Prevalence of<unk> , 1995.<unk>  <unk>  or hypovitaminosis A is a lack of<unk>  A in blood and tissues. It is common in poorer countries, especially among children and women of reproductive age, but is rarely seen in more developed countries. Nyctalopia (night blindness) is one of the first signs of<unk> , as the<unk>  has a major role in phototransduction. Xerophthalmia, keratomalacia, and complete blindness can follow if the deficiency is more severe.<unk>  is the world’s leading cause of preventable childhood blindness, and is critical to achieving Millennium Development Goal 4 to reduce child mortality. About 250,000 to 500,000 malnourished children in the developing world go blind each year from a deficiency of<unk>  A, around half of whom die within a year of becoming blind. The United Nations Special Session on Children in 2002 set a goal of the elimination of<unk>  by 2010. The prevalence of night blindness due to<unk>  is also high among pregnant women in many developing countries.<unk>  also contributes to maternal mortality and other poor outcomes in pregnancy and lactation.<unk>  also diminishes the ability to fight infections. In countries where children are not immunized, infectious diseases such as measles have higher fatality rates. As elucidated by Alfred Sommer, even mild, subclinical deficiency can also be a problem, as it may increase children's risk of developing respiratory and diarrheal infections, decrease growth rate, slow bone development, and decrease likelihood of survival from serious illness.<unk>  is estimated to affect about one-third of children under the age of five around the world. It is estimated to claim the lives of 670,000 children under five annually. Around 250,000–500,000 children in developing countries become blind each year owing to<unk> , with the highest prevalence in Southeast Asia and Africa. According to the World Health Organization (WHO),<unk>  is under control in the United States, but in developing countries,<unk>  is a significant concern. Globally, 65% of all children aged 6 to 59 months received two doses of<unk>  A in 2013, fully protecting them against<unk>  (80% in the least developed countries).
Vitamin A deficiency
Vitamin E deficiency
Vitamin B12 deficiency
Tetra-amelia syndrome
Biotin deficiency
Chromium deficiency
Iodine deficiency
Child abuse