Dengue Virus-Induced Acute Interstitial Nephritis

Introduction: Acute Interstitial Nephritis (AIN) is a common cause of acute kidney injury, manifests as inflammation within the kidney's interstitial tissue. While AIN is often attributed to medications, infections can also be causal factors. This case presents a rare instance of AIN induced by Dengue fever. Case Description: A 57-year-old male with history of hypertension and hyperlipidemia presented with myalgias and dark urine after recent travel to Europe and Africa. Home medications were Amlodipine, Atorvastatin and Sildenafil. Vital signs were unremarkable. Blood work revealed creatinine (Cr) 2.93 mg/dL (baseline 1.2 since 2022), BUN 33 mg/dL, potassium 5.3 mmol/L, bicarbonate 18 mmol/L, phosphorus 6.9 mg/dL, creatine kinase (CK) 1,088,400 U/L, ALT 608 U/L and AST 3,494 U/L. Urinalysis showed brown urine, 3+ blood and 2+ protein but no RBCs. Imaging studies were unremarkable. Upon holding Atorvastatin and administering fluids, CK level gradually improved. Autoimmune and infectious work up revealed positive Dengue virus IgM and IgG. The rest of the work up was negative. Creatinine levels peaked at 4.0 mg/dl on hospital day 3, subsequently decreased to 3.5 mg/dl. However, over the following 9 days, there was no further improvement, which prompted a kidney biopsy revealing AIN with mild to moderate acute tubular necrosis (ATN). The patient was discharged on Prednisone taper for two weeks. Two weeks post-discharge, creatinine levels decreased to 2.4 mg/dl. Discussion: AIN is an immune-mediated syndrome characterized by the presence of inflammatory cell infiltration in glomerular interstitial space. This histological finding can be elicited by several mechanisms, while commonly triggered by medication allergies, systemic infections, including viral ones like CMV, EBV, HBV, and HIV, can also induce AIN. Limited literature exists regarding the histological etiology of kidney injury in Dengue fever. There have been reports of ATN secondary to severe rhabdomyolysis in dengue fever but there has not been any reported case of AIN. Even though amlodipine has been reported to cause interstitial nephritis, the patient had been taking it for more than a year before the presentation, without any worsening of his renal functions.