What do you think Atticus means when he says"I hope and pray I can get jem and scout through it with out bitterness, and most of all,without catching maycombs usual disease"? What is maycombs usual disease?

Atticus mentions Maycomb's usual disease which is prejudice and racism. This sickness is very much a part of the American South and Atticus knows it is difficult to cure. Atticus hopes that he can navigate his kids around the racial ugliness that is taken for "normal" in Maycomb, "people go stark raving mad when anything involving a Negro comes up." Indeed, his children do look to Atticus which gives the reader a bit of hope in the end.