It is recommended that your child should be vaccinated against Measles if they have received a letter from school requesting your consent to do so. Case definition for a suspected measles case. Suspect measles in any individual presenting with:
* fever (≥38℃) and
* rash and
* one or more of the following: cough, coryza (runny nose) or conjunctivitis (red eyes)
What is Measles?
Measles is a highly contagious, serious disease that is usually seen in children, but can affect adolescents and adults as well. It is caused by a virus belonging to the genus Morbillivirus of the family Paramyxoviridae. Measles is one of the leading causes of death among young children even though a safe and cost-effective vaccine is available. In 2015, there were 134 200 measles deaths globally – about 367 deaths every day or 15 deaths every hour.
What are the clinical features of Measles?
* The incubation period is 10 to 14 days (often longer in adults than in children).
* The prodromal phase begins after the incubation period and lasts for several days. It is characterized by malaise, fever, loss of appetite, and ‘the three C’s’: conjunctivitis (red, watery eyes), cough and coryza (runny nose); the illness may resemble a severe respiratory tract infection. Towards the end of the prodrome, just before the appearance of the rash, Koplik’s spots may appear on the buccal mucosa. These are tiny white spots with bluish-grey centres and are pathognomonic for measles, but may easily be overlooked.
* The rash of measles usually appears 3 – 5 days after the start of the prodrome. It begins on the face and spreads down the body to involve the neck, trunk, and lastly the arms and legs, including the palms and soles.
* It is erythematous and maculopapular and becomes confluent as it progresses, especially on the face and the neck.
* During the healing phase, the involved areas (except palms and soles) may desquamate. The rash usually lasts about 5 days. The patient with measles is usually most ill during the first or second day of the rash. Several days after the appearance of the rash the fever abates and the patient begins to feel better.
* The duration of the uncomplicated illness from late prodrome to resolution of the fever and rash, is 7 to 10 days.
How is infection acquired?
Measles is airborne and is spread by droplets from respiratory secretions of infected persons; it is transmitted by breathing, coughing or sneezing, and also by direct contact with infected nasal or throat secretions. It is one of the most communicable of the infectious diseases. Nosocomial (hospital acquired) infections are well described, particularly amongst children.
When are patients with measles most infectious?
The virus remains active and contagious in the air or on infected surfaces for up to 2 hours. It can be transmitted by an infected person from 4 days prior to the onset of the rash to 4 days after the rash erupts. The patient should stay home for at least this period. Immunocompromised patients may not develop a rash.
What specimens should be submitted?
A blood specimen for serology (IgM and IgG) should be collected from all cases that meet the suspected case definition of measles. Throat swabs may be requested in addition during a suspected outbreak. Specimens should be taken within 48 hours of the onset of rash.
* For PCR detection of measles virus
* A dry swab can also be used
What is the treatment for measles?
Treatment is supportive, including antipyretics and fluids as indicated. Bacterial superinfection should be promptly treated with appropriate antimicrobials. Vitamin A should be administered orally to all children with suspected measles as this may decrease the severity of measles complications.
Vitamin A dosage: 50 000IU daily X 2 days for infants < 6 months, 100 000IU daily X 2 days for infants 6-11 months, 200 000IU daily X 2 days for children 12 months or older.
Complications of measles:
The most common complications are pneumonia (either due to the measles virus or as a result of secondary bacterial or viral infection), diarrhoea, croup, otitis media, mouth ulcers and eye pathology (leading to blindness). Rarely, encephalitis may occur resulting in permanent brain damage. Myocarditis, pneumothorax, pneumo-mediastinum, appendicitis and sub-acute sclerosing panencephalitis (SSPE), a fatal chronic infection of the brain, have all been reported but are uncommon complications.
What is the differential diagnosis of Measles?
This includes other infections presenting with a fever and rash:
* Scarlet fever (Streptococcus pyogenes)
* Erythema infectiosum (parvovirus B19)
* Typhoid fever
What are the recommended diagnostic tests for measles?
Both IgM and IgG antibodies are produced during the primary immune response and can be detected in the serum within a few days of rash onset.
A positive measles IgM (serological) test confirms the diagnosis of acute measles infection. Ninety percent of measles cases are IgM positive at 3 days post rash onset. IgM antibody levels peak after about 7-10 days and then decline rapidly, being rarely detectable after 6-8 weeks.
IgG antibody levels peak within 4 weeks and persist long after infection. A positive IgG test cannot exclude a re-infection. A four-fold rise in IgG in paired sera 10-14 days apart may confirm an acute infection. Throat swabs may be recommended at times of outbreaks to confirm the presence of measles virus and to do additional tests such as genotyping. Throat swabs are not recommended in inter-epidemic time periods.
How is measles prevented in SA?
Childhood vaccination is the most important preventive strategy against measles. In South Africa, children are vaccinated against measles as part of the SA-EPI (Expanded Program on Immunization) schedule at 9 months of age with a booster at 18 months of age.
After these 2 doses of vaccine the protection rate is 95%. Immunity persists for many years after vaccination. Adolescents and adults who are unsure if they have been vaccinated during childhood can also receive vaccine, especially if they may be in contact with measles cases (e.g. health care workers, school teachers). The measles vaccine is often incorporated with rubella and/or mumps vaccines. It is equally
effective in the single or combined form. Adding rubella to measles vaccine increases the cost only slightly, and allows for shared delivery and administration costs.
Vaccine or Immunoglobulin?
Vaccinate all people that have been exposed to a known case. One may contract measles even by just being in the same room as someone with proven measles, and even up to two hours after the patient has left the room. However, do not vaccinate pregnant women (it is a live vaccine). The vaccine, if administered within 72 hours of initial measles exposure, or immunoglobulin (IG), if administered within six days of exposure, may provide some protection or modify the clinical course of disease.
If the vaccine is not administered within 72 hours of exposure as post-exposure prophylaxis (PEP), the vaccine should still be offered at any interval following exposure to the disease in order to offer protection from future exposures. People who receive the vaccine or IG as PEP should be monitored for signs and symptoms consistent with measles for at least one incubation period (14 days).
Except in healthcare settings, unvaccinated people who receive their first dose of the vaccine within 72 hours after exposure may return to childcare, school, or work.
Immunoglobulin (IG) as post-exposure prophylaxis may be administered to some measles contacts within 72 hours of exposure (some effect if given within six days). Patients to consider for IG are:
* The immunocompromised
* Non-immune pregnant women (but there is no evidence it prevents fetal loss).
* If the mother is not immune her exposed infant aged under 6 months should be considered for IG as maternal antibodies are absent and the infant thus not protected at all. Children may be vaccinated at 6 months against measles, and again at 12 months.
Because pregnant women might be at higher risk for severe measles and complications, intravenous IG (IGIV) should be administered to pregnant women without evidence of measles immunity who have been exposed to measles. People with severely compromised immune systems who are exposed to measles should receive IGIV regardless of immunologic or vaccination status because they might not be protected by the vaccine.
IG should not be used to control measles outbreaks, but rather to reduce the risk for infection and complications in the people receiving it.
After receipt of IG, people cannot return to healthcare settings. In other settings, such as childcare, school, or work, factors such as immune status, intense or prolonged contact, and presence of populations at risk, should be taken into consideration before allowing people to return. These factors may decrease the effectiveness of IG or increase the risk of disease and complications depending on the setting to which they are returning.
The recommended dose of IGIM is 0.5 mL/kg of body weight (maximum dose = 15 mL) and the recommended dose of IGIV is 400 mg/kg.
What is the recommended public health response in SA to a case of Measles?
Measles is a notifiable disease in SA. All suspected cases must be reported immediately by telephone to the Department of Health. The Department of Health will follow up the cases, and vaccination is offered to at risk contacts. Standardized case investigation forms are used to facilitate contact tracing and establish links between confirmed cases.
All patients presenting at health facilities with suspected measles should be isolated on admission to prevent nosocomial spread.Prevention of nosocomial infections is aided by strengthening compliance with standard infection control precautions, and ensuring “fast-tracking” and isolation of all suspected cases. During a measles outbreak it is recommended that hospitals introduce routine vaccination of all children >6 months of age admitted to hospital irrespective of vaccination history to reduce the risk of nosocomial transmission. Depending on the size of the outbreak, the Department of Health may also decide to institute mass vaccination programmes at schools and other institutions where children congregate.
Currently a mass vaccination campaign is underway in the Western Cape and everybody should adhere to it.
Dr Willem Smit Paediatrician