A study on serodiagnosis of scrub typhus in a Teaching Hospital of
South India

Background: crub typhus is caused by Orientia tsutsugamushi (rickettsial disease) commonly transmitted by the bite of larval chiggers of trombiculid mites. It has been one of the important causes of febrile illness, especially in south India. The clinical diagnosis is difficult owing to the non-specific presentation. We in the current study tried to evaluate the serodiagnosis of scrub typhus with the Weil Felix test and IgM ELISA. Methods: This study was conducted in the Department of Microbiology, Prathima Institute of Medical Sciences, Naganoor, Karimnagar. All the sera samples were subjected to the Weil Felix test using Proteus OX2, OX19, OX-K strain agglutination test, and subsequently, Scrub typhus IgM ELISA test. Results: All the samples were subjected to the Weil Felix test n=4(6.06%) were positive for scrub typhus (OXK antigen) n=11(16.67%) were positive for the spotted group of fever (OX2 antigen) and n=10 (15.15%) were positive of typhus group (OX19 antigen). N=5 sera samples were positive for more than one type of antigens. All the n=66 serum samples were subjected to IgM ELISA for scrub typhus. Out of n=66, only two serum samples (3.03%) were positive by IgM ELISA. Conclusion: Scrub typhus is emerging as an important public health issue. It is one of the important causes of acute febrile illness. Although it is difficult to distinguish scrub typhus based on the clinical symptoms alone a simple test such as Weil Felix was found to be promising in the diagnosis of scrub typhus. ELISA IgM test may be performed additionally in laboratories with adequate facilities. Hence for clinicians, any case with a fever of unknown origin should arouse suspicion of scrub typhus

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Rickettsial neglected zoonoses: prevalence of scrub typhus at central Karnataka

International Journal of Research in Medical Sciences ◽

10.18203/2320-6012.ijrms20173583 ◽

2017 ◽

Vol 5 (8) ◽

pp. 3672

Author(s):

Vinod Kumar C. S. ◽

Satish Patil ◽

B. S. Prasad ◽

N. K. Kalappanavar ◽

S. G. Jayaraj ◽

...

Keyword(s):

Sensitivity And Specificity ◽

Fever Of Unknown Origin ◽

Scrub Typhus ◽

Unknown Origin ◽

Blood Parameters ◽

Elisa Test ◽

Enzyme Linked Immunosorbent Assay ◽

Serum Samples ◽

Igm Antibodies ◽

Igm Elisa

Background: Fever of unknown Origin (FUO) has many multiple causes such as enteric fever, malaria, dengue, tuberculosis, brucellosis. But scrub typhus is less known cause in Indian scenario. The present study reports the prevalence of scrub typhus at central Karnataka and compares the sensitivity and specificity of Weil-Felix test and the IgM ELISA in the detection of infection.Methods: 368 serum samples of FUO cases were collected. Weil-Felix test was performed and also analyzed for IgM antibodies to Orienta tsutsugamushi by IgM ELISA test along with haematological and biochemical investigations.Results: Out of 368 patients of fever of unknown origin, 94 cases were positive by OXK antigens by Weil Felix test and 61 were positive by ELISA test for ST IgM antibodies. Fever was the most common clinical presentation occurring in ST IgM ELISA positive cases, followed by myalgia in 90.1% cases, headache in 77%, hepatomegaly in 65.5%, splenomegaly in 62.2% and rashes were seen in 29.5% patients. Eschar was seen in 13.1% patients, pneumonia in 3.2% and meningo-encephalitis in 1.6%. Sensitivity and specificity of WFT in relation to IgM ELISA at a titre of 160 was 81.97% and 85.67% respectively.Conclusions: With the growing number of cases detected in India, scrub typhus is fast emerging as a public health threat and also due to limited diagnostics leading to underreporting, Weil Felix test could be used in adjunct with Enzyme-linked immunosorbent assay and blood parameters in the diagnosis of rickettsial diseases.

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Scrub typhus (Orientia tsutsugamushi), A rapidly spreading epidemic in Chennai - A standalone lab experience

International Journal of Bioassays ◽

10.21746/ijbio.2016.09.0021 ◽

2016 ◽

Vol 5 (09) ◽

pp. 4896

Author(s):

Sripriya C.S.* ◽

Shanthi B. ◽

Arockia Doss S. ◽

Antonie Raj I. ◽

Mohana Priya

Keyword(s):

Scrub Typhus ◽

Clinical Symptoms ◽

Clinical Manifestations ◽

Febrile Illness ◽

Orientia Tsutsugamushi ◽

The Past ◽

Igm Elisa ◽

The Mean ◽

Specific Symptoms ◽

Symptoms And Signs

Scrub typhus (Orientia tsutsugamushi), is a strict intracellular bacterium which is reported to be a recent threat to parts of southern India. There is re-emergence of scrub typhus during the past few years in Chennai. Scrub typhus is an acute febrile illness which generally causes non-specific symptoms and signs. The clinical manifestations of this disease range from sub-clinical disease to organ failure to fatal disease. This study documents our laboratory experience in diagnosis of scrub typhus in patients with fever and suspected clinical symptoms of scrub typhus infection for a period of two years from April 2014 to April 2016 using immunochromatography and IgM ELISA methods. The study was conducted on 648 patients out of whom 188 patients were found to be positive for scrub typhus. Results also showed that pediatric (0 -12 years) and young adults (20 – 39 years) were more exposed to scrub typhus infection and female patients were more infected compared to male. The study also showed that the rate of infection was higher between September to February which also suggested that the infection rate is proportional to the climatic condition. Statistical analysis showed that the mean age of the patients in this study was 37.6, standard deviation was 18.97, CV % was 50.45.

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Threat of scrub typhus in post-earthquake Nepal

Journal of Chitwan Medical College ◽

10.3126/jcmc.v6i4.16707 ◽

2017 ◽

Vol 6 (4) ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

S Thapa ◽

L B Sapkota ◽

P Hamal

Keyword(s):

Fever Of Unknown Origin ◽

Scrub Typhus ◽

Febrile Illness ◽

Unknown Origin ◽

Serum Samples ◽

Mortality And Morbidity ◽

Medical College ◽

Recent Outbreak ◽

High Index Of Suspicion ◽

A Prospective Study

Scrub typhus is a potentially fatal zoonotic infection, reported from many parts of Asia including Nepal. There is increasing reports of outbreak of Scrub typhus, after the earthquake hit Nepal on April 25, 2015. The recent outbreak of Scrub typhus posed problems in diagnosis and treatment of the disease. It may be related to poor awareness of the disease or lack of suspicion for Scrub typhus which often presents with clinical features indistinguishable from typhoid fever. Since, various parts of Nepal appeared to be suitable hubs for Scrub typhus, the clinical suspicion of Scrub typhus in the differential diagnosis of fever of unknown origin (FUO) is of utmost importance to prevent mortality and morbidity. This is a prospective study conducted in Chitwan Medical College (CMC), Chitwan, Nepal. This study was carried out over a period of 4 months extending from June 2016 to September 2016. A total of 410 serum samples were collected from all patients visiting CMC, clinically suspected of having Scrub typhus infection. The samples were processed for the detection of IgM antibodies for Scrub typhus by ELISA. Results: A total of 410 samples from patients suspected with Scrub typhus infection were processed which included 200 males and 210 females. Out of total 410 samples tested, 181 (44.1%) were seropositive for Scrub typhus. Seropositivity was highest 25.9% among the age group 11-20 years of age. Females were infected more than males. This study implies the re-emergence of Scrub typhus in different regions of Nepal. Although the disease is endemic in our country, it is grossly underdiagnosed owing to non-specific clinical presentation and lack of diagnostic facilities. It is thus suggested that high index of suspicion should be maintained for cases presenting with febrile illness. Infection with Scrub typhus was found high and this calls for an urgent need to introduce vaccine against Scrub typhus.

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Serological evidence of human leptospirosis in patients with acute undifferentiated febrile illness from Uttarakhand, India: A pilot study

Journal of Laboratory Physicians ◽

10.4103/jlp.jlp_121_18 ◽

2019 ◽

Vol 11 (01) ◽

pp. 011-016

Author(s):

Mohit Bhatia ◽

Pradeep Kumar ◽

Pratima Gupta ◽

Puneet Kumar Gupta ◽

Minakshi Dhar ◽

...

Keyword(s):

Pilot Study ◽

Scrub Typhus ◽

Tertiary Care ◽

Febrile Illness ◽

Immunoglobulin M ◽

Serological Evidence ◽

Serum Samples ◽

Malaria Parasites ◽

Human Leptospirosis ◽

Igm Elisa

Abstract CONTEXT: To the best of our knowledge, there are no reports of serological evidence of human leptospirosis from Uttarakhand state in India. AIMS: The aim of this study was to screen for serological evidence of leptospirosis in patients with acute undifferentiated febrile illness at a tertiary care teaching hospital in Uttarakhand. SETTINGS AND DESIGN: A pilot study was conducted from March to November 2017. SUBJECTS AND METHODS: Fifty-three adult patients who presented in Medicine outpatient Department with a history of fever of ≥7 up to 14 days duration with or without other associated symptoms such as a headache, rashes, myalgia, arthralgia, and conjunctival suffusion were enrolled in the study using convenience sampling technique. Blood samples of these patients were collected and subjected to peripheral smear examination for malaria parasites, dengue immunoglobulin M (IgM) immunochromatographic card test, IgM Typhidot, Leptospira and Scrub typhus IgM ELISA, respectively. Aerobic blood culture was performed in 24 cases. Relevant clinico-epidemiological details were obtained as per the pro forma formulated in accordance with the modified Faine’s criteria. STATISTICAL ANALYSIS USED: Descriptive statistics. RESULTS: The study population consisted of 50.94% of males and 49.06% of females with a mean age ± standard deviation of 34.2 ± 15.2 years. Fifty febrile patients had additional symptoms of which myalgia was the most common (81.1%) followed by arthralgia (22.6%). Peripheral smears of all patients were negative for malaria parasites. Dengue and Typhidot IgM positivity was observed in two and eight patients, respectively. Six and five patients were tested positive by leptospira and scrub typhus IgM ELISA, respectively. Salmonella Typhi was isolated from blood sample of only one patient. Serum samples of two patients showed dual positivity. All six leptospira seropositive patients satisfied modified Faine’s criteria. CONCLUSIONS: Leptospirosis is a seemingly unexplored infection in Uttarakhand and should be considered as a differential diagnosis in patients with acute undifferentiated febrile illness.

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Serological Detection and Epidemiological Factors Associated with Scrub Typhus among Undifferentiated Febrile Illness Patients in a Tertiary Care Hospital

Journal of Pure and Applied Microbiology ◽

10.22207/jpam.15.3.37 ◽

2021 ◽

Author(s):

V.M. Somasunder ◽

K. Akila ◽

S. Sijimol ◽

S. Senthamarai ◽

S. Sivasankari ◽

...

Keyword(s):

Rural Areas ◽

Scrub Typhus ◽

Tertiary Care ◽

Febrile Illness ◽

Laboratory Diagnosis ◽

P Value ◽

Care Hospital ◽

Serum Samples ◽

Serological Tests ◽

Igm Elisa

Scrub typhus is an arthropod-borne zoonotic bacterial infection caused by Orientia tsutsugamushi. It presents clinically as a non-specific febrile illness that needs a high index of clinical suspicion for diagnosis. The mortality rate can be as high as 30% if not treated appropriately. Laboratory diagnosis is therefore important for confirming the cause of illness prior to initiating appropriate therapy. Hence we aimed to detect scrub typhus in serum samples of undifferentiated febrile illness patients and to correlate with the socioeconomic status of these individuals. We also aimed to study the seasonal variation associated with the disease. Serum samples from 143 febrile patients who were negative for other febrile illnesses were subjected to scrub typhus IgM ELISA. Scrub typhus IgM antibodies were found in 14 (9.8%) individuals of which 41-60 years being the most affected age group. Scrub typhus positivity was high during the months of October to December (P-value 0.0056) with the individuals from the rural areas being the most affected (P-value 0.027). To conclude, this study emphasises the importance of serological tests to detect scrub typhus and to include it as a differential diagnosis among undifferentiated febrile illnesses.

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Evidence of Chikungunya virus seroprevalence in Myanmar among dengue-suspected patients and healthy volunteers in 2013, 2015, and 2018

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0009961 ◽

2021 ◽

Vol 15 (12) ◽

pp. e0009961

Author(s):

Elizabeth Ajema Chebichi Luvai ◽

Aung Kyaw Kyaw ◽

Nundu Sabiti Sabin ◽

Fuxun Yu ◽

Saw Wut Hmone ◽

...

Keyword(s):

Healthy Volunteers ◽

Neutralizing Antibodies ◽

Chikungunya Virus ◽

Clinical Symptoms ◽

Febrile Illness ◽

Neutralization Assay ◽

Confirmatory Test ◽

Serum Samples ◽

Igm Elisa ◽

Focus Reduction

Introduction Chikungunya virus (CHIKV) is a mosquito-borne virus known to cause acute febrile illness associated with debilitating polyarthritis. In 2019, several institutions in Myanmar reported a CHIKV outbreak. There are no official reports of CHIKV cases between 2011 and 2018. Therefore, this study sought to determine the seroprevalence of CHIKV infection before the 2019 outbreak. Methods A total of 1,544 serum samples were collected from healthy volunteers and patients with febrile illnesses in Yangon, Mandalay, and the Myeik district in 2013, 2015, and 2018. Participants ranged from one month to 65 years of age. Antibody screening was performed with in-house anti-CHIKV IgG and IgM ELISA. A neutralization assay was used as a confirmatory test. Results The seroprevalence of anti-CHIKV IgM and anti-CHIKV IgG was 8.9% and 28.6%, respectively, with an overall seropositivity rate of 34.5%. A focus reduction neutralization assay confirmed 32.5% seroprevalence of CHIKV in the study population. Age, health status, and region were significantly associated with neutralizing antibodies (NAbs) and CHIKV seropositivity (p < 0.05), while gender was not (p = 0.9). Seroprevalence in 2013, 2015, and 2018 was 32.1%, 28.8%, and 37.3%, respectively. Of the clinical symptoms observed in participants with fevers, arthralgia was mainly noted in CHIKV-seropositive patients. Conclusion The findings in this study reveal the circulation of CHIKV in Myanmar’s Mandalay, Yangon, and Myeik regions before the 2019 CHIKV outbreak. As no treatment or vaccine for CHIKV exists, the virus must be monitored through systematic surveillance in Myanmar.

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Seroprevalence of Scrub Typhus among Pyrexia of Unknown Origin Patients: A Study from Tertiary Care Hospital in Eastern Odisha, India

JOURNAL FOR CLINICAL AND DIAGNOSTIC RESEARCH ◽

10.7860/jcdr/2020/45085.14042 ◽

2020 ◽

Author(s):

Shreekant Tiwari ◽

Monalisah Nanda

Keyword(s):

Differential Diagnosis ◽

Dengue Fever ◽

Scrub Typhus ◽

Febrile Illness ◽

Unknown Origin ◽

Clinical Samples ◽

Enzyme Linked Immunosorbent Assay ◽

Care Hospital ◽

Pyrexia Of Unknown Origin ◽

Igm Elisa

Introduction: Scrub typhus is a fatal rickettsial infection. It is caused by mite-borne bacterium Orientia tsutsugamushi which is transmitted by the bite of mite larvae called chiggers. It usually presents with acute febrile illness. Clinicians usually do not consider it as differential diagnosis as it is still an unknown entity. Aim: To assess the seroprevalence of scrub typhus among the pyrexia of unknown cases in Eastern part of Odisha, India. Materials and Methods: This was a cross-sectional study involving 260 serum samples obtained from clinically suspected cases of scrub typhus. Detection of antibodies was done on the samples by Immunochromatography (ICT) and IgM ELISA (Enzyme Linked Immunosorbent Assay). Samples were also processed for dengue fever, malaria, typhoid and leptospirosis which are the other causes of febrile illness in this region and excluded from the study once they come positive. Among these febrile cases which were excluded from study, malaria was predominant (44%) followed by typhoid (34.4%), dengue (15%) and leptospirosis (6.45%). Descriptive statistical analysis was applied to evaluate the results. Results: Out of 260 clinical samples, 74 (28.46%) were positive by IgM ELISA. There was good correlation (98.6%) between ICT and IgM ELISA. Fever was the most common clinical symptom followed by abdominal pain. Pathognomonic feature such as eschar was seen in one patient only. Scrub typhus should be considered as one of the differential diagnosis of Pyrexia of Unknown Origin (PUO) cases, along with dengue fever, malaria typhoid and leptospirosis. Conclusion: IgM ELISA is simple, rapid and economical test and should be used as reference diagnostic test for the diagnosis of scrub typhus.

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Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh

Tropical Medicine and Infectious Disease ◽

10.3390/tropicalmed3030095 ◽

2018 ◽

Vol 3 (3) ◽

pp. 95 ◽

Cited By ~ 7

Author(s):

Stuart Blacksell ◽

Hugh Kingston ◽

Ampai Tanganuchitcharnchai ◽

Meghna Phanichkrivalkosil ◽

Mosharraf Hossain ◽

...

Keyword(s):

General Population ◽

Diagnostic Accuracy ◽

Diagnostic Tests ◽

Scrub Typhus ◽

Febrile Illness ◽

High Sensitivity ◽

Immunofluorescence Assay ◽

Immunoglobulin M ◽

Regional Assessment ◽

Igm Elisa

Here we estimated the accuracy of the InBios Scrub Typhus Detect™ immunoglobulin M (IgM) ELISA to determine the optimal optical density (OD) cut-off values for the diagnosis of scrub typhus. Patients with undifferentiated febrile illness from Chittagong, Bangladesh, provided samples for reference testing using (i) qPCR using the Orientia spp. 47-kDa htra gene, (ii) IFA ≥1:3200 on admission, (iii) immunofluorescence assay (IFA) ≥1:3200 on admission or 4-fold rise to ≥3200, and (iv) combination of PCR and IFA positivity. For sero-epidemiological purposes (ELISA vs. IFA ≥1:3200 on admission or 4-fold rise to ≥3200), the OD cut-off for admission samples was ≥1.25, resulting in a sensitivity (Sn) of 91.5 (95% confidence interval (95% CI: 96.8–82.5) and a specificity (Sp) of 92.4 (95% CI: 95.0–89.0), while for convalescent samples the OD cut-off was ≥1.50 with Sn of 66.0 (95% CI: 78.5–51.7) and Sp of 96.0 (95% CI: 98.3–92.3). Comparisons against comparator reference tests (ELISA vs. all tests including PCR) indicated the most appropriate cut-off OD to be within the range of 0.75–1.25. For admission samples, the best Sn/Sp compromise was at 1.25 OD (Sn 91.5%, Sp 92.4%) and for convalescent samples at 0.75 OD (Sn 69.8%, Sp 89.5%). A relatively high (stringent) diagnostic cut-off value provides increased diagnostic accuracy with high sensitivity and specificity in the majority of cases, while lowering the cut-off runs the risk of false positivity. This study underlines the need for regional assessment of new diagnostic tests according to the level of endemicity of the disease given the high levels of residual or cross-reacting antibodies in the general population.

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Evaluation of a Genus Specific rGroEL 1-524 IgM-ELISA and Commercially ELISA Kits During Course of Leptospirosis in Thailand

10.21203/rs.3.rs-352195/v1 ◽

2021 ◽

Author(s):

Santi Maneewatchararangsri ◽

Galayanee Doungchawee ◽

Thareerat Kalambaheti ◽

Viravarn Luvira ◽

Ngamphol Soonthornworasiri ◽

...

Keyword(s):

Early Detection ◽

Early Diagnosis ◽

Screening Test ◽

Scrub Typhus ◽

Acute Infection ◽

Febrile Illness ◽

High Sensitivity ◽

Elisa Assay ◽

Igm Elisa ◽

Post Onset

Abstract This work, we developed a genus-specific rGroEL1-524 IgM-ELISA assay for using as screening diagnosis of suspected leptospirosis among acute undifferentiated febrile illness patients during acute fever. Ddiagnostic accuracies of rGroEL1–524 IgM-ELISA, and commercial Panbio IgM-ELISA, and Virion-Serion Classic IgG-ELISA were evaluated with Thai 107 leptospirosis sera, and 189 controls, compared to reference culture and/or MAT methods. Sensitivities were 91.7%, 59.6%, and 17.7% for acute- infection, and were 97.1%, 54.8%, and 9.7% for early detection at 1-3 days post-onset of symptoms (DPO1-3), and the specificities were 87.5%, 86.6%, and 74.8% among controls, respectively. The rGroEL1-524 IgM-ELISA had high sensitivity, at 95.9% and 91.2% among culture and MAT negative cases. Impaired specificity on scrub typhus, possibly from antibody-cross reaction to ortholog GroEL. Commercial Panbio IgM-ELISA had sensitivities of 50%, 63.2%, and 89.9% compared with culture, MAT-negative and single MAT-positive cases whereas Virion-Serion IgG-ELISA provided sensitivities of 13.3%, 10.5% and 71.4%, respectively. A rGroEL1-524 IgM-ELISA could be useful as a screening test for early diagnosis. The performance of the commercial ELISA suggests the applicability of IgM-ELISA for diagnosis, while IgG-ELISA is useful for seroprevalence surveys. However, confirmation by reference tests is recommended.

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Diagnostic evaluation of IgM ELISA and IgM Immunofluorescence assay for the diagnosis of Acute Scrub Typhus in central Nepal

10.21203/rs.2.10024/v5 ◽

2020 ◽

Author(s):

Rajendra Gautam ◽

Keshab Parajuli ◽

Tshokey Tshokey ◽

John Stenos ◽

Jeevan Bahadur Sherchand

Keyword(s):

Likelihood Ratio ◽

Predictive Value ◽

Gold Standard ◽

Scrub Typhus ◽

Febrile Illness ◽

Immunofluorescence Assay ◽

Acute Febrile Illness ◽

Central Nepal ◽

Igm Elisa ◽

Typhus Fever

Abstract Introduction Scrub typhus is an acute febrile illness caused by the obligate intracellular bacterium,Orientia tsutsugamushi. Given their affordability and ease of use, antibody based diagnostic assays can be important diagnostic tools for early detection of scrub typhus fever in resource poor countries like Nepal. Immunochromatography (ICT) and IgM ELISA are two of the routinely employed antibody based assays for diagnosis of Scrub typhus fever in Nepal, although the recommended gold standard diagnostic test is IgM Immunofluorescence assay (IFA). This study evaluated the InBios Scrub Typhus Detect™ Immunoglobulin M (IgM) ELISA and IgM Immunofluorescence assays in single serum sample at the time of admission. Methodology Study participants (1585 suspected cases), were enrolled based on acute febrile illness with suspected scrub typhus cases in central Nepal from April 2017 to March 2018. Blood sample was collected from the suspected patients of scrub typhus, presenting with acute febrile illness. IgM antibody to Orientia tsusugamushi was detected by using Scrub Typhus Detect™ Kit (In Bios International, USA) and an in-house IgM IFA (Australian Rickettsial Reference Laboratory, Geelong, Australia. The IFA assay was performed with the Gilliam, Karp, Kato strains and O. chuto antigens following the ARRL protocol. Result Statistical analysis of ELISA IgM results when compared to reference test, IgM IFA results demonstrated the following characteristics, sensitivity 84.0% (95%CI: 79.73%-87.68%), specificity 94.82% (95% CI: 93.43%-95.99%), positive likelihood ratio 16.21% (95% CI: 12.71%-20.67%), negative likelihood ratio 0.17% (95% CI: 0.13-0.21%), disease prevalence 22.08% (95% CI: 20.06%-24.21%), positive predictive value 82.12% (95% CI: 78.28-85.42%) and negative predictive value 95.44% (95% CI: 94.27%-96.38%) respectively. Conclusion The study indicated that the IgM ELISA has the sensitivity 84.0% (95% CI: 79.73%-87.68%) and specificity 94.82% (95% CI: 93.43%-95.99%). Although IgM IFA is considered the gold standard test for the diagnosis of scrub typhus cases, it is relatively expensive, requires trained personal and a microscope with fluorescence filters. Scrub typhus IgM ELISA with appropriate OD cut–off values may be the best alternative test and possible viable option for resource limited endemic countries like Nepal.

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