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Rome (Fides Service) - Human civilisation has produced major environmental changes and radically modified human life styles. Prof. Antonio Aceti and Dr. Simone Lanini, of the Infective Disease Department at the Sant’Andrea hospital in Rome, the faculty of medicine at the Sapienza University in Rome, wrote the following article for Fides on an increasingly important subject: infective diseases in the era of globalisation.
Infective diseases are a battle between two worlds, the world of bacteria and the world of human physiology. Although both worlds are governed by the same physical laws, they reveal some fundamental differences. First of all the world of micro-organisms is about one thousands times older than the world of human physiology and it started its evolution when our planet presented extreme conditions, incompatible with the survival of any other organism; secondly the world of micro-organisms is characterised by a vast bio-diversity and biomass if we think that the 3 billion species of known micro-organisms constitute more than 60% of the biomass which lives on our planet.
These two worlds evolved slowly for a long time until, about 4 or 5 millennia ago, this development accelerated, and has continued to accelerate even more in the last 2 centuries, because of a new event in the natural history of our planet: human civilisation.
Human civilisation has produced major environmental changes and radically modified human life styles destroying a “natural” environment and replacing it with a new “humanised” environment, permitting man to invade the most remote regions of the planet. Because of this microorganisms, which used to live “far away”, came into contact with man adapting themselves to the conditions of the environment. We note that some bacteria of the Legionellae family which in nature live inside Amoeba, learned with time to live in air-cooling systems causing in man pathologies in the respiratory system. We can say then that the rapid changes to which the planet is subject create new opportunities for contact between human beings and various microorganisms, fostering the insurgence of new infective pathologies.
It is commonly agreed that the number of infective pathologies which affect man has increased enormously in recent years. The World Health Organisation has said for example that in the last 20 years no less than 30 new human pathologies have emerged. This fact is important and from certain points of view alarming, but it also needs to be explained.
We can divide the new pathologies in three main categories. First of all pathologies which are not new from clinical points of view, but whose causes were hitherto unknown. This category includes at least 5 forms of viral hepatitis identified in the last 25 years responsible for acute and chronic hepatic illnesses. Secondly we have diseases caused by microorganisms called opportunists because they are able to produce disease only in subjects in situations of high vulnerability. These pathologies are a consequence of the improvement and greater diffusion of medical care, which can prolong life for people who in the past would have died, as in the case of therapy for neoplasm. The third category includes new infective diseases produced for example by the accidental mutation of micro-organisms which have acquired the capacity to infect man, as in the case of HIV, BSE and SARS or are caused by man’s invasion of new areas as it happened with syphilis imported to Europe after the discovery of America.
Infective diseases belong to the first two categories are in fact signs of progress which on the one hand identifies the causes pathological processes and on the other, having found solutions to certain problems, is in a condition to solve new ones whereas in effect the “new ones” are the others.
Globalisation (understood as rapid exchange of news and goods, facility of movement of persons at the planetary level and standardisation of customs and consumer goods) brings new problems with regard to the diffusion of epidemics. Moreover population growth and increasing food demand has favoured the development of new food production methods not exempt from risks for man as in the case of BSE (“mad cow disease”). We should also recall the alarming possibility of re-introducing in industrialised countries, through migratory flows from the poorest regions of the planet, pathologies long considered eradicated.
In effect if on the one hand globalisation has caused new problems, on the other it has also supplied the means to solve them. The rapidity with which the SARS epidemic was tackled, was possible thanks to in integrated network of structures of healthcare and research and an information network able to rapidly spread news from one end of the earth to the other with regard to the diffusion and the characteristics of this new micro-organism. It is realistic to think that the harm caused by SARS, in terms of human life and in material goods, would have been much more serious in the past than they were today.
Massive diffusion of infective pathologies is not a prerogative only of our day, history is full of examples: we think of the plagues, starting with the one mentioned by Tacito, which killed Pericle in the 5th century BC, down to the plague mentioned by Manzoni in less remote times.
As we have already said, it is feared that immigration may reintroduce diseases eradicated in industrialised countries long ago. However in Italy as in other countries, reclamation of land and the introduction of programmes of diagnosis and treatment of illnesses have checked the spread and lethal character of many diseases, also serious ones such as malaria and tuberculosis. With regard to malaria, like all insect carried diseases, a high number of people would have to come into contact with the vector, whereas statistics speak of about 1,000 cases of malaria imported every year to Italy, a number which is certainly not high enough to cause a re-introduction of this disease in our country.
In this era of globalisation infective diseases are certainly a serious threat to humanity because of their rapid diffusion and the possibility of more lethal epidemics. Hence the need to programme conspicuous investments in scientific research and in the training of specialists and building of adequate structures in order to construct an effective and efficient network of health care surveillance. (AA/SL)(AP) (10/9/2004 Agenzia Fides; Righe:86; Parole:1112)
