Using Stable Isotope Techniques to Monitor and Assess the Vitamin A Status of Children Susceptible to Infection in Ethiopia

Vitamin A deficiency is the leading cause of preventable blindness in children and is associated with a higher risk of under five mortality. Approximately 250,000 to 500,000 children in developing countries become blind each year owing to vitamin A deficiency, with the highest prevalence in South Asia and Africa. In Africa, many countries have implemented vitamin A interventions of mega-dose supplementation for children under 5 years, sometimes in combination with food fortification programs.

Vitamin A deficiency is a major nutritional concern; with more than 37.7% of under five children being vitamin A deficient by serum retinol and 50.7% had been sick in the previous 15 days in Ethiopia. Vitamin A deficiency is addressed in the country through vitamin A supplementation every six months for 6-59 months of children and during the first 45 days of delivery for lactating mothers. There are also other vitamin A intervention programs like bio-fortification of orange flesh sweet potato (OFSP) in pocket areas. Unfortunately, assessing vitamin A status, and the effectiveness of government interventions, is challenging in settings where infectious diseases are endemic, as in most African countries including Ethiopia. This is because serum retinol concentration decreases during infection due to the acute phase response.

The overall national prevalence of any helminthes infection in Ethiopia was 29.8% with variable degree of prevalence among regions, where by southern nation nationality people (SNNP) (51%) and Gambella (51%) have the highest prevalence. A survey in 13 foods for education program-supported schools in the SNNP region indicated that prevalence of soil transmitted helminthiasis infections are 44.4%. The proportion of school children infected with any parasite species was 55.4%. A. lumbricoides was the most prevalent species 32.1%, followed by hookworm 21.7%.

Forty seven subjects (26 male and 21 female) met the survey definition of smear positive tuberculosis (TB) cases, with a prevalence of 108/100,000 (72-138). From smear positive TB cases, 37(78.7%) were new cases, 2(4.3%) were on treatment, and 8(17%) were previously treated in the last five years. Malaria prevalence is 4.5% in the malaria endemic area.

Evaluation of Vitamin A status is relatively insensitive when based on changes in serum retinol, which is homeostatically controlled and negatively affected by subclinical infections. Liver stores of vitamin A are the best indicator of vitamin A status, but cannot be routinely evaluated. The isotope dilution technique is the preferred method for determining vitamin A status and assessing the efficiency and effectiveness of intervention programs. It is the only indirect assessment method that provides a quantitative estimate of vitamin A status across the continuum from deficient to excessive vitamin A.