The poliovirus destroys the nervous system, causing paralysis. Today, polio is extremely rare in the United States because of the polio vaccine. It's still common in other countries, though, so children still need to be immunized.

Pneumococcus bacteria can cause serious illness in children, including pneumonia, infection in the blood, and meningitis.

Detailed information on the stages of play for all ages

H. pylori (Helicobacter pylori) is a spiral-shaped bacteria that infects the stomach. It can damage the tissue in your child’s stomach and the first part of the small intestine. This can cause redness and swelling. It may also cause painful sores, called peptic ulcers, in the upper digestive tract.

Biliary atresia is a rare liver disease that occurs in infants. It is often found shortly after birth. The disorder affects tubes in the liver called bile ducts. If not treated with surgery, it can be fatal.

The MMR vaccine is given in 2 doses--at 12 to 15 months and at 4 to 6 years, or at least 1 month after the first dose.

Appendicitis is a painful swelling and infection of the appendix. It is a medical emergency. The appendix can burst or rupture. This is serious and can lead to more infection. If not treated, it can be fatal.

Anorectal malformations are birth defects, or problems that happen as an unborn baby is developing during pregnancy. With this defect, the anus and rectum don’t develop properly. They are the lower part of the digestive tract.

Kyphosis is a deformity of the backbone (spine). It's when the bones of the spine (vertebrae) in the upper back curve outward more than they should.

Addison disease is when the adrenal glands don't make enough of two steroid hormones. The hormones are cortisol and aldosterone. Cortisol controls the body's metabolism, blocks inflammatory reactions, and affects the immune system. Aldosterone manages sodium and potassium levels. Addison disease is fairly rare and may first appear at any age.