Etiology of acute febrile illness in the peruvian amazon as determined by modular formatted quantitative PCR: a protocol for RIVERA, a health facility-based case-control study.

BACKGROUND: The study of the etiology of acute febrile illness (AFI) has historically been designed as a prevalence of pathogens detected from a case series. This strategy has an inherent unrealistic assumption that all pathogen detection allows for causal attribution, despite known asymptomatic carriage of the principal causes of acute febrile illness in most low- and middle-income countries (LMICs). We designed a semi-quantitative PCR in a modular format to detect bloodborne agents of acute febrile illness that encompassed common etiologies of AFI in the region, etiologies of recent epidemics, etiologies that require an immediate public health response and additional pathogens of unknown endemicity. We then designed a study that would delineate background levels of transmission in the community in the absence of symptoms to provide corrected estimates of attribution for the principal determinants of AFI. METHODS: A case-control study of acute febrile illness in patients ten years or older seeking health care in Iquitos, Loreto, Peru, was planned. Upon enrollment, we will obtain blood, saliva, and mid-turbinate nasal swabs at enrollment with a follow-up visit on day 21-28 following enrollment to attain vital status and convalescent saliva and blood samples, as well as a questionnaire including clinical, socio-demographic, occupational, travel, and animal contact information for each participant. Whole blood samples are to be simultaneously tested for 32 pathogens using TaqMan array cards. Mid-turbinate samples will be tested for SARS-CoV-2, Influenza A and Influenza B. Conditional logistic regression models will be fitted treating case/control status as the outcome and with pathogen-specific sample positivity as predictors to attain estimates of attributable pathogen fractions for AFI. DISCUSSION: The modular PCR platforms will allow for reporting of all primary results of respiratory samples within 72 h and blood samples within one week, allowing for results to influence local medical practice and enable timely public health responses. The inclusion of controls will allow for a more accurate estimate of the importance of specific prevalent pathogens as a cause of acute illness. STUDY REGISTRATION: Project 1791, Registro de Proyectos de Investigación en Salud Pública (PRISA), Instituto Nacional de Salud, Perú.

Cross Reactivity of Dengue, Scrub Typhus and Malaria among COVID-19 Positive Patients: A Tropical World Threat & A Sero-Diagnostic Challenge

Purpose: Diagnosis of acute undifferentiated febrile illness (AUFI) has been a challenge and burden in clinical practice in the tropics. COVID-19 cases that present with fever alone may be difficult to distinguish from other AUFIs in the tropics. Malaria, Scrub Typhus and Dengue fever are among the most common endemic diseases in the tropics. With the availability of rapid sero-diagnostic tests for these infections, it has been observed that patient's samples frequently show seropositivity for two or more infections posing challenges in clinical diagnosis and treatment. This study was performed to determine the false-positive serological test (seropositivity) in COVID-19 patients for Scrub typhus, Dengue and Malaria. Material(s) and Method(s): The present study was a type of observational prospective study conducted from April 2020 to November 2020. A total of 574 febrile patients which were positive in Real time PCR for Covid-19, were included in the study. Result(s): Dengue IgM antibody positive for 124, Scrub typhus IgM antibody positive in 107 and no positive in malarial test, were found. Conclusion(s): Our experience suggests that false-positive in the serological test should be interpreted with caution and requires surveillance. There should be a continuous follow-up of these patients during COVID-19 pandemic and the importance of recognising false positive serological results in patients with COVID-19, especially in the resource-constrained tropical settings. Copyright © 2022 Ubiquity Press. All rights reserved.

Changing Trends in the Seroprevalence of Leptospirosis in Kelambakkam: A Ten-Year Retrospective Study

Introduction: Leptospirosis is a zoonotic infection affecting humans. The main sources of infection are animal reservoir hosts and man is the accidental host in the disease transmission process. The diagnosis is usually made by microscopy, culture, molecular techniques, and serological tests like ELISA, MAT (Microscopic Agglutination Test) and MSAT (Macroscopic Slide Agglutination Test). The ELISA method to detect IgM antibodies is used as a good cost-effective testing method. An increasing titre of IgM antibody is a sign of active leptospirosis. Aims and Objectives: The study aimed to evaluate the seroprevalence of Leptospirainfection over a 10-year period in a tertiary care hospital located in Kelambakkam village in Chengalpattu district. Material and Method: The samples were tested for the presence of specific Leptospira IgM antibodies in the patient’s serum using the Panbio Leptospira IgM ELISA kit. The samples were reported as positive/negative/equivocal accordingly. Results: This retrospective study included a total of 2035 patients, clinically suspected of leptospirosis, over a 10-year period from 2011 to 2021. 186 patients tested positive for specific IgM antibodies by ELISA method,giving an overall prevalence rate of 9.14%. Conclusion: The seroprevalence of leptospirosis over a time period of more than 10 years is highlighted in our study. Clinical suspicion of leptospirosis should be kept in mind at all times, especially now during the COVID-19 pandemic. The Panbio Leptospira IgM ELISA test kit used in our study proves to be a very useful method for diagnostic purposes, especially in limited-resource settings. Copyright © 2022: Author(s).

False Positivity of Anti-SARS-CoV-2 Antibodies in Patients with Acute Tropical Diseases in Thailand.

Serology remains a useful indirect method of diagnosing tropical diseases, especially in dengue infection. However, the current literature regarding cross-reactivity between SARS-CoV-2 and dengue serology is limited and revealed conflicting results. As a means to uncover relevant serological insight involving antibody classes against SARS-CoV-2 and cross-reactivity, anti-SARS-CoV-2 IgA, IgM, and IgG ELISA, based on spike and nucleocapsid proteins, were selected for a fever-presenting tropical disease patient investigation. The study was conducted at the Faculty of Tropical Medicine during March to December 2021. The study data source comprised (i) 170 non-COVID-19 sera from 140 adults and children presenting with acute undifferentiated febrile illness and 30 healthy volunteers, and (ii) 31 COVID-19 sera from 17 RT-PCR-confirmed COVID-19 patients. Among 170 non-COVID-19 samples, 27 were false positives (15.9%), of which IgA, IgM, and IgG cross-reactive antibody classes were detected in 18 (10.6%), 9 (5.3%), and 3 (1.8%) cases, respectively. Interestingly, one case exhibited both IgA and IgM false positivity, while two cases exhibited both IgA and IgG false positivity. The false positivity rate in anti-SARS-CoV-2 IgA and IgM was reported in adults with dengue infection (11.3% and 5%) and adults with other tropical diseases (16.7% and 13.3%). The urea dissociation method applied to mitigate false positivity resulted in significantly decreased ELISA-based false and true positives. In conclusion, the analysis of antibody against SARS-CoV-2 in sera of patients with different tropical diseases showed that high IgA and IgM false positivity thus potentially limits serological assay utility in fever-presenting patients in tropical areas.

Coinfection of leptospirosis and coronavirus disease 2019: A retrospective case series from a coastal region in South India.

During the monsoon season of 2020, the coastal areas of South India were endemic to both leptospirosis and coronavirus disease 2019 (COVID-19). This study aimed to investigate the clinical features and outcomes of patients infected with both infections. A retrospective review of charts of all patients with COVID-19 who were also diagnosed with leptospirosis by immunoglobulin M enzyme-linked immunosorbent assay was undertaken. The clinical features, laboratory report, treatment details, and outcomes of all the included patients were recorded. The collected data were summarized as the frequency with percentage for categorical data and the mean or median for continuous data. Twenty-four cases of coinfections were admitted between July and November 2020. Most of these patients were categorized as severe COVID-19 (n = 15, 62.5%). Acute kidney injury was seen in 79.2% (n = 19) patients, while raised bilirubin was present in 79.2% (n = 19) of the patients. All patients had raised C-reactive protein, while all but one had raised procalcitonin. Thrombocytopenia, leucocytosis, and leukocytopenia were seen in 91.7% (n = 22), 45.8% (n = 11), and 12.5% (n = 3) of the patients. The median duration of hospital stay was 11 (8.25-15) days. A total of 79.2% (n = 19) of the patients improved and were discharged, while 20.8% (n = 5) died during the hospital stay. In conclusion, patients with fever and atypical manifestations such as hepatic dysfunction, renal dysfunction, and thrombocytopenia should be evaluated for leptospirosis even if they are COVID positive.

Sero-Surveillance to Monitor the Trend of SARS-CoV-2 Infection Transmission in India: Study Protocol for a Multi Site, Community Based Longitudinal Cohort Study.

Introduction: Large-scale sero-prevalence studies with representation from all age groups are required to estimate the true burden of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in the community. Serial serological surveys in fixed cohorts enable study of dynamics of viral transmission and correlates of immune response over time in the context of gradual introduction of COVID-19 vaccines and repeated upsurge of cases during the pandemic. Methods: This longitudinal study will involve follow-up of a cohort of 25,000 individuals (5,000 per site) aged 2 years and above recruited from five existing demographic surveillance sites in India. The cohort will be tested for the presence of IgG antibodies against S1/S2 spike protein subunits of SARS-CoV-2 in four rounds; once at baseline and subsequently, at intervals of 4 months for a year between January 2021 and January 2022. Neutralization assays will be carried out in a subset of seropositive samples in each round to quantify the antibody response and to estimate the durability of antibody response. Serial serological surveys will be complemented by fortnightly phone based syndromic surveillance to assess the burden of symptomatic acute febrile illness/ influenza like illness in the same cohort. A bio-repository will also be established to store the serum samples collected in all rounds of serological surveys. Discussion: The population based sero-epidemiological studies will help to determine the burden of COVID-19 at the community level in urban and rural Indian populations and guide in monitoring the trends in the transmission of SARS-CoV-2 infection. Risk factors for infection will be identified to inform future control strategies. The serial serological surveys in the same set of participants will help determine the viral transmission dynamics and durability of neutralizing immune response in participants with or without symptomatic COVID infection.

Scrub typhus in two COVID-19 patients: a diagnostic dilemma.

The authors describe a case series of co-infection with COVID-19 and scrub typhus in two Indian patients. Clinical features like fever, cough, dyspnea and altered sensorium were common in both patients. Case 1 had lymphopenia, elevated IL-6 and history of hypertension, while case 2 had leukocytosis and an increased liver enzymes. Both patients had hypoalbuminemia and required admission to the intensive care unit; one of them succumbed to acute respiratory distress syndrome further complicated by multiple organ dysfunction syndrome. Seasonal tropical infections in COVID-19 patients in endemic settings may lead to significant morbidity and mortality. Therefore, high clinical suspicion and an early diagnosis for co-infections among COVID-19 patients are essential for better patient management.

Clinical profile, management and outcome of patients with leptospirosis during the times of COVID-19 pandemic: A prospective study from a tertiary care centre in South India.

Leptospirosis is a rodent-borne acute febrile illness, classically seen after heavy rainfall and floods. This study aimed to describe the clinical profile, management strategies and outcome of patients with leptospirosis amidst the Coronavirus disease-2019 outbreak. A prospective study of adult patients with undifferentiated fever (5-15 days) was conducted in South India between October 2020 and February 2021. The demographic, clinical details, laboratory details, treatment and outcome of leptospirosis positive (based on serology) and negative patients were compared. A chisquare test was used for qualitative variables, while an independent t-test or Mann Whitney U test was used for continuous variables. Of the 206 patients with suspected acute febrile illness, a total of 63 patients were diagnosed with leptospirosis based on serology results. The median sequential organ failure assessment score was higher in those with leptospirosis (p<0.001). Myalgia, abdominal pain, jaundice, decreased urine output, myocarditis, and dialysis requirement were more common in patients with leptospirosis. Leucocytosis and raised procalcitonin/C-reactive protein were more common in patients with leptospirosis. The duration of stay and antibiotic consumption was higher in patients with leptospirosis. Acute febrile illness such as leptospirosis should be suspected in tropical areas with significant risk factors. The presence of conjunctival suffusion, hepatic and renal dysfunction should warrant a serology test for leptospirosis.