Epidemiology of violence and war.

The magnitude of the threat that violence and war pose to the health, the quality of life, and the very survival of humanity is obvious. A number of scientific disciplines have provided, each through its own methodology, insights into the causation, genesis, and dynamics of violence and war. Although epidemiological and psychological methodologies received priority, the multidisciplinary approach to this problem seems to be the most appropriate. This essay attempts to approach holistically the study of epidemiology of violence and war and the ways of preventing these severe problems of the contemporary society. Conceptual models of the causative mechanisms and dynamics of violence and war, mapping the various psychic, social, and environmental factors, are presented. These models, besides advancing abstract ideas, also provide a concrete framework for determining and exploring the interactions and dynamics of the factors and processes which lead to violence and war. The types of interventions outlined for control and prevention are intended to make an impact upon "critical points" within the dynamics of the process which produces violence and war, and are conceived to be implemented on both the national and international level. The importance of family, community, and school influences is considered, but the role of international organizations, including the United Nations, and other governmental and non-governmental organizations is also stressed. Discussion is focused on the factors which favour peace and hamper aggression, on "internationalization" and global society versus xenophobia and nationalism. The conclusions state that there is sufficient knowhow to devise and implement a reasonable and effective international programme for the control and prevention of violence and war, provided there is adequate public and political willingness and support.

Homage to Andrija Stampar.

Andrija Stampar (1888-1958) was one of the founders of the World Health Organization, Chairman of the Interim Commission, and President of the First World Health Assembly. His name is a byword to all students of public health and is familiar to readers of World Health Forum from our fortieth anniversary article about the early days of WHO (1) and the reminiscences of Szeming Sze (2).

Epidemiological model of hepatitis B with age structure.

Multistate epidemiological model with age structure is constructed on the grounds of natural history of the hepatitis B. Essential epidemiological classes constitute the basis of the model. Epidemiological parameters and the coefficients of transfer among the classes were determined from available information. Uncertainty of infectiousness of some classes of the population was an important constraint in model formulation. Population structure, the distribution of epidemiological classes and other parametric values were rather arbitrarily set but these can be changed as more accurate information becomes available. As new information on natural history may become available this can be incorporated into the present model, with appropriate modifications of its structure. The computer program+ of the model has been written in BASIC language, and can be accommodated within microcomputers. The model is used for simulation of endemic and epidemic situations. It is applied for simulating the natural course of infection as well as the effects of various public health interventions, such as passive and active immunization and/or application of appropriate sanitary and hygienic measures. The cost-effectiveness analysis of various public health control programmes can also be carried out with the model. The model is evaluated through the simulations of actual and hypothetical situations. The model in its present form, permits simulation of the disease dynamics in various populations and epidemic situations. It seems to be a useful tool in the study of hepatitis B dynamics, its epidemic patterns and in the search for the effective and cost-effective, control strategies.

Impact of hepatitis B immunization strategies on infection rates in Italy: a deterministic computer simulation.

The impact of different immunization strategies on hepatitis B infection rates in Italy over a 20 year period is simulated by the means of a simple deterministic mathematical model. The anticipated effect of vaccination of health workers only, of newborns from HBsAg+ mothers, of all newborns, of the entire population are simulated. Immunization of newborns from HBsAg+ mothers is by far the strategy with the greater effectiveness per unit cost.

Problems and progress in immunization.

Advances in immunology, microbial genetics, molecular biology and biochemistry are opening prospects for new purified and synthetic antigens against infectious diseases, cancers of viral origin and some immunodeficiencies. Immunization programmes against major childhood diseases with commonly used vaccines gave excellent results and are leading to their virtual eradication in developed countries. However some vaccines like the one against pertussis proved to be of considerably lower effectiveness. Results achieved in developing countries are in general lagging behind due to lower immunization coverage. While in some countries immunization strategies for eradication of measles are discussed, in others it is questionable whether immunization should continue due to failures of immunization programmes. Evaluation of the effectiveness of national immunization programmes by surveillance and various other methods including the use of epidemiological models point ot the deficiencies of vaccine potency and/or stability and the inadequacy of vaccination schemes and coverages. There is a need to determine optimal immunization programmes for control and possible eradication with currently available antigens and new ones. For newly developed vaccines, ever increasing in number, but with the uncertainty of their appropriate public health use, it is essential to study their optimal and most cost-effective uses e.g., pertussis vaccination is an old unsolved problem and that against hepatitis B a new one. Better results can be obtained with current vaccines by appropriate modification of immunization programmes. Some of the proposed strategies for using recently developed vaccines are questionable and need critical examination.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiological model of hepatitis B.

This is a preliminary report on a multistate epidemiological model without age structure constructed on the grounds of the natural history of hepatitis B. In determining twelve essential epidemiological classes and related epidemiological parameters the lack of precise definitions of certain classes and their infectiousness was an important constraint in model formulation. For this reason the distribution of some classes and their parametric values were rather arbitrarily set. As more exact information on natural history becomes available it can be directly incorporated into the present model. The computer programme of the model has been written in basic language. The model was used for the simulation of endemic and epidemic situations. It was applied for simulating the natural course of infection as well as the effects of various public health interventions, such as passive and active immunization and/or application of appropriate sanitary and hygienic measures. The model is evaluated through the above simulations of actual and hypothetical situations. The cost-effectiveness analysis of various public health interventions can also be carried out with the model. The model in its present form, in spite of some uncertainties as far as epidemiological parameters are concerned, seems to be useful in the study of hepatitis B dynamics and its epidemiological patterns and in the search for effective and cost-effective control strategies. The model needs further refinement.

Epidemiological models of poliomyelitis and measles and their application in the planning of immunization programmes.

This report describes the construction and application of epidemiological models of measles and poliomyelitis. In these models, epidemiological classes and their age structure have been based on the natural history of these diseases in the population aged 0 - 19 years. The flow of the population through the classes has been expressed as an equation system suitable for computer interpretation. The models have been used to simulate both the natural course of the diseases and the effect of various immunization schemes. The models were also used to explore prospects for control and eradication of these diseases with specific immunization programmes, and their relative effectiveness and cost-effectiveness are discussed.

Immunization during a cerebrospinal meningitis epidemic in the Mongolian People's Republic, 1974-75.

An epidemic of cerebrospinal meningitis (CSM) in the Mongolian People's Republic, starting in 1969, reached its peak in 1974. In that year and in early 1975, 65 000 children in the 0-8-years age group in the main towns and in the provinces were immunized with meningococcal vaccine of serogroup A. The morbidity rates due to CSM were 12 times higher in the non-immunized than in the immunized children. This result demonstrates the value of an immunization programme to control epidemics of CSM.

Prospects for the prevention of bacterial meningitis with polysaccharide vaccines.

MOST SUPPURATIVE INFECTIONS OF THE MENINGES ARE CAUSED BY FIVE BACTERIAL SPECIES: Escherichia coli, Haemophilus influenzae type b, Streptococcus pneumoniae, Neisseria meningitidis, and group B streptococcus. The immune response of adults to pneumococcal capsular polysaccharides has been studied in great detail and their responses to meningococcal and H. influenzae type b capsular polysaccharides are quite similar. Immune responses of adults to E. coli and group B streptococcal antigens are disappointing. The responses of children below the age of 7 years differ both quantitatively and in duration. Early experience shows that useful antibody titres can be achieved with certain antigens but further studies are required. In order to prevent bacterial meningitis by immunization, three vaccine formulations will need to be developed. When epidemic meningococcal disease occurs in a population, the vaccine containing only components of the meningococcus would be applied to a large segment of the population to terminate the epidemic. The second vaccine would contain components of H. influenzae type b, pneumococcus, and the meningococcus and would be administered in the first year of life, and repeated at suitable intervals to maintain life-long immunity. The third vaccine, designed to prevent neonatal meningitis caused by E. coli K1 and group B streptococci, would be administered to women preferably during the third trimester of pregnancy, so that their offspring would inherit sufficient antibodies to protect them during the first 3 months of life.The vaccine against the meningococcus is a reality and has been used extensively during major epidemics, with excellent results. The two vaccines for control of endemic bacterial meningitides do not exist as yet, but the prospects are good.