Case Presentation: Mr. D is a 60-year-old male building superintendent with a history of asthma and moderate alcohol use disorder who presented with six days of fatigue. Later, he developed headache, substernal pleuritic chest pain, epigastric and RUQ abdominal pain, nausea, vomiting, and weight loss of around 20 pounds in a week. The patient reported no night sweats, fevers, chills, recent swelling, difficulty with urination, or recent travel, but endorsed a work-related exposure to rats. Exam was notable for jaundice, scleral icterus, and two petechiae over the right buccal mucosa. Labs were notable for a creatinine of 5.06 mg/dL, alkaline phosphatase of 134 U/L, AST of 57 U/L, ALT of 40 U/L, albumin of 3.2 g/dL, total bilirubin of 9.6 mg/dL, direct bilirubin of 8.1 mg/dL, and platelet count of 24,000/uL. MRCP at the time revealed no biliary obstruction . Further workup of thrombocytopenia revealed no other possible etiologies. The patient was found to be leptospirosis IgM-positive seven days after admission despite a negative serum and urine PCR, and he was given seven days of oral doxycycline with resolution of his symptoms and thrombocytopenia.
Discussion: Leptospirosis is a common, widespread zoonotic infection worldwide. It is most prominent in tropical regions. The incidence of leptospirosis in New York City (NYC) is quite rare, with between 5-9 cases annually between 2017-2020. A spike in cases has been observed since the COVID-19 pandemic, with 17 cases reported in 2021 and 24 cases reported in 2023. The primary source of transmission in NYC appears to be rat urine, primarily the Norway rat. The primary form of leptospirosis reported is anicteric leptospirosis, which is defined by a biphasic illness with an acute and immune phase of illness and presents with acute febrile bacteremia and constitutional symptoms. Common features include anemia, neutrophilia, proteinuria, pyuria, granular casts, and conjunctival suffusion. Approximately 5-10% of symptomatic leptospirosis cases are characterized as icteric leptospirosis (Weil’s disease), which is a rapidly progressive, multiorgan illness with 5-15% mortality. Of those with Weil’s disease, only some develop ARDS/pulmonary hemorrhage. Cases associated with pulmonary hemorrhage often present with thrombocytopenia and a DIC-like picture. While leptospirosis is a common zoonotic infection, thrombocytopenia is a rare presenting feature, with only two case reports reporting thrombocytopenia as a feature of leptospirosis. Testing for leptospirosis often includes molecular PCR (blood, urine, CSF), which is specific and rapid, especially during the early course of the illness. While a single positive PCR is enough for the confirmation of the infection, its sensitivity varies depending on the timing of the collection given the transient nature of the bacteria in bodily fluids. Overall, negative PCR does not rule out leptospirosis as with our patient.
Conclusions: Prevalence of leptospirosis has been low in the United States but has been increasing in urban areas with rodent burden. As such clinicians need to have a higher index of suspicion and a lower threshold to treat patients with more severe illness, even if PCR testing is negative. Thrombocytopenia and hyperbilirubinemia are often a presenting illness script for hepatobiliary etiologies, but leptospirosis should be present on the differential diagnoses list for patients when more common causes for such abnormalities have been ruled out.