Morbidity

8.5. To get an accurate estimate of the incidence and severity of diseases that may be related to nutritional state is obviously difficult; diarrhoeal disease is the condition that has received most attention in so far as the young child is concerned. For a reliable check on incidence, observations really need to be made on the population sample at least every two weeks, and if the cause is also to be determined, this becomes a highly skilled and formidable undertaking. Interpretation can be complicated by large swings in seasonal incidence, as observed in the Gambia, Nigeria, and Nepal. Figure 21 (see

FIG. 21. Incidence of Diarrhoea in Northern Nigeria According to Season (Incidence is Number of Attacks per Child per Three Months) (Data by courtesy of A.M. Tomkins)) shows differences in attacks for diarrhoea in the wet and dry seasons in Malumfashi, northern Nigeria, by age. We also need to know not only the frequency of episodes of infection but also their duration, which is an important indicator of severity. Both Mata in Costa Rica and Tomkins in Nigeria have shown that the duration of an infection is much longer in a malnourished, than in a well-nourished, individual, even though the number of episodes may have been very similar.

It is only fair to conclude that, although a reduction in morbidity, particularly from diarrhoeal disease, could be a very relevant indicator of the success of a maternal-child intervention, because of the number of variables and the resources required, the approach is more suitable as a research tool than for the routine assessment of a public health programme.