians from RMRC, Dibrugarh went to the affected site for investigation.

 ~ Methodology Top

Pyrexia case (>38° C) admitted as well as out-patients in the Longding Community Health Center (CHC) and Pongchau, Primary Health Center along with villagers with similar symptoms from the affected villages formed the study group. A thorough clinical investigation was carried out in all the cases with pyrexia from the outbreak area. After obtaining written informed consent from the patient/attendant, 2 ml venous blood was collected from 32 suspected cases. Furthermore, 18 control samples were collected from apparently healthy individuals without any history of pyrexia in previous 3 months from the same locality. Demographic details of the study group are mentioned in [Table 1].
Table 1: The demographic detail of the samples collected and their test result against scrub typhus, leptospira and malaria

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Of 32 suspected cases, one sample was lost, and 31 cases along with 18 healthy controls were tested for the presence of IgM specific scrub typhus using Scrub Typhus IgM ELISA (InBios International, USA), IgM specific leptospira using Leptospira IgM ELISA (InBios International, USA), and thick and thin blood slides were screened for malaria parasite at RMRC, Dibrugarh.

 ~ Results and Discussion Top

Detail of the deaths provided by District Medical Officer's Office, Longding, Arunachal Pradesh, are mentioned in [Table 2]. As per the death report ~61% of the expired cases could not receive or reach medical facility. This may be associated with the remote hilly terrain and lack of proper communication network of the villages. Furthermore, the district has limited medical facility with only eight medical officers covering a population of >60,000, which makes the majority of the population dependent on alternative medicine or quacks. Yet again out of ~39% expired cases those availed medical facility, ~14% death occurred at the hospital. Although the patients were referred to better medical facility however they could not afford to undertake the journey due to the poor financial condition.
Table 2: Number of deaths in respective villages, sex, place of death and accessibility to medical treatment

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All most all the death cases and suspected cases were farmers and rural inhabitants. The clinical presentations of the suspected cases (age range: median age: ±standard deviation) are mentioned in [Table 3]. Common symptoms were pyrexia, headache, myalgia, arthralgia, nausea, oral ulcer, abdominal pain, breathlessness and renal failure and common signs were lymphadenopathy and hepatosplenomegaly. Eschar was seen in two cases out of 31 tested cases. Scrub typhus IgM antibodies was detected in 30 (97%) samples (10 male and 20 female), leptospira IgM antibodies were detected in 8 (25.8%) samples (3 male and 5 female), which were also co-infected with scrub typhus. Malarial parasite was not observed in any of the samples and all the 18 control samples were negative against above mentioned tests, shown in [Table 1]. Immediately the diagnosis was communicated to the District Medical Office, Longding, Arunachal Pradesh and was suggested to treat the cases with doxycycline or azithromycin as per standard guidelines.
Table 3: Symptoms and signs of the suspected cases

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Interestingly, the incidence among children aged <15 years was also observed, which may be partly explained by an increased exposure opportunity for this age group during working or playing or while carried on their mother's back during work. In our result, it was observed that the number of suspected deaths due to scrub typhus and leptospira co-infection was higher in females than males (P = 0.1). Furthermore, it was noted that among the 30 samples positive for scrub typhus, 66.7% were females compared to 33.3% in males (P = 0.001) and out of 8 sample co-infected with leptospira 62.5% were female and 37.5% is male. This may be due to delayed treatment seeking behaviour of the females, as well as to greater exposure to mites/mammals, in the field and to the rodents during household activities at home.

The constraint of the current study is that the diagnosis of scrub typhus and leptospira was made only on the basis of ELISA and the presence of eschar in only couple of patients. However, patients without eschar were reported to recover after doxycycline therapy, with rapid resolution of symptoms in 1–3 days in studies elsewhere.[5] IgM specific ELISA against leptospira has emerged as a reliable diagnostic test with good specificity and sensitivity.[6] Moreover, there are reports that leptospira specific microscopic agglutination test and ELISA results has a good correlation.[7] Further, scrub typhus and leptospira IgM antibodies were not detected in any of the 18 healthy controls. Though subclinical infection with leptospira occurs, however in the present study 100% of the controls and 75% of the symptomatic cases were negative for leptospira IgM.

Month wise number of indoor pyrexia cases at the Longding CHC during 2011–2013 is shown in the epidemic curve [Figure 1]. It has been observed that the average number of indoor pyrexia cases at Longding CHC per month was ~30 as per previous 3 years records, whereas in the month of October and November there was 2-fold or more increase in cases (up to ~79 patients/month). This suggests a seasonal outbreak of pyrexia is predominant in this region. As O. tsutsugamushi lacks a proper cell wall instead have a slime layer, the cephalosporin group of antibiotics is virtually ineffective against scrub typhus.[8],[9] It was also reported that doxycycline is an effective therapy for patients with leptospirosis.[10] Therefore, doxycycline/azithromycine is recommended to treat patients with scrub typhus/leptospirosis and seasonal therapy may be life-saving in these regions when clinical suspicion is high. Rifampicin and azithromycin are alternatives in cases resistant to doxycycline.[11] However, there is a need for individual diagnosis, as both the infection requires specific treatment protocol and meticulous supportive therapy is essential to prevent complications. Scrub typhus infection may be prevented by wearing proper dresses and use of insect repellent cream containing N, N-diethyl-m-toluamide to minimise exposure to infected mites.[12] Simultaneously, animal exposure may be avoided which harbour leptospires and use boiled water for drinking.
Figure 1: Epidemic curve shows the frequency of indoor fever cases per month over three years (2011–2013) in Longding Community Health Centre, Arunachal Pradesh

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In Arunachal Pradesh, Jhum cultivation is still practiced and after clearing the jungles it becomes ideal for scrub vegetations. This may be the major cause of the predominance of scrub typhus in these regions. Mammals (wild/domestic) harbour leptospires and shed the bacteria in the urine; they may disseminate the organism to a water source (streams and springs). During winter season due to the scarcity of water in this hilly terrain villagers, and other mammal (wild/domestic) shares the same limited water source, which may be the major cause of leptospira infection. And it is well-known that population of rodent increases in the harvest season and rodents harbour leptospira and carry chiggers on their fur, this may be associated with the high incidence of co-infection in this season.

This is the first report of scrub typhus and leptospira co-infection from Northeastern region of India. Lack of surveillance, non-specific clinical presentations and lack of access to specific laboratory tests, are the major cause of predominance and under diagnosis of scrub typhus and leptospira in the regions like Arunachal Pradesh. Early diagnosis is important because there is usually an excellent response to treatment and timely anti-microbial therapy may prevent complications. Present report will be beneficial for undertaking future detailed surveillance, patient management, developing effective public health responses and public awareness to scrub typhus and leptospira. State health authorities in Arunachal Pradesh may include testing for scrub typhus and leptospira in their panel of a laboratory test for early diagnosis of this life-threatening but treatable disease. Mass awareness of the problem may be initiated by the state health authorities for the general population, as well as clinicians working in these remote areas, for preventing high mortality from these treatable but neglected tropical diseases.


The authors acknowledge the Community Health Center, Longding, Arunachal Pradesh and Primary Health Center, Ponchau, Longding, Arunachal Pradesh authorities for providing the samples and medical records of the patients. We also offer sincere gratitude to Dr. Lobsang Jampa, State Epidemiologist and Dr. Hage Taki, Jt Director NVBDCP, Arunachal Pradesh. We thank Mr. BK Goswami, Mr. CK Bhattacharjee, Mr. H Borchetia, Mr. R Sonar, and Ms. N Begum for their excellent assistance in the field and laboratory. Aurhors are very much greatfull to the Malariology and En-tamology section, RMRC, NE Region, Dibrugarh for their technical support and co-operation in this study.

Financial support and sponsorship

This work was supported by the Indian Council of Medical Research (ICMR), Ministry of Health and Family Welfare, Government of India.

Conflicts of interest

There are no conflicts of interest.

 ~ References Top

Subbalaxmi MV, Madisetty MK, Prasad AK, Teja VD, Swaroopa K, Chandra N, et al. Outbreak of scrub typhus in Andhra Pradesh – Experience at a tertiary care hospital. J Assoc Physicians India 2014;62:490-6.  Back to cited text no. 1
Chaudhry R, Premlatha MM, Mohanty S, Dhawan B, Singh KK, Dey AB. Emerging leptospirosis, North India. Emerg Infect Dis 2002;8:1526-7.  Back to cited text no. 2
Wang CC, Liu SF, Liu JW, Chung YH, Su MC, Lin MC. Acute respiratory distress syndrome in scrub typhus. Am J Trop Med Hyg 2007;76:1148-52.  Back to cited text no. 3
Daher E, Zanetta DM, Cavalcante MB, Abdulkader RC. Risk factors for death and changing patterns in leptospirosis acute renal failure. Am J Trop Med Hyg 1999;61:630-4.  Back to cited text no. 4
Vivekanandan M, Mani A, Priya YS, Singh AP, Jayakumar S, Purty S. Outbreak of scrub typhus in Pondicherry. J Assoc Physicians India 2010;58:24-8.  Back to cited text no. 5
Winslow WE, Merry DJ, Pirc ML, Devine PL. Evaluation of a commercial enzyme. Emerg Infect Dis 2002;8:1526-7.  Back to cited text no. 6
Walker DH. Rickettsiae: General concept. Medical Microbiology. 4 th ed. Ch. 38. Galveston (TX): University of Texas Medical Branch at Galveston; 1996.  Back to cited text no. 7
Murray PR, Rosenthal KS, Pfaller MA. Inhibition of cell wall synthesis. Medical Microbiology. 7th ed., Ch. 19. Elsevier; 2012.  Back to cited text no. 8
McClain JB, Ballou WR, Harrison SM, Steinweg DL. Doxycycline therapy for leptospirosis. Ann Intern Med 1984;100:696-8.  Back to cited text no. 9
Fernandez AD, Liang JR. Scrub Typhus. eMedicine; 2009. Available from: [Last updated on 2009 Jun 29].  Back to cited text no. 10
Chen-Hussey V, Behrens R, Logan JG. Assessment of methods used to determine the safety of the topical insect repellent N, N-diethyl-m-toluamide (DEET). Parasit Vectors 2014;7:173.  Back to cited text no. 11
Fu XP, Liu YY, Zhang BH, Wang JQ, Zhang JS, He JR, et al. Laboratory confirmation of scrub typhus outbreak in Pinggu district, Beijing. Chin J Vector Biol and Control 2011;22:137-40.  Back to cited text no. 12


  [Figure 1]

  [Table 1], [Table 2], [Table 3]


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