The question then arises of whether this unexpectedly large change can be attributed to NCDDP activities. Detailed information on changes in other macro factors operating in Egypt are unavailable to us at the moment. The general feeling is that, apart from other health campaigns, no sudden major change occurred in determining forces. Other health campaigns, particularly the Expanded Program for Immunization (EPI) program, are believed to have considerably improved immunization29 practices in Egypt. However, immunization campaigns did not start before 1986, and the benefits of measles vaccination (as one component of EPI) are expected at ages beyond nine months. Following 1986, the change in mortality might have occurred due to the interaction of a multitude of determining forces.

The fact that the decline in mortality occurred in 1985 is the only piece of evidence in favor of NCDDP. The trend post 1985 is quite puzzling: the lack of increase in the speed of decline implies either that increased vaccination levels did not translate into mortality reductions or that NCDDP effects are decreasing over time. However, in the absence of reasonable justification for the change in mortality between 1984 and 1985, and in spite of lack of convincing evidence of the mechanisms operating, there is no basis to refute the claim that NCDDP activities are responsible for such a change. Thus the final conclusion drawn is that an average decline of around eight per thousand in infant mortality can be attributed to NCDDP activities.

The fact that the logic of disproof rather than proof is the basis of our conclusions in favour of NCDDP strongly indicates the need to perform more analysis attempting to document clearly with supporting evidence the mechanisms that are operating.

# **SUMMARY AND** DISCUSSION

The previous analysis illustrated that, in spite of the seemingly simple conceptualization of the role of ORT in reducing mortality, a great deal of complexity is involved in attempting to estimate the potential demographic impact of ORT. This complexity arises in part from the different combinations of actions that may constitute an ORT program. The potential of an ORT intervention is strongly linked to the configuration of treatments adopted which in turn influence the resulting health status of individuals. The implicit curative conceptualization of the ORT intervention in Egypt, the weak state of information on the epidemiology of diarrhea, and the lack of supportive evidence on changes in health status of children cured from dehydration suggest the need for greater care in anticipating the potential of ORT. An upper ceiling for the potential impact of ORT in Egypt is a 25% reduction in IMR.

Despite marked improvements in knowledge, data on ORT practice suggest that the full potential of NCDDP, even in its simplest curative route, has not been achieved. The national estimate of ORS utilization during last episode is only around 30%. Assuming a higher level of ORS utilization (42%) and allowing for differential treatments by type of episodes, the maximum expected reduction in infant mortality is reduced to 19%. Furthermore, the available ethnographic studies suggest a low quality of utilization which, in **turn,** greatly reduces the expected mortality impact of ORS. The infant mortality and diarrhea associated mortality 22