The measles virus is a type of paramyxovirus. It contains 2 proteins on the outer membrane. The first is the fusion protein (F), which is responsible for the fusion of the virus to the host cell membranes, viral penetration, and the destruction of red blood cells. The second is the hemagglutinin protein (H), which helps in the absorption of the virus into cells. The core contains single-stranded RNA (ribonucleic acid).¹

Environmental factors such as heat, sunlight, acidic conditions, ether, and trypsin may inactivate the virus. The virus typically survives in the air or on objects and surfaces for less than 2 hours.¹

Measles is highly contagious. Transmission occurs primarily by direct contact via respiratory droplets from an infected person to a susceptible individual from coughing, sneezing, or close personal contact. The virus is still active and contagious for up to 2 hours in the air or on infected surfaces. The virus can be transmitted several days before to several days after development of a rash from an infected individual.²

Measles infection affects the entire body. Although the first site of infection is the lining of the nasopharynx, after viral invasion and replication in the respiratory epithelium and regional lymph nodes, the infection enters the bloodstream, which is known as primary viremia. Further infection and replication at regional and distal sites can lead to a second viremia and subsequent infection of other body organs.¹

General Clinical Features of Measles Infection by Phases¹

Complications of measles can include diarrhea, pneumonia, otitis media, and rarely, encephalitis, seizures, and death. Approximately 30% of measles cases can have complications.^1,3

Measles Complications by Incidence Based on Surveillance Data in the United States Between 1985–1992¹

In pregnant women, measles can result in higher risk of miscarriage, premature labor, and low birth weight. There is lack of evidence to attribute measles illness to associated birth defects.¹

Complications are more common among children under 5 years old and adults 20 years and older.¹

Complications From Measles Are More Common Among Young Children and Adults¹

Although identification of the measles virus is not routinely recommended, identification and verification are helpful for geographic tracking or epidemiologic surveillance.¹

A measles diagnosis can be made through analyzing samples from urine, nasal passages, blood, and throat. For every suspected case, samples for virus culture should be collected and sent to state public health laboratories or the Centers for Disease Control and Prevention (CDC). Samples should be collected within 7–10 days after rash onset.¹