Bacteria, viruses, and parasites can cause a wide variety of illnesses, and can infect any of the organs of the body. Viruses are often responsible for respiratory illnesses (such as the common cold) and digestive illnesses (such as diarrhea).
Disability will not pay for any more time off work than that for pregnancy. After that, many employers let you stay off for the full 3 months for maternity leave but the disability cuts off after 6 or 8 weeks, depending on how you delivered. That's not just how Aflac does it, that's how all disability works.
Keep in mind that sick time must first be exhausted, so if you have sick time to cover the first 6-8 weeks you are out on leave, you will not be eligible for Short Term Disability payments. STD only covers the medical portion of the maternity leave, and will not be approved during the child bonding portion of the leave.