P3.N273: Severe dengue mimicking Kawasaki disease in an infant: a case report.

Introduction: Dengue virus infection is an endemic arbovirus disease in Asia and America. Kawasaki disease (KD) is a systemic vasculitis without a well defined etiology. Dengue and KD present with fever and cutaneous rash, which can lead to confusion in diagnoses between them. In this report, a case of an infant with severe dengue that mimicked incomplete Kawasaki disease is described.

Case Description: A 1-year-old preterm and previously healthy girl presented to the emergency room with fever, diffuse cutaneous rash, cervical lymphadenopathy and prostration for 5 days, in poor general condition. She evolved with refractory septic shock, and needed mechanical ventilation, being successfully extubated after 2 days with no further complications. After 3 days, she continued to present fever, and since she met clinical and laboratory criteria for incomplete KD (fever ≥ 5 days, cutaneous rash, cervical lymphadenopathy, elevation of inflammatory markers, anemia, reduced albumin and ≥ 10 white blood cells per high powered field on urinalysis), it was chosen to start intravenous immunoglobulin and methylprednisolone. She also received acetylsalicylic acid, with improvement of the rash. After 6 days of admission, serologies of the 8th day of symptoms (before immunoglobulin) came back with positive dengue IgM, which could also explain the clinical presentation. Acetylsalicylic acid and corticosteroid were then discontinued and she was discharged with diagnosis of improved severe dengue, with complete resolution of the condition.

Discussion: Dengue is an arbovirus infection that typically presents with 2 to 7 days of fever, myalgia and rash. Severe cases can progress to bleeding and shock. Cases of KD in children with dengue have previously been described. However, in this case, the infant presented with clinical and laboratory findings compatible with incomplete Kawasaki disease, which was initially treated as such with intravenous immunoglobulin and corticosteroids. Further investigation of other causes, with positive dengue IgM, revealed that the condition could be fully explained by severe dengue. For a diagnosis of KD, there should be no other causes justifying the symptoms, which was not the case. In cases of prolonged fever, autoimmune and infectious causes should be considered, as the treatment for severe presentations may initially be similar. Another important aspect is that this patient received acetylsalicylic acid, which is contraindicated in dengue since it enhances the risk of hemorrhage due to an already decreased platelet count. Luckily, this did not happen in this case.

Conclusion: This case demonstrates the overlap of two potentially serious conditions with initially similar presentations. The investigation of other causes justifying the symptoms led to the discovery of a case with limited prior description, highlighting the need to consider differential diagnoses in nonspecific febrile conditions to provide targeted treatment.