Rickets, scientific nomenclature: rachitis (from Greek ῥαχίτης rhakhítēs,[6] meaning 'in or of the spine'), is a condition that results in weak or soft bones in children and may have either dietary deficiency or genetic causes.

[2] Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping.

[23] Exclusively breast-fed infants may require rickets prevention by vitamin D supplementation or an increased exposure to sunlight.

[24] In sunny countries such as Nigeria, South Africa, and Bangladesh, there is sufficient endogenous vitamin D due to exposure to the sun.

However, the disease occurs among older toddlers and children in these countries, which in these circumstances is attributed to low dietary calcium intakes due to a mainly cereal-based diet.

[28] Sunlight, especially ultraviolet light, lets human skin cells convert vitamin D from an inactive to active state.

In the absence of vitamin D, dietary calcium is not properly absorbed, resulting in hypocalcaemia, leading to skeletal and dental deformities and neuromuscular symptoms, e.g. hyperexcitability.

Persistent thick fog and heavy industrial smog permeating the city blocked out significant amounts of sunlight to such an extent that up to 80 percent of children at one time had varying degrees of rickets in one form or the other.

[33] It is sometimes known "the English Disease" in some foreign languages (e.g. German: Die englische Krankheit, Dutch: Engelse ziekte, Hungarian: angolkór, Swedish: engelska sjukan).

The correlation between human skin color and latitude is thought to be the result of positive selection to varying levels of solar ultraviolet radiation.

[37] Similar to the environmental mismatch when dark-skinned people live at high latitudes, Rickets can also occur in religious communities that require long garments with hoods and veils.

[38] These hoods and veils act as sunlight barriers that prevent individuals from synthesizing vitamin D naturally from the sun.

[42] This can be explained by limited sun exposure due to cultural practices and lack of vitamin D supplementation for breast-feeding women.

[citation needed] A systematic review published in the Cochrane Library looked at children up to three years old in Turkey and China and found there was a beneficial association between vitamin D and rickets.

[54] The radiologic picture and the laboratory findings of serum calcium, phosphate and alkaline phosphatase are important differentiating factors.

Blount's disease is an important differential diagnosis because it causes knee deformities in a similar fashion to rickets namely bow legs or genu varum.

This issue appears to be more common for solely nursing infants of black mothers, in winter in temperate climates, suffering poor nutrition and no vitamin D supplementation.

[56] Treatment involves increasing dietary intake of calcium, phosphates and vitamin D. Exposure to ultraviolet B light (most easily obtained when the sun is highest in the sky), cod liver oil, halibut-liver oil, and viosterol are all sources of vitamin D.[57] A sufficient amount of ultraviolet B light in sunlight each day and adequate supplies of calcium and phosphorus in the diet can prevent rickets.

[4] Greek physician Soranus of Ephesus, one of the chief representatives of the Methodic school of medicine who practiced in Alexandria and subsequently in Rome, reported deformation of the bones in infants as early as the first and second centuries AD.

Rickets was not defined as a specific medical condition until 1645, when an English physician Daniel Whistler gave the earliest known description of the disease.

In 1650 a treatise on rickets was published by Francis Glisson, a physician at Caius College, Cambridge,[65] who said it had first appeared about 30 years previously in the counties of Dorset and Somerset.

[66] In 1857, John Snow suggested rickets, then widespread in Britain, was being caused by the adulteration of bakers' bread with alum.

[67] German pediatrician Kurt Huldschinsky successfully demonstrated in the winter of 1918–1919 how rickets could be treated with ultraviolet lamps.

[68][69][10] In 1923, American physician Harry Steenbock demonstrated that irradiation by ultraviolet light increased the vitamin D content of foods and other organic materials.

[70] However, beginning around 2003, rickets reemerged as an issue in the US for some populations[71] causing the American Academy of Pediatrics recommended that all infants have Vitamin D intake of 200 IU per day.