Sayyiduna Abu Hurayrah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "No disease is contagious, and it is not permissible to bring the sick to the healthy, so that the healthy may stay wherever he wishes." It was said: O Messenger of Allah! What is the reason for this? He (peace and blessings be upon him) said: "It is a harm."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14239