All that seems is not COVID: a Weil’s syndrome in a global COVID-19 pandemic context

A 34-year-old male patient, a cocaine consumer (who had recently started a job as a bricklayer on a rural farm), was discharged from the emergency department with flu-like symptoms. 4 days later, he was readmitted as suspicious for COVID-19 infection. However, he presented jaundice, acute renal failure, and hemoptysis.

Initially, the chest X-ray (Figure 1) showed bilateral, peripheral, alveolar-interstitial opacities, predominantly in the lung bases and right lung, which given the current epidemiological situation, were compatible with COVID-19 infection. However, RT-PCR for SARS-COV2 was negative.

A contrast-enhanced CT (Figures 2 and 3) scan showed multiple rounded, patchy, peripheral, and confluent ground-glass opacities, predominantly in both lower pulmonary lobes, associated with areas of confluent air space consolidation.

A second chest X-ray (Figure 4) was performed (6 hours after the first one) before his admission in the intensive care unit, showing a bilateral increase in alveolar opacities predominantly in the right lung, presenting at present clear areas of bilateral consolidations which given its rapid evolution and the appearance of hemoptysis were compatible with alveolar haemorrhage. Successive controls with chest X-rays showed complete resolution of the areas of alveolar consolidations (Figures 5a and 5b).

Weil syndrome is a severe form of presentation of Leptospira infection in humans [1].

Leptospirosis is a zoonosis with a worldwide distribution and a notably higher incidence in tropical and subtropical countries, where the incidence varies between 10 and 100 cases per 100,000 inhabitants [2]. Only 783 cases were reported in the European Union countries by 2016, with an incidence of between 0.1-0.2 cases per 100,000 inhabitants [3]. This pathology was first recognised as an occupational disease associated with agriculture, sewage maintenance and animal farming due to its transmission through contact with urine, water or soil contaminated by the urine of animals such as rodents, dogs and livestock. These constitute the main vectors of the infection and one of the critical antecedents for its diagnosis. In recent years, climate change, the increase in ecotourism and, in general, the more significant interaction between humans and animals has led to a rise in its incidence, and it is now considered an emerging zoonosis [2].

The clinical course is typically biphasic, with the first stage of flu-like symptoms representing the blood circulation of the bacteria. This stage is followed by an immune phase, in which the leptospiral toxins and the body's immune reaction produce the complications of infection, such as liver failure, kidney failure, and massive pulmonary haemorrhages [1], The classic triad of Weil's disease is characterised by jaundice, acute kidney failure, and haemorrhages [3].

The diagnosis of leptospirosis is determined by the modified Faine criteria proposed by the WHO, which include three pillars: clinical findings, epidemiological factors, and laboratory and bacteriological results [4].

The radiological manifestations of the disease are unspecific, being the radiological findings caused by the appearance of petechiae and areas of multifocal pulmonary haemorrhage. The most frequently reported radiological manifestations are ground-glass opacities, airspace nodules, "crazy paving" pattern, and confluent areas of airspace consolidation, with resolution within two weeks in most patients [5–8].

Our patient presented a typical biphasic clinical course with a prior visit to the emergency department four days before with flu-like symptoms and the later appearance of jaundice, acute kidney failure, and hemoptysis. However, the early diagnosis was limited by the current global pandemic context of COVID-19 since the clinical and radiological findings of the first phase of leptospirosis are practically superimposable to SARS-COV2 infection. In addition, the history of cocaine consumption in this patient also suggested the differential diagnosis with crack lung due to the CT scan findings.

Finally, the appearance of jaundice, acute kidney failure and, especially, the hemoptysis, the rapid progression of the opacities to consolidations, and the recent epidemiological background of the patient (who reported at that time had started 15 days ago a job as a bricklayer in a rural farm with contact with the ground, in an unhygienic environment) was the keys to the final presumptive diagnosis. The final diagnosis was confirmed by IgM serology positive for Leptospira.

Take-home message

For diseases such as this one, where radiological findings are non-specific, correlation with the clinical course, epidemiological history, and clinical-radiological evolution is crucial in the differential diagnosis, even more in the current context of a global pandemic of COVID-19.

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