Management of Dengue Fever with Severe Thrombocytopenia in a Patient While on Warfarin: A Case Report

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Dengue fever is a potentially lethal illness that is universally prevalent in the tropics. Dengue hemorrhagic fever is characterized by a ‘leakage phase’ (or critical phase) usually lasting 48 hours following an initial febrile phase. During the leakage phase, an increase in capillary permeability leads to extravasation of fluid and haemoconcentration. During the latter part of febrile phase and early leakage phase (or even later), there is a steady drop in platelet count. Some patients with dengue fever will develop severe thrombocytopenia during the course of the illness even without going into a critical phase and the platelet count does not necessarily indicate the severity of infection. At occasions, it can drop as low as 500/μl in previously healthy individuals (normal platelet count in a healthy adult: 150,000-400,000/μl). The exact mechanism of this drop is unclear but presumed to be immunological. The low platelet count leaves the patient at a significant risk of spontaneous bleeding. The management is further complicated by pre-existing co-morbidities that interfere with the usual therapeutic guidelines. Use of oral anticoagulants is one such situation where management of dengue fever could be challenging. We report a patient with severe dengue infection with very low platelet counts without bleeding manifestations who was on anticoagulation with warfarin for atrial fibrillation with severe mitral regurgitation awaiting prosthetic mitral valve replacement.

A fifty one year old Sri Lankan male, presented with fever for three days and arthralgia, myalgia and retro orbital headache. There were no other systemic symptoms to suggest any focus of infection. He had mitral regurgitation following papillary muscle rupture due to a myocardial infarction one year ago complicated with atrial fibrillation for which he was on anticoagulant therapy with warfarin. His target PT INR (Prothrombin Time International Normalized Ratio) of 2-3, maintained with 7mg of warfarin per day. His other medications included; digoxin, and a combination of hydrochlorothiazide and furosemide. His 2D echocardiography done on August-2016 revealed grade 1V mitral regurgitation with left ventricular ejection fraction of 60%. On admission, he was hemodynamically stable with an irregularly irregular pulse at a rate of 76 beats per minute and a blood pressure of 110/60mmHg. All the peripheral pulses were felt and capillary refilling time was <2 seconds. On auscultation, there was a pan-systolic murmur at cardiac apex with radiation to axilla.