Whereas there is much information concerning the effects of vitamin A status on response to infectious challenge, the effects of infection or trauma on vitamin A metabolism and status are less well documented. These relationships need to be understood to optimize clinical and public health programs to improve vitamin A status and health of children in less-developed countries. We measured acute changes in retinol and retinol-binding protein in 57 young South African children hospitalized following respiratory epithelial damage resulting from accidental ingestion of kerosene. In addition, vitamin A status, as measured by the modified relative dose response test, of these children 3 mo later was compared with that of neighborhood control children to determine whether their illness had depleted retinol stores. Plasma retinol was already significantly below control levels when children were admitted [geometric mean (95% CI): 0.57 micromol/L (0.48-0.67) compared with 1.15 micromol/L (1.02-1.30) for controls] and decreased further the following morning [0.38 micromol/L (0.31-0.46)]. Significant differences in retinol-binding protein were not detected until the next morning [5.99 mg/L (4.70-7.63) compared with 14.0 mg/L (11.8-16.6) for controls] and were not as large as the relative differences in retinol. This dissociation between changes in retinol and its binding protein suggests that there may be increased retinol uptake by certain tissues during the acute phase response. The proportion of case children (37/46, 80%) with inadequate liver retinol stores 3 mo after the illness was slightly, but not significantly (chi2 = 2.16, P = 0.14), greater than the proportion of control children (28/42, 67%). Acute respiratory illness therefore did not further deplete retinol stores in this population in which stores were already frequently inadequate.

Kerosene pneumonitis is usually self-limiting and secondary infection is rare. Long-term studies in developed countries have produced conflicting results about complications. The position in developing countries, where children are exposed to adverse environmental and nutritional factors, is unknown. The aim of the present work was to determine whether there is an increase in respiratory or other illnesses following kerosene pneumonitis and whether these changes could be related to the severity of the initial lung damage. Fifty-seven children with clinical signs of pneumonitis were examined on admission and after overnight observation. Clinical signs were assessed for their usefulness for predicting severity. Cases and matched neighbourhood controls were seen every 2 weeks for 3 months. The time to predict most reliably the severity of short-term ill effects was 12-24 hours after the initial insult. There was no significant difference in respiratory symptoms during the 3-month follow-up in cases compared with controls. However, mild diarrhoea and fever were reported significantly more often in cases than in controls. Morbidity after clinical recovery was not shown to be a problem, irrespective of the severity of the acute event.

The ratio plasma retinol-binding protein (RBP) : transthyretin (TTR) has been proposed as a means to improve the assessment of vitamin A status of individuals with concurrent infection or inflammation. We have measured RBP and TTR in stored sera from South African children who had accidentally ingested kerosene. Samples were collected from these children in hospital when suffering acute inflammation and respiratory distress, and from them and neighbourhood control children 3 months later. Vitamin A status was defined by modified relative dose response (MRDR) tests of liver retinol stores at 3 months and by serum retinol concentration both when children were ill and when they were well. Illness was defined as either being in hospital or, at follow-up, as having a raised plasma α1-acid glycoprotein (AGP) level. The RBP : TTR value was significantly decreased by both illness and low liver retinol stores. When the effects on RBP : TTR of illness and vitamin A stores were considered together for the 3-month follow-up samples, only vitamin A status significantly decreased the value. We calculated sensitivity and specificity of the RBP : TTR ratio against established measures of vitamin A status using a cut-off value of 0·3 for RBP : TTR and standard cut-off values for MRDR (0·06) and plasma retinol (0·7 μmol/l). Compared with MRDR, RBP : TTR had sensitivities of 76 % and 43 % and specificities of 22 % and 81 % to detect vitamin A deficiency in hospitalized and well children respectively. Compared with plasma retinol, sensitivities were 88 % and 44 % and specificities were 55 % and 64 % in hospitalized and well children respectively. Only for the case of clinically well children with biochemical evidence of subclinical inflammation did sensitivity (62 % and 100 % against MRDR and plasma retinol respectively) and specificity (100 % and 60 % against MRDR and retinol) approach useful levels for an assessment tool. Overall, although a trend supporting the theory behind the use of the RBP : TTR for assessment of vitamin A status in infection was observed in the current study, the ratio did not provide adequate sensitivity and specificity to be a useful assessment tool.

Excessive interferon-gamma (IFN-g) production appears to be a primary immunological lesion in vitamin A-deficient experimental animals but comparable data from humans is lacking. We investigated IFN-g production in South African children by measurement of urinary excretion of neopterin, a product of IFN-g-activated monocytes or macrophages. Preschool children were examined during an acute inflammatory illness resulting from accidental ingestion of kerosene and they and a neighbourhood control child were examined 3 months later when well. Vitamin A status was assessed by the modified relative dose response (MRDR) test at 3 months and serum retinol and acute phase proteins were measured at both time points. Urinary neopterin was measured for forty cases in hospital, forty-six cases after recovery, and forty-one controls. Significantly increased neopterin excretion was seen following kerosene ingestion and in association with raised serum acute phase protein concentrations. There was no relationship between neopterin excretion at either time point and vitamin A status as assessed by MRDR test. Urinary neopterin was negatively correlated with serum retinol but no significant relationship was observed when acute phase protein concentrations were included in a multiple regression, suggesting the correlation was secondary to illness-induced changes in serum retinol. The results indicate that, contrary to what is observed in rodents under experimental conditions, poor vitamin A status is not associated with altered regulation of IFN-g production in children.