The symptoms of fifth disease are worse in adults. Kids get a rash, runny nose, fever and headache which goes away after about a week. In adults it presents more like the flu, without rash, and significant joint pain for up to three weeks.
There was a young lass about age four or so, a few years ago, who developed breast cancer.
That’s not a bug, that’s a feature.
Highest in women who have just given birth, though (they should never be given aspirin because of the high risk). A childhood friend of mine died from it.
Of course it should also be noted that different cancers affect children than affect adults. Calling Leukemia one disease would be almost akin to lumping together chicken pox with small pox.
Asthma actually fits this bill in two ways. Most people have worse asthma symptoms as children, then the symptoms lesson as their lungs grow and the bronchi get larger. Many people (like me) who suffered a lot as kids are virtually symptom-free as adults. But I’m told that as you age, the problems tend to come back and get worse.
Note: this plot point may have been taken from the true-life experience of Gene Tierney Gene Tierney - Wikipedia (Christie never acknowledged this, but Tierney’s story was well-known when the book was being written)
People who have had chicken pox can get it again in old age, at which time it is called Shingles. Which is significantly worse in adults than their Chicken Pox was when they were children.
In case anyone wants to know which book, it was
The Mirror Crack’d
My old boss has a rare form of adult on set cystic fibrosis, which kills most children who have it, but as an adult, it progresses very slowly, likely due to a mature immune system. Don’t get me wrong because I like this boss, and it sucks that it will eventually kill him, but he’s been dying from it for more than a decade and he is already in his mid 60s, so by the time it does him in, he will still have had a pretty good life. Other than it making him short of breathe all the time, and making him a bit skinnier than normal, it doesn’t seem to affect his retirement or him coming out to dinner with us.
The younger victims’ systems put up a more robust fight, causing them to basically drown in their own tissues.
In general, older people acquire a more varied arsenal of antibodies as they experience less lethal flu strains.