Protein-energy malnutrition (PEM) is likely to be the major health problem and a leading cause, directly or indirectly, of death during an emergency. Children under 5 years of age are usually the worst affected, but older children and adults are often also affected or at risk. The condition takes several forms:

· Marasmus - characterized by severe wasting of fat and muscle, which the body breaks down for energy, leaving "skin and bones". This Is the most common form of PEM in nutritional emergencies.

· Kwashiorkor - characterized essentially by oedema (usually starting in the feet and legs); sometimes accompanied by a skin rash and/or changes in hair colour (greyish or reddish).

· Marasmic kwashiorkor - characterized by a combination of severe wasting and oedema.

Micronutrient deficiencies in an emergency situation are among the main causes of long-lasting or permanent disability, and most of them are associated with an increased risk of morbidity and mortality. It is useful to distinguish between the deficiencies that are common to many populations, particularly in developing countries, such as iron, iodine, and vitamin A deficiencies, and those that are more specifically seen in emergencies, such as thiamine, vitamin B, and vitamin C deficiencies, and must be looked for systematically.

· Iron deficiency and anaemia are most prevalent and severe in young children (aged 6-24 months) and women of reproductive age (particularly pregnant women). Anaemia develops slowly and is not clinically apparent until it becomes severe, even though there are functional consequences before this stage. In addition to anaemia, the major manifestations of iron deficiency are:

- in children and adolescents, impairment of cognitive functions and attentiveness;

- in pregnant women, increased risk of low-birth-weight infants, and of perinatal and maternal mortality;

- in all individuals, reduced work capacity and impaired cognition.

· Iodine deficiency is a "geographical" disease, present in most countries of the developing world. It occurs in areas where the soil is poor in iodine and the iodine content of plant foods consequently low, resulting in low iodine intake in the population. Young children and pregnant women are the most vulnerable to iodine deficiency. Iodine deficiency is the main cause of preventable brain damage in childhood, and gives rise to stillbirths and miscarriages, varying degrees of mental retardation, and goitre.

· Vitamin A deficiency occurs in several developing countries and is the main cause of preventable blindness in childhood. In addition to night blindness and ocular lesions of varying severity, called xerophthalmia, vitamin A deficiency is associated with an increased risk of mortality, especially among children with measles. Young children and pregnant women are the most vulnerable to vitamin A deficiency.

Prevention of micronutrient deficiency aims to increase the body's stores of micronutrients so that the individual can better withstand any sudden reduction in micronutrient intake or increase in demand. In practice, this involves providing the relevant micronutrients in appropriate quantities, ideally by improving the diet and increasing the consumption of micronutrient-rich foods. Unless and until this can be done, the alternative is to provide micronutrient supplements and foods fortified with micronutrients. In most cases, the most effective strategy is to combine dietary approaches, including supplementation and food fortification.

Treatment of micronutrient deficiency involves administration of appropriate doses of the missing micronutrients in medicinal form.