Leptospirosis as frequent cause of acute febrile illness in southern Sri Lanka

Clinical spectrum of endemic leptospirosis in relation to cytokine response

OBJECTIVES

To describe the clinical spectrum and the cytokine response of leptospirosis patients in an endemic setting of Sri Lanka.

METHODS

Patients presenting to the university teaching hospital, Anuradhapura, Sri Lanka with a leptospirosis-compatible illness were recruited over a period of 12 months starting from June 2012. Daily clinical and biochemical parameters of the patients were prospectively assessed with a follow-up of 14 days after discharge. A magnetic bead-based multiplex cytokine kit was used to detect 17 cytokines.

RESULTS

Of the 142 clinically suspected leptospirosis patients recruited, 47 were confirmed and, 29 cases were labeled as "probable." Thrombocytopenia and leukocytosis were observed at least once during the hospital stay among 76(54%) and 39(28%) patients, respectively. Acute kidney injury was observed in 31 patients (22%) and it was significantly higher among confirmed and probable cases. Hu TNF-α and IL-1β were detected only in patients without complications. Hu MIP-1b levels were significantly higher among patients with complications. During the convalescence period, all tested serum cytokine levels were lower compared to the acute sample, except for IL-8. The cytokine response during the acute phase clustered in four different groups. High serum creatinine was associated GM-CSF, high IL-5 and IL-6 level were correlates with lung involvement and saturation drop. The patients with high billirubin (direct)>7 mmol/l had high IL-13 levels.

CONCLUSIONS

Results of this study confirms that the knowledge on cytokine response in leptospirosis could be more complex than other similar tropical disease, and biosignatures that provide diagnostic and prognostic information for human leptospirosis remain to be discovered.

Evaluation of a genus-specific rGroEL1-524 IgM-ELISA and commercial ELISA kits during the course of leptospirosis in Thailand

In the present study, we developed a genus-specific rGroEL_1-524 IgM-ELISA assay for use in screening diagnosis of suspected leptospirosis among acute undifferentiated febrile illness patients during acute fever. The diagnostic accuracies of the rGroEL_1–524 IgM-ELISA, commercial Panbio IgM-ELISA, and Virion-Serion Classic IgG-ELISA were evaluated using 133 Thai leptospirosis sera and 210 controls. Sensitivities were 91.7%, 59.6%, and 17.7% for acute infection, and the specificities were 92.6%, 90.2%, and 88.3% for the non-leptospirosis control, respectively. The rGroEL_1-524 IgM-ELISA had high sensitivity, at 92.3% and 91.7%, among culture-positive and MAT-negative cases at 1–3 days post-onset of symptoms (DPO1–3), respectively. Impaired specificity on scrub typhus was found, possibly from antibody cross-reaction to ortholog GroEL. Commercial Panbio IgM-ELISA had sensitivities at DPO1–3 of 30.8% and 41.7% for culture-positive and MAT-negative cases whereas Virion-Serion IgG-ELISA showed sensitivities of 5.9% and 13.3%, respectively. The rGroEL_1-524 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.

Evaluation of the Panbio Leptospira IgM ELISA among Outpatients Attending Primary Care in Southeast Asia

Despite estimates suggesting Leptospira spp. being endemic in Southeast Asia, evidence remains limited. Diagnostic accuracy evaluations based on Leptospira ELISA mainly rely on hospitalized and severe patients; therefore, studies measuring the pathogen burden may be inaccurate in the community. We evaluated the Panbio Leptospira ELISA IgM among 656 febrile outpatients attending primary care in Chiangrai, Thailand, and Hlaing Tha Yar, Yangon, Myanmar. ELISA demonstrated limited diagnostic accuracy for the detection of acute leptospiral infection using the manufacturer recommended cutoff, with a sensitivity of 71.4% and specificity of 36.4%, and an area under the receiver operator characteristic curve value of 0.65 (95% CI: 0.41-0.89), compared with our reference test, the PCR assay. ELISA also performed poorly as a screening tool for detecting recent exposure to Leptospira spp. compared with the "gold-standard" microscopic agglutination test, with a specificity of 42.7%. We conclude that the utility of the Leptospira IgM ELISA for both serodiagnosis and seroprevalence is limited in our setting.

Improving the leptospirosis disease burden assessment by including ambulatory patients from outpatient departments: a cross-sectional study

Background: In Sri Lanka, the disease burden of leptospirosis is estimated based on a routine notification system, which is predominated by patients ill enough to be hospitalized. The notification system does not function well with ambulatory patients in outpatient departments (OPDs). The objective of this study was to determine the proportion of leptospirosis in an OPD setting in a regional public hospital in Sri Lanka to provide further estimation of disease burden.

Methods: This study was conducted in the OPD of the Rathnapura Provincial General Hospital from August to September 2017. Suspected leptospirosis patients were recruited based on standardized criteria and tested using the microscopic agglutination test and quantitative polymerase chain reaction. The number of OPD patients was compared with the reported patient numbers with leptospirosis from the hospital during the same period as the denominator, and the 95% confidence interval was calculated for the proportions using Poisson distribution.

Results: During the study period, of 2,960 fever patients presenting to the OPD, 33 (1.1%) were suspected to have leptospirosis; 8/33 suspected (22.3%) cases were confirmed as being due to leptospirosis. There were 82 notifications of leptospirosis cases from hospital inpatients during the same period, none from the OPD. The total missing proportion from the surveillance system was 28.6% (95% CI, 19.4-40.4%). Among OPD patients, 12 (36.4%) had been given antibiotics from a primary care center prior to the OPD visit. No OPD patient was admitted to the hospital for inward care.

Conclusions: More than 25% of cases of leptospirosis were not identified because they were not sick enough to be admitted nor subjected to routine leptospirosis diagnostic testing.These data have public health implications if the sources of leptospirosis transmission are to be controlled.

Seroprevalence of Leptospirosis among High-Risk Individuals in Morocco

Background

Leptospirosis is an anthropozoonotic reemerging neglected infectious disease underreported in most developing countries. A cross-sectional study was performed between 17 and 23 February 2014 to estimate the seroprevalence of leptospirosis among high-risk populations in Casablanca (Morocco).

Methods

A total of 490 human serum samples (97.6% males) were collected in 3 high-risk occupational sites including the biggest meat slaughterhouse (n = 208), a poultry market (n = 121), and the fish market (n = 161). A total of 125 human blood samples were also collected from the general population and used in this study as a control group. To detect the presence of anti-Leptospira, sera were screened with in-house IgG and IgM enzyme-linked immunosorbent assay (ELISA). Positive samples were tested by Microscopic Agglutination Technique (MAT) using a panel of 24 serovar cultures and cut point of 1 : 25.

Results

Seroprevalence of leptospirosis among the control group was 10.4% (13/125). A high seropositivity among the overall seroprevalence of 24.1% (118/490) was observed in the high-risk groups of which 7.3% (36/490), 13.7% (67/490), and 3.1% (15/490) were for anti-Leptospira IgM, IgG, and both IgG and IgM antibodies, respectively. Most of the positive individuals were occupationally involved in poultry (37.2%), followed by the market fish (26.1%) and the meat slaughterhouse (14.9%) workers. Among all ELISA-positive serum samples, 20.3% (n = 24) had positive MAT responses, of which the Icterohaemorrhagiae (n = 7) is the most common infecting serogroup followed by Javanica (4), Australis (2), and Sejroe, Mini, and Panama (one in each). In the remaining 8 MAT-positive sera, MAT showed equal titers against more than one serogroup.

Conclusion

Individuals engaged in risk activities are often exposed to leptospiral infection. Therefore, control and prevention policies toward these populations are necessary.

Leptospirosis in Indonesia: diagnostic challenges associated with atypical clinical manifestations and limited laboratory capacity

BACKGROUND

The burden of leptospirosis in Indonesia is poorly understood. Data from an observational study conducted from 2013 to 2016 in seven cities across Indonesia was used to estimate the incidence of leptospirosis and document its clinical manifestations in patients requiring hospitalization.

METHODS

Specimens from patients hospitalized with acute fever were collected at enrollment, 14-28 days, and 3 months. Demographic and clinical information were collected during study visits and/or retrieved from medical records and double-entered into clinical report forms. After initially screening for dengue virus and other pathogens, specimens were tested at a central Reference Laboratory for anti-Leptospira IgM using commercial ELISA kits and for Leptospira DNA using an in-house quantitative real-time PCR assay.

RESULTS

Of 1464 patients enrolled, 45 (3.1%) confirmed cases (by PCR and/or sero-coversion or four-fold increase of IgM) and 6 (0.4%) probable cases (by high titer IgM) of leptospirosis were identified by the Reference Laboratory. Disease incidence at sites ranged from 0 (0%) cases in Denpasar to 17 (8.9%) cases in Semarang. The median age of patients was 41.2 years (range of 5.3 to 85.0 years), and 67% of patients were male. Twenty-two patients (43.1%) were accurately diagnosed at sites, and 29 patients (56.9%) were clinically misdiagnosed as having another infection, most commonly dengue fever (11, 37.9%). Clinically, 20 patients (39.2%) did not present with hyperbilirubinemia or increased creatinine levels. Two patients (3.9%) died, both from respiratory failure. Fifteen patients (29.4%) clinically diagnosed with leptospirosis at sites were negative based on IgM ELISA and/or PCR at the Reference Laboratory.

CONCLUSIONS

Leptospirosis remains an important cause of hospitalization in Indonesia. It can have diverse clinical presentations, making it difficult to differentiate from other common tropical infections. PCR combined with ELISA is a powerful alternative to the cumbersome gold-standard microscopic agglutination test, particularly in resource-limited settings.

Study protocol: characterising the clinical, epidemiological and aetiological aspects of leptospirosis in Sri Lanka: a hospital based clinico-epidemiological study

INTRODUCTION

Sri Lanka has one of the highest incidences of leptospirosis worldwide. We hypothesised that different geographical locations and patient context will have a distinct molecular epidemiology of leptospirosis, based on microgeographical characteristics related to regiona-specific Leptospira predominance. Our objective is to characterise the clinical, epidemiological and molecular aspects of leptospirosis in Sri Lanka to understand disease progression, risk factors and obtain isolates of Leptospira.

METHODS AND ANALYSIS

We designed a multicentre prospective study in Sri Lanka to recruit undifferentiated febrile patients and conduct follow-ups during hospital stays. Patients will be recruited from outpatient departments and medical wards. This study will be conducted at two main sites (Anuradhapura and Peradeniya) and several additional sites (Awissawella, Ratnapura and Polonnaruwa). Blood and urine will be collected from patients on the day of admission to the ward or presentation to the outpatient department. Bedside inoculation of 2-4 drops of venous blood will be performed with Ellinghausen-McCullough-Johnson-Harris (EMJH) semisolid media supplemented with antibiotics. Regionally optimised microscopic agglutination test, culture and qPCR-evidence will be performed to confirm the presence of Leptospira in blood which in turn will confirm the presence of disease. Whole genome sequencing will be carried out for all isolates recovered from patients. Multilocus sequence typing (MLST) will be used for the genotyping of new isolates. Sri Lankan isolates will be identified using three published MLST schemes for Leptospira.

ETHICS AND DISSEMINATION

Ethical clearance for the study was obtained from Ethics Review Committees (ERC), Medicine and Allied Sciences (FMAS), Rajarata University of Sri Lanka (RUSL) and University of Peradeniya. All genomic data generated through this project will be available at GenBank. Anonymised data will be deposited at the ERC, FMAS, RUSL.

A Large Leptospirosis Outbreak following Successive Severe Floods in Fiji, 2012

Severe flooding has been linked to outbreaks of leptospirosis. Two sequential extreme flood events in Western Fiji caused the largest outbreak of leptospirosis recorded in the South Pacific, with 1,217 total suspected cases, of which 314 were probable and confirmed. Most (83%) cases occurred within 6 weeks of the flood events, displaying a biphasic epidemic curve associated with the floods. Given the temporal proximity of cases to flooding events, most of the transmission appeared to occur during or immediately after the floods; therefore, prevention of exposure to contaminated environments is a priority in the immediate flood and post-flood period. In addition, genotyping studies suggest that multiple animal reservoirs were implicated in the outbreak, reaffirming the importance of integrated human and animal health strategies for leptospirosis control.

Diversity of infectious aetiologies of acute undifferentiated febrile illnesses in south and Southeast Asia: a systematic review

BACKGROUND

Acute undifferentiated febrile illness (AUFI) is caused by a multitude of diverse pathogens, with significant morbidity and mortality in the developing world. The objective of this review was to characterise the diversity and relative importance of common infectious aetiologies of AUFI in South and Southeast Asia.

METHODS

We conducted a comprehensive literature review to identify common aetiologies of AUFI in Asian countries. Four medical and life sciences databases including PubMed, Medline, Embase and Cochrane Central, and Google Scholar were searched for articles published from January 1998 to March 2019.

RESULTS

Forty-three studies met the inclusion criteria. Among AUFI cases, viral aetiologies at 18.5% (14888) were more common than bacterial aetiologies (12.9% [10384]). From 80,554 cases, dengue fever was the most common aetiology (11.8%, 9511), followed by leptospirosis (4.4%, 3549), typhoid (4.0%, 3258), scrub typhus (4.0%, 3243) and influenza other than H1N1 (3.1%, 2514). In both adults and children: dengue fever was the leading cause of AUFI with 16.6% (1928) and 18.7% (1281) of the total cases. In admitted patients, dengue fever was the main cause of AUFI at 16.4% (2377), however leptospirosis at 13.9% (2090) was the main cause of AUFI for outpatients. In South Asia, dengue fever was the main cause of AUFI, causing 12.0% (6821) of cases, whereas in Southeast Asia, leptospirosis was the main diagnosis, causing 12.1% (2861) of cases.

CONCLUSIONS

In this study the most common causes of AUFI were viral, followed by bacterial and protozoal (malaria) infections. Dengue was the commonest virus that caused AUFI while leptospirosis and typhoid were important bacterial infectious causes. Therefore, it is imperative to maintain a sound epidemiological knowledge of AUFI so that evidence-based diagnostic criteria and treatment guidelines can be developed.

Sequel and therapeutic modalities of leptospirosis associated severe pulmonary haemorrhagic syndrome (SPHS); a Sri Lankan experience

BACKGROUND

The emergence of leptospirosis-associated severe pulmonary hemorrhagic syndrome (SPHS) with high case fatality has been reported from many countries. Understanding of clinical disease and sequel of SPHS needs larger studies with adequate numbers. The purpose of this study was to describe the characteristics and sequel by different therapeutic approaches for SPHS in Leptospirosis in Sri Lanka.

METHODS

This study was conducted at Teaching Hospital-Karapitiya (THK), Galle, Sri Lanka from June 2015 to December 2017. THK is the main tertiary care center for the Southern Province. All confirmed-cases of leptospirosis who presented during this period and were admitted to five medical units of THK were included in this study. SPHS was defined as a patient presenting; haemoptysis, arterial hypoxemia (Acute Lung Injury Score < 2.5), haemoglobin drop (10% from the previous value), or diffused alveolar shadows in the chest radiograph, without alternative explanation other than leptospirosis.

RESULTS

Of the 128 MAT confirmed cases of leptospirosis, 111 (86.7%) had acute kidney injury (AKI) whilst SPHS was seen in 80 (62.5%). Patients typically developed SPHS within the first week of illness, mostly on days 4 and 5. The case fatality rate of this study sample was 28.1% (n = 36), while for patients with SPHS, it was 41.5%. Most of the deaths (n = 19) were within the first 3 days of admission (on the same day 8, and within next 48 h 11). Among SPHS patients, 59 received therapeutic plasma exchange (TPE). The survival rate was higher (n = 35, 74.5%) when the TPE was performed within the first 48 h of detecting SPHS compared to patients in whom the procedure was done after 48 h (n = 5, 54.5%). Of the 19 leptosprosis patients with SPHS who did not receive TPE, 17 died (89.5%). However, the group of patients who received TPE was primarily the patients survived beyond day 3.

CONCLUSIONS

We observed that during the study period, SPHS was common and the mortality rate was higher in the study area. The treatment modalities tested need further evaluation and confirmation.

Respiratory Viral Infection: An Underappreciated Cause of Acute Febrile Illness Admissions in Southern Sri Lanka

The contribution of respiratory viruses to acute febrile illness (AFI) burden is poorly characterized. We describe the prevalence, seasonality, and clinical features of respiratory viral infection among AFI admissions in Sri Lanka. We enrolled AFI patients ≥ 1 year of age admitted to a tertiary care hospital in southern Sri Lanka, June 2012-October 2014. We collected epidemiologic/clinical data and a nasal or nasopharyngeal sample that was tested using polymerase chain reaction (Luminex NxTAG, Austin, TX). We determined associations between weather data and respiratory viral activity using the Spearman correlation and assessed respiratory virus seasonality using a Program for Appropriate Technology definition. Bivariable and multivariable regression analyses were conducted to identify features associated with respiratory virus detection. Among 964 patients, median age was 26.2 years (interquartile range 14.6-39.9) and 646 (67.0%) were male. One-fifth (203, 21.1%) had respiratory virus detected: 13.9% influenza, 1.4% human enterovirus/rhinovirus, 1.4% parainfluenza virus, 1.1% respiratory syncytial virus, and 1.1% human metapneumovirus. Patients with respiratory virus identified were younger (median 9.8 versus 27.7 years, P < 0.001) and more likely to have respiratory signs and symptoms. Influenza A and respiratory viral activity peaked in February-June each year. Maximum daily temperature was associated with influenza and respiratory viral activity (P = 0.03 each). Patients with respiratory virus were as likely as others to be prescribed antibiotics (55.2% versus 52.6%, P = 0.51), and none reported prior influenza vaccination. Respiratory viral infection was a common cause of AFI. Improved access to vaccines and respiratory diagnostics may help reduce disease burden and inappropriate antibiotic use.

Estimating the burden of leptospirosis in Sri Lanka; a systematic review

Background

Although the assessment of disease burden should be a priority for allocating resources, leptospirosis is grossly underestimated despite its true burden in Sri Lanka. This study aimed to assess the morbidity and mortality of leptospirosis based on routine surveillance data, hospital reported data and scientific publications from Sri Lanka.

Method

A systematic review was carried out, and Pub Med, MEDLINE®, BIOSIS Previews, Zoological Record, Web of Science Core Collection, Current Contents Connect, KCI-Korean Journal Database, BIOSIS Citation Index, Data Citation Index, SciELO Citation Index and Google Scholar databases were searched. Quarterly epidemiological bulletin (QEB), indoor morbidity & mortality returns (IMMR) and hand searches of local literature were performed in local libraries. Forty-two relevant full texts, 32 QEBs, and 8 IMMR were included in the full text review. Adjustments were made for under diagnosis, underreporting and chance variability.

Results

The estimated annual caseload of leptospirosis in Sri Lanka from 2008 to 2015, was 10,423, and the cumulative annual incidence of leptospirosis that required hospitalization was 52.1 (95% CI 51.7–52.6) per 100,000 people. The estimated number of annual deaths due to leptospirosis was approximately 730 (95% CI 542–980), with an estimated pooled case fatality ratio of 7.0% (95% CI 5.2–9.4). The most common organs involved were the kidney, liver and heart, with median rates of 48.7, 30, and 14.2%, respectively.

Conclusion

Our systematic review shows gross underestimation of the true leptospirosis burden in the national statistics of Sri Lanka, and the hospitalization rates estimated in our study were compatible with the total burden estimate of 300·6 (95% CI 96·54–604·23) per 100,000 people published previously.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3655-y) contains supplementary material, which is available to authorized users.

An Improved Enzyme-Linked Immunoassay for the Detection of Leptospira-Specific Antibodies

Leptospirosis is a neglected zoonotic disease with worldwide endemicity and continues to be a significant public health burden on resource-limited populations. Previously, we produced three highly purified recombinant antigens (rLipL32, rLipL41, and rLigA-Rep) and evaluated their performance of detecting Leptospira-specific antibodies in enzyme-linked immunosorbent assay (ELISA) as compared with the microscopic agglutination test (MAT). The overall sensitivity of this assay approached 90%. Recently, another recombinant antigen (rLigB-Rep) was prepared. We tested each individual antigen and a 1:1:1:1 mixture of these four antigens for the detection of Leptospira-specific antibodies in ELISA. The performance of these recombinant antigens was evaluated with a much larger febrile patient panel (337 MAT-confirmed positive sera and 92 MAT-negative sera from febrile patients). Combining the detection results of immunoglobulin M and immunoglobulin G from these four individual antigens, the overall sensitivity was close to 90% but the specificity was only 66%, based on the MAT reference method. The overall sensitivity and specificity of the four-antigen mixture were 82% and 86%, respectively. The mixture of four antigens also exhibited a broader reactivity with MAT-positive samples of 18 serovars from six major pathogenic Leptospira species. Given the limitations of MAT, the data were further analyzed by Bayesian latent class model, showing that ELISA using a 1:1:1:1 mixture still maintained high sensitivity (79%) and specificity (88%) as compared with the sensitivity (90%) and specificity (83%) of MAT. Therefore, ELISA using a mixture of these four antigens could be a very useful test for seroprevalence studies.

Evaluation of the WHO 2009 classification for diagnosis of acute dengue in a large cohort of adults and children in Sri Lanka during a dengue-1 epidemic

BACKGROUND

Dengue is a leading cause of fever and mimics other acute febrile illnesses (AFI). In 2009, the World Health Organization (WHO) revised criteria for clinical diagnosis of dengue.

METHODOLOGY/PRINCIPAL FINDINGS

The new WHO 2009 classification of dengue divides suspected cases into three categories: dengue without warning signs, dengue with warning signs and severe dengue. We evaluated the WHO 2009 classification vs physicians' subjective clinical diagnosis (gestalt clinical impression) in a large cohort of patients presenting to a tertiary care center in southern Sri Lanka hospitalized with acute febrile illness. We confirmed acute dengue in 388 patients (305 adults ≥ 18 years and 83 children), including 103 primary and 245 secondary cases, of 976 patients prospectively enrolled with AFI. At presentation, both adults and children with acute dengue were more likely than those with other AFI to have leukopenia and thrombocytopenia. Additionally, adults were more likely than those with other AFI to have joint pain, higher temperatures, and absence of crackles on examination whereas children with dengue were more likely than others to have sore throat, fatigue, oliguria, and elevated hematocrit and transaminases. Similarly, presence of joint pain, thrombocytopenia, and absence of cough were independently associated with secondary vs primary dengue in adults whereas no variables were different in children. The 2009 WHO dengue classification was more sensitive than physicians' clinical diagnosis for identification of acute dengue (71.5% vs 67.1%), but was less specific. However, despite the absence of on-site diagnostic confirmation of dengue, clinical diagnosis was more sensitive on discharge (75.2%). The 2009 WHO criteria classified almost 75% as having warning signs, even though only 9 (2.3%) patients had evidence of plasma leakage and 16 (4.1%) had evidence of bleeding.

CONCLUSIONS/SIGNIFICANCE

In a large cohort with AFI, we identified features predictive of dengue vs other AFI and secondary vs primary dengue in adults versus children. The 2009 WHO dengue classification criteria had high sensitivity but low specificity compared to physicians' gestaldt diagnosis. Large cohort studies will be needed to validate the diagnostic yield of clinical impression and specific features for dengue relative to the 2009 WHO classification criteria.

Fatal co-infection with leptospirosis and dengue in a Sri Lankan male

Background

Leptospirosis and dengue are endemic in countries with subtropical or tropical climates and have epidemic potential. The incidence of both these diseases peaks during monsoons and both diseases present with similar clinical manifestations making differentiation of leptospirosis from dengue difficult. It is important to distinguish leptospirosis from dengue as early antibiotic therapy in leptospirosis leads to a favourable outcome, while dengue has no specific treatment, yet early recognition is vital for close monitoring and careful fluid management. Despite the high prevalence of both these infections, co-infection of leptospirosis and dengue has not been reported previously in Sri Lanka. We present the first case of co-infection with leptospirosis and dengue in a Sri Lankan male.

Case presentation

A 52 year old previously healthy Sri Lankan male was admitted to our facility with a history of fever for 4 days associated with headache, generalized myalgia, reduced urine output. On examination, he was rational, hypotensive, tacycardic, tacypneic and he did not have clinical evidence of fluid leakage or pneumonitis. His serology showed high titre of dengue IgG and IgM and rising titre of leptospirosis antibody. His course of illness was complicated with septic shock, acute renal failure, acute respiratory distress syndrome and disseminated intravascular coagulation and he succumbed to his illness on the eighth day of admission.

Conclusion

In areas where both leptospirosis and dengue are endemic, both infections should be include in the differential diagnosis when evaluating patients with acute febrile illness and should consider the possibility of co-infection. Leptospirosis, being a condition having definitive antibiotic therapy, should always be ruled out even if the patient is positive for dengue serology in regions endemic to both these diseases as early initiation of antibiotic therapy can reduce mortality significantly.

Diagnosis of Leptospirosis: Comparison between Microscopic Agglutination Test, IgM-ELISA and IgM Rapid Immunochromatography Test

BACKGROUND

Leptospirosis is diagnosed on clinical grounds, and confirmed by microscopic agglutination test (MAT). IgM-ELISA (Serion-Virion) and immunochromatography test (Leptocheck-WB) are two immunodiagnostic assays for leptospirosis. Their sensitivity, specificity and applicability in Sri Lanka have not been systematically evaluated.

METHODS

Clinically diagnosed leptospirosis patients (n = 919) were recruited from three hospitals in the Western Province of Sri Lanka, during June 2012 to December 2013. MAT, IgM-ELISA and Leptocheck-WB were performed on all patient sera. MAT titer of ≥ 400 in single sample, four-fold rise or seroconversion ≥ 100 in paired samples were considered as positive for MAT. For diagnostic confirmation, MAT was performed during both acute and convalescent phases. Anti-leptospiral IgM ≥ 20 IU/ml and appearance of a band in the test window were considered as positive for IgM-ELISA and Leptocheck-WB test respectively. Patients with an alternative diagnosis (n = 31) were excluded. Data analysis was performed using two methods, i) considering MAT as reference standard and ii) using Bayesian latent class model analysis (BLCM) which considers each test as imperfect.

RESULTS

MAT, IgM-ELISA and Leptocheck-WB positivity were 39.8%, 45.8% and 38.7% respectively during the acute phase. Acute-phase MAT had specificity and sensitivity of 95.7% and 55.3% respectively, when compared to overall MAT positivity. IgM-ELISA and Leptocheck-WB had similar diagnostic sensitivity when compared with acute-phase MAT as the gold standard, although IgM-ELISA showed higher specificity (84.5%) than Leptocheck-WB (73.3%). BLCM analysis showed that IgM-ELISA and Leptocheck-WB had similar sensitivities (86.0% and 87.4%), while acute-phase MAT had the lowest sensitivity (77.4%). However, acute-phase MAT had high specificity (97.6%), while IgM-ELISA and Leptocheck-WB showed similar but lower specificity (84.5% and 82.9%).

CONCLUSIONS

Both IgM-ELISA and Leptocheck-WB shows similar sensitivities and specificities. IgM-ELISA may be superior to MAT during the acute phase and suitable for early diagnosis of leptospirosis. Leptocheck-WB is suitable as a rapid immunodiagnostic screening test for resource limited settings.

Neglected bacterial zoonoses

Bacterial zoonoses comprise a group of diseases in humans or animals acquired by direct contact with or by oral consumption of contaminated animal materials, or via arthropod vectors. Among neglected infections, bacterial zoonoses are among the most neglected given emerging data on incidence and prevalence as causes of acute febrile illness, even in areas where recognized neglected tropical diseases occur frequently. Although many other bacterial infections could also be considered in this neglected category, five distinct infections stand out because they are globally distributed, are acute febrile diseases, have high rates of morbidity and case fatality, and are reported as commonly as malaria, typhoid or dengue virus infections in carefully designed studies in which broad-spectrum diagnoses are actively sought. This review will focus attention on leptospirosis, relapsing fever borreliosis and rickettsioses, including scrub typhus, murine typhus and spotted fever group rickettsiosis. Of greatest interest is the lack of distinguishing clinical features among these infections when in humans, which confounds diagnosis where laboratory confirmation is lacking, and in regions where clinical diagnosis is often attributed to one of several perceived more common threats. As diseases such as malaria come under improved control, the real impact of these common and under-recognized infections will become evident, as will the requirement for the strategies and allocation of resources for their control.

Concomitant leptospirosis-hantavirus co-infection in acute patients hospitalized in Sri Lanka: implications for a potentially worldwide underestimated problem

Two global (re-)emerging zoonoses, leptospirosis and hantavirus infections, are clinically indistinguishable. Thirty-one patients, hospitalized in Sri Lanka for acute severe leptospirosis, were after exclusion of other potentially involved pathogens, prospectively screened with IgM ELISA for both pathogens. Of these, nine (29·0%) were positive for leptospirosis only, one (3·2%) for hantavirus only, seven (22·5%) for both pathogens concomitantly, whereas 13 (41·9%) remained negative for both. Moreover, in a retrospective study of 23 former patients, serologically confirmed for past leptospirosis, six (26·0%) were also positive in two different IgG ELISA hantavirus formats. Surprisingly, European Puumala hantavirus (PUUV) results were constantly higher, although statistically not significantly different, than Asian Hantaan virus (HTNV), suggesting an unexplained cross-reaction, since PUUV is considered absent throughout Asia. Moreover, RT-PCR on all hantavirus IgM ELISA positives was negative. Concomitant leptospirosis-hantavirus infections are probably heavily underestimated worldwide, compromising epidemiological data, therapeutical decisions, and clinical outcome.

Unsuspected leptospirosis is a cause of acute febrile illness in Nicaragua

Background

Epidemic severe leptospirosis was recognized in Nicaragua in 1995, but unrecognized epidemic and endemic disease remains unstudied.

Methodology/Principal Findings

To determine the burden of and risk factors associated with symptomatic leptospirosis in Nicaragua, we prospectively studied patients presenting with fever at a large teaching hospital. Epidemiologic and clinical features were systematically recorded, and paired sera tested by IgM-ELISA to identify patients with probable and possible acute leptospirosis. Microscopic Agglutination Test and PCR were used to confirm acute leptospirosis. Among 704 patients with paired sera tested by MAT, 44 had acute leptospirosis. Patients with acute leptospirosis were more likely to present during rainy months and to report rural residence and fresh water exposure. The sensitivity of clinical impression and acute-phase IgM detected by ELISA were poor.

Conclusions/Significance

Leptospirosis is a common (6.3%) but unrecognized cause of acute febrile illness in Nicaragua. Rapid point-of-care tests to support early diagnosis and treatment as well as tests to support population-based studies to delineate the epidemiology, incidence, and clinical spectrum of leptospirosis, both ideally pathogen-based, are needed.

Leptospirosis, transmitted by pathogenic species of the bacterium Leptospira, is distributed worldwide but infections due to unrecognized epidemic or endemic disease are under-appreciated. We prospectively studied patients ≥2 years of age who presented with acute febrile illness in Nicaragua and systematically collected detailed information about exposures and features of the illness as well as serum and blood to confirm acute infections. Among 704 patients with paired sera tested by MAT, we found acute leptospirosis in 6.3% (44/704). Patients with acute leptospirosis were more likely to present during rainy months and to report rural residence and fresh water exposure. Leptospirosis is a common (6.3%) but unrecognized cause of acute febrile illness in Nicaragua.

Outbreak of leptospirosis after white-water rafting: sign of a shift from rural to recreational leptospirosis in Sri Lanka?

This paper reports the first recreation-related leptospirosis outbreak in Sri Lanka in 20 office workers who were involved in white-water rafting during a staff outing. Two weeks after the rafting event on 7 September 2012, six participants developed fever, of which four had classical clinical features of leptospirosis. Four weeks after the exposure, an outbreak investigation was conducted for 19 of the 20 participants. Of the six fever patients, four were confirmed as having acute leptospirosis using either single sample MAT titre ≥ 1/400 (n = 2) or positive IgM ELISA (n = 2). An afebrile patient with headache and myalgia also had a MAT titre ≥ 1/400. Seventeen of the 19 participants investigated showed anti-leptospiral antibodies. None of the participants had a history of leptospirosis or recent outdoor exposures other than the rafting event. This outbreak provides evidence of the changing epidemiology of leptospirosis and suggests a wider range of risk exposures including those related to recreational activities of more affluent urban populations in addition to the well recognized occupational hazards of rural farming.

Diagnosis of canine leptospirosis by a highly sensitive FRET-PCR targeting the lig genes

Canine leptospirosis is underdiagnosed due to its wide spectrum of clinical presentations and the lack of a rapid and sensitive test for the accurate diagnosis of acute and chronic infections. In this study, we developed a highly sensitive and specific fluorescence resonance energy transfer (FRET)-PCR to detect common pathogenic leptospires in dogs, including Leptospira interrogans serovars Autumnalis, Canicola, Copenhageni (Icterohaemorrhagiae serogroup) and Pomona, and Leptospira kirschneri serovar Grippotyphosa. This PCR targets the lig genes, exclusively found in the pathogenic Leptospira species but not in saprophytic species (L. biflexa). A robust, high-stringency step-down real-time platform was coupled to the highly specific detection of leptospiral DNA by fluorescently labeled FRET probes. This enabled the detection of a single copy of the lig gene in a PCR containing DNA from up to 50 µL canine blood or 400 µL urine. Sensitivity determination by use of limiting serial dilutions of extracted leptospiral DNA indicated that the lig FRET-PCR we established was almost 100-fold more sensitive than the widely accepted lipL32 SYBR assay and 10-fold more sensitive than a 16S rRNA TaqMan assay. Application of this method to 207 dogs with potential leptospiral infection enabled us to diagnose three cases of canine leptospirosis characterized by low amounts of leptospiral DNA in body fluids. Detection of canine leptospirosis with the lig FRET-PCR was more sensitive with the lig FRET-PCR than with the 16S rRNA TaqMan PCR, which detected only 2 of the 3 cases, and the lipL32 SYBR PCR, which detected none of the 3 dogs with leptospirosis.

Chikungunya as a cause of acute febrile illness in southern Sri Lanka

Background

Chikungunya virus (CHIKV) re-emerged in Sri Lanka in late 2006 after a 40-year hiatus. We sought to identify and characterize acute chikungunya infection (CHIK) in patients presenting with acute undifferentiated febrile illness in unstudied rural and semi-urban southern Sri Lanka in 2007.

Methodology/Principal Findings

We enrolled febrile patients ≥ 2 years of age, collected uniform epidemiologic and clinical data, and obtained serum samples for serology, virus isolation, and real-time reverse-transcriptase PCR (RT-PCR). Serology on paired acute and convalescent samples identified acute chikungunya infection in 3.5% (28/797) patients without acute dengue virus (DENV) infection, 64.3% (18/28) of which were confirmed by viral isolation and/or real-time RT-PCR. No CHIKV/DENV co-infections were detected among 54 patients with confirmed acute DENV. Sequencing of the E1 coding region of six temporally distinct CHIKV isolates (April through October 2007) showed that all isolates posessed the E1-226A residue and were most closely related to Sri Lankan and Indian isolates from the same time period. Except for more frequent and persistent musculoskeletal symptoms, acute chikungunya infections mimicked DENV and other acute febrile illnesses. Only 12/797 (1.5%) patients had serological evidence of past chikungunya infection.

Conclusions/Significance

Our findings suggest CHIKV is a prominent cause of non-specific acute febrile illness in southern Sri Lanka.

Bronsvoort BM, Handel I, Agwanda B, Cutler SJ, Olack B, Ahmed A, Hartskeerl RA, Njenga MK, Cleaveland S, Breiman RF. Urban leptospirosis in Africa: a cross-sectional survey of Leptospira infection in rodents in the Kibera urban settlement, Nairobi, Kenya

Leptospirosis is a widespread but under-reported cause of morbidity and mortality. Global re-emergence of leptospirosis has been associated with the growth of informal urban settlements in which rodents are thought to be important reservoir hosts. Understanding the multi-host epidemiology of leptospirosis is essential to control and prevent disease. A cross-sectional survey of rodents in the Kibera settlement in Nairobi, Kenya was conducted in September-October 2008 to demonstrate the presence of pathogenic leptospires. A real-time quantitative polymerase chain reaction showed that 41 (18.3%) of 224 rodents carried pathogenic leptospires in their kidneys, and sequence data identified Leptospira interrogans and L. kirschneri in this population. Rodents of the genus Mus (37 of 185) were significantly more likely to be positive than those of the genus Rattus (4 of 39; odds ratio = 15.03). Questionnaire data showed frequent contact between humans and rodents in Kibera. This study emphasizes the need to quantify the public health impacts of this neglected disease at this and other urban sites in Africa.

Detection of Leptospira-specific antibodies using a recombinant antigen-based enzyme-linked immunosorbent assay

We produced three highly purified recombinant antigens rLipL32, rLipL41, and rLigA-Rep (leptospiral immunoglobulin-like A repeat region) for the detection of Leptospira-specific antibodies in an enzyme-linked immunosorbent assay (ELISA). The performance of these recombinant antigens was evaluated using 121 human sera. Among them, 63 sera were microscopic agglutination test (MAT)-confirmed positive sera from febrile patients in Peru, 22 sera were indigenous MAT-negative febrile patient sera, and 36 sera were from patients with other febrile diseases from Southeast Asia, where leptospirosis is also endemic. Combining the results of immunoglobulin M (IgM) and IgG detection from these three antigens, the overall sensitivity is close to 90% based on the MAT. These results suggest that an ELISA using multiple recombinant antigens may be used as an alternative method for the detection of Leptospira-specific antibodies.

Unsuspected rickettsioses among patients with acute febrile illness, Sri Lanka, 2007

We studied rickettsioses in southern Sri Lanka. Of 883 febrile patients with paired serum samples, 156 (17.7%) had acute rickettsioses; rickettsioses were unsuspected at presentation. Additionally, 342 (38.7%) had exposure to spotted fever and/or typhus group rickettsioses and 121 (13.7%) scrub typhus. Increased awareness of rickettsioses and better tests are needed.