Medical Q&As

Recurrent infections - 4 year old child?

My daughter started school in September and has been ill 6 times since, including vomiting and high temperatures. Her doctor is not too concerned saying she is mixing with other kids and it happens a lot. She was in playschool for 2 years and rarely got ill. I'm worried that there is something more serious wrong with her. Is her immune system so low, that it can't recover in time before the next illness? She is 4 years old.

The scenario you describe is very common. When young children start going to school they are exposed to a great deal more infectious agents than they would have been exposed to in playschool or at home. Immunity against disease develops as a result of forming antibodies in response to being infected. There are many hundreds of viruses that young children can be exposed to and when a child is exposed to a particular virus the child usually develops life-long immunity against that specific virus. For example, there are approximately 70 different strains of the rhinovirus, which is the virus that causes the common cold. If a child becomes infected against one strain of the rhinovirus they are protected against being infected with that strain again but that same child could become infected with any of the other strains of rhinovirus. In other words you do not develop cross immunity between the different strains of rhinovirus. Therefore you could have a scenario where a child appears to develop one cold after another but on each occasion the child is being infected with a different strain of rhinovirus. If we then consider the various other viruses such as Coxsackie virus, respiratory syncitial virus and echovirus and their various sub strains, we reach a situation where the potential exists for a child to be infected by any one of hundreds of strains of virus. Given the close physical proximity of children to each other in the average class room it is not difficult to imagine how children can infect each other very easily. I would expect that over the coming couple of years that your child’s frequent bouts of infection should decline sharply. This decline will happen simply because the child’s immune system will have been exposed to a myriad of viruses and will have developed the specific antibodies against those viruses.