|Medicine - Epidemiology (ECHO - NOHA - Network on Humanitarian Assistance) (European Commission Humanitarian Office, 1994, 120 p.)|
|Chapter 1: Epidemiology and biostatistics|
|Section 1 - Presentation and summarising of data|
|Section 2 - Measures of disease frequency and association|
|Section 3 - Planning and conducting an investigation|
|Chapter 2: Health Care Planning|
|Section 1 - Priorities and objectives in the context of planning|
|Section 2 - Obstacles to planning|
|Section 3 - Different stages of the planning process|
|Section 4 - Economic evaluation of health care programmes|
|Chapter 3: Health and development|
|Section 1 - Overview and general aspects|
|Section 2 - Operational aspects|
A - Rapid needs assessment: national response to disaster
Following a natural disaster, there is usually a lack of specific reliable information on the extent of damage and of medical need. Often the problem lies rather with an excess of contradictory ill-founded or exaggerated information. The rapid acquisition accurate information or of estimates of known accuracy are prerequisites both for planning of anational relief programme and for guiding international assistance. Data collection need not impede initial relief work since this can begin on the basis of the information obtained. When adequate preparedness fordisaster exists, this information will become available and will include accurate and up-to-date information relevant to the disaster affected area including an inventory of the medical facilities, available personnel, material, transport and communications, both within the disaster area and in adjacent parts of the country. This knowledge will allow a reasoned first estimate to be made of the extent and nature of the likely need created by a given event, and of the resources availableto meet that need. The assessment of needs and priorities involves several steps. Data must be collected, interpreted, and disseminated to potential users, and finally utilized in defining priorities and making decisions. Only the first two aspects are considered here.
Types of data required
Two broad categories of information are required by health administrators :
1) General statements about the extent of damage, the area and population affected, functional damage to public services, telecommunications, highways and roads, power and other utilities. The collection of this information is independent of the health administration.
2) Specific medical, epidemiological and administrative information on health problems and available resources. No universal answers can be given as to the health information which will be needed, nor on the most effective and least costly methods of collection.
Here, as in most other areas which are under discussion, the solution most suitable to local conditions must be selected and measures for implementation included in the predisaster plan of operations. The following types of data have been shown to have practical value following recent disasters:
Number and proportions (or rates) of injuries : several categories of injuries need to be defined. The most pragmatic classifications are based on the site (e.g. fractures of arms and legs) or the severity of trauma. The latter classification is the basis for effective triage in the field. Gross data on the total number of persons injured are to little value to relief officials unless some indication is provided on the type of treatment required, for instance, ambulatory treatment or major surgery.
Epidemiological data on sex and age are also required and can be obtained on a sample basis. Spotsurveys in Guatemala following the earthquake of February 1976 suggested that children under five and adults over 50 have a considerably higher rate of trauma. Such information has direct implications for the type of treatment facilities and material required.
Incidence of communicable disease
The risk of outbreaks of communicable diseases is usually of major concern both to the general public and to the administration. A quick survey of the site of impact will provide baseline data and should lead to the setting-up of an epidemiological surveillance system based on reporting of suspect cases of selected diseases. This can be made using simple symptom reporting from out-patient and hospital departments. The time necessary for disease transmission and therefore for the building-up of an epidemic, precludes outbreaks in the first few days of the emergency.
Inventory of remaining health facilities
A detailed inventory of functional health facilities will include much information not included in a general survey of damage. For relief purposes, the emphasis is placed on describing the damage to existing facilities. Field surveys by experienced professionals combined with low-flying reconnaissance missions by helicopter have been effective in providing a quick assessment, but a more detailed inventory must be obtained by ground survey.
Inventory of medical supplies
A quick survey of supplies available at the site of the disaster may indicate that urgently needed drugs or material could be easily salvaged and used. In Nicaragua, a survey of the medical warehouses in Managua a few days following the devastating earthquake which destroyed the city in 1972, showed that over one million dollars worth of medical and surgical supplies were immediately salvageable although the warehouses had been reportedly totally destroyed. The assessment of available supplies should not be limited to the site of the disaster but, if necessary, should be carried out at national level.
Inventory of essential services available within or outside the stricken area
The assessment of available resources should not be limited to the area of impact. For instance, a daily monitoring of beds available in all hospitals within and outside the disaster area following the Nicaragua and Guatemala earthquakes dramatically improved the use of resources and reduced the need to evacuate patients to hospitals in other countries.
Water supply and sanitation facilities
Health problems are not limited to the management of mass casualties : the provision and repair of damaged water supplies and sanitation systems are important. A survey of the water supply systems in urban or rural areas should be included in the early assessment of health needs. In the assessment of water supply and sanitation it is important that assessment teams be constituted of experts familiar with the sanitary conditions existing before disaster. Experience has shown that engineers unfamiliar with poor rural conditions - and especially foreign experts - tend to overestimate the emergency requirements and falsely attribute to the effect of the disaster deficiencies in sanitation and water supplies which actually reflect long-term development problems and which existed before.
Techniques and methods
The techniques and methods for the quick collection of data exist with a sufficient level of accuracy for emergency purposes. However, the personnel with the necessary experience for this task may be under strong emotional or political pressure : exaggeration is often the rule and may reflect the interest of the administrators in attracting maximum attention for the population for whom they are responsible. Long delays may occur before information is transmitted to the central level unless telephone or radio is available. Reports received during the first twelve hours generally speak only of casualties and damage in the most accessible areas. For example, following the Guatemala earthquake, it was not until forty-eight hours after the impact that any specific information on the extent of the damage outside Guatemala City was available, although there had been earlier rumours of widespread damage in rural areas. The major advantage of this source of information lies in the fact that it is part of a normal and therefore organized reporting process and can be improved to meet the special requirements of an emergency situation. It is particularly valuable when a continuous flow of quantified data is required to monitor major changes in the situation.
A systematic rapid sample survey of the areas affected by the disaster is necessary to provide an immediate overview of the situation. One cannot overemphasise that the survey should cover the entire area and not be limited to sectors reported damaged. Failure to comply with this conditions may result in isolated localities being left unattended for aconsiderable period of time.
Advantages of a survey being promptly carried out are many : it quickly provides standardized information which would otherwise not be available until normal communications are re-established. Following the earthquakes in the rural parts of Peru(1971) and Guatemala, field surveys provided the national emergency committees with a comprehensive overview of the extent of damage within three to five days. The participation of a trained statistician is recommended in the planning of a survey. The results of the survey following a disaster will only be of value if it has been properly planned and data adequately processed. If this is not done the data may be invalid. With regard to the large variety of data to be collected, survey teams should be multidisciplinary and call on the best expertise available in the country. In the health sector, epidemiologists are best qualified to assume this responsability and provide a diagnosis on the public health situation.
Aerial and satellite photography
Recently, greater use of sophisticated technology such as photography by high-flying aircraft and satellites has been made in quantifying the extent of damage. The accuracy is known to be useful for the assessment of macro-damage, but its potential in health remains to be determined. The technology is not readily available to most disaster-affected countries and its cost may limit future application.
Implementational aspects of a needs assessment exercise
The objective of the assessment is to determine which human or material resources will be required to cope with the emergency. These resources must be readily and promptly available : if too much time elapses between the identification of a need and the arrival of supplies at the side, they may no longer be useful. For example, after an earthquake first-aid and surgical supplies must be delivered within the first few days to outlying health services. The international community, by-and-large, is not often in a position to respond so quickly. Following the Nicaragua and Guatemala earthquakes, the number of aircraft arriving with medical supplies was reaching a peak two weeks after the impact, by which time the priority had already shifted to the provision of sanitation and other forms of reconstruction.
The responsibility and authority for conducting an assessment of needs lies with the government of the disaster-affected country. Should the national resources be found insufficient for relief, external assistance from bi-lateral or international sources will have to be sought. However, when a disaster is of such magnitude as to make extensive international aid necessary, it often happens that nationals with the necessary expertise are too scarce to conduct on their own an adequate assessment of the extent of the damage and of the needs. Moreover, potential donors need objective and detailed information on material requirements in order to plan their action and make estimates of the expenditure involved.
It must not be forgotten that they have to justify their action to their governing bodies. Consequently, if often happens that teams or individuals are sent to the affected area by each organization to carry out an independent survey and provide first-hand data on the requirements. The participation of the international community in a joint assessment of disaster situations, under the authority of the disaster-affected country would contribute greatly to a better and more efficient response to the challenge of natural disasters.
B - Medical supply management
During the emergency, most medical supply needs can be met with the use of local supplies. The primary problem in crisis management is distributing the supplies that are localy available. Other significant areas are inventory preparation and control and the use of donated international supplies are as follows : centralized reporting system ; preparation of a list of essential medical supplies ; inventory preparation and control ; compiling the inventory of supplies available in the Nation ; medical supply distribution, field receipt (sorting and storing), and requisition of supplies ; cheking distribution networks ; arrival of incoming supplies.
C - Disease surveillance after disaster
Field investigation or rumors and reports of communicable disease
Rumors and unconfirmed reports frequently circulate after a major disaster, but until recently epidemiologists were not asked to take part in relief efforts except when there was need to investigate the more serious of these. In recent major disasters, the appropriate evaluation of rumors has been made possible through this increasingly earlier involvement of epidemiologists in the relief response. This can be attributed to two factors. The most obvious is that prompt investigation can take place before a situation gets out of hand. Perhaps more important, however, has been the existence of the opportunity to educate members of disaster agencies, the media and the national health authorities about appropriate ways to interprate and respond to rumors.
Gaining access to laboratories to obtain definitive diagnosis and support for epidemiologic investigations
When the epidemiologist, investigating a rumor, encounters patients with symptoms compatible with the disease in question, it is imperativ to collect specimens appropriate for diagnosis, and to properly handle and transport them to a competent laboratory, where they should receive priority attention. Selected laboratory investigation of symptoms or symptom complexes (such as fever-diarrhoea) reported to be increasing may also be required for undertaking appropriate public health measures and developing guidelines for proper management of patients.
There are reasons that it may be necessary to obtain laboratory confirmation of selected notifiable diseases from a sample of patients. The first of these is that not all notifiable communicable disease can be diagnosed with confidence on the basis of clinical criteria alone. Second, the public health laboratory is essential to the promotion of efficient communicable diseases control. The medical officers are primarily concerned with communicable diseases in general population, rather than in individual patients. For such persons, the diagnosis of typhoid fever or measles in a hospitalized patient only represents the tip of an iceberg. Because epidemiology units do not have the authority or resources to adequatly carry out control measures, it is critical to, as effectively as possible, present information from surveillance and the field investigation to key decisions makers. Epidemiologic information, implications, and an outline of alternatives of action must be summarised in the presentation in nontechnical terms understandable to laymen.
D - Emergency assessment of nutritional status
Suitable methods must be adopted for the rapid objective measurment of the nutritional status:
- of individuals eligible for special food relief
- of communities in order to detect changes with time and decide priorities in food distribution (nutritional surveillance).
Weight-for-height is the best indicator for the diagnosis of nutritional status, nutritional surveillance and individual screening. Weight-for-age and arm circumference are less reliable for assessment and screening but can be used to measure changes with time. Oedema rates are a valuable indicator when kwashiorkor is the prevalent form of PEM in the area. Results of surveys and surveillance must be interprated with caution. That can be misleading unless the individuals measured are representativ of the whole population and the technique is standardized and properly used.
Why measure malnutrition in emergencies ?
During a nutritional emergency the relief foods may be scarce and should be given to the people in greatest need. Since much of a population may be able to supply part of all of its own food, it is very useful to have an objective and quantifiable measure of nutritional status. Measurment of nutritional status in emergencies relies mainly upon talking body measurment (anthropometry), particularly height, weight, and arm circumference. Valuable information may also be obtained from simpler methods, for example monitoring clinic records or measuring the prevalence of oedema. The commonest reasons for measuring malnutrition in a relief program are:
- Initial assessment : a rapid survey of population should be done before initiating a relief program, in order to identify the areas or groups that are most affected. Surveys of this type need to be carrefully designed and conducted by an experienced team. They will not be considered further.
- Individual screening : body measurment may be used to select the malnourished individuals eligible for food relief for themselves or their whole family.
- Nutritional surveillance of the population: the repeated measuring of entire communities gives an idea of differences among the various population groups and changes in nutritional status with time. It may be used to decide priorities in the contribution of relief and will also provide some information about the effectivness of the relief program. In nutritional surveillance one is not interested in monitoring the progress of a child, but in knowing whether the overall nutritional condition of a village (or camp) A, is good or bad, is better or worse than that of village B and C (and so requires more supplies and personal), and whether it is improving or deteriorating with time. Nutritional surveillance should not be confused with the "surveillance" or follow up of an individual child in nutritional centers or health services.
Indicators of malnutrition
Clinical signs of PEM or specific deficiencies - Clinical signs are signs that can be rapidly assessed by touching or examining the child concerned rather than by instruments or tests.
Body measurements - They are used to detect malnutrition, but not food shortage, since malnutrition can also be caused by ignorance of faulty feedings habits in the presence of sufficient food. The results of body measurements can be misleading if considered in isolation. Chronic under nutrition leads to a slowing in a child's rate of growth. A chronically malnourished child will be short for his age ("stunted") although he may be of otherwise normal proportion. An acute episod of severe undernutrition results in a loss of muscle and fat which are used up to provide energy and the individual becomes thinner without significant effect upon height ("wasting").
In an emergency what is important is the measurement of acute malnutrition, the effects of chronic malnutrition being of less concern. Because both stunting and wasting result in low weight-for-age, relating body measurements to age is not recommanded. Two measurements are commonly used to access acute malnutrition ("wasting"):
- arm circumference (AC).
Presence of diseases associated with PEM - These, include measles, diarrhoea (defined for instance as three or more loose stools per day), whooping cough, etc.
Mortality data - PEM is associated with increased mortality among young children (e. g. from measles, etc.). The data collected should expressed as rates ; for example, the rate per thousand of marasmus among infants (aged 0-1) in a refugee camp is :
Number of infants with marasmus in the camps
--- x 1000
Total number of infants in the camps
Very great efforts should be made to measure children accurately. Small errors (e. g. 2 - 3 cm in height) in the measurement of a younger child may lead to significant errors in the classification of child's nutritional status. Only one indicator should be selected. Weight-for-height, the recommended body measurement in times of emergency, is a sensitive indicator of acute malnutrition. It is fairly independent of sex, race, and age (up to about 10 years of age). It requires a sufficient number of robust scales and adequate training of personnel. Neither condition is easy to meet in an acute emergency situation. If ages are not known, arm-circumference-for-height is the best alternative. Measuring arm circumference instead of weight results in only a marginal saving of time compared to that required for traveling and assembling people. Several techniques such as the QUAC stick (Annex 5) have been divided to simplify field work and are useful for the screening of large numbers of children. As a second alternative, measurement of arm circumference alone (without measurement of height) is acceptable in situation where resources are extremely limited. Considerable time is saved by not measuring height. The sensitivity of the measurement as an indicator is poor but sufficient when PEM is severe and whitespread.
Other indicators of the evaluation of relief programs
The following indicators can be useful in evaluating a relief program:
- age distribution of children attending relief centers compared with the age ditribution from census data,
- monthly attendance rate of children registered (this is obtained by deviding the monthly average number of those attending by the total number of children registered),
- malnutrition rates in people attending relief centers compared with similar rates obtained by an occasional survey of random sample and house-to-house visits in the same area.
E - Organisation of nutritional relief : general food distribution, mass and supplementary feeding
There are four ways in which food relief may be organised :
- general food distribution : dry food is distributed to people who are able to prepare their own meals,
- mass feeding : prepared meals from a central kitchen are served to the population,
- supplementary feeding : in addition to the ration (dry foods or meals) for the whole family, vulnerable groups receive an extra meal or ration to meet their particular needs,
- intensive or therapeutic feeding of PEM cases.
Food must be nutritionaly valuable as well as acceptable to the local population. Remember that foods that are not consumed have no nutritional value ! Average rations must be cumulated to provide at least 6.3 MJ (1500 K cal.) / person / day for a few weeks and 7.5 MJ (1800 K cal.) / person / day for longer periods. Organisation and planning (ration cards, distribution schedule) are the keys to the sucess or failure of a relief program.
The type of food distribution employed will depend entirely upon local circumstances. A refugee camp, where individuals have cooking facilities may be adequately served by the distribution of dry rations alone. Where a large rural population is affected, a special arrengement may be needed e. g. some people with full rations, some with partial rations and selected groups with supplementary rations. Wherever possible, assist people at their homes and avoid setting up refugee camps. Distributing food to nomadic groups is difficult, and no easy way of doing so has been found. Points at which people congregate (e. g., water sources) may be selected as the best places where distributing food.
Basic considerations of selecting foods : the food must:
- correspond to the nutritional needs and food habits of the
- fulfill special logistic requirements, i. e. be easy to transport, store, and distribute, and
- be available in sufficient quantities.
Calculating dry rations, to be done on a family rather than an individual basis, since in this way the number of people attending distributions will be reduced and administration simplified.
Organising a distribution : the key to run a successful food distribution program is to be well organised. The participation of the community in the relief program and in decision-making will help towards an orderly distribution. However, responsible post (store keeping, administration) must be given to reliable individuals outside the community to rule out personal bias, preferences, or vulnerability to pressure.
Mass feeding (cooked meals) is usually limited to institutions and refugee camps. Choice of food, calculating food rations and organisation of cooking facilities (kitchens, personnel and equipment, fires and fuel, hygien and food storage).
Major deficiency diseases in emergencies
Protein-energy malnutrition (PEM) is the most important health problem during a nutritional emergency. Severe PEM can present several forms : nutritional marasmus is characterized by a severe wasting away of fat and muscle ("skin and bone"). It is the commonest form in most nutritional emergencies. Kwashiorkor is characterized by oedema, usually starting at the lower extremities. Marasmic kwashiorkor is a combination of wasting and oedema. Mineral and vitamin deficiencies may also be important. Severe anemia is common and requires a daily intake of iron for an extended period of time. Vitamin A deficiency, the most important vitamin deficiency, is characterized by night blindness and / or eye lesions which may lead to permanent total blindness. The severe forms are usually associated with PEM. Other deficiency conditions are less common ; beri-beri, pellagra, scurvy, rickets.
Mineral and vitamin deficiencies must be identified and the individuals affected or at risk treated by administration of the missing nutrient.
Protein-energy malnutrition (PEM)
It is a problem in main developing countries even in normal times. In times of nutritional emergency it is primarily the most acute forms of PEM that have to be dealt with. These are characterized by a rapid loss of weight and may be evident in a much wider range of age groups than usual. For example, significant numbers of older children, adolescents, and adults may also be affected. Past experience has shown that many emergencies affect the supply of food to only a proportion of the population concerned. It is often the case that only a small proportion of the total population presents clinical signs of severe PEM. For each case of severe clinical PEM there may well be ten moderate cases and hundred children of "near normal" nutritional status. Progession from moderate to clinically severe forms is rapid.
Nutritional results from prolonged starvation : the main sign is a severe wasting away of fat and muscle. It is the most frequent form of PEM in cases of severe food shortage.
Kwashiorkor : the main sign is oedema, usually starting at the lower extremities and extending in more advanced cases, to the arms and face.
Vitamin A deficiency and xerophtalmia : vitamin A deficiency is the leading cause of permanent blindness in pre-school children. It is almost always associated with some degree of PEM. Xerophtalmia is the term used to describe the eye signs caused by vitamin A deficiency which is most likely to be a problem in areas where the diet of the very poor, even in normal times, do not meet requirements. Since vitamin A is stored in the leaver, a sudden deterioration in the diet does not necessarily produce an immediate sharp rise in the incidence of cases, and there may well be a delay of several months until vitamin A deficiency occurs.
Opportunity cost is the sacrifice in real terms suffered by an
economic subject who makes a choice between several possible actions: when this
subject engages in a particular activity, e.g. a production activity (let's say,
a health care programme), the cost borne by him consists in the value of the
opportunities which he passed over, i.e. in the value of the goods and services
which cannot be created elsewhere because the resources employed are no longer
available for other uses (...).The principle of opportunity costs highlights the
profound significance of a firm's production costs [or of a service, such as a
health care programme].They represent the value of the production factors
[labour, capital, etc.] in the best possible other forms of use to which these
factors could be assigned". Raymond Barre, Economie politique, volume 1, P.U.F.,
1978, pp 15 and