|Public Health Action in Emergencies Caused by Epidemics (WHO - OMS, 1986, 285 p.)|
The number of outbreaks of communicable disease has been increasing in recent years. There may be several reasons for this: the increased rapidity of national and international travel and the greater distances travelled; extensive deforestation and irrigation works; neglect of insect and rodent vector control programmes; explosive urbanization and overcrowding associated with poor sanitary conditions; more frequent opportunities for collective gatherings resulting, for example, from improvements in public transport; frequent movements of populations and refugees; social or recreational events; tourism; and large-scale industrial food processing. Some of the increase, however, may be apparent rather than real, since better medical and epidemiological coverage in developing countries has improved the surveillance of these diseases, and outbreaks are now reported that would formerly have gone unnoticed. These reasons may also explain why a disease formerly considered as only occurring sporadically is now endemic or epidemic, although the possibility of changes in pathogenicity or virulence must not be overlooked.
At its foundation in 1948, the World Health Organization was given a mandate by its Member States to help countries facing outbreaks of communicable diseases when they cause problems too great to be dealt with by national resources alone or represent a risk to international health. WHO staff have intervened in epidemics on many occasions and have thereby acquired a great deal of experience based on field operations. An informal consultation on strategies for the control of emergencies caused by epidemics of communicable diseases was convened in Geneva in November 1981. Public health experts from a number of countries exchanged experiences and made recommendations for future WHO activities in this field. They also suggested that WHO should prepare a technical guide to serve as a quick reference on practical measures for public health officers facing an outbreak of a communicable disease, for use primarily under field conditions, in developing countries.
A number of difficulties were encountered in attempting to prepare such a guide, the first being that of defining when an epidemic disease could be considered as constituting an emergency for the public health service, i.e., an epidemic emergency situation. A definition has been worked out that takes the epidemiological context into account and covers cases when the incubation period of the disease is too long for it to cause panic among the population.
The selection of diseases that can cause epidemics also gave rise to difficulty. Some diseases, such as influenza, are well known to cause epidemics in all countries. Other diseases are usually sporadic or endemic but may be able to cause an epidemic in unusual situations, say, in a refugee camp or among a group of tourists, e.g., schistosomiasis or Legionnaires disease. The increasing frequency of travel and population movements has meant that certain tropical diseases have occurred in temperate regions as imported cases of exotic diseases. It is also obvious that an epidemic disease highly prevalent in one part of the world may be rare or absent elsewhere. A decision - perhaps a somewhat arbitrary one - was therefore taken to try and make the coverage as complete as was reasonably possible in order to facilitate differential diagnosis under unusual circumstances, so that certain diseases have been included although they are unlikely to cause emergencies. In contrast, although they may cause epidemics, sexually transmitted diseases have not been included as they do not give rise to emergencies as defined in this guide.
A competent epidemiologist should have an adequate knowledge of other relevant specialities: pathology, microbiology, entomology, veterinary health, and sanitary engineering. It was therefore thought necessary to include some of this diverse background information, but it has been kept within reasonable bounds and limited to what is needed by a reader who is not necessarily a specialist in these disciplines.
References to the many valuable specialized books that might be consulted have been limited, since a sudden outbreak of a communicable disease is not likely to leave much time free for visiting libraries. Where it was felt that further reading could be recommended, preference (purely arbitrary) has been given to widely available WHO documents.
As this guide is intended for practical use, an attempt has been made to arrange the text in the order of the steps that should be taken in an emergency: organizing the emergency health service, following proven procedures for field investigations, analysing methodically the results of investigations, implementing the appropriate control measures and evaluating them. For the readers convenience in an emergency situation, additional practical information is given in the annexes. Reference should also be made to DUNSMORE, D. J., Safety measures for use in outbreaks of communicable disease, published by the World Health Organization.
Many diseases are known under several different names. The guide follows the International nomenclature of diseases, published jointly by the Council for International Organizations of Medical Science (CIOMS) and the World Health Organization, for those diseases covered so far, namely diseases of the lower respiratory tract, mycoses, bacterial diseases, and viral diseases. Other common synonyms have been included as appropriate.