From: Luke 4:38-44
The Cure of Peter's Mother-In-Law
 And He (Jesus) arose and left the synagogue, and entered Simon's house. Now Simon's mother-in-law was ill with a high fever, and they besought Him for her.  And He stood over her and rebuked the fever, and it left her; and immediately she rose and served them.
 Now when the sun was setting, all those who had any that were sick with various diseases brought them to Him; and He laid His hands on every one of them and healed them.  And demons also came out of many, crying, "You are the Son of God!" But He rebuked them, and would not allow them to speak, because they knew that He was the Christ.
Jesus Preaches in Other Cities in Judea
 And when it was day He departed and went into a lonely place. And the people sought Him and came to Him, and would have kept Him from leaving them;  but He said to them, "I must preach the Good News of the Kingdom of God to the other cities also; for I was sent for this purpose."  And He was preaching in the synagogues of Judea.
38-39. In the public life of Jesus we find many touching episodes (cf. for example Luke 19:1; John 2:1) which show the high regard He had for everyday family life.
Here we can clearly see the effectiveness of prayer on behalf of other people: "No sooner did they pray to the Savior", St. Jerome says, "than He immediately healed the sick; from this we learn that He also listens to the prayers of the faithful for help against sinful passions" ("Expositio In Evangelium Sec. Lucam, in loc.").
St. John Chrysostom refers to this total, instantaneous cure: "Since this was a curable type of illness He displayed His power through the way He brought healing, doing what medicine could not do. Even after being cured of fever, patients need time to recover their former strength, but here the cure was instantaneous" ("Hom. on St. Matthew", 27).
The Fathers saw in this lady's fever a symbol of concupiscence: "Peter's mother-in-law's fever represents our flesh affected by various illnesses and concupiscences; our fever is passion, our fever is lust, our fever is anger--vices which, although they affect the body, perturb the soul, the mind and the feelings" (St. Ambrose, "Expositio Evangelii Sec. Lucam, in loc.").
On the practical consequences of this St. Cyril says: "Let us receive Jesus Christ, because when He visits us and we take Him into our minds and hearts, even our worst passions are extinguished and we are kept safe to serve Him, that is, to do what pleases Him" ("Hom. 28 In Mattheum").
43. Our Lord again stresses one of the reasons why He has come into the world. St. Thomas, when discussing the purpose of the Eucharist, says that Christ "came into the world, first, to make the truth known, as He Himself says: `for this I was born, and for this I have come into the world, to bear witness to the truth' (John 18:37). Hence it was not fitting that He should hide Himself by leading a solitary life, but rather that He should appear openly and preach in public. For this reason He tells those who wanted to detain Him, `I must preach the Good News of the Kingdom of God to the other cities also; for I was sent for this purpose.' Secondly, He came in order to free men from sin; as the Apostle says, `Christ Jesus came into the world to save sinners' (1 Timothy 1:15). This is why Chrysostom says, `Although Christ might, while staying in the same place, have drawn all men to Himself to hear His preaching, He did not do so--in order to give us the example to go out and seek the lost sheep, as the shepherd does, or as the doctor does, who visits the sick person.' Thirdly, He came so that `we might obtain access to God' (Romans 5:2)" ("Summa Theologiae", III, q. 40, a. 1, c.).
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.