I say, and with God's success: If someone emits semen without desire, such as due to illness, fatigue, carrying something heavy, or being struck on the back, then it is not obligatory for him to perform ghusl; because the condition for the obligation of ghusl upon emission is the separation of semen from its place and its resting place due to desire, and since the condition is not fulfilled, ghusl is not required. Refer to: رد المحتار 1: 108، والوقاية ص94، والسعاية 1: 310، والهداية 1: 17، والاختيار 1: 20، والكنْز ص4، والملتقى ص4، ومختصر القدوري ص3، والله أعلم.