The location or the job is then said to be not conducive or, as Indians say, does not not suit you. And these people soon get sick of all this getting sick, and soon quit.
I have seen this happen to newbies in my precious company who did not like the city or the job. Uncannily, they used to fall genuinely ill or have some accident which could be pretty serious, and if not anything else, a very very bad case of cold which would prevent them from being able to work well. Naturally, already dissatisfied, they would find another reason to not stay. Perhaps this new city did not suit their health, and they would actively look out and soon shift jobs...even without another in hand in some cases.
It is difficult to say whether the subconscious does this. For subconscious thoughts and depressed state of mind can make you susceptible to illnesses like cold, flu, gastric troubles, and any other infections. It can make dormant health problems resurface - tooth troubles, backaches, allergies...all suddenly resurface, and since they are old troubles, people tend to disregard them.
However, freak accidents on the road? Well, one can never tell. Perhaps the mind becomes a little hazy and preoccupied. Depression in its severe forms can cause people to be indifferent to their surroundings, unhappiness can perhaps cause them to be just about careless enough to increase the probability of an accident.
The person either then becomes used to the environment, and accepts the 'hardships', and stays continuously but mildly ill, else quits and joins another organization where they tend to be better.
In some cases of course, initial adjustments to a new environment can cause the same symptoms, but then it does not last more than a month or so.
The above is based on observation of colleagues, friends and myself in various circumstances.
M tended to fall severely ill in earlier part of her job when she was uncomfortable with her boss, and then again now.
I had fallen ill pretty regularly in the initial part of my job for about 10 months, thanks to my first boss, which was followed by
a pretty healthy two years, with hardy any major illnesses, nothing that would really lay me up in bed or impede work. I see things repeating.
There have been trainees from other cities who have fallen ill at every pretext, with no lack of precaution from their end - continuous nagging colds, infections, falls from bikes, stairs, etc. Name it. Jaundice to fractures.