See this thread ....
http://www.freerepublic.com/focus/news/3717837/posts?
I had to scroll through a LOT of pages before I finally was able to find any indication of little Ritchies condition. It seems he has an autoimmune disease.
Autoimmune diseases are an unfortunate and aberrant reaction to immune challenges such as those that occur following infections. They happen when the immune system mistakenly starts making antibodies against self proteins instead of the pathogen proteins. They can also occur after taking medications. I had a cat who nearly died from severe autoimmune disease after giving her antidepressants (yes, those can be prescribed to pets).
Do not be tempted into embracing antivax hooey because of this. You need to consult closely with specialists; they may recommend avoiding vaccines and doing everything you can to decrease the chance that he will be exposed to disease. In this case, then you will want to make sure that any children whom he may encounter are fully vaccinated, because herd immunity would be the only thing protecting him.