Vitamin A deficiency is considered a public health problem if prevalence rate of night blindness in children between 6 months to 6 years is more than –
**Core Concept**
Vitamin A deficiency is a significant public health concern worldwide, particularly in children, as it can lead to night blindness, impaired immune function, and increased risk of infections. The World Health Organization (WHO) has established criteria to determine the prevalence of Vitamin A deficiency in populations.
**Why the Correct Answer is Right**
Night blindness, or xerophthalmia, is an early sign of Vitamin A deficiency. The WHO defines a Vitamin A deficiency as a public health problem if more than 5% of children between 6 months and 6 years of age have night blindness. This is because Vitamin A plays a crucial role in the health of the retina, and deficiency can lead to impaired vision in low light conditions. The prevalence of night blindness in this age group is used as an indicator of Vitamin A status in a population.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is a lower threshold than the WHO's recommended 5% prevalence rate.
**Option B:** This option is incorrect because it is not a specific percentage value that has been established by the WHO or other reputable health organizations.
**Option C:** This option is incorrect because it is a higher threshold than the WHO's recommended 5% prevalence rate.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that Vitamin A deficiency can be prevented through dietary supplementation, especially in areas where the staple diet is lacking in Vitamin A-rich foods like sweet potatoes, carrots, and dark leafy greens. This can be achieved through fortification of staple foods or through vitamin A supplementation programs.
**Correct Answer:** D. 7%.