It is physical sickness, but physical sickness can be brought on by sin. Matter of fact, all sickness is a punishment for sin. However, it does not mean the sick person was the one who sinned. If a homosexual gets AIDS, and a mosquito bites him and then bites another person, it does not mean THAT person committed that dreadful sin. But people do get sick due to their own sin problems, but it does not automatically mean that.
The apostles asked Jesus about a man blind since birth. They asked who sinned- him or his parents? Jesus said he was blind for a different reason- so that He could miraculously make him see, so that witnesses can clearly see that Jesus truly was the Son of God. But Jesus also said, "What is easier to say, be healed, or your sins are forgiven you?" Conclusion: sickness is caused by sin, but there are some exceptions, but we all sin anyways and all deserve the consequences thereof, however being that Christ paid for the Christians sins, we may ask the elders to pray over us, because the prayer of a righteous man is powerful and effective.
That's right, there is a connection between health issues,(both physical and spiritual) and sin. Today modern medicine and science has convinced the world there is no connection, because they do not believe in the spiritual. Even such spiritual matters as being given over to reprobate mind and mind of confusion like homosexuality, transgender thoughts are explained away, not even considered "mental illness" no more by modern science, but even now are being accepted and embraced.
Evil spirits can both effect the physical body and the mind, but even many Christians don't truly believe in such things.