In well-nourished children the effects on growth of minor diseases are minimal. An ill child is a poorly growing child, although the extent of slowing down depends on number of factors. Poorly nourished children are more susceptible to and more severely affected by infection than well-nourished children. Infection in turn lowers the nutritional intake of the child, who in turn becomes prone to repeated infections. Measles and whooping cough are severe diseases in developing countries where chronic under nutrition may affect two third of the population. In malnourished children suffering from measles the mortality is many times higher than in well nourished children.
In developed countries with good nutrition measles is no longer considered a severe disease and when it occurs it is more frequently in older children from 3 to 5 years rather than under two years. But in poorly nourished children the weight loss associated with measles may take from 4 weeks to 3 months to regain. Longitudinal studies have been carried out by researchers in Guatemala and Jamaica to examine the effect of infectious disease on growth in the first three years. Short term weight loss was frequently seen. In Jamaica the long term picture was one of catch-up growth causing complete restoration of growth status, but in Guatemala it was not completely restored. Therefore, it is very important to protect children from catching infections by taking preventive measures for their overall better growth.