| 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, 101.3°F (38.5°C) 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. |
||||
|
||||
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.