Health Topics A-Z

Varicose veins, or varicosities, are swollen, twisted veins that lie just under the skin. They usually occur in the legs.

Viral Hepatitis (a kind of hepatitis caused by a virus) can cause liver inflammation and damage. There are five main types: hepatitis A, B, C, D, and E.

Vision loss includes a range of conditions—from low vision to blindness—that make everyday activities harder. 

Vitiligo is a chronic autoimmune skin condition that causes loss of skin pigment.

West Nile virus is a mosquito-borne virus that can cause no symptoms at all or life-threatening brain inflammation. It is the leading cause of mosquito-borne disease nationwide.

Zika virus infection is a mosquito-borne illness that can cause serious health complications, particularly for people who are pregnant. First discovered in Uganda in 1947, the virus has since spread to multiple regions of the world and sparked major outbreaks in the Americas. NIH supports research to better understand Zika virus and its mosquito vector, the disease it causes, and ways to combat it.