Preschool children are at greater risk because it coincides with the peak prevelance of severe protein energy malnutrition.
Majority of the cases of corneal xeropthalmia occur between 1 and 3 years.
There is a progressive increase in the prevalence up to the age of 12-13 years.
The normal lesions, however are rarely seen in the children above the age of 6 years.
Gender: Xeropthalmia is more frequent in boys than in girls. However, incidence of keratomalacia is similar in both the sexes.
Low purchasing power of families.
Children from rural and tribal families belonging to low income groups are vulnerable to Vit A deficiency.
The incidence is high in interior and remote villages with no transport facilities and no access to any services.
Illiteracy of mothers and lack of awareness of importance of diet in diseases.
Food fads and false beliefs:
Avoidance of Vit A rich foods like colostrum, green leafy vegetable, papaya etc by Young children, pregnant & lactating women, because of false beliefs.
Inadequate dietary intake:
Vitamin A deficient diets are consumed by pregnant and lactating mothers as a result, the off spring is born with poor liver stores of Vitamin A.
Also the intake of vitamin A by the children either during the weaning period or at later ages is inadequate and provides only 25-30% of recommended intake.
Animal foods like eggs, milk and liver provide vitamin A. But these are expensive and the communities cannot afford these. Consequently they depend on plant foods which provide only provitamin A.
Illiteracy & Ignorance: Due to female illiteracy and consequent ignorance, supplementation with vitamin A rich foods is delayed and certain rich sources of β-carotene like green leafy vegetables and papaya are avoided with the belief that these are deleterious to the health of children, due to lack of awareness, the community does not make use of primary health services like diarrhea control, immunization, Vitamin A supplementation and other basic health services.
Improper methods of cooking: Boiling or prolonged heating at high temperature has deleterious effects in the retention of carotenes. Presence of oil helps in retaining β-carotene better. Vitamin A is lost by oxidation also.
Seasonal effects: Seasonal changes in vitamin A deficiency are related to time of harvest. Green leafy vegetables availability is high in rainy/ winter season. Mangoes are available for two months in summer. Vit A status during this season may change towards positive side.
Drought: Extent of vitamin A deficiency is more during drought, due to non availability of leafy vegetables. Prevalence is higher in areas which are chronically drought prone.
Regional differences: In India, prevalence of Vitamin A deficiency is more than the WHO critical limits in most of the states. It is relatively higher in southern and eastern parts of the country. NNMB surveys indicate higher prevalence of xerophthalmia in the states of AP, Gujarat, Karnataka, Orissa, Uttar Pradesh and West Bengal.
Inadequate dietary intake of vitamin A or is precursor (β-carotene) in pregnancy, lactation & infancy is the most important contributing factor.
As a result of low dietary intake of Vitamin A in pregnant women off spring is born with poor liver stores of Vit A.
Intake of vitamin A by the children either during weaning period or at later ages is obviously inadequate and provides only 25-30% of the recommended intakes.
Infections and associated morbidity: Common childhood infections like measles, diarrhea, respiratory tract infections and infestations like ascariasis and giardiasis interfere with the absorption of vitamin A.