Leptospirosis is largely an animal-borne infection that can cause a wide range of symptoms, out of which some can be mistaken for other diseases. In this part of our COVID coinfection series, we bring to you the diagnosis and treatment interventions of leptospirosis occurring along with COVID-19.

For our comprehensive coverage and latest updates on COVID-19 click here.

Pathogenesis

Leptospirosis is caused by a pathogenic spirochete of the genus leptospira. The primary source of these bacterial diseases is the urinal shedding of organisms from sick animals (reservoir and carrier hosts like rodents, cattle, and so on). Human infection occurs as a result of contact with infected urine or urine-contaminated media.

In leptospirosis, the most persistent pathologic finding is capillary vasculitis, which is characterised by endothelial oedema, necrosis, and lymphocytic infiltration. Capillary vasculitis affects every organ system.

Diagnosis

Seroconversion, a fourfold increase in antibody titre, or isolation of leptospires from clinical specimens are required for a definite diagnosis of leptospirosis. Positive serology, ideally utilising the Microscopic Agglutination Test (MAT), using a variety of leptospira strains for antigens that should be typical of local strains.

1. Enzyme-Linked Immunosorbent Assay (ELISA): ELISA is a sensitive and specific test for leptospirosis immunology diagnosis. Due to its relative simplicity in comparison to the MAT, it is particularly useful as a serological screening test (Microscopic Agglutination Test). Additionally, the ELISA test may be utilised in epidemiological research to ascertain the sero-incidence/seroprevalence of leptospirosis).
2. Rapid immunodiagnostics: The lepto dip-stick, lepto lateral flow, and leptotek dri dot tests are IgM-based. These are screening tests, and the results must be validated with MAT.
3. Isolation (and type) of pathogenic leptospires from blood or other clinical specimens: Isolation and culture can be extremely challenging, needing specialised media and extended incubation times.

Clinical characteristics

Leptospirosis presents clinically in a variety of ways. As with COVID, the sickness severity varies from asymptomatic, moderate self-limiting febrile sickness to fulminant deadly disease. Typically, the condition manifests as one of the following clinical categories:

1. Illness resembling influenza
2. Jaundice, renal failure, hemorrhagic symptoms, and myocarditis are all characteristics of Weil's syndrome
3. Meningitis/menigo-encephalitis
4. Pulmonary bleeding associated with respiratory failure

Clinical sickness might persist anywhere from a few days and three weeks or more. In general, the sickness progresses in two stages:

1. The acute phase of the disease is marked by the rapid development of a high temperature, myalgia (calves and lumbar area), and headache (retro-orbital/frontal). Additionally, nausea, vomiting, stomach discomfort, diarrhoea, cough, and conjunctival suffusion (a pathognomonic sign of leptospirosis) occur during the early phase.
2. The later phase of the disease develops 4-9 days after the beginning of symptoms and is marked by a persistent fever and systemic consequences such as jaundice, renal failure, haemorrhage, and respiratory failure.

Considerations for certain treatment interventions

1. All suspected cases of leptospirosis patients in leptospira endemic areas during the rainy season should get presumptive leptospirosis therapy, namely Tab. Doxycycline 100 mg twice daily for seven days.
2. In children younger than six years of age, 30 to 50 mg/kg/day of Cap. Amoxycillin/Cap. Ampicillin should be administered in split doses six hours apart for seven days.
3. In the community environment, leptospirosis should be diagnosed and managed clinically in accordance with national recommendations for leptospirosis prevention and control.

This article is part of our new series on managing COVID-19 coinfections. Stay tuned for a new update every week. To read the previous parts, click COVID-19 & seasonal illness- Protocol for determining co-infection, Managing dengue with COVID-19: Clinical considerations, COVID-19 + Influenza/bacterial co-infection & Malaria and COVID-19 co-infection: Management guidelines

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

The author is a practising super specialist from New Delhi