That can be mainly attributed to different lifestyle.
Health-wise, a similar picture. In Thailand two ear infections that required medical attention, in Europe one. I got as many colds in Thailand (about 10) as the rest of my life in Europe. As many sunburns in Thailand (about 5 to 10) as the rest of my life in Europe. I remember one diarrhea in Europe, and had 5 to 10 (mostly mild, one but one required medical attention) in Thailand.
There is one positive: I haven't vomited once in Thailand, but about 5 times in Europe (one alcohol overdose, others food related).