Covid-19 and leptospirosis: Cytokine storm and the use of steroids

Fulminant Leptospirosis Presenting with Rapidly Developing Acute Renal Failure and Multiorgan Failure

Leptospirosis, caused by pathogenic spirochetes of the Leptospira genus, is a common zoonosis in tropical and subtropical regions and can lead to an epidemic following heavy rainfall or flooding. The primary reservoirs of Leptospira include rodents, wild animals, dogs, cats, amphibians, and others, but the brown rat (Rattus norvegicus) remains the main source of human Leptospirosis. Humans are often accidental hosts and they can be infected through cuts, abrasions, mucosa, conjunctiva, or by ingesting contaminated water. The clinical manifestation of leptospirosis can vary from mild, nonspecific symptoms to a fatal outcome involving liver and renal failure, pulmonary hemorrhage, meningitis, and septic shock. The severity of fatal outcomes is likely to be due to virulence factors, host susceptibility, and epidemiological conditions. L. interrogans are associated with high-risk individuals, particularly patients older than 60 years of age in clinical settings. The current case study showed a foreign worker who presented with rapidly deteriorating clinical signs of fever, jaundice, impaired consciousness, and oliguric acute renal failure. Drawing from our experience, it is advisable to consider the possibility of leptospirosis diagnosis in patients who show clinical symptoms such as fever, hepatic failure with jaundice, and acute renal failure. This is particularly important for those individuals with a prior history of pathogen exposure. This case study had a strong suspicion of leptospirosis, which was confirmed by the microscopic agglutination test (MAT) and, later, the patient's recovery following treatment.

LigA formulated in AS04 or Montanide ISA720VG induced superior immune response compared to alum, which correlated to protective efficacy in a hamster model of leptospirosis

Leptospirosis is a zoonotic disease of global importance. The current vaccine provides serovar-specific and short-term immunity and does not prevent bacterial shedding in infected animals. Subunit vaccines based on surface proteins have shown to induce protection in an animal model. However, these proteins were tested with non-clinical adjuvants and induced low to moderate protective efficacy. We formulated a variable region of Leptospira immunoglobulin-like protein A (LAV) in clinical adjuvants, AS04 and Montanide ISA720VG, and then evaluated the immune response in mice and protective efficacy in a hamster model. Our results show that animals immunized with LAV-AS04 and LAV-Montanide ISA720VG (LAV-M) induced significantly higher levels of LAV-specific antibodies than LAV-Alum. While LAV-Alum induced Th2 response with the induction of IgG1 and IL-4, AS04 and LAV-M induced a mixed Th1/Th2 response with significant levels of both IgG1/IL-4 and IgG2c/IFN-γ. Both LAV-AS04 and LAV-M induced the generation of a significantly higher number of cytotoxic T cells (CTLs). The immune response in LAV-AS04- and LAV-M-immunized animals was maintained for a long period (>180 days) with the generation of a significant level of B- and T-cell memory. The strong immune response by both vaccines correlated to enhanced recruitment and activation of innate immune cells particularly DCs at draining lymph nodes and the formation of germinal centers (GCs). Furthermore, the immune response generated in mice correlated to protective efficacy in the hamster model of leptospirosis. These results indicate that LAV-AS04 and LAV-M are promising vaccines and can be further evaluated in clinical trials.

Pulmonary haemorrhage as the earliest sign of severe leptospirosis in hamster model challenged with Leptospira interrogans strain HP358

Background

Severe leptospirosis is challenging as it could evolve rapidly and potentially fatal if appropriate management is not performed. An understanding of the progression and pathophysiology of Leptospira infection is important to determine the early changes that could be potentially used to predict the severe occurrence of leptospirosis. This study aimed to understand the kinetics pathogenesis of Leptospira interrogans strain HP358 in the hamster model and identify the early parameters that could be used as biomarkers to predict severe leptospirosis.

Methodology/Principal findings

Male Syrian hamsters were infected with Leptospira interrogans strain HP358 and euthanized after 24 hours, 3, 4, 5, 6 and 7 days post-infection. Blood, lungs, liver and kidneys were collected for leptospiral detection, haematology, serum biochemistry and differential expression of pro- and anti-inflammatory markers. Macroscopic and microscopic organ damages were investigated. Leptospira interrogans strain HP358 was highly pathogenic and killed hamsters within 6–7 days post-infection. Pulmonary haemorrhage and blood vessel congestion in organs were noticed as the earliest pathological changes. The damages in organs and changes in biochemistry value were preceded by changes in haematology and immune gene expression.

Conclusion/Significance

This study deciphered haemorrhage as the earliest manifestation of severe leptospirosis and high levels of IL-1β, CXCL10/IP-10, CCL3/MIP-α, neutrophils and low levels of lymphocytes and platelets serve as a cumulative panel of biomarkers in severe leptospirosis.

As the severe form of leptospirosis could progress rapidly and be potentially fatal if not treated earlier, deciphering the pathophysiology kinetics of infection is crucial to determine the parameters of disease severity. To understand this, we challenged hamsters with the highly virulent Leptospira interrogans strain HP358. Pulmonary haemorrhage was observed as the earliest pathological change followed by liver and kidneys damages. The increased expression of IL-1β, CXCL10/IP-10, CCL3/MIP-α, high neutrophils and low lymphocytes and platelets production observed in the present study indicate that these parameters could serve as a cumulative panel of biomarkers in severe leptospirosis.

Role of Diagnostics in Epidemiology, Management, Surveillance, and Control of Leptospirosis

A One Health approach to the epidemiology, management, surveillance, and control of leptospirosis relies on accessible and accurate diagnostics that can be applied to humans and companion animals and livestock. Diagnosis should be multifaceted and take into account exposure risk, clinical presentation, and multiple direct and/or indirect diagnostic approaches. Methods of direct detection of Leptospira spp. include culture, histopathology and immunostaining of tissues or clinical specimens, and nucleic acid amplification tests (NAATs). Indirect serologic methods to detect leptospiral antibodies include the microscopic agglutination test (MAT), the enzyme-linked immunosorbent assay (ELISA), and lateral flow methods. Rapid diagnostics that can be applied at the point-of-care; NAAT and lateral flow serologic tests are essential for management of acute infection and control of outbreaks. Culture is essential to an understanding of regional knowledge of circulating strains, and we discuss recent improvements in methods for cultivation, genomic sequencing, and serotyping. We review the limitations of NAATs, MAT, and other diagnostic approaches in the context of our expanding understanding of the diversity of pathogenic Leptospira spp. Novel approaches are needed, such as loop mediated isothermal amplification (LAMP) and clustered regularly interspaced short palindromic repeats (CRISPR)-based approaches to leptospiral nucleic acid detection.

Covid-19 and leptospirosis, pulmonary involvement and response to steroids: A comparative observational study from a rural Tertiary care center in Kerala

Background:

COVID-19 is an emerging infectious disease with a global outreach. Leptospirosis is a zoonotic disease mainly confined to tropical areas. In both cases, most of those affected are asymptomatic or have only mild respiratory disease. Those who turn critical develop acute respiratory distress syndrome (ARDS) and/or multiple-organ failure occurs rapidly, with high fatality.

Methodology:

This is a retrospective observational study from 2020 involving COVID-19 and leptospirosis patients. The data were collected using a semi-structured proforma, and analysis was performed using Easy R (EZR) software.

Results:

There were five patients with COVIDC-19 and four patients with leptospirosis; with pulmonary involvement. All the patients were males. There was no significant difference in age, the onset of pulmonary involvement, time of initiation of steroids, duration of steroids, and outcome between the two groups. However, in the case of COVID-19, it took a longer period for clearing of infiltrates.

Conclusion:

Though COVID-19 and leptospirosis are two different diseases, both of them show a similar life-saving response to steroids, the common factor in the pathogenesis being cytokine storm. Primary care physicians in tropical areas of the world should be aware of the similarities between these two diseases, especially the initial clinical presentation, the pathogenesis, and the response to steroids.