Infection, malnutrition and growth

Abstract

The concomitant appearance of famine and pestilence has been documented in classical religious texts since the beginning of written history. But it was not until recently that the inter-relationships between infection and nutrition were scientifically described.' Infectious disease was found urbe an important feature of kwashiorkor in the early descriptions by Cicely Williams and others. However its role in the genesis of malnutrition was mostly overlooked, due to the dramatic recovery of children with severe energy—protein malnutrition, following dietary therapy. This observation established the paradigm that all malnutrition was due to lack of food. Two forms of nutrition and infection interaction were recognized: synergism and antagonism) In synergism a nutritional deficiency exacerbates an infection, and an infection aggravates a given nutritional deficiency. The effect of the interaction is said to be greater than the added value of the two forces. This type of interaction is commonly seen in developing countries where infectious diseases are highly prevalent and diets are often deficient. In contrast, antagonism consists of impairment of an infectious process due to deficiency in one or more nutrients. This type of interaction is observed in experimental animals,' but rarely occurs in humans, except under extreme nutritional deprivation.2 Anorexia is a defence mechanism and rapid feeding of deprived humans and animals to satisfy caloric needs results in exacerbation of infection and excess mortality.'' The prospective field study of poor rural populations has shown that malnutrition—infection interactions explain most of the prevailing morbidity, severe malnutrition, growth retardation and mortality, especially among children:" In such cases, growth faltering in infants at the breast begins around 3 to 6 months, or even earlier in those who are bottle-fed.7.8 To some, it is uncertain whether stunting is due to inadequate food supplementation after mother's milk becomes insufficient, due to repetitive infectious disease, or to the combination of both factors.' In developing countries a decline in supply of human milk not accompanied by adequate supplementation is the rule; however the striking event is repetitive infectious diseases during weaning." Acceptance that infection might be more important than the diet in the genesis of malnutrition has met with scepticism from the public health community. However the discovery, of monocyte mediators released during infection, on the one hand ,10.11 arid on the other, the virtual eradication of malnutrition in regions and countries after significant control of infections,'" have emphasized the role of infection and infectious disease in the cause of malnutrition.