Measles is a highly contagious viral infection associated with clinical symptoms 
such as fever, cough, conjunctivitis, coryza, eruption and increased serum 
immunoglobulin M (IgM) antibodies. A clinical diagnosis is easily established 
when the chain of infection can be followed. However, Japan is currently 
experiencing sporadic measles outbreaks, which complicate the establishment of 
diagnosis. Furthermore, other exanthematous infections such as rubella, human 
parvovirus B19, human herpesvirus 6 (HHV-6) and HHV-7 present with clinical 
symptoms and IgM antibody levels similar to those in measles. Therefore, 
real-time polymerase chain reaction virogene testing has been part of Japan's 
standard diagnostic protocol for measles since 2010. This report presents two 
pediatric cases clinically resembling measles that were diagnosed as HHV-6 based 
on a virogene detection test. This underscores the importance of performing 
pathogen testing to confirm a diagnosis when measles is suspected.