|Handbook on War and Public Health (ICRC, 1996, 470 p.)|
|Chapter 6 - EPIDEMIOLOGY|
|III. EPIDEMIOLOGICAL PROGRAMS|
|4. EARLY-WARNING SYSTEMS|
The Choice of Indicators
The choice of indicators depends on the probable causes of drought. Although these indicators are interwoven in a complex manner, a certain hierarchy among them can be established, based not on their power to precipitate the problem, but on their capacity to reflect the seriousness of the situation. This approach is particularly warranted for humanitarian organizations working in emergency situations. Their problem is deciding to intervene early enough to prevent the disaster from reaching its ultimate stage (dramatic malnutrition and mortality). For example, very generally speaking, surveillance may be:
· ecological (pluviometry),
· agronomical (state of the crops),
· economic (state of market prices, migration of workers),
· social (population movements - migration),
· nutritional (changes in the malnutrition rate),
· monitoring the mortality rate.
A major decrease in measured rainfall compared with the usual norms will not call forth immediate food aid. It warrants, however, closer surveillance of subsequent, related phenomena.
Levels of Intervention
An EWS is pointless unless the alarm it sounds gives rise to an intervention. Alerts prompted by threatened floods, volcanic eruptions, or earthquakes give rise to population evacuation. Emergency measures are all the more effective if prepared in advance.
In cases of drought, decisions to intervene are more difficult. Intervention must take place before the beginning of great migratory movements, which are usually accompanied by high mortality. Migration in fact begins when the crisis is already serious, and the migration is in itself an additional source of stress for the physiologically most vulnerable groups.
Theoretically, then, it is at the moment when the EWSs begin to produce signs of agricultural and economic crises that aid interventions should be planned. The implementation of this principle, however, is hindered by several obstacles:
· Indicator unreliability
Locally recorded agronomical indicators are fairly reliable, but give a geographically limited view of the scope of the problem. In contrast, a satellite picture of the region gives an overall view, but does not lend itself to accurate analysis.
· Lack of resources
Anticipating disasters is not high on governments' priority lists; they prefer to focus resources on programs that have an immediate impact, rather than on EWSs, the utility of which is less obvious.
· Political difficulties
Political leaders are loath to admit that a crisis is near, and tend to downplay its extent. Only in a serious nutritional crisis will they admit the truth.
· The unwieldy nature of interventions
Relief interventions are generally logistically ponderous, and decision-makers prefer to wait for solid evidence 77 before putting them into motion.
77 Today's mentality considers "evidence" to be a high mortality rate.
Under such circumstances, EWSs have a limited value, unless their predictive value is improved in future and decision-makers' mentalities change.
Epidemiology is an important component of relief actions. Epidemiological tools are necessary in all fields: nutrition, environmental hygiene, communicable diseases, curative medicine. Moreover, their integration in the framework of epidemiological programs permits a global approach to crisis situations (initial assessment) as well as providing the opportunity to monitor crisis evolution (epidemiological surveillance).