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What are the symptoms of infectious diseases?

Key facts

  • Serious infectious diseases can cause severe illness in children. Even if treated, some of these diseases can have life-long effects on the children who catch them.

  • It is useful for all parents to know how to recognise the early signs of these diseases so they can get help for their children, if needed.

  • If you decide not to vaccinate your child, they will be at increased risk of catching an infectious disease, and of getting seriously ill.

Last updated on 9 June 2023.
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It is useful for parents to be able to recognise early signs of serious infectious diseases in their children, so they can get help if needed.

The risks associated with serious infectious diseases are higher for children who have not been vaccinated or who have not had all their vaccinations on time, than for those who are fully vaccinated. This includes the risk of the child catching the infection, and the risk of the infection developing into serious illness. Even with treatment, some of these diseases can have life-long effects on the children who catch them. Some children do not survive a serious childhood illness.

Symptoms to watch out for

Most serious infectious diseases in babies and children start out looking like a common cold. It can be difficult to tell when it is something more serious. Below is a list of symptoms that could be a sign of serious disease.

It is important to note that not all children who are seriously ill have one of the symptoms listed. If your child seems unusually sick, you should:

  • call an ambulance on 000
  • or go to your local emergency department or see your doctor as soon as you can
  • or call Health Direct on 1800 022 222.

Fever is a sign of many infectious diseases. The symptoms of fever can vary. A child may have a fever if they have a high body temperature, if their skin is hot to the touch, or if they are shivering even though they are warmly dressed. Fever can also make babies and young children sleepy, drowsy, or lethargic, or make their skin look pale or mottled. Fever can be a little harder to pick up in babies as they often don’t show specific symptoms; they just seem to be very sick.

When a baby or child who has a fever is also crying more, or more intensely, than they usually do, or if their crying has an unusually piercing or high-pitched sound it could be a sign of meningitis (a brain infection). Meningitis can be caused by Hib, meningococcal disease, or pneumococcal disease.

Your baby or child should be taken to hospital immediately if they have a fever and at the same time:

  • light seems to hurt their eyes
  • they have a stiff neck and are not turning their head to look at you
  • they have a bulging soft spot (also called a ‘fontanelle’) on the top of their head
  • they have a rash that does not fade when you press on it with a drinking glass

If you need an ambulance to take you and your child to a hospital, call 000.

If your baby or child has a fit (seizure) and they have never had one before, it could be a sign they have meningitis. Call an ambulance on 000.

Sometimes babies or children who have serious lung infections (like pertussis or pneumonia) have long coughing fits. These coughing fits can make it difficult for them to breathe. If they are not able to breathe properly while they are coughing, their lips can turn blue. Sometimes babies will vomit after a coughing fit. Sometimes they will make a choking sound, or they will seem to be coughing silently. These are symptoms of lung infections such as pneumonia and might be caused by pertussis (also known as ‘whooping cough’), Hib, or pneumococcal disease.

Sometimes babies or children who are seriously ill will get blue lips while coughing or just after a coughing fit. Sometimes they stop breathing altogether for a moment or two after a coughing fit. These are symptoms of lung infections and can be caused by pertussis (also known as ‘whooping cough’), Hib, or pneumococcal disease.

If your child develops a rash, test to see if it fades (or ‘blanches’) when you push on it. Some parents do this by pushing the skin with a finger for a few seconds, then letting go. Others push a clear drinking glass onto the skin, bottom-side down, and then look to see if the rash fades underneath the bottom of the glass. A rash that doesn’t fade could be caused by meningococcal disease or pneumococcal disease. Usually, the rash does not appear until the baby or child is very sick. If your child has a rash like this, call an ambulance on 000.

Rashes that start when, or soon after, a child gets a fever, runny nose, sore throat, swollen or tender neck, or headache are a sign of many serious infectious diseases.

If your baby or child has an injury that causes a break in the skin, dirt can get into the wound. If that dirt contains tetanus spores, then they can get a tetanus infection. Animal bites, scratches from thorns or sharp stones in the garden, and punctures from old nails can cause tetanus infection. Wounds can become infected very quickly, so it is important to see a doctor straight away if your child gets an injury like this.

Babies and children who have not been vaccinated can get rotavirus gastroenteritis. Rotavirus gastroenteritis (or ‘gastro’) is worse than other types of gastro and can cause babies and children to get dehydrated. Babies and children should be taken to a doctor immediately if they are not drinking or eating, vomiting, experiencing diarrhoea, being very sleepy or lethargic, or being difficult to wake up.

What should I do if there is an outbreak of disease?

If you are aware of an outbreak of disease and you want to protect your child from getting sick, get in touch with your healthcare provider. It’s never too late to vaccinate. Some parents reconsider vaccinating their children if there is an outbreak of a disease in their community. 

What should I do if I think my child has an infectious disease?

If your child is sick and you suspect they have an infectious disease, then you should contact your healthcare provider. It is important to call before you visit so they can make sure there is no-one in the waiting room who could be vulnerable to a vaccine-preventable disease, such as people with certain illnesses, or people who are having certain medical treatments.

Medicines like antibiotics and immunoglobulins (also known as ‘antibodies’) are available for some infectious diseases. It is usually best to start treatment as soon as possible.