The temperature above the normal temperature of the body is called fever. It is a normal illness for people.
However, in some cases, fever can be long-lasting and fatal, and now the weather changes, in these contexts, teach to recite the prayer along with the poison of fever, cold, etc.
The meaning of the fever described in the hadith is - بِسْمِ اللَّهِ الْكَبِيرِ أَعُوذُ بِاللَّهِ الْعَظِيمِ مِنْ شَرِّ عِرْقٍ نَعَّارٍ وَمِنْ شَرِّ حَرِّ النَّارِ ‘Arir al-Hir-Ri-Ari-Ari-Ari-Ari-Ari-Ari-Ari-Ari-Ari-Ari-Ari-Ari-A-A-Ar-A-A-Tei- Meaning: In the name of Allah, I pray for Allah's refuge; from the attack of the heavy blood pressure and the evil of the fire of Hell.’ (Tirmidhi: 2075; Nasa'i; Maqbool Doa: 163)
Abdullah Ibn Abbas (RA) said, ‘Fever and other pain is the Messenger of Allah (PBUH). May Allah teach us this duaa purana allah keep us all free from all kinds of ailments.ameen.
English 
বাংলা