Q&A: Incubation Period for Rubeola

Rubeola is a highly contagious viral illness that occurs worldwide. The infection is characterized by fever, malaise, cough, coryza, and conjunctivitis, followed by exanthem. Following exposure, approximately 90 percent of susceptible individuals will develop the disease. The period of contagiousness is estimated to be from five days before the appearance of the rash to four days afterward. The illness may be transmitted in public spaces, even in the absence of person-to-person contact.

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This is a Question & Answer revision article designed for medical students and professionals preparing for the PLAB, MRCP or USMLE examinations. They are based on actual questions from these examinations. You may find the Infectious Disease articles more useful, or one of our many articles on Diseases & Conditions, Medical Syndromes, Health & Wellness or Home Remedies.

In this article:
Rubeola clinical syndromes
MCQ: clinical scenario
MCQ: answer
MCQ: explanation

Rubeola clinical syndromes

Rubeola (otherwise called Measles) virus infection can cause a variety of clinical syndromes, including:

• Classic measles infection in immunocompetent patients
• Modified measles infection in patients with pre-existing but incompletely protective anti-measles antibody
• Atypical measles infection in patients immunized with the killed virus vaccine
• Neurologic syndromes following measles infection, including acute disseminated encephalomyelitis and subacute sclerosing panencephalitis
• Severe measles infection
• Complications of measles including secondary infection, giant cell pneumonia, and measles inclusion body encephalitis

MCQ: clinical scenario

The incubation period for the onset of rubeola is approximately:

a) 3-6 hours
b) 12-24 hours
c) 2-4 days
d) 3-6 days
e) 1-3 weeks

MCQ: answer

The correct answer is E.

MCQ: explanation

The incubation period is generally 8 to 12 days from exposure to onset of symptoms; the average interval from exposure to appearance of the rash is 14 days. In family studies, the average interval between appearance of rash in the source case and subsequent cases is 14 days, with a range of 7 to 21 days.

Reference(s)
1). UpToDate: Measles: Clinical manifestations, diagnosis, treatment, and prevention. Available online: https://www.uptodate.com/contents/measles-clinical-manifestations-diagnosis-treatment-and-prevention