Oligosymptomatic diphtheria infection in adults: two contacts of the Peruvian index case after 20 years without disease report.

In Peru, diphtheria infection was eradicated in the last two decades. However, recently, diphtheria pharyngeal infection was confirmed and reported in a 5-year-old boy (index case). We report two more cases of this outbreak (in the index case parents) with confirmed diphtheria infection and tox gene identified by molecular assay, who were in close contact with the index case and never presented any symptoms. Both parents had a congestive pharynx with erythematous plaques at the back of it. In adults, diphtheria infection can be oligosymptomatic or mimic viral pharyngitis, which could lead to misdiagnosis and, furthermore, an increased risk of transmission in regions with lower immunization rates.