The Brief Case: Secondary Measles and the Pitfalls of Diagnostic Testing

Abstract

A 34-year-old male patient with no significant past medical history presented to the emergency department of our hospital for evaluation of intractable nausea and vomiting, a mild sore throat, and a rash that had developed 3 days prior to presentation. The rash had first appeared on his face and then spread caudally to his shoulders and anterior chest. A physical examination was remarkable for a maculopapular rash most prominent over the face but also involving his torso (Fig. 1), back, and upper and lower extremities, including the palms and soles, as well as erythematous lesions on his buccal mucosa and a nontender hyperpigmented plaque at the base of his penis. The remainder of the physical exam, including of the abdomen and lungs, was unremarkable. The patient was born in Mexico and immigrated to the United States at the age of 15. His initial laboratory studies were notable for elevated liver enzymes (aspartate transaminase, 72 U/liter; alanine transaminase, 128 U/liter; alkaline phosphatase, 132 U/liter) and a normal complete blood count. The emergency room physician considered the diagnosis of measles, as a measles outbreak was ongoing in neighboring New York, and placed the patient on airborne precautions. On evaluation by an infectious disease specialist, the patient denied ever leaving the State of Connecticut since his initial move or being in close contact with any persons with upper respiratory symptoms or a rash but admitted to having unprotected sex with a prostitute 5 months prior to presentation. He reported receiving age appropriate measles, mumps, and rubella (MMR) vaccinations. Based on his clinical findings and exposure history, secondary syphilis was considered much more likely than measles, and airborne precautions were temporarily discontinued. When a Treponema pallidum antibody test returned negative and a rapid plasma reagin (RPR) was nonreactive, the diagnosis of measles was reconsidered and airborne precautions reinstituted. A repeat complete blood count on day 2 of hospitalization revealed a higher percentage of atypical lymphocytes (16%). A measles IgG (chemiluminescent immunoassay [CLIA], LIAISON XL; DiaSorin) at the Yale New Haven Hospital virology laboratory was strongly positive at Ͼ10ϫ the cutoff on a sample collected on day 4 of illness, while an IgM test (laboratory-developed immunofluorescence assay [IFA]) performed at a commercial reference laboratory was negative. After consultation with the virology laboratory director, a nasopharyngeal swab was sent urgently for measles real-time reverse transcriptase PCR (RT-PCR) testing to the Connecticut Department of Health (CT DPH) laboratory, and it returned positive (cycle threshold 31). IgM and IgG testing performed at the Centers for Disease Control and Prevention (CDC) laboratories were subsequently both positive (see Table 1). Upon further inquiry, the patient reported recently visiting the city of White Plains, NY, and to being in close proximity to a coworker who had upper respiratory symptoms. The penile skin lesion was ulti...