The present study tested the hypothesis that inadequate Zn intake might be responsible for failure to thrive and impaired catch-up growth in young rural Gambian children, and that Z n supplements might be beneficial. Gambian children might be deprived of Zn because of its poor availability from their predominantly plant-based diet. Rural Gambian children (1 10; fifty boys, sixty girls) aged between 057 and 2.30 years were divided into two matched groups, one to receive 70 mg Zn twice weekly for 1.25 years, and the other a placebo. Growth and mid-upper-arm circumference were measured at weekly intervals throughout the study and illnesses were monitored. Capillary blood and urine samples were collected a t 0, 2 and 8 weeks. Body weights and arm circumferences showed a linear increase, plus a seasonal effect (rainy season faltering). For body weight there was no significant overall effect of the supplement. For arm circumference, a very small (2%) but significant (P < 0.01) difference favoured the supplemented group. Plasma thymulin was much lower at the first clinic than at the second and third clinics, and in vitvo Zn stimulation was greater a t the first clinic. There was, however, no effect of Zn in vivo.

Hepatitis B (HB) breakthrough infections, identified by the presence of HB core (c) antibody, were found in 32 of 358 Gambian children vaccinated with plasma-derived HB vaccine. Over 2 years, 15 of these children lost their HBc antibodies. These children had significantly higher HB surface antibody levels before infection than those who retained HBc antibodies. One child, who responded well to the vaccine, had HB viral DNA detected in the presence of HBs antibodies. The S gene sequence of this DNA showed nucleotide changes that resulted in an amino acid substitution at residue 141 (lysine to glutamic acid) of the surface antigen. This finding suggests the child was infected with a variant virus that was not neutralized by antibodies resulting from HB vaccination.

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Malnutrition in infancy is a global problem which leads to retardation of childhood growth and development. There is a pressing need to improve weaning strategies for infants of the developing world. Traditional Gambian weaning foods are watery and of low energy density, but addition of energy in the form of fat and carbohydrate leads to thick, viscous gruels which are difficult to ingest. Partial digestion with amylase (EC 3.2.1.l)-rich flour reduces their viscosity while retaining their energy density. The aim of the present study was to measure the digestibility of a maize-based weaning food, before and after amylase digestion, in malnourished children using a 13C breath test. Ten children (aged 7-16 months; mean weight-for-age Z score -0.8) received isovolumetric and isoenergetic quantities of a maize-based weaning food naturally abundant with 13C. Breath samples were collected at intervals of 30 min for 5 h thereafter and 13C0, enrichment was measured by isotope-ratio mass spectrometry. Percentage dose of l3c recovered increased from a mean 13.7 (SD 37)% before, to 18.3 (SD 5.6)% after ingestion of amylase-treated weaning foods (P < 0.1). There was a significant inverse relation between age and weight, and percentage dose of 13C recovered in children receiving amylase-treated feeds. There were no differences in concentrations of amylase in saliva of infants or breast milk of their mothers. Partial digestion of supplementary foods may improve the nutrition of undernourished weaning children, not only by reducing their viscosity, thereby increasing ingestion, but also by improving their digestion and thereby their absorption.

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