Measles is caused by a virus called Morbillivirus, a paramyxovirus.
The measles virus is very contagious and is spread by infected people coughing out droplets infected with the virus which other people then breathe in and so become infected. People who have been vaccinated with measles, mumps and rubella vaccine and are immune should not become infected. The incubation period for measles is 10-14 days — that is the time lag between a person being exposed to the virus and developing measles infection.
The first sign of measles infection is the appearance of small blue-white spots on a bright red background inside the cheeks in the mouth. The spots are about 1-2 millimetres in diameter and are known as Koplik’s spots. Koplik’s spots will fade and disappear after the measles rash starts on the skin.
The measles rash starts after the Koplik’s spots and consists of separate pink/red lesions that become joined together as the rash spreads. The ‘spots’ are flat red areas to start with, but then become raised up.
The rash starts around the ears and on the hairline. After 1-2 days the rash may spread to the body, arms and legs and start to fade on the face. Measles rash may be itchy, but is not intensely itchy.
From 2 to 5 days before the rash appears until about 4 days after the rash has started — which is often when it starts to disappear.
The rash will last 4-7 days.
While measles is a potentially serious disease, most people make a full recovery. You should keep your child comfortable and if their fever is a problem give them paracetamol. Paracetamol should be given as directed on the bottle to reduce the fever and ease headaches. Do not give your child aspirin.
If your child gets a secondary bacterial infection on top of the measles infection, your doctor will probably prescribe antibiotics, however, antibiotics will not help the measles, as measles is caused by a virus.
Rubella, which is commonly known as German measles, is caused by the rubella virus which is a togavirus.
German measles (rubella) is caught in the same way as measles. An infected person coughs or sneezes and so spreads droplets containing the virus, which other people breathe in and, if they are not immune, become infected with rubella.
The incubation period for German measles is 12 to 23 days — that is the time lag between being exposed to the virus and developing German measles.
The rash is pink and flat. The spots are very small, giving the rash a fine appearance. It is similar to the measles rash but less extensive and fades more quickly.
The rash starts around the hairline and affects the face and neck first. It will then spread to the body and the arms and legs.
A person with rubella will be infectious from one week before the rash starts until 4 days after the rash has started. However, newborn children who are infected may be infectious for a few months.
The rash usually lasts between 3 and 5 days and starts about 2 days after the person starts to feel unwell. Rubella is generally a much milder and less infectious illness than measles. Some cases are so mild that they are hardly detectable — these are called ‘subclinical’ infections.
German measles is such a mild disease that usually none of the symptoms needs to be treated. If children get a middle ear infection then the doctor will usually prescribe antibiotics. See your doctor if you think your child has any complications of German measles infection.
German measles in a pregnant woman, though, is very serious and may result in miscarriage or stillbirth or permanent damage to the growing baby.
|Chickenpox vesicle (on adult). The appearance of a fluid filled blister (vesicle) against a red background is characteristic of chickenpox.|
|Classical vesicle of chickenpox containing clear fluid and set against a background of a red areola.|
Chickenpox (also known as varicella) is caused by a member of the family of viruses called the herpes viruses. The virus that causes it is called the varicella-zoster virus.
Chickenpox is extremely contagious. Chickenpox infection is spread between people by tiny droplets infected with the virus being sprayed out by the infected person when they cough or sneeze. These droplets are then inhaled and taken in to the respiratory system of another person. If this person is not immune to chickenpox they will become infected.
The fluid-filled blisters (called vesicles) on the skin and mucous membranes are also full of infectious virus.
The incubation period can vary between 10 and 21 days, but is usually 14 to 15 days — that is the time lag between being exposed to the virus and developing chickenpox.
Chickenpox rash evolves through 3 stages, and a person may have examples of each type of spot at any one time. New crops of spots appear over a period of 2 to 4 days.
Chickenpox rash is often intensely itchy.
The rash starts on the trunk (body) and then later appears on the face, arms and legs. It is unusual for the rash to affect the palms and soles. Chickenpox spots (lesions) can sometimes be found on the eyelids and inside the mouth and the vagina.
Your child will be infectious from a few days before the symptoms start until all the vesicles have crusted over. So, until the last crop of vesicles has all crusted over, your child will be infectious.
The rash will last for between a few days to 2 weeks.
Chickenpox is usually a fairly mild illness of childhood. Sometimes the skin may become secondarily infected with bacteria through scratching of the spots. Should this happen, your doctor may prescribe antibiotics.
|A child with fifth disease. This picture is of a very mild example. Normally the rash is a very striking red rash across the cheeks giving the appearance of ‘slapped cheeks’.|
Slapped cheek disease, which is also known as fifth disease or erythema infectiosum, is caused by a virus called human parvovirus B19.
Fifth disease is caught by breathing in tiny droplets of moisture that are infected with the virus from a person who has the infection. The tiny droplets of moisture may be spread via a cough or sneeze by the infected person.
The rash is bright red and slightly raised. It gives the characteristic look of slapped cheeks on the face. This is followed by a lacy appearance which gives a blotchy look to the rash. The rash is not usually itchy.
The rash starts on the cheeks, but quickly appears on the body and arms and legs.
Your child will be infectious from a few days to one week before the rash appears. Once the rash has appeared, your child is probably no longer contagious.
The rash should go after about a week but can come and go for a few weeks after that. Exposure to sunlight may reactivate the rash.
Fifth disease is a mild illness and does not usually need any treatment. A child infected with fifth disease will have a mild fever, which may need treating with children’s paracetamol (not aspirin), and very rarely may have aching joints.
Last Reviewed: 18 October 2007