Return to Table of Contents: WVA Bulletin Vol. 19 Nr. 1 January 2002

History of Diseases Spreading Through International Trade

Lessons for the Future

By V. Kouba, Formerly: Chief, Animal Health Service, Food and Agriculture Organisation, of the United Nations, Professor of Brno Univ. of Vet. Sciences, PB 516, 17000 Praha 7, Czech Republic.

Introductory lecture presented at the 32nd Congress of the World Association for the History of Veterinary Medicine (WAHVM), 15-18 August 2001, Oslo, Norway.

Photo: Vaclav Kouba

Prof.MVDr Vaclav Kouba, PhD,DrSc., born in Czech Republic in 1929, graduated in 1953 at Brno University of Veterinary Medicine. Formerly: Chief, Animal Health Service, Food and Agriculture Organization of the United Nations (FAO), Rome; Veterinary Public Health Expert, World Health Organization (WHO), Geneva; Informatics Expert, International Office of Epizootics (OIE), Paris; Member of Committee on Education, World Veterinary Association (WVA); Chief-Editor of global FAO-OIE-WHO Animal Health Yearbook; National Chief Epizootiologist and Technical Director of Veterinary Services, Prague; Professor of Epizootiology, Brno University of Veterinary Medicine; Visiting Professor of Havana, Mexico City, Kosice and Prague Universities.

Key criterion of veterinary medicine historical mission is its practical impact on global animal population health. Its usefulness depends on how far is able to protect healthy animals, to recover health of sick animals and to reduce, eliminate and eradicate transmissible diseases.

Unfortunately, historical facts document serious discrepancy between rapidly increasing quantity and quality of scientific knowledge and rapidly worsening of animal diseases global situation. Among main causes belongs spreading of infectious and parasitic diseases through international trade in animals, their products and objects which could be contaminated by pathogens. Public health, economic, ecological and social negative impacts of diseases spreading are enormous.

The purpose of this paper is historical analysis of animal diseases introduction through international trade during last decades of the 20th century, i.e. from 1980 when regular reporting of disease "import" was started. Analyses of previous periods were published for example by Blancou and Meslin (1). Import of animal commodities represented a risk not only of diseases introduction but also of after-import spreading with multiplying negative, often long-term or permanent, catastrophic consequences. Discovery in time, control and eradication of introduced and spread diseases were usually very difficult and costly. Not all "imported" diseases could be blocked within quarantine to avoid secondary outbreaks. Most introduced diseases couldn't be eradicated.

Material and methods

·         The analysis is based upon country official data as reported annually to international organizations. Data on international trade in animal commodities are from FAO Trade Yearbooks (5). Data on diseases introduction related to international trade are from FAO-WHO-OIE Animal Health Yearbooks (4) and OIE World Animal Health yearbooks (Country Reports and Tables) (7). Data on cases reported during the year 2000 are from OIE Internet pages. The analysis was supported by OIE documents (6) as well by authors' publications (2,3) and international experience.

·         The analysis of reports on disease introduction related to international trade was subdivided according to the OIE List A and List B diseases. Numbers of reports on diseases recognition in country for the first time and reports on diseases reappearance (reintroduced or reemerged) after more than 3 years were analyzed as well.

·         There were a lot of cases of disease "import", some of them were discovered and reported to international organizations (international information system covered only about 1/10 of known species of transmissible diseases), some were discovered and not reported (e.g., most diseases were not obligatory notifiable and not controlled) and much more cases were not discovered at all (e.g., due to lack of active investigations able to detect subclinical carriers, etc.). Emerging diseases represented a new insidious threat.


·         Diseases spread through international trade was linked with increasing import of animal commodities. (Graphs 1 and 2). During 1961-1999 international import in monetary value of live animals increased 9 times, of meat and meat preparations 20 times and of dairy products 17 times! Analogically increased national trade in these commodities. It was obvious that simultaneously increased disease spreading risk. Unfortunately, protective measures instead to be strengthened were not adjusted. Public veterinary services, responsible for protection of country animal population health, were left more or less the same or even reduced. The main "reason" was an economic one, in spite of the fact that worldwide trade in livestock and meat rose up to US$ 51 billion in the last year of evaluated period.

·         International trade in animals and their products during 1980-2000 caused spread of many animal diseases. Number of official annual reports on the OIE List A and List B diseases introduction related to international trade reached 600 (20 % of the List A and 80 % of the List B). More than hundred cases of introduction of other animal diseases were reported as well.

·         From 120 annual reports on OIE List A diseases introduction the major shares had foot-and-mouth disease, rinderpest, contagious bovine pleuropneumonia and Newcastle disease. Alarming are reports on increasing number of FMD introduction cases after the "WTO Agreement on the Implementation of Sanitary and Phytosanitary measures" came into force in 1995 (from 29 cases during 1980-2000 were 21 reported during 1995-2000 !).

·         From 90 reports on the introduction of OIE List B multiple species diseases the major share had paratuberculosis. From 191 annual reports on the introduction of cattle diseases the major share had enzootic bovine leukosis. From 69 reports on the introduction of sheep and goat diseases the major share had scrapie. From 34 reports on the introduction of equine diseases the major share had piroplasmosis. From 20 reports on the introduction of swine diseases the major share had atrophic rhinitis. From 76 reports on the introduction of avian diseases the major share had chlamydiosis.

·         Number of reports on animal diseases "recognized in country for the first time" reached 487.

·         Disease reappearance, i.e. reintroduced or reemerged, was reported 338 times. The analysis includes only reports of the reappearance when the interval between last previous and new cases was 3 and more years. The reason was that the reappearance after less than 3 years could be in some cases the result of a recidive due to surviving subclinical carries of pathogens.

Example: Foot-and-mouth diseases reintroduction in Japan after 92 years.

·         Among many factors facilitating spread of animal diseases through international trade belonged for example:

1.     Mono-etiological instead of poly-etiological risk assessment based on theoretical mathematical calculations without considering: characteristics of transmissible diseases and their etiological agents ability to reproduce and propagate; true diseases occurrence, trend and dynamics; ability of diagnostic methods to discover all affected animals; veterinary services abilities; post-introduction efficiency; human factors; etc..

Example: Taiwan had been free of FMD (foot-and-mouth disease) over 68 years before 1997. FMD occurred in March 1997 and stormed the whole island that led to tremendous economic impact due to the loss of exportation market... During four-months a total of 6,147 farms was infected ! (OIE)

Incorrect risk assessment caused that among imported animals and their raw animal products were sometimes also carriers of etiological agents species, types, subtypes and strains which in importing countries were considered as exotic.

2.     In the middle of the nineties certain international organizations started policy of "facilitating trade" at the expense of animal and human health. For the first time in the history was introduced legal framework conducing to benevolent risky trade officially admitting and even supporting also diseases spreading through international trade. Previous international recommendations of minimal health requirements for protective import conditions were converted in binding maximum limits. This changed the principle of "health first" into "business first" !.

Simultaneously, reporting on animal diseases status was significantly reduced instead to provide more information needed for countries' decision about import conditions. Previous reporting of disease occurrence grading and disease import cases was replaced by only one uninterpretable symbol "+" !

3.     Benevolent international regulations not respecting that the trade in animals and their raw products was much more risky than in all other commodities. Profiting traders didn't cover losses caused by diseases "import", which was opposite situation in comparison with cases of defective industrial commodities import.

Example: Eradication of Cochliomyia hominivorax, horrible myiasis affecting all mammals, including man, introduced through legal trade (accompanied by standard international attests confirming disease free status !) from South America into North Africa , cost 80 million US$ (losses not included); exporting country (traders) contributed nothing ! (FAO)

4.     International agreements unfavourable to importing country protection, i.e. without sufficient quality guarantee of pathogen free animal commodities and without fair reclamation procedure. Illegal import and almost uncontrollable re-export made veterinary control much more difficult.

5.     Low self-sufficiency in national production of food of animal origin which was requiring larger imports; instable trade partnerships, too many and too distant origin and destination places.

6.     Lack of ability to apply effective preventive, control and eradication measures under more complicated conditions than before and to control increasing trade; weak public veterinary services being unable to monitor animal population health situation at field level, to inspect on the spot rapidly increasing export/import ; issuing veterinary export certificates by not always independent and reliable non-government specialists; self-declaring specific "disease free zones" for export in countries with instable situation (new cases) and without adequate investigations and international inspection; unjustified concessions due to traders' pressure to reduce protective measures against diseases introduction.

7.     Controlling only limited number of selected diseases and certifying their "free status" for animals and products to be exported, ignoring not notifiable and not controlled transmissible diseases and the possibility of test false negative results.

8.     Absolutely insufficient research, education and training in population medicine, preventive and control measures at national and global levels (incomparable with economically well supported flourishing individual curative medicine).

9.     Human factors: exporting country not reporting true disease situation; risk underestimation; inexperience, errors; irresponsibility, cheating, corruption, outside "pressure"; falsification of identity and health certificates; low discipline when applying laws, regulations, norms and measures; low authority of veterinary services; not considering lessons from historical experience.


The analysis proved alarming worsening of disease situation in the world during recent decades.

It is obvious that the grade of disease spreading through international trade was directly correlated with diseases occurrence and control deficiency in exporting countries, trade size and frequency as well as with the numbers of and distances between origin and destination places.

There were many cases when, in spite of favorable risk assessment, risk reducing measures and standard veterinary certification, specific diseases spread through import into countries free of these diseases.

Not all introduced diseases could be blocked in the quarantine to avoid creating secondary outbreaks. Not all introduced diseases could be eradicated or only after longer period requiring a lot of economic and other inputs. The recovery, i.e. eradication, was feasible only in very limited number of cases due to lack of necessary inputs, mainly in developing countries.

Disease reintroduction represented serious impact due to devaluation of eradication programmes which had been usually very demanding, expensive and requiring long period. In one moment the result of many years of intensive successful work was converted into zero.

Animal disease import risk was generally underestimated giving priority to instantaneous profit of traders and ignoring potential disease spread with often irreparable consequences. "Import" of diseases represented for importing country the "purchase of problems".

Too many cases of disease introduction through trade proved that old traditional veterinary import conditions, certifications and measures didn't correspond with historically changing situation, requiring much better and more consistent protection measures than in the past.

Veterinary services were able to recover health and save life of many sick animals, solving mostly local problems. However, simultaneously many times more animals became sick due to diseases spreading mainly through international and national trade. De facto, it was gradually started trend towards the globalization of animal diseases, which is against the historical mission of veterinary medicine to promote, protect and restore animal population health in the whole world.


Increasing intensity of international trade in animals and raw animal products caused increasing spread of diseases among countries and continents. The situation was getting worse as never, in spite of having much better scientific knowledge and practical experience as in previous periods. Very few successfully finished national eradication programmes were unable to compensate rapidly spreading diseases in the whole world. Too many results in diseases control and eradication achieved by previous generations were gradually devaluated.

The lesson for the future consists in avoiding repetition of past mistakes and in supporting trade in pathogen free healthy animals and wholesome animal products only. Historical analyses are necessary for identifying factors facilitating diseases spreading through international trade and for applying correcting actions.

In importing countries, increase of animal production to be supported as much as possible and thus to reduce the need for risky import. Country protection to be strengthened and factors increasing diseases introduction risk to be avoided or reduced to acceptable minimum. In exporting countries, improvement of animal health quality through diseases reduction and eradication to be supported as the best way to facilitate fair trade in animals and raw animal products and thus avoiding transmissible diseases "export".

Public veterinary services to be radically strengthened to be able to cope with rapidly increasing trade. Wide gap in research of animal population health and disease at national and global levels to be filled, adequate methods to be developed and intensive education and training in preventive population medicine to be introduced or extended.

The lesson for the future: to stop neglecting historical experience and to apply consistently the principle of preventive medicine - Primum non nocere. Nobody wants next generations to blame us for letting animal diseases global situation worse than it was before.

Historia est magistra vitae!


(1) Blancou J, Meslin FX. International trade and human or animal diseases: a historical review. Proceedings of the World Veterinary Congress, Yokohama, 1995,p.4.

(2) Kouba V. Epizootiologia general, 2nd edit. Havana, Edicion Pueblo y Educacion, Instituto del Libro, 1987, 867 pp.

(3) Kouba V. Analysis of diseases spreading through international trade in animals in developing countries. Agricultura Tropica et Subtropica, Prague Agriculture University, 2001, Vol. 33, 70-74.

(4) FAO-OIE-WHO Animal Health Yearbook. Rome, FAO, 1980-1996.

(5) FAO Trade Yearbook. Rome, FAO, 1966-1996.

(6) Risk analysis, animal health and trade., 1993, 12(4), 1005-1362.

(7) World Animal Health. International Office of Epizootics, Paris, 1991-2000.

List of Figures

Graph 1. International trade in animals, meat and dairy products. World.

Graph 2. International trade in major animal commodities. World.

Return to Table of Contents: WVA Bulletin Vol. 19 Nr. 1 January 2002