Measles is a highly contagious, serious respiratory viral disease characterised by fever, and maculopapular erythematous rash. Symptoms include fever, cough, coryza, conjunctivitis, koplik’s spots and generalized maculopapular erythematous rash. Measles infection can result in serious complications such as blindness, encephalitis, or severe respiratory infections such as pneumonia.
Before widespread vaccination in 1980, measles was responsible for an estimated 2.6 million deaths worldwide each year. Despite the availability of a safe and effective vaccine, measles remains one of the leading causes of death among young children around the world, according to the World Health Organization (WHO). Approximately 1 in 1000 cases result in death.
How does measles cause illness?
The measles virus is spread through the air from person to person by breathing, coughing, or sneezing. The virus quickly spreads to the immediate lymph nodes where the T and B cells become infected, and the lymphoid tissues are damaged resulting in the decrease of white blood cells found in the blood. Traveling through the blood the measles virus is initially spread throughout the rest of the respiratory system and the reticuloendothelial system, which is a part of the immune system that consists of the phagocytic cells. The measles virus is a lytic virus which means it multiplies or reproduces very quickly. The virus will travel through the blood and take over the cell via the RNA in the cytoplasm. In lytic reproduction, and in the measles virus reproduction, the virus will attack the cell and churn out as many new viruses as it can before it destroys and practically explodes the cell before it moves on to the next cell. Once the virus has multiplied, it travels through the blood again and spreads to the skin, viscera, kidney, and bladder. Measles starts off with symptoms of the common cold and after a couple of days Koplik spots appear in the mouth. Koplik spots are small red spots with bluish-white specks in the center of each and they are diagnostic indicators of the disease. After about 3 to 4 days the spots disappear and rash appears, about 14 days after initial incubation with the addition of a nonproductive cough and increased fever. Five to ten days after the rash persists it begins to subside but the measles virus is still present in the body. Infected persons are contagious for about five days before the rashes appear and five days after it has appeared.
An illness characterised by all of the following:
- generalised maculopapular rash, starting on the head and neck
- fever (at least 38ºC if measured) present at the time of rash onset
- cough or coryza or conjunctivitis or Koplik’s spots present at the time of rash onset.
See below for an audio visual describing the symptoms of measles (3.15 min in length)
Spread of infection
About 10 days, but may be 7–18 days from exposure to onset of fever. The incubation
period may be longer in those given immunoglobulin after exposure.
Mode of transmission
Airborne spread or by direct contact with nasal or throat secretions of cases.
Measles virus is highly contagious and can remain so for up to 2 hours in the air or on surfaces.
Period of communicability
For public health purposes, this can usually be considered from 5 days before to 5 days
after rash onset, counting the day of rash onset as day 1.
Anyone born from 1 January 19691 who has not had measles infection or has not
- been fully vaccinated for their age.
- Anyone born between 1969 and 1981 who only received a single dose of measles
- vaccine between the ages of 10 and 15 months (because of possible interference from the mother’s antibodies).
You are considered immune if :
Your date of birth before 1 January 1969 (they are presumed to be immune following
- exposure to the wild virus).
- You have documentation of immunity or previous infection.
- You have documentation of two doses of measles vaccine.
- If in doubt, vaccinate as there are no undue effects from vaccinating an individual who is immune.
The live attenuated measles vaccine induces an immune response that is similar to naturally acquired immunity and can be boosted by challenge from wild or vaccine virus.
Measles vaccine is at least 95% effective and seroconversion rates are close 100%. Primary vaccine failure of the first dose at 12 months of age or older occurs in up to 5% of people, but 95% of first dose failures will seroconvert from a second dose.
Maternal antibodies are the most common cause of primary vaccine failure. The age of first immunisation with measles vaccine must balance the chance of seroconversion with the risk of infection. This is why, in countries with endemic measles, the first dose of measles containing vaccine (MCV) is given as early as nine months, often complemented by another dose during the second year of life.
Transmssion Based Precautions
N95 Masks to be used if susceptible and in close contact.
Isolate until 4 days after onset of rash.
Please refer to the Auckland Regional public health website for further information