The doctor is unable to detect common parasite. Because it does not have the proper tools or is it possible that doctors do not have enough expertise around the world, most of which are also confronted with this issue.
The doctor can not detect the parasite. Because without the right tools or the possibility that the doctor is not specialized enough. Most of the world is still faced with this issue.
To see a doctor in general can not detect worm. Because of the lack of proper tools or possible that doctors do not have the expertise. Most of which all over the world is also faced with this problem.