SB 7.5.27
santi hy asadhavo loke
durmaitras chadma-vesinah
tesam udety agham kale
rogah patakinam iva
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In due course of time, various types of diseases are manifest in those who are sinful. Similarly, in this world there are many deceptive friends in false garbs, but eventually, because of their false behavior, their actual enmity becomes manifest.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Being anxious about the education of his boy Prahlada, Hiranyakasipu was very much dissatisfied. When Prahlada began teaching about devotional service, Hiranyakasipu immediately regarded the teachers as his enemies in the garb of friends. In this verse the words rogah patakinam iva refer to disease, which is the most sinful and miserable of the conditions of material life (janma-mrtyu-jara-vyadhi). Disease is the symptom of the body of a sinful person. The smrti-sastras say:
brahma-ha ksaya-rogi syat
surapah syavadantakah
svarna-hari tu kunakhi
duscarma guru-talpagah
Murderers of brahmanas are later afflicted by tuberculosis, drunkards become toothless, those who have stolen gold are afflicted by diseased nails, and sinful men who have sexual connections with the wife of a superior are afflicted by leprosy and similar skin diseases.