Correct answer to Mondays #USMLE-style question is D! See explanation and recommended Firecracker review below. Any questions? Ask and well answer! D) The findings of cough, conjunctivitis, and coryza (rhinitis), together with fever and a descending maculopapular rash, indicate a diagnosis of measles (rubeola). The patient’s unvaccinated status placed her at risk of contracting the virus, most likely during her visit to England, where recent outbreaks of measles have occurred. After an incubation period of 8-12 days, a prodromal phase occurs that typically includes fever and malaise, followed by cough, conjunctivitis, and coryza (often referred to as the 3 C’s of measles). Next, during the exanthematous phase, a blanching, maculopapular rash develops with a characteristic cranial to caudal progression. Koplik spots, a pathognomonic finding of measles, may be present 2-3 days before the appearance of the rash. However, these small (1-3 mm) erythematous spots with blue-white centers on the buccal mucosa do not appear in all patients with measles and are transient, lasting only 12-72 hours. Measurement of acute and convalescent serum IgM and IgG antibodies is the most common test used to confirm measles infection, with a ≥4-fold rise in titers considered diagnostic. IgM antibodies are usually present within 1-3 days after rash onset and peak 2-4 weeks later, while IgG antibodies are usually undetectable for up to 7 days after rash appears and peak about 2 weeks after rash onset. Less common diagnostic methods are viral culture or polymerase chain reaction (PCR). Explanation of incorrect answers: A) Rapid antigen testing on nasal washes is used for diagnosis of influenza and respiratory syncytial virus (RSV) infections. B) Direct fluorescent antibody testing on nasal washes is used to detect a variety of respiratory viruses, including influenza, parainfluenza, adenovirus, RSV, and human metapneumovirus (hMPV). C) Antigen testing on urine is commonly used for diagnosis of infections by Legionella species. Streptococcus pneumoniae, and Histoplasma capsulatum. E) Serum antigenemia testing is performed to detect and monitor treatment response for cytomegalovirus (CMV) infections. **** Review these topics on Firecracker! Measles & Mumps (Paramyxoviruses): https://med.firecracker.me/topics/3015 Rubeola: https://med.firecracker.me/topics/1131
Posted on: Tue, 08 Jul 2014 15:00:01 +0000
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