To the Editor:
Measles, one of the most transmissible diseases, is most contagious before rash manifestation. Search for the pathognomonic Koplik’s spots could be critical for the early diagnosis in this prodromal period.
Case Description
A 47-year-old man had high-grade fever with a peak temperature of 39.7°C, photophobia, rhinitis, and dry cough. On the fifth day, a maculopapular rash appeared on his head.
The patient had a faint maculopapular rash on his head, disseminated white spots with a reddish background on the buccal mucosa, and tongue coating (Figure). Laboratory tests were normal except for leukocytes 11,300 per cubic millimeter (64% neutrophils and 17% band cells) and C-reactive protein 13 mg/dL (normal <0.5). Measles was confirmed by testing with anti-measles immunoglobulin-M antibodies. Despite intense contact investigation, no known source of infection was recognized.
Discussion
Koplik’s spots are highly characteristic of the prodromal phase of measles and are seen in up to 70% of patients when the rash has just erupted.1, 2 Although Henry E. Koplik (1859-1927) was not the first to describe his eponymous spots, he emphasized their association with measles, their evolving appearance, and their importance in infection control. Koplik’s spots start 2 to 3 days before the widespread rash as millimetric, irregular, and slightly raised bluish-white “grains of salt on a red background” opposite the molars on buccal mucosa, and afterward involve diffusely the rest of the buccal mucosa and disappear before skin eruption resolves. Occasionally, conjunctival, vaginal, and gastrointestinal mucosa are involved.3 Almost all patients with Koplik’s spots have tongue coating. Koplik’s spots may be absent in patients who contract measles despite having had the vaccination.4 Koplik’s spots have been reported with other viral diseases, such as parvovirus B19 infection.5
Measles (or rubeola from “rubeo,” the Latin word for “red”) is a highly transmissible disease. Patients are highly infectious for approximately 4 days before and 4 days after the onset of the rash, and clinical measles develops in 9 of 10 susceptible persons who have had close contact with a patient with measles. The incidence is extremely low in developed countries, and measles was considered to have been eliminated in 2000 in the United States.6However, transmission among persons who travel to endemic areas and occasional local transmission continue to occur. Most cases are related to unvaccinated people who acquire the infection while traveling abroad or to people from areas with low vaccine coverage. Furthermore, measles immunity could be incomplete, and it is still possible to contract measles after having had the appropriate vaccinations. In general, patients who have been vaccinated tend to have mild or atypical disease, and Koplik’s spots may be absent. Recent declines in the vaccination rate have led to outbreaks in the United States and Europe, making measles potentially reemerging.7Early detection is needed to limit spread and prevent resurgence. Seeking Koplik’s spots in the appropriate context provides an opportunity to clinically diagnose measles 1 or 2 days before the rash.
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-Giuseppe Famularo, MD, PhD
This article originally appeared in the June issue of The American Journal of Medicine.
