Children - Contagious childhood diseases (Part 1)

Parents often wonder whether it is necessary to keep their children at home when they are sick –how long are they contagious, and should they stay home? The answer varies depending on the disease.

Contagious diseases are easily transmitted from one person to the next. They can be caused by a virus, bacterium, parasite or fungus. The expression “causal agent” refers to the microbe that causes the disease.

Parents often wonder whether it is necessary to keep their children at home when they are sick –how long are they contagious, and should they stay home? The answer varies depending on the disease.


Definition, symptoms and causal agents Gastroenteritis is an inflammation of the digestive tract that causes vomiting or diarrhea, along with abdominal pain. It can be caused by a virus, bacteria or parasite.

Transmission Depending on the microbe at cause, infectious gastroenteritis is usually transmitted by the fecal-oral route or by consuming contaminated water or foods. The fecal-oral route means that the hands were contaminated by the stools. It is therefore crucial to teach our children to wash their hands with water and soap every time they go to the washroom, without exception, as well as before meals.

Treatment The treatment for gastroenteritis involves preventing dehydration and alleviating symptoms. When the child is no longer vomiting or expresses the wish to drink, you can offer a rehydration solution. They are sold in drugstores, but can also be home-made. The solutions available in pharmacies come in liquid form or as lollipops that can be frozen. Some children prefer the latter because the taste is less pronounced.

You can also easily prepare a home-made oral rehydration solution. Be sure to respect the proportions, however. Here are two options: 1) Mix one litre of water, 30 ml (6 tsp.) of sugar and 5 ml (1 tsp.) of salt. OR 2) Mix 360 ml (1½ cup) of pure unsweetened orange juice, 600 ml (2½ cups) of water and 2.5 ml (1/2 tsp.) of salt. These solutions keep for 12 hours at room temperature and for 24 hours in the refrigerator.

It is recommended that you get children to drink one sip at a time, waiting a few minutes between sips. This will prevent overtaxing the stomach, which is already irritated by the infection. When children tolerate the solution well and have not vomited for a few hours, you can let them drink a few sips at a time. They can probably begin eating again, if they express the wish to do so. You should begin with foods that are easy to digest, like bananas, rice, toast, or apple sauce (small amounts).

Very importantly, do not try to stop the diarrhea with medication, since diarrhea serves to evacuate the microbe that causes gastroenteritis.

A medical consultation is advisable in the following situations:
- Presence of blood or pus in the stools
- Inability to hold liquids or vomiting for more than 8 hours
- No urination for more than 12 hours
- Severe abdominal pain for more than 2 hours
- Fever of 38.5ºC or higher
- Symptoms of dehydration (dry mouth or lips, significant irritability, sunken eyes, sunken fontanelle in babies, rapid breathing, loss of skin elasticity)

Going back to school? Your children can go back to school once they have started eating again and they feel well enough to take part in classroom activities. If they had diarrhea, it is recommended that you wait until their stools are back to normal.

Vaccine There are two vaccines against two specific types of gastroenteritis. One if for infants and only protects against gastroenteritis caused by the rotavirus. It is administered at the age of two months and only protects for the first two years of life, which is when the risk of serious complications is greatest. The other vaccine is intended for individuals going on a trip and protects against traveller’s diarrhea (the “turista”).


Definition, symptoms and causal agents Conjunctivitis is an infection of the white of the eye. It can be caused by a virus or bacteria, but can also be the result of an allergy, exposure to a chemical, or a foreign body in the eye. In all these cases, the white of the eye is red. If the infection is caused by a virus, you will note a clear and watery discharge. If the causal agent is a bacterium, however, the discharge will be thicker, greenish or yellowish, and will tend to form a crust (especially upon waking in the morning).

Transmission When caused by a virus or bacterium, conjunctivitis is very contagious. Affected children are contagious until the infection is cured. In the case of bacterial conjunctivitis, they are no longer considered contagious after 24 hours of antibiotic treatment. It is important for children to wash their hands regularly, especially after touching their eyes.

Treatment Pharmacists can advise you on the treatment for most cases of conjunctivitis. They can recommend antibiotic drops or an antibiotic pomade, if necessary, and will show you how to use it. They will advise you on whether or not it would be appropriate to consult a doctor. It is essential to remember that these antibiotic products must be disposed of at the end of treatment, or at the very latest a month after opening.

To relieve discomfort, you can apply warm compresses to the affected eye for a few minutes 3 to 4 times a day.

If the infection is caused by a virus, eye drops will be ineffective. Just like the common cold that often comes with it, a viral infection must run its course.

Going back to school? Children with bacterial conjunctivitis should stay home for the first 24 hours of an antibiotic treatment. If they have viral conjunctivitis, they need not miss school. Do encourage them, however, to wash their hands regularly.

Vaccine There is no vaccine against conjunctivitis.


Definition, symptoms and causal agents A streptococcal infection is an infection that affects the throat. It is caused by a bacterium. Only 15 percent of throat infections are cause by streptococcus; most are caused by viruses.

All throat infections are accompanied by redness and soreness. Streptococcal infections, however, appear suddenly and also come with a high fever (over 38.5ºC). In addition, the physician will note the presence of white or yellow spots on your child’s otherwise red throat. Viral infections, for their part, often come with other respiratory symptoms such as a cough or nasal discharge.

Transmission Throat infections, whether they be streptococcal or viral, are spread through respiratory secretions, which are scattered through the air when a sick individual coughs or sneezes.

Treatment If the infection is viral, there is no specific treatment. An analgesic can be administered to relieve the pain. Another recommendation is to give your child soft foods (compote, soup, ice cream, etc.), as swallowing may be painful.

In the case of a streptococcal infection, the doctor will prescribe an antibiotic. It is important to take the antibiotic as prescribed, even if the symptoms disappear before the end of the treatment. An untreated streptococcal infection can lead to scarlet fever, a complication that can have serious repercussions, particularly on the heart and joints.

Going back to school? If the infection is viral, children can go back to school when they have no fever and feel well enough to take part in school activities. In the case of a streptococcal infection, they should stay home for the first 24 hours of the antibiotic treatment and until they can take part in classroom activities normally.

Vaccine There is no vaccine against streptococcus.


Teach your kids to wash their hands every time they go to the washroom, after sneezing or blowing their nose, and both before and after a meal, whether or not they are sick.

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