The most common indicator used for estimating vitamin A deficiency (VAD) in a community is Bitot’s Spot (BS). Bitot’s spot is a white, foamy, cheesy, thickened, superficial layer of sloughed, flattened cells containing a desquamated keratinized surface, a prominent granular cell layer and complete absence of goblet cells(1). VAD is regarded as a public health problem in a community if the prevalence of Bitot’s spots amongst under 6 years children is 0.5% or more(2). In a vitamin A (VA) deficient community, adminis- tration of mega-dose of vitamin A is recommended. The schedule for the oral prophylactic dose of vitamin A is one dose of 1,00,000 IU to infants in age group of 6-11 months and six monthly doses of 2,00,000 IU to children in the age group of 12-36 months(3). The impact of VA supplemen-tation on VAD status in a community is re-assessed by studying the prevalence of Bitot’s spots in children under 6 years of age. There are conflicting reports on the duration after which Bitot’s spots disappear and percentage of Bitot’s spots that disappear after administration of mega dose of vitamin A in scientific literature.

Community based studies on reduction in prevalence of Bitot’s spots after vitamin A administration amongst preschoolers have been reported. A study from Bangladesh(4) reported a progressive decrease in prevalence of Bitot’s spots to less than 0.5% after vitamin A supplementation (Table I). However, in studies from Nepal and Indonesia, the prevalence of Bitot’s spots continued to indicate that VAD was a public health problem in the population despite a decline after mega dose of vitamin A(5,6) (Table I).

Community based studies

Bangladesh
1981(4)

1-5

12494

single dose

0.5%

0.42% (3 months)
0.24% (6 months)
0.15% (9 months)

Nepal
1980-81(5)

1-5

1326

single dose

3.37%

2.24%(6 months)

Indonesia
1975(6)

1-6

1197

every 6 months

4.7%

3.37% (6 months)

Controlled logitudinal
studies

Indonesia
1990(7)

3-6

88

single dose

100%

6.8% (5 weeks)

Indonesia
1982(8)

<5

48

single dose

100%

0% (3-4 months)
0% (5-6 months)

India
1976(9)

<5

25

every 4 months

100%

68%(12 months)

The numbers in parentheses indicate duration of follow up.

Controlled longitudinal studies have been conducted in preschool children with Bitot’s spots. Results from Indonesia revealed that after five weeks, there was a 93.2% reduction in prevalence of Bitot’s spots after receipt of mega dose of vitamin A(7). Similarly, a vitamin A supplementation trial on 48 preschoolers with Bitot’s spots showed that all BS disappeared after 3 months(8). However, a four monthly vitamin A supplementation in preschoolers with Bitot’s spots done in India reported that after one year of supple-mentation with mega doses of vitamin A, the prevalence of Bitot’s spots was reduced by only 32%(9) (Table I).

Seasonal variation in prevalence of Bitot’s spots has been documented in community based studies with the peak prevalence observed in May-June(10). In disadvantaged and resource poor communities the Bitot’s spots may disappear in children after administration of vitamin A; however a possibility of appearance of Bitot’s spots in new subjects exists(11-13). Persistent Bitot’s spots which could be due to other reasons and do not respond to mega dose of vitamin A administration are known to occur in the community. The etiology of these persistent Bitot’s spots is not clearly under-stood(1,14,15).

The existing scientific data reveals that Bitot’s spots prevalence decrease after administration of mega doses of Vitamin A, but within how much duration the prevalence comes down to less than 0.5% is not exactly known. Hence, the re-survey data on impact of megadose of vitamin A administration on prevalence of Bitot’s spots should be carefully interpreted. There is a need to undertake longitudinal studies on this issue.

Vani Sethi,
Umesh Kapil,
Department of Human Nutrition,
All India Institute of Medical Sciences,
New Delhi 110 029, India.
E-mail: [email protected]