Measles: Not just a childhood rash
ABSTRACTIn recent years, the number of US measles cases has increased, and outbreaks in adults continue to be reported in communities with a high number of unvaccinated people. These trends underscore the need for high overall measles vaccination coverage, and for physicians to entertain the diagnosis of measles in adult patients with a febrile illness and rash.
KEY POINTS
- Measles is one of the most contagious infectious diseases, with a secondary attack rate of at least 90% in susceptible household contacts.
- Since 1993, most reported cases of measles have been directly or indirectly linked to international travel, and many have occurred in adults.
- Acute measles encephalitis, a neurologic complication of measles, is more common in adults than in children and is characterized by the resurgence of fever during the convalescent phase, along with headaches, seizures, and altered consciousness.
CLINICAL FEATURES OF MEASLES
The first sign of measles is a distinct prodrome, which occurs after an incubation period of 10 to 12 days. The prodrome is characterized by fever, malaise, anorexia, conjunctivitis, coryza, and cough and may resemble an upper respiratory tract infection; it lasts 2 to 4 days.
Towards the end of the prodrome, the body temperature can rise to as high as 40°C, and Koplik spots, pathognomonic for measles, appear. Koplik spots, bluish-gray specks on an erythematous base, usually appear on the buccal mucosa opposite the second molars 1 to 2 days before the onset of the rash, and last for 1 to 2 days after the onset of the rash. Thus, it is not unusual for Koplik spots to have disappeared at the time the diagnosis of measles is entertained.
The classic measles rash is an erythematous maculopapular eruption that begins on the head and face and spreads to involve the entire body. It usually persists for 4 to 5 days and is most confluent on the face and upper body. The rash fades in order of appearance, and may desquamate. People with measles appear ill, especially 1 to 2 days after the rash appears.
The entire course of measles usually lasts 7 to 10 days in patients with a healthy immune system. The cough, a manifestation of tracheobronchitis, is usually the last symptom to resolve. Patients are contagious 2 to 4 days before the onset of the rash, and remain so through 4 days after the onset of the rash.
COMPLICATIONS
Respiratory complications
Pneumonia is responsible for 60% of deaths associated with measles.13 Although radiographic evidence of pneumonia is found in measles patients with no complications, symptomatic pneumonia occurs in 1% to 6% of patients. It is the result of either direct invasion by the virus or secondary bacterial infection,17 most often with Staphylococcus aureus and Streptococcus pneumoniae. Other respiratory complications include otitis media, sinusitis, and laryngotracheobronchitis.
Neurologic complications
Acute measles encephalitis is more common in adults than in children. Occuring in 1 in 1,000 to 2,000 patients,18 it is characterized by the resurgence of fever during the convalescent phase of the illness, along with headaches, seizures, and altered consciousness. These manifestations may be mild or severe, but they lead to permanent neurologic sequelae in a substantial proportion of affected patients. It is not clear whether acute measles encephalitis represents direct invasion of the virus or a postinfectious process from a hypersensitivity to the virus.19
Subacute sclerosing panencephalitis is a rare, chronic, degenerative central nervous system disease that occurs secondary to persistent infection with a defective measles virus.20 The prevalence is estimated at 1 per 100,000 cases. Signs and symptoms appear an average of 7 years after the initial infection and include personality changes, myoclonic seizures, and motor disturbances. Often, coma and death follow.
This condition occurs particularly in those who had measles at a very young age, ie, before the age of 2 years, and it occurs despite a vigorous host-immune response to the virus. Patients have high titers of measles-specific antibody in the sera and cerebrospinal fluid.
Other complications
Diarrhea and stomatitis account for much of the sickness and death from measles in developing countries.
Subclinical hepatitis occurs in at least 30% of adult measles patients.
Less common complications include thrombocytopenia, appendicitis, ileocolitis, pericarditis, myocarditis, and hypocalcemia.
MEASLES DURING PREGNANCY
Measles during pregnancy may be severe, mainly due to primary measles pneumonia.21 Measles is associated with a risk of miscarriage and prematurity, but congenital anomalies of the fetus have not been described, as they have for rubella infection.22
