Seroprevalence of Scrub typhus at a tertiary care hospital in Andhra Pradesh

Herd and animal level seroprevalence and associated risk factors of Leptospira interrogans sensu lato serovar Hardjo in cattle in southwest Ethiopia

Leptospirosis is a significant zoonotic disease that causes high economic losses in cattle production due to its association with abortions, stillbirths, infertility, and reduced milk yields. However, the epidemiology of bovine leptospirosis in Ethiopia is poorly understood. From October 2020 to October 2021, a cross-sectional study was conducted to investigate the seroprevalence of serovar Hardjo in cattle in southwest Ethiopia, as well as the associated risk factors. To test for the existence of L. Hardjo antibodies, blood samples were taken from 461 cattle. Indirect ELISA was used to identify the presence of antibodies against L. Hardjo in sera samples. We conducted a multivariable random-effect logistic regression analysis to identify potential risk factors associated with L. Hardjo seropositivity. An overall L. Hardjo seroprevalence of 24.7% (95% CI: 20.2-48.8) and 53.5% (95% CI: 45.7-90.5) was recorded at the animal level and the herd level, respectively, in the study areas. This study revealed six factors influencing L. Hardjo seropositivity in cattle herds. Large herds had twice the odds of seropositivity (OR = 2.0, 95% CI: 1.1-3.8) compared to small herds. Co-grazing cattle exhibited higher odds (OR = 2.2, 95% CI: 1.2-4.1) of seropositivity. Extensive management systems significantly increased the odds (OR = 10.3, 95% CI: 1.7-61.8) compared to semi-intensive systems. Highland cattle had higher odds (OR = 3.7, 95% CI: 1.4-10.3) than lowland cattle. Older cattle (OR = 4.6, 95% CI: 2.4-8.9) were more likely to be seropositive. At the herd level, extensive management (OR = 2.8, 95% CI: 1.3-5.8) and large herds (OR = 2.5, 95% CI: 1.3-4.7) increased the risk of seropositivity. Herds with sheep/goats (OR = 2.3, 95% CI: 1.3-4.1) were also at higher risk, highlighting significant L. Hardjo seropositivity risk factors in cattle herds. The study findings showed that leptospirosis was highly prevalent across the study areas. As a result, use proper management, raise zoonotic awareness for leptospirosis, and conduct molecular bovine leptospirosis research in study areas were recommended.

Evaluation of InBios Scrub Typhus Detect IgM Rapid Test in acute fever cases from Southwest and East India

BACKGROUND OBJECTIVES

Scrub typhus is clinically undifferentiated from other aetiologies for acute febrile illness such as enteric fever, dengue, malaria, and leptospirosis. Rapid ELISA tests are being used as an alternative to immunofluorescence assay in tropical countries.

METHODS

In this study, we compared and evaluated commercially available InBios Scrub Typhus Detect IgM Rapid Test (USA) for diagnosing human scrub typhus infection using archived and prospectively collected samples against the reference standard, InBios Scrub Typhus Detect IgM ELISA (USA).

RESULTS

The data analysis of archived samples on rapid test revealed a moderate sensitivity of 53.92% and a specificity of 100%. Meanwhile, prospective serum samples demonstrated higher sensitivity and specificity of 96.4% and 94.6%, respectively.

INTERPRETATION CONCLUSION

The InBios Scrub Typhus Detect IgM rapid test can be a good point-of-care assay during surveillance, outbreak investigations, and case identification.

Unveiling the burden of scrub typhus in acute febrile illness cases across India: A systematic review & meta-analysis

Background & objectives Scrub typhus is an emerging mite-borne zoonotic infection that has been overlooked, despite being one of the most widespread severe vector-borne diseases. With an estimated one billion people at risk worldwide and one million annual cases, it poses a significant public health concern. While various studies have investigated the prevalence of scrub typhus in different regions of India, a comprehensive regional systematic review and meta-analysis on the seropositivity of scrub typhus among acute febrile cases has been lacking. To address this gap, we conducted a systematic review and meta-analysis to compile information on the current seroprevalence of scrub typhus in acute febrile illness cases in India. Methods A literature search of multiple databases on prevalence of scrub typhus in acute febrile illness in India, 60 eligible studies out of 573 studies. The prevalence of individual studies was double arcsine transformed, and the pooled prevalence was calculated using inverse variance method. Results In total, these studies encompassed 34,492 febrile cases. The overall seroprevalence of scrub typhus among acute febrile illness cases in India was found to be 26.41 per cent [95% confidence interval (CI): 22.03-31.03]. Additionally, the pooled case fatality rate (based on data from six studies) among scrub typhus-positive cases yielded a case fatality rate of 7.69 per cent (95% CI: 4.37-11.72). Interpretation & conclusions This meta-analysis shows that scrub typhus is a significant health threat in India. Preventive measures to control scrub typhus need to be given priority.

Scrub typhus seroprevalence from an eastern state of India: findings from the state-wide serosurvey

BACKGROUND

Scrub typhus is a mite-borne infectious disease caused primarily by the obligate intracellular bacteria Orientia tsutsugamushi, which is transmitted by chigger mites. The objective of this study was to determine the prevalence of scrub typhus among adults in Odisha, an eastern state of India.

METHODS

A descriptive cross-sectional study was conducted to analyse 1840 serum samples from five districts (Khordha, Cuttack, Ganjam, Malkangiri and Sundargarh) of Odisha collected during 2020-2021. Both immunoglobulin G (IgG) and IgM antibodies against scrub typhus were tested using commercial enzyme-linked immunosorbent assay kits. Point estimates of the 95% confidence interval and adjusted odds ratio were calculated.

RESULTS

Of 1840 participants, the prevalence of IgG positivity was 1034 (56.19%) and that of IgM was 523 (28.42%). The majority of participants were in the 18-45 y age group (53.7%). Cuttack had the highest IgG positivity (64.54%) and Malkangiri had the lowest (29.32%). The highest and lowest positivity for IgM were found in Malkangiri (40.84%) and Cuttack (25.30%), respectively.

CONCLUSIONS

With an increasing number of infections detected in the state, scrub typhus is emerging as a public health threat. Increasing awareness among the general public and healthcare professionals through health education campaigns regarding scrub typhus is essential. Early detection of the disease through the establishment of a laboratory surveillance system is required to control the transmission of scrub typhus.

Evaluation of an in-house PCR for diagnosing scrub typhus along with a preliminary study of genotypic characterization of Orientia tsutshugamushi circulating in Chhattisgarh: A prospective clinico-microbiological study

PURPOSE

Scrub typhus, caused by Orientia tsutsugamushi (O. tsutsugamushi) present nonspecific clinical features during manifestation of acute undifferentiated febrile illness (AUFI) to render its early diagnosis difficult. Accordingly, this study was undertaken to assess an in-house groEL PCR versus IgM ELISA for the diagnosis of scrub typhus and to genotypically characterise the randomly selected scrub typhus positive cases.

METHODS

Blood samples, collected from two hundred twenty one (221) AUFI cases were subjected to groEL PCR and IgM ELISA for diagnosis of scrub typhus. Eleven randomly selected PCR positive cases were processed for DNA sequencing to determine the genetic diversity of O. tsutsugamushi in Chhattisgarh.

RESULTS

Scrub typhus prevalence of 35.2% were detected among AUFI cases using both in-house groEL PCR and IgM ELISA. PCR alone showed sensitivity, specificity, positive and negative predictive values of 66.6% (CI: 55.08-76.94), 100% (CI: 90 to 100),100% (CI: 93.15 to 100) and 57.37% (CI: 44.05 to 69.96) while for IgM ELISA, these parameters were 62.8% (CI: 51.13-73.50), 100% (CI: 90 to 100), 100% (CI: 92.75 to 100) and 54.68% (CI: 41.75 to 67.18) respectively. PCR and ELISA could detect scrub typhus in 37.2% and 33.3% cases, when tested alone. groEL PCR detected the O. tsutsugamushi throughout the course of infection. Phylogenetic analysis depicted 5 of 11 positive cases belonged to Kuroki, Japan strain of O. tsutsugamushi, followed by Gilliam and Karp strain in 4 and 2 cases respectively.

CONCLUSION

Scrub typhus should be considered in differential diagnosis of AUFI. groEL PCR may aid on to IgM ELISA test for optimum laboratory diagnosis of scrub typhus by its implementation especially in seronegative cases. Predominance of Kuroki-like strain followed by Gillian and Karp strains of O. tsutsugamushi in Chhattisgarh confirm variable geographical distribution of O. tsutsugamushi and provide the baseline epidemiological data which will eventually be used to help the researchers for developing better diagnostic tests and vaccine covering the predominant genotypes.

Seroprevalence and Associated Risk Factors of Leptospira interrogans Serogroup Sejroe Serovar Hardjo in Dairy Farms in and around Jimma Town, Southwestern Ethiopia

A cross-sectional study was conducted on selected dairy farms in and around Jimma town, Oromia, southwestern Ethiopia from November 2019 to May 2020 to determine the seroprevalence of Leptospira interrogans serogroup Sejroe serovar Hardjo (L. hardjo). Furthermore, information was gathered on individual animal and herd level by using pretested semistructured questionnaire to assess associated risk factors. A stratified and simple random sampling procedure was used for the selection of dairy farms and individual animal's, respectively. Indirect enzyme-linked immunosorbent assay (I-ELISA) was used in this study to detect antibody against L. hardjo. Out of 384 animal's sera, 94 animals were seropositive against L. hardjo antibodies. From 77 dairy farms selected for the study, 57 of them were distinguished as positive for L. hardjo. The overall seroprevalence of leptospirosis caused by L. hardjo was 24.48% (95% CI: 20.18%–28.78%) and 74.03% (95% CI: 64.23%–83.82%) at individual animal and farm level, respectively. The result of multilogistic regression analysis revealed that management system (p < 0.05; OR = 4.25 (95% CI: 2.31–7.82)), hygienic status of the farm (p < 0.05; OR = 0.35 (95% CI: 0.20–0.61)), age of animals (p < 0.05; OR = 8.30 (95% CI: 1.87–36.89)), history of abortion (p < 0.05; OR = 8.37 (95% CI: 1.73–40.42)), herd size (p < 0.05; OR = 2.32 (95% CI: 1.17–4.61)), and access of rodents to the farm (p < 0.05; OR = 0.17 (95% CI: 0.03–0.86)) were significantly associated with the occurrence of L. hardjo infection. However, breed, parity, and introduction of new animals to the farm were insignificantly associated (p > 0.05). Management system of the animal, hygienic status of the farm, herd size, age of animals, previous history of abortion, and access of rodents to the farm were identified as potential risk factors of L. hardjo disease occurrence. Thus, limiting rodents contact with cattle and their feed and water as well as good sanitary practices and husbandry management should be undertaken.

First seroprevalence report of scrub typhus from the tribal belts of the Nilgiris district, Tamil Nadu, India

Background & objectives

Scrub typhus, an acute febrile Rickettsial disease is caused by the bacterial pathogen Orientia tsutsugamushi which is spread by the bite of infected chigger mite vectors belonging to the family Trombiculidae. A study was undertaken to find out the prevalence of scrub typhus among the indigenous population from Nilgiris, Tamil Nadu.

Methods

This study was conducted among 214 patients with fever of unknown aetiology and a recent history of febrile illness attending the Nilgiris Adivasi Welfare Association medical facilities available at Nilgiris district, Tamil Nadu. Serum samples were tested for scrub typhus IgM enzyme-linked immunosorbent assay.

Results

Overall, 13 (6.07%) of the 214 samples tested were positive for scrub typhus. This is the first seroprevalence report of scrub typhus from the indigenous people belonging to Irula, Kurumba, Paniyar, and Kota tribes from the Nilgiris district, Tamil Nadu.

Interpretation & conclusions

Early diagnosis and effective management will protect this indigenous population from this disease. This report would help in creating awareness regarding scrub typhus infection among clinicians and public health authorities in the region and take appropriate measures for treatment and control.

Seasonal abundance of Leptotrombidium deliense, the vector of scrub typhus, in areas reporting acute encephalitis syndrome in Gorakhpur district, Uttar Pradesh, India

The rickettsial pathogen Orientia tsutsugamushi, causing scrub typhus, has been implicated as a major cause of acute encephalitis syndrome (AES) in many places in India including Gorakhpur district of Uttar Pradesh. Seasonal abundance of the principal vector mite of the pathogen, Leptotrombidium deliense, its animal hosts, and prevalence of infection on them are important attributes in the assessment of outbreaks of the disease. Hence, these aspects were investigated, seasonally, in rural villages of Gorakhpur district, where peak incidence of AES cases were reported. A total of 903 animals (rodents/shrews) was collected using 6484 Sherman traps in eight study villages (14% overall trap rate). A sum of 5526 trombiculid mites comprising 12 species was collected from 676 live rodents/shrews screened. Suncus murinus, the Asian house shrew was the predominant species (67%). Among trombiculids, the principal vector mite, L. deliense, was predominant (64.7%) and its infestation index (i.e., average number of chiggers per host animal) was 5.3. The L. deliense infestation index was higher during July to November with a peak in October. Out of 401 animal sera samples screened, 68% were positive for antibodies against O. tsutsugamushi. Of 465 blood samples tested by nested PCR, seven were positive for the 56 kDa gene of O. tsutsugamushi. In conventional PCR, 41 out of 265 samples were positive for the 60 kDa groEL gene of O. tsutsugamushi. Among the 5526 mite samples, tested as 352 pools through nested PCR, four pools were positive for 56 kDa gene. Phylogenetic analysis of 56 and 60 kDa genes confirmed circulation of Karp and TA678 (rodents) and TA678 (mite) serotypes of O. tsutsugamushi in Gorakhpur. Peak incidence of AES in Gorakhpur district occurs during the rainy season (July-October), coinciding with the peak abundance of L. deliense. These results indicate involvement of L. deliense as the vector mite transmitting the scrub typhus pathogen O. tsutsugamushi to humans in the rural areas of Gorakhpur district, India.

Burden of scrub typhus among patients with acute febrile illness attending tertiary care hospital in Chitwan, Nepal

OBJECTIVES

Scrub typhus is an emerging neglected tropical disease, reported from many parts of Asia including Nepal. This study aims to determine the seroepidemiology of scrub typhus among febrile patients attending Chitwan Medical College Teaching Hospital (CMC-TH), Bharatpur, Nepal.

STUDY DESIGN AND SETTING

This was a hospital laboratory-based prospective study conducted in CMC-TH (a 750-bed hospital) located in Bharatpur, Chitwan district of Nepal.

PARTICIPANTS

A total of 1797 patients visiting CMC-TH with acute febrile illness (temperature more than 38°C) were enrolled in this study.

METHODS

A total of 1797 blood samples were collected from patients presenting with acute febrile illness. The samples were processed for detection of antibody for scrub typhus by ELISA for specific IgM antibody and Weil-Felix test.

RESULTS

Out of 1797 serum sample of febrile patients, 524 (29.2%) were scrub typhus positive. Maximum seropositive cases were from Chitwan district, 271 (51.7%) with predominance among women, 314 (35.9%). Scrub typhus was common among age group 51-60 years (37.2%) and farmers, 182 (37.8%). Highest seropositivity was found in July, 60 (57.7%). Fever was common clinical symptom. Thrombocytopenia was seen in 386 (73.7%) and raised transaminase aspartate aminotransferase, 399 (76.1%) among seropositive cases. Weil-Felix test positive were 397 (22.1%) and IgM ELISA positive were 524 (29.2%). The correlation between IgM ELISA and Weil-Felix test showed statistically significant association (r=0.319, p<0.001).

CONCLUSION

High prevalence of scrub typhus implies that patients with acute febrile illness should be investigated for scrub typhus with high priority. There is utmost need of reliable diagnostic facilities at all levels of healthcare system in Nepal. Infection with scrub typhus was found high and this calls for an urgent need to introduce vaccine against scrub typhus. More sustain and vigorous awareness programmes need to be promoted for early diagnosis, treatment and control.

Scrub typhus in patients with acute febrile illness: a 5-year study from India

BACKGROUND

Scrub typhus was once thought to be a disease of rural origin and was confined to specific pockets in South Asia. Early diagnosis and treatment is extremely important as it is associated with high mortality if left untreated.

AIM

To delineate the clinical and molecular epidemiology of scrub typhus in patients presenting with acute febrile illness from various parts of India.

METHODS

During the study period of 5 years (October 2013 to October 2018), a total of 1742 patients with acute febrile illness <15 days were enrolled after taking informed consent. Patients were diagnosed using IgM Enzyme-linked immunosorbent assay (ELISA) based on the pre-determined region specific cut offs. Patients with positive IgM ELISA were also subjected to IgM Immunofluorescence assay and nested polymerase chain reaction (PCR) assay. The demographic and relevant clinical details of the patients were documented and analyzed.

RESULTS

A total of 210 (12.1%) patients were diagnosed with scrub typhus. Of these, nested PCR was positive in only 85 patients. Sequencing and phylogenetic analysis showed that the predominant circulating genotypes were Gilliam and Karp. On multivariate analysis, acute respiratory distress syndrome, myocarditis, encephalitis/encephalopathy, jaundice and splenomegaly were significantly more common in those patients who were diagnosed with scrub typhus. A total of 14 patients diagnosed with scrub typhus succumbed to the illness.

CONCLUSION

Patients with fever, headache, pulmonary manifestations, CNS manifestations, myocarditis, transaminitis or thrombocytopenia presenting in the monsoon and post-monsoon season should be evaluated for scrub typhus irrespective of the geographical location in India.

Seroprevalence & seroincidence of Orientia tsutsugamushi infection in Gorakhpur, Uttar Pradesh, India: A community-based serosurvey during lean (April-May) & epidemic (October-November) periods for acute encephalitis syndrome

Background & objectives

In India, acute encephalitis syndrome (AES) cases are frequently reported from Gorakhpur district in Uttar Pradesh. Scrub typhus is one of the predominant aetiological agents for these cases. In order to delineate the extent of the background of scrub typhus seroprevalence and the associated risk factors at community level, serosurveys during both lean and epidemic periods (phase 1 and phase 2, respectively) of AES outbreaks were conducted in this region.

Methods

Two community-based serosurveys were conducted during lean (April-May 2016) and epidemic AES (October-November 2016) periods. A total of 1085 and 906 individuals were enrolled during lean and epidemic AES periods, respectively, from different villages reporting recent AES cases. Scrub typhus-seronegative individuals (n=254) during the lean period were tested again during the epidemic period to estimate the incidence of scrub typhus.

Results

The seroprevalence of Orientia tsutsugamushi during AES epidemic period [immunoglobulin (Ig) IgG: 70.8%, IgM: 4.4%] was high as compared to that of lean AES period (IgG: 50.6%, P <0.001; IgM: 3.4%). The factors independently associated with O. tsutsugamushi positivity during lean AES period were female gender, illiteracy, not wearing footwear, not taking bath after work whereas increasing age, close contact with animals, source of drinking water and open-air defecation emerged as additional risk factors during the epidemic AES season. IgM positivity was significantly higher among febrile individuals compared to those without fever (7.7 vs. 3.5%, P=0.006). The seroincidence for O. tsutsugamushi was 19.7 per cent, and the subclinical infection rate was 54 per cent.

Interpretation & conclusions

The community-based surveys identified endemicity of O. tsutsugamushi and the associated risk factors in Gorakhpur region. The findings will be helpful for planning appropriate interventional strategies to control scrub typhus.

Clinical Profile and Therapeutic Response of Scrub Typhus in Children: A Recent Trend from Eastern India

OBJECTIVE

The aim of this study was to assess the clinico-laboratory parameters, complications and therapeutic responses in children with scrub typhus in Eastern India.

MATERIALS AND METHODS

In this prospective, observational study, all children (age, <12 years) with suspected scrub typhus with a compatible clinical scenario were enrolled consecutively over six months. Cases confirmed by means of a positive IgM serology or a positive Weil-Felix reaction (OXK = 1/80 or above) were administered enteral doxycycline (4.5 mg/kg/day).

RESULTS

Out of 94 recruited children, 61 had confirmed scrub typhus (mean age = 6.1 years, M:F = 1.1:1) with or without complications and having a considerably higher incidence of neurological presentation (meningoencephalistis n = 21, 34.4%). The most frequent manifestations included vomiting (n = 39, 63.9%), abdominal pain (n = 33, 54.1%), lymphadenopathy (n = 36, 59%), hepatosplenomegaly (n = 32, 52.5%), pedal edema (n = 32, 52.5%) and eschar formation (n = 30, 49.2%). Low hemoglobin levels, leukocytosis, thrombocytopenia, hypoalbuminemia, hyponatremia, increased liver enzymes and increased C-reactive protein were associated with delayed defervescence (>48 h).

CONCLUSION

Scrub meningoencephalitis, with a notably higher incidence, showed favorable therapeutic response. Prompt and empiric doxycycline therapy could be lifesaving.

Scrub typhus: Overview of demographic variables, clinical profile, and diagnostic issues in the sub-Himalayan region of India and its comparison to other Indian and Asian studies

Background:

India is a tropical country with a high burden of febrile zoonotic/infectious illnesses, scrub typhus being such a cause with multiple epidemics reported from different regions of the country.

Objective:

This study was plotted to document the clinical and diagnostic manifestations, treatment, and outcomes of scrub typhus in the sub-Himalayan region of India and to compare the results with other Indian and Asian studies.

Materials and Methods:

This was a retrospective observational study involving collection of data for 54 IgM ELISA-confirmed in-patient cases of scrub typhus at a tertiary care institute in Uttarakhand, India, from their case records.

Results:

The majority of patients were from rural background. Housewives constituted 28 (51.85%) patients. The most common symptoms were due to involvement of gastrointestinal tract in the form of abdominal pain in 39 (72.22%) and vomiting in 29 (53.7%) patients. Central nervous system involvement in the form of altered sensorium in 14 (25.9%) patients and pulmonary involvement as cough in 28 (51.85%) patients was observed. An eschar was found in 7 (12.96%) patients and upper eyelid edema in 40 (74.07%) patients. The most common laboratory abnormality documented was elevation of liver transaminases (aspartate aminotransferase > alanine aminotransferase), 40 (74.07%), and blood urea levels, 47 (87.03%). There was no difference in the clinical presentation, severity, or mortality in pregnant females when compared with nonpregnant females. One (1.45% mortality) died in our study.

Conclusion:

Scrub typhus is an important cause of acute febrile illness with variable, often nonspecific and multisystem involvement. Early recognition and antibiotic administration are the key to reduce complications and mortality, especially for a primary care physician.

Under-diagnosis of rickettsial disease in clinical practice: A systematic review

BACKGROUND

Rickettsial diseases present as acute febrile illnesses, sometimes with inoculation eschars.

METHODS

We performed a systematic review of studies published between 1997 and 2017 to assess the underestimation of non-eschar rickettsial disease (NERD) relative to eschar rickettsial disease (ERD), as a cause of acute fever in patients with rickettsial diseases that commonly present with eschar(s): scrub typhus (ST), Mediterranean spotted fever (MSF), and African tick-bite fever. We compared ERD/NERD ratios according to study design: 'complete approach' studies, with testing performed in all patients with 'unspecified febrile illness'; versus 'clinical judgement' studies, with testing performed if patients presented with specific symptoms.

RESULTS

In 'complete approach' studies, ERD/NERD ratios were significantly lower, suggesting a considerable under-diagnosis of NERD in 'clinical judgement' studies. Based on these results, we estimate that the diagnosis of rickettsial disease was missed in 66.5% of patients with ST, and in 57.9% of patients with MSF.

CONCLUSIONS

Study design influences the reported eschar rates in ST and MSF significantly. NERD is likely to be a vastly underdiagnosed entity, and clinicians should consider and test for the disease more often.

PROSPERO REGISTRATION NUMBER

CRD 42016053348.

Scrub typhus point-of-care testing: A systematic review and meta-analysis

BACKGROUND

Diagnosing scrub typhus clinically is difficult, hence laboratory tests play a very important role in diagnosis. As performing sophisticated laboratory tests in resource-limited settings is not feasible, accurate point-of-care testing (POCT) for scrub typhus diagnosis would be invaluable for patient diagnosis and management. Here we summarise the existing evidence on the accuracy of scrub typhus POCTs to inform clinical practitioners in resource-limited settings of their diagnostic value.

METHODOLOGY/PRINCIPAL FINDINGS

Studies on POCTs which can be feasibly deployed in primary health care or outpatient settings were included. Thirty-one studies were identified through PubMed and manual searches of reference lists. The quality of the studies was assessed with the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). About half (n = 14/31) of the included studies were of moderate quality. Meta-analysis showed the pooled sensitivity and specificity of commercially available immunochromatographic tests (ICTs) were 66.0% (95% CI 0.37-0.86) and 92.0% (95% CI 0.83-0.97), respectively. There was a significant and high degree of heterogeneity between the studies (I2 value = 97.48%, 95% CI 96.71-98.24 for sensitivity and I2 value = 98.17%, 95% CI 97.67-98.67 for specificity). Significant heterogeneity was observed for total number of samples between studies (p = 0.01), study design (whether using case-control design or not, p = 0.01), blinding during index test interpretation (p = 0.02), and QUADAS-2 score (p = 0.01).

CONCLUSIONS/SIGNIFICANCE

There was significant heterogeneity between the scrub typhus POCT diagnostic accuracy studies examined. Overall, the commercially available scrub typhus ICTs demonstrated better performance when 'ruling in' the diagnosis. There is a need for standardised methods and reporting of diagnostic accuracy to decrease between-study heterogeneity and increase comparability among study results, as well as development of an affordable and accurate antigen-based POCT to tackle the inherent weaknesses associated with serological testing.

A review of the global epidemiology of scrub typhus

Scrub typhus is a serious public health problem in the Asia-Pacific area. It threatens one billion people globally, and causes illness in one million people each year. Caused by Orientia tsutsugamushi, scrub typhus can result in severe multiorgan failure with a case fatality rate up to 70% without appropriate treatment. The antigenic heterogeneity of O. tsutsugamushi precludes generic immunity and allows reinfection. As a neglected disease, there is still a large gap in our knowledge of the disease, as evidenced by the sporadic epidemiologic data and other related public health information regarding scrub typhus in its endemic areas. Our objective is to provide a systematic analysis of current epidemiology, prevention and control of scrub typhus in its long-standing endemic areas and recently recognized foci of infection.

Clinical and paraclinical profile, and predictors of outcome in 90 cases of scrub typhus, Meghalaya, India

BACKGROUND

India is an integral component of "tsutsugamushi triangle" which depicts a part of the globe endemic to scrub typhus. Owing to frequent outbreaks witnessed in different parts of the country in the recent past, scrub typhus is described as a re-emerging infectious disease in India. The present study aimed to study the clinical and paraclinical profile, complications and predictors of outcome among 90 cases of scrub typhus diagnosed in a hospital of north-eastern India from Sept 2011 to Aug 2012.

METHODS

A longitudinal study was conducted in a hospital of Meghalaya, India between Sept 2011 and Aug 2012. Diagnosis of scrub typhus was arrived by SD BIOLINE tsutsugamushi (solid phase immunochromatographic assay) rapid diagnostic test for antibodies (IgM, IgG or IgA). Descriptive analyses of age, gender, geographic area, symptoms and signs, treatment, laboratory findings, complications, and outcome were conducted. Relative risk (RR) with 95 % confidence interval (CI) was computed for Multiple Organ Dysfunction Syndrome (MODS) and mortality. Binary logistic regression was applied to the significant correlates (P < 0.05) on univariate analysis to identify the predictors of MODS and mortality in scrub typhus.

RESULTS

As many as 662 clinically suspected scrub typhus patients were tested and 90 (13.6 %) were diagnosed to have scrub typhus. Out of 90 patients, 52.2 % (n = 47) were males and their mean (SD) age was 36.29 (13.38) years. Fever of <7 days (n = 75, 83.3 %), myalgia (n = 56, 62.2 %), pain abdomen (n = 24, 26.7 %), headache (n = 24, 26.7 %), nausea/vomiting (n = 21, 23.3 %), dry cough (n = 21, 23.3 %), hepatomegaly (n = 24, 26.7 %), splenomegaly (n = 22, 24.4 %), and lymphadenopathy (n = 20, 22.2 %) were the predominant clinical features. Eschar was seen in 10 patients (11.1 %). One third (n = 30) of the patients developed at least one systemic complication. Acute hepatitis (n = 15, 16.7 %), pneumonitis (n = 14, 15.6 %), and acute kidney injury (n = 11, 12.2 %) were the common complications. MODS was seen in 14.4 % (n = 13) and 38.5 % (n = 5) of the patients with MODS died. Overall, case fatality rate was 5.15 % (n = 5). On univariate analysis, platelets <100 000/mm³, serum creatinine >1.5 mg/dl, and transaminase (AST, ALT or both) >500 U/L were associated with MODS (P < 0.001) and mortality (P < 0.05). In addition, serum bilirubin >3 mg/dl was also associated with MODS (P < 0.001). On applying binary logistic regression, serum creatinine >1.5 mg/dl was a predictor of MODS (OR: 76.1, 95 % CI: 4.9-1175.6) and mortality (OR: 18.03, 95 % CI: 1.38-235.1).

CONCLUSION

In this study setting, approximately one-seventh (13.6 %) of the acute undifferentiated febrile illness were due to scrub typhus. Systemic complications were common (33.3 %). Serum creatinine >1.5 mg/dl was a predictor of MODS and mortality.

Redefining Gold Standard Testing for Diagnosing Leptospirosis: Further Evidence from a Well-Characterized, Flood-Related Outbreak in Sri Lanka

A gap in the leptospirosis field remains the lack of well-characterized sample collections that allow for comparison of new methods to standard ones. In the context of a flood-related outbreak of leptospirosis evaluated in Anuradhapura, Sri Lanka, a specimen bank was obtained with detailed metadata accompanied by gold standard diagnostic test results. Blood samples collected on admission and 14 days later from suspected cases of leptospirosis were tested using microscopic agglutination test (MAT) (17 serovars), an in-house enzyme-linked immunosorbent assay (ELISA) using a locally obtained strain of Leptospira kirschneri as sonicated antigen, a commercially available ELISA based on sonicated Leptospira biflexa, and a quantitative polymerase chain reaction (qPCR) assay targeting the pathogenic Leptospira-specific 16S rRNA gene. Of 62 patients presenting within the first 2 days of illness, 31 had confirmed leptospirosis based either on paired-sample MAT or qPCR. During the acute phase, qPCR was most sensitive, detecting 74% of definitively diagnosed cases; immunoglobulin G (IgG) ELISA (in-house), IgG ELISA (commercial), and MAT had sensitivities of 35.5%, 12.0%, and 22.6%, respectively, in detecting definitively diagnosed cases using acute phase serum. Of 40 patients with paired sera, 10 were qPCR positive. Of these, five samples were negative by paired-sample MAT. Of the 11 MAT-positive samples, only five were detected using qPCR confirming that both tests are needed for maximal sensitivity. Regional leptospiral serovar-specific IgG ELISA was superior to MAT. Knowing the regionally dominant serovars improves serological sensitivity in the analysis of acute specimens by ELISA, but qPCR was most sensitive in this patient population.