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Febrile Pneumonia in a Medical Student returning from Southeast Asia
BACKGROUND
A 25-year-old fourth-year Filipino medical student presents to a California walk-in clinic with an intermittent fever, chills, and cough lasting almost 5 days. He has had progressively worsening muscle aches. Over the last 48 hours, he has noticed increasing difficulty in taking a deep breath. Because the patient has had no prior medical illnesses and only occasional colds, he did not seek medical care earlier.

For the first 2 days of this illness, the patient had a mild runny nose, a sore throat, and some diarrhea, all of which were self-limited. Since his illness began, he has had an on-and-off headache, in addition to increasing weakness and anorexia. On systemic review, the findings are otherwise essentially negative, including the absence of a rash, headache, abdominal pain, vomiting, and back pain. The patient smokes less than a pack of cigarettes per day but does not have chronic bronchitis. He denies using alcohol, illicit drugs, and prescription medications.

The patient is finishing an 8-week hospital-based rotation in Southeast Asia in which he was an acting intern. He wanted to study internal medicine and critical care medicine in the region because he aspires to work in international health. During his rotation, he was in Manila for 4 weeks and then Singapore for 2 weeks. A week and a half ago, he returned to the United States to finish his final 2 weeks at the hospital associated with his California medical school.

The patient reports that, during his elective, several nursing staff had been sick with respiratory symptoms "at the same time" and that the morale was poor among those who were relatively well. On further questioning, the patient states that he had direct contact with several patients in the ICU and emergency department. Additionally, he recalled escorting several septic patients to the radiology department for their imaging studies.

The patient is 5 ft 9 in tall and weighs 155 lb (70.3 kg). He appears apprehensive and acutely ill, with a cough but no sputum. His vital signs are as follows: temperature, 101.3F (38.5C) on admission to the emergency department; blood pressure, 110 mm Hg systolic, 65 mm Hg diastolic; heart rate, 108 beats per minute; and respiratory rate, 18 breaths per minute with no retractions. The patient's mental status is normal with a nonfocal neurologic examination; he has no meningismus. The patient's mucous membranes are dry, and he has a few petechiae on his upper palate and no pharyngeal exudates. The patient has diffuse bilateral rhonchi with few bibasilar rales. Slight splinting is observed on both sides when the patient is asked to take a deep breath. No murmur or gallop is noted. The patient has no edema or rash in the extremities. Examination findings of the abdominal, genitourinary, and musculoskeletal areas are negative.

CBC findings are as follows: WBC count, 2.5 X 109/L (no left shift); lymphocyte count (LYC), 0.8 X 109/L; hemoglobin (Hgb), 11 mg/dL; hematocrit (Hct), 33%; and platelet count, 89,000 per cubic milliliter. Chemistry findings are as follows: sodium, 131 mg/dL; BUN, 35 mg/dL; creatinine (Cr), 1.6 mg/dL; aspartate aminotransferase (AST), 73 mg/dL; alanine aminotransferase (ALT), 65 mg/dL; lactate dehydrogenase (LDH), 397 mg/dL; and O2 saturation, 89%. ABG measurements are pH, 7.32; pCO2, 31 mm Hg; and pO2, 56 mm Hg.
Hint
This is an acute, febrile, progressively worsening respiratory illness. Epidemiologic clues include the patient^s recent international travel and exposure to a hospital health care worker.
Author: Asim A. Jani, MD, MPH, FACP
University of South Florida College of Medicine, Division of Internal Medicine, Florida Department of Health; Epidemic Intelligence Service, EPO, CDC - State Branch, Virginia Department of Epidemiology, Richmond, VA

Answer
Severe acute respiratory syndrome (SARS) is probable on the basis of both the clinical and the radiographic criteria. (Note that this working diagnosis is based on the features of the case definition used in the SARS outbreak, ie, syndromic definition, rather than on confirmed laboratory results. Laboratory evidence is not required to meet the criteria for defining a case of SARS.)

The chest radiograph depicts bibasilar interstitial infiltrates and a hazy appearance in both lobes. No pleural effusion or cavitation is seen. The chest CT scan depicts patchy ground-glass opacification of both lower lobes that is most prominent in the retrocardiac region.

Although several features of this case support a range of differential diagnoses, this scenario includes some of the distinctive characteristics of the newly described disease, SARS. The most important epidemiologic feature is travel to one of the main countries known to have documented or suspected community transmission of SARS, namely, Singapore (as of February 1, 2003). Other noteworthy features include the initial atypical pneumonia with a fever, myalgias, and a dry cough, followed by increasing lower respiratory symptoms and signs within an illness period of about 1 week. This illness also seemed to occur after a 2- to 10-day incubation period, which is considered the incubation period for SARS.

As a health care worker, the patient likely had direct exposure to the respiratory secretions of infected patients in Singapore. Additionally, he had diarrhea, a less common feature. Although this finding may dissuade clinicians form diagnosing SARS, it is noted in as many as 10% of cases. The patient^s leukopenia, lymphopenia, and elevated LDH level, along with hyponatremia and an elevated ALT level, also support the working diagnosis.

Given the patient^s stable initial course for the first 2-3 days, followed by worsening findings in the lower respiratory tract, the course is consistent with the natural history of SARS observed thus far. The infection-control practices that may have been in place during the student^s rotation are unclear, and appropriate protection protocols, including use of N-95 masks, universal precautionary measures, respiratory protection, and negative isolation, may not have been in use. Among other staff, medical students may take greater personal risk in caring for patients because of their idealism and altruism.

This patient smokes, and factors such as older age and comorbid conditions (eg, smoking or diabetes mellitus) may increase a patient^s risk of severe disease progression. The radiographic features are typical for the worsening SARS presentation. With an obvious A-a gradient, the incipient picture is that of an ominous challenge in air-exchange resulting in shunt physiology. Laboratory tests to confirm the presence of the SARS-coronavirus are available. Serologic tests must be performed on an acute and convalescent basis (>21 d after the onset of symptoms). At the time of this patient^s presentation, which was only 10-14 days postexposure and less than 1 week into the course of natural illness, the enzyme-linked immunosorbent assay (ELISA) results would likely have been falsely negative and certainly not adequate to rule out coronavirus-associated SARS.

Image courtesy of Michael E. Katz, MD, Department of Radiology, West Boca Medical Center.