Part two in our two part series about measles!
Again, TL;DR at the bottom and here's another plug for Dr. Anna Pickens' EM in 5: http://www.emdocs.net/em-in-5-measles/
This section goes over the diagnosis, management, and complications of measles.
Measles virus is a single-stranded, enveloped, RNA virus of the genus Morbillivirus within the family Paramyxoviridae. It is spread via respiratory droplets that may remain in the air for up to two hours.
Incubation period: 6-21 days (median 13 days)
Prodrome (days 2-4): fever, malaise, and anorexia followed by “the 3C’s” (conjunctivitis, coryza, and cough). This phase of infection can last up to 8 days.
Koplik spots typically present 48 hours prior to the onset of the exanthem. They are white/gray/bluish elevations, described as “grains of salt” on an erythematous base. These are typically seen on the buccal mucosa, but may spread to the soft and hard palates. These generally last for 12-72 hours.
Exanthem: starts 2-4 days after onset of fever. Classically is a blanching, maculopapular rash that starts on the hairline and progresses downward and outwards to the extremities. It tends to coalesce and become non-blanching with time.
Patients will become clinically better within 48 hours of the appearance of rash, the rash will darken in color, and eventually desquamate.
Measles may vary in severity and there are several clinical variants including: modified measles (milder symptoms) in those with pre-existing measles immunity, those who have received IVIG, and in babies with passive immunity from placental migration of immunoglobulins; atypical measles in those who have received the killed virus vaccine (not seen frequently now), which is characterized by higher and more prolonged fevers, pneumonitis, and transaminitis. Patients that are immunocompromised will also not present classically.
Immunocompromised patients and pregnant patients are more likely to develop complications.
Superimposed infection is common because T-cells and dendritic cells are directly infected, which leads to immune suppression that can persist for up to three years. Infections include:
Gastrointestinal (most common) - diarrhea, gingivostomatitis, appendicitis
Pulmonary (most common cause of death) - bronchopneumonia, croup, bronchiolitis
Encephalitis: occurs several days after rash. Patients have neurodevelopmental sequelae in 25% of cases, fatal in 15% of cases
Acute Disseminated Encephalomyelitis (ADEM): occurs several weeks after rash. Demyelinating disease likely due to immune response to the virus. Fatal in 10-20% of cases and survivors commonly have residual neurologic abnormalities.
Subacute Sclerosing Panencephalitis (SSPE): occurs 7-10 years after infection. More likely the younger the time of infection
Stage I (weeks-years): insidious neurological symptoms (trouble concentrating, lethargy, personality changes, strange behavior)
Stage II (3-12 months): dementia, myoclonus
Stage III (variable): myoclonus resolves, neurologic function deteriorates leading to flaccidity/decorticate rigidity, autonomic dysfunction
Stage IV: death
First off, isolate your patient if you suspect measles!! Place the patient in a negative pressure room. Despite the high efficacy of MMR, there is still a 1% chance that you are not immune. As such, everybody entering the room should wear an N95 mask and the patient should wear a mask during transport.
Test used depends on the prevalence of disease and the local governing body for infection control. In general, IgM and IgG are tested in the serum and a nasopharyngeal swab should be obtained for serological testing. False positive PCR does not rule out infection.
Mainly supportive and treating any superimposed bacterial infections. In children, they tend to have low vitamin A levels, which can contribute to delayed recovery and more complications. Low vitamin A levels also causes blindness in children in the developing world. As such, children benefit from vitamin A supplementation. Ribavirin can also be considered especially for higher risk individuals (< 12 months, requiring ventilatory support, and severe immunosuppression).
Measles is transmitted airborne, stays in the air for 2 hours
Characterized by a prodrome of fever, malaise, coryza, conjunctivitis, and cough for 2-4 days followed by a maculopapular rash that progresses downward
Measles can be complicated by bacterial infections. Most common cause of death is from pneumonia
Long-term effects include severe neurological sequelae: encephalitis, acute disseminated encephalomeningitis, and subacute sclerosing panencephalitis
Diagnose via IgM, IgG, nasopharyngal swab
Treatment primarily supportive
Consider vitamin A and ribavirin