Table 1.

Childhood diseases in the differential diagnosis of measles [10].

Childhood disease	Clinical diagnosis
Dengue fever	Dengue has a similar presentation to prodromal and post-rash measles. Relevant epidemiology and serologic testing can diagnose dengue
Childhood respiratory viruses, including rhinoviruses, parainfluenza, influenza, adenovirus, and respiratory syncytial virus (RSV)	Fever due to measles infection is usually more severe than for other childhood respiratory viruses, diagnosed from nasal swab using polymerase chain reaction (PCR)
Childhood viral infections with skin rash include varicella, human herpesvirus 6 (roseola infection), parvovirus B19 (erythema infectiosum), and rubella	Measles has a distinctive clinical progression of the rash, which can be brown, blanches on pressure, and is associated with coryza and conjunctivitis. Serology can diagnose other childhood virus infections
Group A Streptococcus infections, including scarlet fever and toxic shock syndrome	Scarlet fever presents with an erythematous skin rash and pharyngitis. Toxic shock syndrome results in hypotension and organ system dysfunction. Isolation of group A Streptococcus is diagnostic
Meningococcemia can include a petechial rash, fever, vomiting, headache, and sepsis	Meningococcal infection is confirmed by bacterial culture
Rocky Mountain spotted fever can include a maculopapular rash	Rocky Mountain spotted fever is associated with tick exposure and diagnostic serology or skin biopsy
Mycoplasma pneumoniae respiratory tract infection can present with an erythematous maculopapular or vesicular rash	The diagnosis of Mycoplasma pneumoniae may be difficult, but pneumonia is the main feature
Infectious mononucleosis can result in a generalized maculopapular, urticarial, or petechial rash	Infectious mononucleosis includes fever, fatigue, pharyngitis, and lymphadenopathy and is diagnosed by serology and virology
Exanthematous drug eruption can resemble a measles rash	A history of recent drug exposure, with resolution of the rash after drug withdrawal
Fordyce spots (small yellow/white granules on the buccal mucosa) are benign ectopic sebaceous glands. In early measles infection	Fordyce spots can be confused with Koplik spots in early measles infection
Multisystem inflammatory syndrome in children (MIS-C) from SARS-CoV-2 includes fever, abdominal pain, conjunctivitis, and rash	The diagnosis of MIS-C can be confirmed by RT-PCR testing for SARS-CoV-2