INTRODUCTION: Hantavirus cardiopulmonary syndrome (HCPS) is a rare and potentially fatal viral infection. Early clinical suspicion of HCPS is essential in patients presenting with rapid progression from a febrile prodrome to shock.
CASE PRESENTATION: An 18 yr-old-man who recently relocated from the southwestern US to the midwest presented with acute respiratory failure following five days of cough,feverand malaise believed to be part of a viral upper respiratory infection.On exam, he was alert, diaphoretic & flushed.Vitals:T100,HR109/min,RR 26/min, BP111/74 and SpO2 99%(FIO2 = 1.0).Chest auscultation revealed bilateral basilar crackles and the heart exam showed a normal S1 and S2. Initial laboratory studies showed a WBC 18K with 25% bands, hematocrit 45%, platelets 74K.ABG 7.39/39/111/99%. Basic chemistry panel was normal. Initial CXR (Fig 1A)showed bilateral interstitial opacities. Respiratory failure rapidly progressed and mechanical ventilation was initiated. Shock developed and vasopressor infusion was initiated. Repeat labs showed hematocrit 52%, platelets 43K/αl, serum creatinine 2.3 mg/dL and lactate =10 mmol/L. CXR showed worsening pulmonary infiltrates and bilateral pleural effusions. Bronchoscopy was performed and initial results were non-diagnostic. The patient's clinical condition continued to worsen and he died 12 hours after admission. An autopsy was performed(Figure2),the alveoli were filled with proteinaceous fluid,Immunoblasts in blood and multiple organs and immunohistochemical studies performed at CDC were consistent with Hantavirus infection.
DISCUSSIONS: Hantaan virus was isolated in 1951–1953 outbreak of fever, hemorrhage, and renal failure among UN troops during the Korean War. In 1993, a “mystery” disease intruded into rural communities of the southwestern United States. The Centers for Disease Control and Prevention (CDC) framed the problem: young, healthy adults were dying of an infectious disease that had a high case-fatality rate. Then, Sin Nombre virus was isolated and Hantavirus Cardiopulmonary Syndrome was recognised with upto 80% mortality. It's an RNA virus of Family Bunyaviridae. Transmitted through aerosolization of saliva, urine, and feces from rodents.Person-to-person transmission is very rare. CLINICAL MANIFESTATIONS: The prodrome typically lasts 3–5 days, during which the patient has myalgia, malaise, and fever of abrupt onset. At the time of hospitalization, patients are entering the next stage of disease, which is characterized by cardiopulmonary involvement. At this stage, cough is generally present but gastrointestinal manifestations may dominate the clinical picture. Chest radiographs reveal interstitial edema. The presence of pleural effusions in the early stages of disease are in contrast to the typical radiographic findings in ARDS. Thrombocytopenia is first abnormal and the most useful test and is rare in other illnesses that have prodromes resembling that of HCPS. Presence of circulating immunoblasts, which are often interpreted to be atypical lymphocytes, and an elevated hematocrit is charecterstic feature. There is usually a rapid decompensation, 1/3rd of patients die 24–48 h after admission, even in ICUs. In addition to the severe permeability defect in the lung, myocardial depression is common. This pattern of mixed hypovolemic shock (internal fluid shift) and cardiac shock with high peripheral vascular resistance is found-unlike classic septic shock. DIAGNOSIS: Most valuable and widely used test is the IgM capture ELISA, which detects IgM in all acute cases. Immunohistochemisty antibodies to viral nucleocapsid (N) antigen is confirmatory. In UNM (University of NewMexico) retrospective study of 52 patients with HCPS and 128 SNV seronegative patient blood smear,after the onset of pulmonary edema detected radiographically, the presence of 4/5 findings (thrombocytopenia, myelocytosis, hemoconcentration, lack of significant toxic granulation in neutrophils, and more than 10% of lymphocytes with immunoblastic morphologic features) has a sensitivity for HCPS of 96% and a specificity of 99%.
CONCLUSION: Hantavirus cardiopulmonary syndrome is a rare and potentially fatal viral infection which presents with a complex hemodynamic pattern suggesting hypovolemic and cardiogenic shock. It should be suspected in patients, particularly those residing in the southwestern US, who present with a rapidly progressive febrile illness.
DISCLOSURE: Yousef Shweihat, No Financial Disclosure Information; No Product/Research Disclosure Information