What is the ruling on a woman touching her disabled brother-in-law to clean him and perfume his body, even though he has no desire for women and cannot see well?

It is impermissible for a woman to touch her husband's brother because he is not a mahram to her, even if he is disabled and has no inclination towards women. This is because the concession regarding those who have no inclination towards women is in looking at them without a hijab, not in touching. Exceptions to this rule are dire necessity and extreme need, such as when there is no one else to attend to his affairs besides her, in matters of medical treatment or cleaning, provided there is no fear of fitna. Nevertheless, if someone else from his mahrams can perform these tasks, then it is not permissible for her to do so.