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Overview
Measles
Summary
• Measles is the most serious of the common childhood viral illnesses.
• Infants younger than one year of age, malnourished children and immunocompromised children are at risk for fatal measles.
• There is an effective vaccine against measles that can be given from nine months of age.
Description
The main features of measles are a running nose, cough, conjunctivitis and high fever, leading up to the appearance of a skin rash. Complications can be severe, including middle ear infection, croup, pneumonia, diarrhea and encephalitis.
Cause
Measles is caused by the measles virus, which occurs in humans everywhere in the world, except in highly isolated groups or where almost 100% of the population has been vaccinated.
Measles is a virus of humans and only causes infection in humans, but it has relatives that infect animals, notably the virus that causes the disease distemper in dogs and the virus that causes rinderpest in cattle and other hoofed animals.
Measles virus is spread in droplets from the nose and throat of people with measles. Another person in the vicinity breathes in these droplets and the virus infects the surface cells of that person's upper airways. Spread from person to person is assisted by the fact that a runny nose with sneezing (as in the beginnings of a cold) and coughing occurs in the early stages of the illness. The virus is also found in the urine of an infected person. A person is infectious from about three days before the rash appears and for up to five days after its appearance. Measles is highly contagious and almost everyone coming into contact with an infectious person will contract the disease, unless they have had measles before or have been vaccinated.
Symptoms
The earliest symptoms of measles are:
• Fever (climbing over three days to 39 to 40.5 degrees Celsius)
• Runny nose
• A harsh, dry cough
• Red, inflamed eyes (conjunctivitis) and aversion to bright light
After these symptoms begin, small white spots (sand-grain size) on a red base can be seen upon careful examination of the inside of the mouth, usually opposite the molar teeth on the inside of the cheeks. These are known as Koplik's spots. They are unique to measles and can therefore confirm the diagnosis of measles if an experienced health care professional identifies them. However, they appear and disappear in the space of less than a day and can easily be missed.
The symptoms above become increasingly severe and are at their worst when the rash appears. The rash of measles starts along the hairline of the neck and from behind the ears, and then spreads rapidly, within 24 hours, over the entire face, upper arms and chest. Over the next 24 hours it spreads over the back, stomach and thighs, eventually reaching the feet on the third day.
The rash starts as faint spots, which then become reddish and raised. As the rash progresses the individual spots characteristically tend to merge into one another; in severe cases the whole face may be swollen and disfigured. Once the rash reaches the feet, there is usually a sudden improvement, including a drop in temperature. (If the temperature does not drop at this point, a complication should be suspected.) The rash will start to fade and turn brownish, and some peeling occurs.
It is useful to remember that although the process is not visible, the rash is occurring internally as well, throughout the respiratory tract and the gut. This explains the cough, and stomach-ache with diarrhea that can also occur.
Complications
There are many serious complications that can occur in measles. Complications are more likely in malnourished children, and vitamin A deficiency in particular worsens the course of measles. (This is because vitamin A is important for the strength of the skin and membranes of the eye, respiratory tract and gut.)
Measles also tends to be more severe in infants younger than one year and in any person who is immunosuppressed, for example due to HIV infection or leukemia.
In impoverished areas of South Africa measles took a high toll on children until determined vaccination campaigns reduced the problem. The complications that can occur in measles are as follows:
• Croup (inflammation of the vocal cords and upper airways) is apparent by difficult and noisy efforts to breathe in. (Urgent medical attention is necessary because of the danger of complete obstruction of the airways.)
• Pneumonia can be due purely to the measles virus itself, but is more often because of added infection of the damaged airways and lung surfaces by other viruses or bacteria. Pneumonia becomes evident through rapid, difficult breathing, worsening cough and chest pain.
• Middle ear infection is very common and is apparent from pain in the ear. (This possibility should be kept in mind in distressed infants, since they cannot communicate the site of pain.)
• Diarrhea is usually mild but in malnourished children it can be severe and prolonged and further compromise the child's nutrition.
• Inflammation of the gut can, very occasionally, lead to appendicitis in measles.
• Bacterial infection (profuse pus) of inflamed eyes and scarring of the cornea with partial blindness is another risk for malnourished children if the eyes are not attended to early enough.
• Measles is such a serious infection and leaves the individual's immune system suppressed for some weeks to months afterward. It is believed that in the South African and other Third World contexts this contributes to flaring up or reappearance of tuberculosis in children.
• Another more immediate consequence of the immune dysfunction in measles can be severe herpes ulceration of the mouth.
• Encephalitis (inflammation of the brain) occurs in about 1/1 000 cases of measles. The risk increases with the age of the child. Because the encephalitis is believed to be an "allergic" type of reaction to the virus in the brain, there is no correlation between the severity of the measles and the risk of encephalitis. In other words, it can be a complication even of mild cases. Encephalitis usually occurs from two to seven days after the start of the rash, when the child should be starting to recover. Symptoms are recurrence of fever, onset of headache, apathy, irritability and confusion. Some children may have seizures. Most children recover from measles encephalitis in two to three days, but about 1/3 remains comatose for days to weeks. At least 10 percent of children with measles encephalitis die and some are left with mental retardation, deafness, paralysis or epilepsy.
• A delayed, fatal form of encephalitis appearing weeks to months after measles can occur in immunocompromised persons.
• Sub-acute sclerosing pan-encephalitis (SSPE) is an extremely rare but dread condition occurring usually many years after measles. For unknown reasons the virus persists in a weakened form in the brain of a very small number of people infected with measles, and eventually begins to cause degeneration in areas of the brain. It usually first becomes evident in subtle changes in personality, sleep patterns and intellect (for example, fall-off in schoolwork). Other early changes are failing eyesight and repetitive jerky movements. There is a slow downhill progression to death in every case.
• Very rarely the rash may be dark ("black" measles) due to bleeding into the skin. This severe type of measles has a high fatality.
Prevalence
The prevalence of measles in South Africa has decreased in the last decade or two through concerted efforts to vaccinate all children. Measles has been more successfully controlled in some regions, including the Western Cape, than in others, such as the Eastern Cape, due to differences in healthcare infrastructure.
In developing countries without measles vaccination programs, measles is common in children under two years: with high and continual prevalence of the virus, children are likely to encounter it early in life. However, with increased vaccination coverage there was a shift in South Africa to outbreaks among school-going children between five and 14 years of age.
In developed countries measles tends to be seen in adolescents or young adults as a consequence of waning immunity following incomplete vaccination. Measles has been virtually eliminated from the United States by a very strict vaccination program that has prevented the virus circulating in this population. In 1998 only 100 cases of measles occurred in the whole of the US and these all occurred through infected travelers entering the country. This type of measles control can be achieved with sufficient commitment and expenditure in any country.
Risk factors
Anyone who has not been properly vaccinated against measles is at risk for the disease and its complications. However, certain risks are much greater for the poorest members of South African society due to malnutrition, HIV prevalence and lack of adequate medical attention. Overcrowding may play a role by exposing children to a large "infective dose" of virus initially.
Measles is also more severe in infants younger than one year, a group in whom successful vaccination is difficult to achieve. Allowing measles to continue to circulate puts such children at risk. It should be borne in mind that measles vaccination is not simply a matter of protecting one's own child, but protecting others' as well.
When to see a doctor
Although measles is a serious illness, it usually follows a brief and predictable course so the majority of children can be managed at home, possibly with some supervision from a healthcare professional. Any complications will require a visit to your doctor or clinic for assessment and treatment. Some complications, such as severe croup, pneumonia, dehydrating diarrhea or encephalitis, are emergencies that require admission to hospital.
Diagnosis
An experienced health care professional can usually diagnose measles on the basis of the typical rash, but with the decreasing frequency of the disease there will soon be many doctors who have seen very few cases in their working lives. Mild measles is easily confused with rubella (German measles) and several other viral and non-viral rash illnesses.
Measles is a modifiable disease and it is currently a requirement of the Department of Health in South Africa that all suspected cases of measles be investigated and has laboratory testing at government expense. This requires a blood sample to check for the presence of measles antibodies and a urine sample from which the virus can be cultured.
In cases of pneumonia or other complications during measles, samples such as sputum might be collected for the laboratory to identify any additional viruses or bacteria responsible. This helps in the choice of the correct antibiotic.
Treatment
The majority of persons with measles can be managed at home, with simple remedies such as an antipyretic (agent that reduces fever), for example paracetamol or mefenamic acid, and a cough mixture.
Nutrition is very important, especially when the child was not well nourished beforehand. It may be difficult to get children to eat because of vomiting, herpes mouth ulcers or lack of appetite. High-energy liquid foods and extra vitamins should be given. Additional fluids should be given by mouth when there is diarrhea. A suitable homemade solution is as follows:
• ½ a teaspoon of salt
• 8 level teaspoons of sugar
• 1 L of boiled, cooled water
• Dissolve the salt and sugar in the water. (Do not be tempted to add extra salt or sugar, as this can be harmful.)
In infants, breast-feeding should be maintained and encouraged even if diarrhea is present. More severe diarrhea will require management in hospital.
The World Health Organisation (WHO) recommends that children younger than one year be given vitamin A supplements to reduce the risk of complications. Consult your health care professional about the appropriate dose of vitamin A, which is taken by mouth.
Cleaning of the eyes with warm, salty water and cotton wool helps prevent bacterial infection. Antibiotic ointment may be necessary if infection sets in, but a steroid eye ointment should not be used.
The mouth should be cleaned and rinsed with warm, salty water. Herpes ulceration and additional bacterial infection may require an anti-viral drug and possibly an antibiotic.
In general, antibiotics should only be given if there is a complication such as ear infection, pneumonia or dysentery (bacterial diarrhea). However, children at high risk of complications (severe malnutrition, AIDS) could be given broad-spectrum antibiotics at the outset to try to prevent the almost inevitable complication of bacterial infections.
Children with encephalitis require close nursing in hospital and a sedative drug if convulsions are a feature.
Prevention
By the time it is apparent from the rash that someone has measles, he or she has already been infectious for about three days. However, contact with others should still be avoided for five days after the rash appears. School-age children should remain out of school for this period. You should be aware that someone exposed to measles may be incubating the virus and if so, would become infectious about nine days after exposure. These facts can be important if you want to protect vulnerable persons, for example babies, immunocompromised persons and anyone with chronic illness.
In the event of exposure of a vulnerable person, measles can be prevented or modified to a variable extent by giving immunoglobulin (a protein capable of acting as an antibody) by intramuscular injection within five days. Immunoglobulin is prepared from adult serum that contains antibodies to measles, and provides "instant immunity".
Routine measles vaccination is given at nine and 18 months in South Africa. In private healthcare it may be given as the combined measles, mumps and rubella (MMR) "three in one" vaccine at 15 months. Vaccination of children younger than nine months is not reliable, because the mother's antibodies still present in the child's blood can neutralise the vaccine. On the other hand, these antibodies give some natural protection to children in the first months of life.
In the past few years, universal vaccination days for measles and polio have been organised by the Department of Health in South Africa. These are days when all children under five years should receive the vaccine, regardless of their previous vaccination record, in an effort to cover not only those children who have not received vaccine for some reason, but also the small percentage in whom the vaccine does not "take" or work for whatever reason. In any event, a booster vaccine helps to give long-term immunity.
The measles vaccine is a live measles virus that has been severely "handicapped" or attenuated by culturing techniques in the laboratory. After inoculation the measles vaccine virus will infect a person and cause the proper, protective immune response to measles without causing measles. However, up to 20% of people contract a mild fever and rash, usually six to eight days after vaccination. Unfortunately, about one per million people who have the vaccine get an "allergic" type of encephalitis (compared to the 1/1 000 risk after natural measles infection) and there is also a one per million risk of SSPE.
Live virus vaccines should not be given to pregnant women or very severely immunocompromised people (such as those suffering from leukemia). Measles vaccine is recommended for children with HIV infection because they are at risk for severe measles and they tolerate the vaccine well.
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