LIQUIDATION AND ELIMINATION OF INFECTIOUS DISEASES
Author: Petar Georgiev
This issue from our booklist will deal with a much debated controversy on development of epidemiology in Eastern Europe. I have been very dubious, before, writing this article and since it has been of fundamental importance for understanding an East-West debate in science continuing for more than half a century. It is still continued by an army of pseudo-epidemiologists, who, are eager to wage their warfare in the good tradition of T. Lysenko and his anti-genetic doctrine. But let us try to explain and step-by-step.
Lysenko's debate is a topic for another presentation. Here, in this review I shall try to give some standpoints on, whether, epidemiology is a unified scientific discipline and can it serve for a methodology in the New Public Health. While it is a personal view, nevertheless, it reflects many matters of turmoil and not least in science and politics. The dilemma has been carried over in the years of the Cold War and through to the beginning of the 21st century. So, why is it that scientists in Eastern Europe can't accept some standards from general science and are in opposition to a normal development in a discipline. Is it because of cultural backwardness, or because of economic insufficiency, or maybe both? Answers are of lifelong magnitude, since, some scholars have been trained from early years to believe in some tenets which later prove wrong and this same people are in a key positions of power which they are not giving loose easily, up to date. Some critics will say, notably, this is a silly explanation and yet it is true.
What is the essence of debate in epidemiology? Firstly, scholars in Eastern Europe don't recognize the concept of controls in epidemiology. While this is a basic property in quasi-experimental research and opponents are against using referent subjects /i.e., neither healthy and nor sick with other form of disease different from that under investigation/. This is bias number one and it leads to a lack of comparable measures of risk - such as, odds ratio and others. I haven't seen in the literature a single paper dealing with odds ratio concept and coming from an Eastern European country. Exception is made for research, which, is being done full time and in a surrounding of western university experts. Secondly, epidemiologists from the East protest against the violation of the classical causal triad and being desecrated by the proponents of chronic disease epidemiology. This sounds to me more like a scholastic church debate. Notwithstanding, it is of great weight when a piece of research is classified as epidemiology or let us say clinical research in non-infectious surrounding. What if a vector of disease or an environment are apparently missing? Does that means that a causal mechanism is not plausible? This and other questions are ill manipulated by some epidemiologists in the East and they simply don't give away the name of their discipline. Thirdly, some viable scholars from the West are continuously instigating panic and alarm in science. While this attitude has it's common sense roots and it is sometime doing more harm than aid. I mean, that, some scholars from western universities come here and they simply look for easy prey. While methods like brain washing, brain drainage, brain storming are well developed as a treatment for a Third World country and it doesn't make tribute for a future member of a European Community to be treated in such a dishonored manner. I must insist on more careful attitude from the western European counterparts and in terms of budget offerings, methodological considerations and other items of a democratic dialogue.
Now, I see that some of my points are not clear enough. They need more explanation to the public, however, we are not in a position to do more extensive research on this topic for the time being. Moreover, I think most of the controversies would be truncated with elapse of time. Future will show more evidence on the place of Eastern Europe in a unification agenda. Finishing my piece of review and I am willing to say few words for author of monograph Dr P. Georgiev. He is a customized cadre of the old epidemiologic school, however, he managed to maintain a clear cut view on processes and tendencies during a socialist period. His editorial effort led to the first history of Bulgarian epidemiology in the XXth century, which, is also included in our booklist. For the moment and we finish our presentation with future promises to clarify the issues at hand.
SUMMARY: Contemporary anti-epidemic practice achieved spectacular results with variola liquidation, malaria eradication and elimination of such diseases as diphtheria, tetanus, rabies, children'sí rheumatism etc. Implementing appropriate programs of WHO against variola, malaria, poliomyelitis, diphtheria produced multitude of concrete effects about each disease, that explain realization of their liquidation or elimination. Moreover, programs outlined unspecific problems, not related with peculiarity of one or another infectious disease. National programs for liquidation of Morbilli, Epidemic Parotitis, Pertussis, Rubeola, Viral Hepatitis B, Typhus, Exanthematicus etc. reveal at this stage as optimistic prospects thus significant difficulties. Evaluation of these difficulties is related to the specific features and epidemiology of each infection, but also to problems of common characteristic.
Progress in epidemiology of infectious diseases now is in stage require generalization one by one facts and data accumulated by implementing liquidation and elimination programs. Such a generalization would enrich theory and practice of modern epidemiology and would meet demands for evaluation chances of success to eradicate and eliminate other infectious diseases - task of special international group of WHO.
Our long standing experience of implementing Bulgarian National programs against Malaria, Variola, Diphtheria, Poliomyelitis, Rabies, Childrens Rheumatism and realization of vaccination programs against Morbilli, Epidemic Parotitis, Pertussis, Rubeola etc. determinate our aim to grow general conclusion in these processes and to specify concrete characteristics of each disease and in this way to outline the substance of Liquidation theory of Infectious diseases today.
To implement our goal we analyze results of Bulgarian National Liquidation Programs for the past 30 years.
Final results of fulfillment of National Programs for Malaria eradication, especially Malaria tertiana show success to uproot an antroponoza due to source of infection elimination (treatment and sanitation) by means of etiotropic remedies and great restriction of vector. Methods of active and passive tests of population residing in regions with Malaria are required in the final stage of consolidation. Criteria for complete eradication are two years break of etiotropic prophylaxis and desinsection and finally, eradication is regional and demands constant epidemiological control.
Long-term struggle against Poliomyelitis should be successful because the disease is antroponoza and is without transitional host. Despite presence of healthy carriers, vaccination and post-infectious immunity create entire insusceptibility. In period of sporadic morbidity epidemiologic control of health service succeed in quick liquidation of any new outbreak of disease.
Elimination of Diphtheria is achieved with very effective vaccine which make population insusceptive; the illness to appearance of new toxicogenic strains from nontoxicogenic and that define the goal as elimination.
Our long standing surveillance of Childrens Rheumatism prove chance for elimination of this antroponoza. It is a disease not provided with vaccination, with rather broad number of healthy and chronic streptococcal carriers and hereditary predisposition, easily activated by external factors. Major efforts is treatment and sanitation /emergency prophylaxis/ of courses with streptococcal infection /ill and carrier/, accounting allergic condition of macroorganism and removing unfavorable external factors.
During last 15 years human Brucellosis related to domestic /farm/ animals was successfully eliminated. This result is due to active veterinary and sanitary-hygienic measures.
Another Zoonosis - Rabies was eliminated in consequence of annihilation of wild reservoir and vaccinal treatment of bitten persons.
Implementation of vaccination programs against Morbilli, Epidemic Parotitis and Pertussis raise serious thoughts.
Morbilli antroponoza with life-time post infectious immunity, no healthy carriers, with efficient vaccine, could be liquidated. In Bulgaria is achieved status of low non-epidemic morbidity and practically zero lethality but there are available effective cyclic recurrence with minor outbreaks. Data undoubtedly show insufficient effectiveness of vaccine, used in National liquidation program.
Epidemic Parotitis presents similar results, because the disease has resembling features with measles.
During last 30 years killed vaccine is employed against Pertussis. Morbidity analysis show constant trend of decrease, especially after 1974. This trend is due to good protective quality of Bulgarian vaccine, which comprise since 1974 antigens resembling those Pertussis strains, circulating among population. Main goal - to liquidate this antroponoza with vaccination - on this stage is unattainable.
Analysis of results and data deriving from implementation of global programs during recent decades and national effort from programs in current implementation, enable to draw some basic scientific views about liquidation and elimination.
Leading elements of liquidation theory is postulate. When a link /section/ of epidemic process is removed by effective prophylaxis measure regardless of the infectious disease, the disease cease to exist. Epidemic process has three sections: Source of infection (men or live animal); Environment (biotic or abiotic) and Susceptible (receptive) population. Epidemiological theory generalizing common and formal regularities in the development of each epidemiological process, leads the attention for decisive part of these three sections for any particular disease. Clearly the struggle against Variola for instance, could be successful if human community is unreceptive. For this case with vaccination third section of epidemic process is removed.
During 50ís and 60ís chances for eradication of Malaria greatly improved with removing first section (sick men or sick men or carrier) by effective etiotropic medication and by strongly restricting the row of the second section (vector, treated with DDT).
In this way many countries including Bulgaria, successfully eradicated Malaria due to implementation of WHO Program. Now great confidence could be expected with aid of malaria vaccine toward restriction of third section (receptive population) and that increases chances of global eradication.
Previously mentioned consideration would enrich in practice and that would endorse theory for Liquidation and Elimination of Infections diseases.
Copyright © 2005 by the author.