1. Something is wrong with your body internally. This can trigger messages to be sent to your brain. These messages can be in the medium of pain, or communication to your subconsciousness.
2. If your dream tells you that it is not a tangible disease that is bothering you, then the disease is a metaphor. It could be a problem in your home environment, or workplace.
3. Dreaming of disease can be an epidermic that is beyond your control.
4. A sense of helplessness during the day can trigger a dream about a disease.

If you dream that someone else is having a disease, it can mean:

1. You have knowledge that person is ill.
2. You have observed that person having difficulties.
3. You know that person is not behaving naturally because of certain reasons.

To dream of having a disease, or seeing someone with a disease, is a warning. Dreams of disease are threats. What can the dreamer do? They can reflect on what they are able to do, to prepare to handle the threats.