Acta.vet.Brno, 2003,72:453-460
GLOBALIZATION OF COMMUNICABLE DISEASES OF ANIMALS –
CRISIS OF
VETERINARY MEDICINE
V. KOUBA
Former Chief, Animal Health Service, Food and Agriculture Organization
of the United Nations
Abstract
.....
The analysis of animal diseases globalization
is based on official reports on
communicable disease introductions through international trade. Number of available reports on these cases
during 1980-2000 reached 607 : 117 OIE List A disease cases (including 33 of
foot-and-mouth disease), 365 OIE List B disease cases (74 of multiple animal species
diseases, 142 of cattle diseases, 42 of sheep and goat diseases, 29 of horse
diseases, 12 of pig diseases, 49 of avian diseases, etc.), 108 OIE List C
disease cases and 17 cases of other diseases. The import of diseases
transmissible to man was reported 212 times (34.93 %). Cases of disease reappearance, i.e. newly
imported or reemerged after 3 and more years, were reported 329 times. Number
of reports on animal disease "recognized in country for the first
time" reached 420 cases. All reported data represent only "the tip of
the iceberg". Disease import is usually followed by spreading extremely
difficult to control, often no manageable and with catastrophic consequences. Very
limited number of successful communicable disease control and eradication programmes
together with all recoveries of individual diseased animals cannot compensate at
all rapidly increasing animal population morbidity in the world. No one animal
disease has been globally eradicated yet. Diseases import devaluates the
results of control and eradication programmes. Diseases are spreading as never
in the past when the trade used to be of much minor size and intensity at much
shorter distances to much lesser number of destination places. The situation is
getting worse every day towards man-made global ecological irreparable disaster.
Continuing worldwide mass spreading of communicable diseases, not being blocked
by effective measures, represents serious
global crisis of veterinary medicine which historical mission is to promote,
protect and recover animal health.
Animal population morbidity
- infectious disease - disease export - disease import - disease reappearance -
disease spreading - disease first discovery - international trade – post-import spread
Key criterion
of veterinary medicine historical mission is its practical impact on global
animal population health. The usefulness of this scientific branch depends on
how far it is able to protect healthy animals, to recover health of diseased
animals and to reduce, eliminate and eradicate diseases. Unfortunately, available
facts document serious discrepancy between rapidly increasing amount of
scientific knowledge and rapidly worsening of animal health global situation. Among
main causes belongs the propagation of infectious and parasitic diseases
through international trade in animals and their products. Increasing public
health, economic, ecological, social and animal welfare negative impacts of
diseases spreading are enormous. The purpose of this paper is to analyze
globally communicable diseases spreading through international trade from 1980
when regular reporting on animal disease import was started. Analysis of previous periods was published by
B l a n c o u and M e s l i n (1995) using unofficial literature sources only.
Import of animals and animal products represents a risk not only of disease
introduction but also of post-import spreading with multiplying negative, often
long-term or permanent, catastrophic consequences. Unfortunately, due to
immense diversity of individual diseases under different conditions it was not
possible to elaborate any international standards for objective measuring of
epizootiological risks (OIE 1993). The majority of imported diseases cannot be
blocked within short quarantine if any. Discovery in time, successful control
and eradication of introduced and spread diseases are usually extremely
difficult and very often practically impossible.
The analysis is based on country official data
as reported by the governments to international organizations. Data on
international trade are from FAO Trade Yearbook (FAO 1966-2002). Data on
diseases introduction through trade are from two international yearbooks - OIE
World Animal Health (OIE 1991-2002) and FAO-WHO-OIE Animal Health Yearbook (FAO
1980-1996) (international collection of data on “disease import" was
introduced by the author when he was its Editor-in-Chief). The analysis is supported
by the examples from FAO and OIE documents as well as from literature sources.
International information system is based only on etiological agent species structure
regardless of enormous number of their different strains, serotypes, etc. which
for importing country can often represent exotic danger. This information
system covers only about 1/10 of known species of transmissible diseases,
including 1/5 of known zoonoses. The system does not include conditionally
pathogenic agents, strains resistant to treatment means, etc.
Many countries
did not send the regular annual reports or only incomplete ones and therefore
their data were not available for the inclusion in this analysis. The number of
reporting countries varied from 110 (1983) to 169 (1991); in average about 75 %
countries only. There are a lot of cases of animal disease import, some are
discovered and reported to international organizations, many are discovered and
not reported (e.g., most diseases are not obligatory notifiable and not controlled),
much more cases are discovered too late for reporting them as imported ones and
even much more cases are not discovered at all (e.g., subclinical carriers).
Therefore, the analysis could not be complete, i.e. it covered only a small
part of the reality which is much worse than officially reported.
Important factor was the grade of
detectability (sensibility) of available diagnostic methods and the grade of
reporting on disease import cases.
Some cases were reported with delay due to late discovery of imported diseases
which creates difficulties in controlling them. The delay was usually related to
long incubation periods which can be up to several months (e.g.
paratuberculosis) or several years (e.g. BSE) as well as to the ability of
veterinary service to detect imported disease in time.
The analysis of
reports on animal disease introductions through international trade was
subdivided according to international classification of communicable diseases:
OIE Lists A, B and C. In case of reporting the import of the same disease in
following year or repeatedly during the same year, only one report was included
in this quantitative analysis. The available reports were related mainly to
disease import through trade in live animals. Microscopic pathogens import
through animal products (such as Salmonella
spp. in fresh meat) was very difficult to identify due to their rapid
distribution, processing and consumption and quite insufficient etiological investigations.
Additionally, there were analyzed the numbers
of reports on specific disease “recognition in country for the first time”. A
lot of them were imported from abroad. Analysis of reports on specific disease
reappearance (reimported or reemerged) includes only cases which reappeared
after 3 and more years. The reason is that the reappearance after less than 3
years could be in some cases the result of the pathogens survival in
animal-carriers or in the environment.
In 1996 FAO-WHO-OIE Animal Health Yearbook disappeared
and regular reporting on diseases import cases, on diseases recognition for the
first time and on diseases reappearance was abolished by the International
Office of Epizootics (OIE). Therefore,
later these data found in the OIE World Animal Health yearbooks were only ad hoc ones. The analysis based on official
numeric facts was complemented (when specific data for global quantification
were not available) by selected examples from the literature to document
certain aspects of international disease spreading. Particular attention was given
to the ratio primary/secondary outbreaks expressing the grade of disease post-import
spreading.
Diseases spread through international trade is
directly correlated with increasing import of animals and animal products. According to FAO
Trade Yearbooks international legal import of these commodities increased during
1961-2000 in monetary values 17 times (from 4653 to 80358 million
International trade in animals and animal
products during 1980-2000 caused spread of many animal diseases. Number of cases
officially reported to international organizations on diseases import reached
607. (Table 1).
From 117 OIE List A disease cases the major
shares had foot-and-mouth disease - FMD (28.23%), rinderpest (17.09%), Newcastle
disease (14.53%), contagious bovine pleuropneumonia (7.69%), classical swine
fever (5.98%) and bluetongue (5.13%).
The structure of 365 OIE List B disease cases
was as follows: From 74 multiple species disease cases the major shares had
paratuberculosis, echinococcosis, screwworm (Cochliomyia
hominivorax), rabies, anthrax and heartwater. From 142 cattle disease cases
the major shares had bovine leucosis, tuberculosis, brucellosis, IBR-IPV, babesiosis, anaplasmosis,
theileriosis, BSE and cysticercosis. From 42 sheep and goats disease cases the
major shares had caprine arthritis/encephalitis, maedi-visna, ovine
epididymitis, brucellosis (B. melitensis), ovine pulmonary adematosis and
scrapie. From 29 equine disease cases the major shares had equine
piroplasmosis, equine viral arteritis, equine infectious anaemia and contagious
equine metritis. From 12 swine disease cases the major shares had atrophic
rhinitis and porcine cysticercosis. From 49 avian disease cases the major
shares had Marek´s disease, avian chlamydiosis, infectious bursal disease,
mycoplasmosis and infectious laryngotracheitis. From 17 other disease cases the
major shares had leishmaniosis, rabbit haemorrhagic septicaemia and bee acariosis.
From 108 OIE C disease cases the major shares
had distomatosis, warble infestation, avian leucosis, caseous lymphangitis,
mucosal disease, contagious pustular dermatitis and filariosis. From 17 other disease (outside of the OIE
information system) cases the major share had Ebola-Marburg virus infection,
influenza-parainfluenza and sheep babesiosis.
Number of reports on animal diseases
"recognized in country for the first time", i.e. imported or
discovered with delay, reached 420. Disease reappearance, i.e. reintroduced or
reemerged, was reported 329 times. The analysis includes only reports of the
reappearance when the interval between last previous and new cases was 3 and
more years. (Table 2). The longest periods were reported on FMD reappearance in
Within the total of reported cases following
proportions were represented by diseases transmissible to man (zoonoses): 34.93%
of reports on disease import, 15% of reports on specific disease discovery for
the first time and 30.51% of reports on disease
reappearance (KOUBA 2001). (Table 3). The majority of known zoonoses is not
included into OIE disease lists (e.g. plague, Ebola-Marburg virosis, Salmonella typhimurium in mammals,
trichophytosis, etc..).
The majority of
communicable disease import cases (about 70%) was reported from developing
world with about 25 % of global animal import where the impacts are very
serious due to weak veterinary services and lack of means to control imported diseases (K o u b a 2000).
To document the
difficulty to discover particular diseases and to report true disease situation
following example is used: "It is assumed, that for every case of
salmonellosis recorded in humans in the
All transmissible
diseases spread at different speed and extent, mostly unnoticed due to subclinical
forms. Almost free spreading is characteristic for diseases outside of
veterinary control, i.e. for the majority of diseases. Many communicable
diseases are able to penetrate the barriers even of the best isolated and
controlled laboratories. Example: ”In 1978,
the
The ratio primary/secondary outbreaks,
expressing the grade of disease post-import spreading, is documented by following
examples: “In Taiwan FMD occurred in 1997 and stormed the whole island that led to
tremendous economic impact... During four months a total of 6,147 farms was
infected !” (OIE 1997, p. 317-318); the
ratio = 1 : 6147. In European Union during 1977-1987 average
ratio primary/secondary outbreaks of FMD was
Other important
criterion is represented by territorial spread of imported diseases. Example: “In
1988 was discovered for the first time in the Eastern Hemisphere the horrible
myiasis Cochliomyia homivorax, affecting
all mammal species including man, imported by sheep from American continent;
during several months it invaded 25000 km2 in the North Africa with
more than 2.7 million domestic animals” (FAO 1992).
Discussion
There were many
cases when, in spite of favourable risk assessment, risk reducing measures and international
standard veterinary certification, specific diseases spread through import into
countries free of these diseases or contributed to worsening of existing
situation. Examples see in Table 4 (these data, as not reported to OIE or FAO, were
not included in the global analysis numbers mentioned above).
In the majority of communicable diseases
clinical investigation alone is not able to discover the true situation which
is therefore unknown and these diseases can freely spread unnoticed. Emerging
diseases, new more virulent and resistant strains represent an insidious threat
even for human health and life.
Many introduced
diseases cannot be blocked in the quarantine to avoid secondary outbreaks. Late
discovery gives the chance for territorial spreading making impossible the
application of effective eradication measures in time. The recovery, i.e.
eradication, is feasible only in very limited number of diseases due to lack of
necessary methods and inputs. Even the countries considered as the best
prepared had difficulty to block and eradicate imported diseases. Example: Eradication
of FMD introduced in
Disease first introduction into countries
previously specifically free is particularly lamentable. Dramatic consequences
had the import of cattle subclinically affected by BSE conducing to significant
reduction of production and consumption of beef in many countries. Other example:
paratuberculosis of cattle imported in this disease free
Disease reintroduction represented serious
impact due to devaluation of successful eradication which was usually very demanding, expensive
and requiring long period. In one moment
the result of many years of intensive work was converted into zero. In
Eradication of imported diseases, mainly so
called exotic ones, is extremely difficult and costly. Example: Eradication of Cochliomyia
hominivorax, introduced through trade into
There were also
cases of conscious spreading of infected, or suspect to be infected, commodities
into many countries. Example: "A large rendering company in UK continued
and expanded its export of meat and bone meal, which may have been contaminated
with BSE, for 8 years after EU ban in 1988, to 70 countries in the Middle and
Far East” (H o d g e s 2001).
Serious problem is represented by different
regional strains unknown in other regions and considered there as exotic. Their
introduction complicates the diagnosis and anti-epizootic measures. Example: “Globalization also means global scope for
diseases that were previously limited to specific regions. The rapid spread of
the FMD Pan-Asian strain is witness to this. As
Conclusion
The analysis proved
alarming worsening of animal health in the world during recent period.
Available data used for this analysis represent only a small “tip of the iceberg”,
i.e. the true situation is many times worse than reported. The disease
spreading through international trade is directly correlated with disease occurrence,
grade of true situation ignorance and grade of disease control deficiency in
exporting countries, trade size and frequency as well as with the numbers and
distances between origin and destination places. (Analyses identifying factors
facilitating diseases spreading through international trade and identification
of correcting measures require separate papers.)
Weakened (somewhere ad absurdum) public veterinary services, are very often not able to
assure disease-free or pathogen-free animal export and to manage disease import
cases. Veterinary services are able to
recover health and save life of many diseased animals, solving mostly local
problems. However, simultaneously many times more animals become infected,
invaded and clinically sick due to diseases spreading mainly through trade. The
analysis documents that it has been started the globalization of communicable diseases
of animals. There is a real risk that next generations will blame us for
letting animal health global situation much worse than it was before. The
lesson for the future was published by KOUBA 2002 recommending the steps for
avoiding further worsening of global epizootiological situation.
Increasing
intensity of international trade in animals and animal products caused
increasing spread of diseases among countries and continents. The situation has
been getting worse as never, in spite of
having much better scientific knowledge as in previous periods. Very few
successfully finished national eradication programmes are unable to compensate
rapidly spreading of animal diseases in the whole world. Too many results of
diseases control and eradication achieved by previous generations were
gradually devaluated through disease import which demotivates the efforts to
start new programmes or continue with existing ones.
The situation is approaching
every day towards man-made irreparable global ecological disaster. Continuing
worldwide mass spreading of communicable diseases, not being blocked by
effective measures, represents serious
global crisis of veterinary medicine which historical mission is to promote,
protect and recover animal health in the whole world.
References
BLANCOU, J., MESLIN,
F.X. 1995: International trade and human or animal
diseases: a historical review. Proceedings of the World Veterinary
Congress,
CHROUST, K., BÍLÝ, V., PAVEL, V. 1997: Podkožní
střečkovitost (hypodermóza) skotu a její
tlumení. Veterinářství, 47 (12):514-515
(in Czech)
DAVIES, G.
1993: Risk assessment in practice: a foot and mouth disease control
strategy for
the European Community.
Rev.sci.tech.Off.int.Epiz. 12 (4):
1109-1120
FAO 1966-2002:
FAO Trade Yearbook.
FAO 1979: FAO-OIE-WHO Animal Health
Yearbook,
FAO 1980-1996: FAO-OIE-WHO
Animal Health Yearbook.
FAO 1992: The
FAO 2001: Empres.
HODGES, J. 2001: Editorial. Livestock
Production Science 69, p. 59
KOUBA, V. 2000: Analysis of diseases spreading through international trade in animals
in developing countries. Agricultura Tropica et Subtropica, Prague
Agriculture Univ., 33: 70-74
KOUBA, V. 2001: Globalizace animálních
infekcí a mezinárodní obchod. Zprávy Centra epidemiologie a mikrobiologie,
Státní zdravotní ústav, Praha, 10
(12): 483-485 (in Czech)
KOUBA, V. 2002:
History of diseases spreading through international trade – lesson for the
future. World Veterinary
Association Bulletin, 19 (1): 18-21
OIE. 1993: Risk analysis, animal health and trade. Rev.sci.tech.
Off.int.Epiz. 12(4): 1005-1362
OIE: 1991-2002:
World Animal Health (yearbook).
PAVLÍK,
STERNEBERG, T., CHORAINE, P. 2002: Foot
and Mouth Disease. World Veterinary Association Bulletin 19
(2)
TOMA, B., VAILLANCOURT, J-P., DUFOUR, B.,
ELOIT, M., MOUTOU, F., MARSH, W., BÉNET, J., SANAA, M., MICHEL P. 1999: Dictionary of Veterinary Medicine, Iowa
State University Press/Ames: p.147.
Table 1
Number of country reports on the introduction
of communicable diseases through animal import, world, 1980-2000
==================================================================
OIE Code Animal Species Number of reports %
==================================================================
List A diseases multiple 117 19.28
----------------------------------------------------------------------------------------------------------------
List B
diseases
multiple 74 12.19
cattle
142 23.39
sheep and goats
42 6.92
horses
29 4.78
pigs
12 1.98
poultry
49 8.07
others
17 2.80
-----------------------------------------------
Subtotal 365
---------------------------------------------------------------------------------------------------------------- List C
diseases 108 17.79
----------------------------------------------------------------------------------------------------------------
Others
diseases
17 2.80
==================================================================
Total 607 100.00
==================================================================
Sources: FAO/WHO/OIE Animal Health Yearbook (1980-1996)
and OIE World Animal Health yearbook (1991-2002)
Note: In 1996 special regular reporting on diseases
“import” was abolished, i.e. later reports were only ad hoc.
Table 2
Country reports on reappearance of animal communicable diseases, world,
1980-2000
==================================================================
Intervals in years Number of
reports %
---------------------------------------------------------------------------------------------------------------
3 – 10
240
72.97
11 – 20 49
14.89
21 – 30
18
5.47
31 – 40 13
3.95
41 – 50
1
0.30
51 – 60 0
0.00
61 – 70
5
1.55
> 70 2
0.61
?
1
0.30
--------------------------------------------------------------------------------------------------------------
Total
329
100.00
=================================================================
Sources: FAO/WHO/OIE Animal Health Yearbook (1980-1996)
and OIE World Animal Health yearbook (1991-2002)
Table 3
Number of country reports on cases of
the import of animal communicable diseases, their first discovery and
reappearance (total and zoonoses), world, 1980-2000
===================================================================
Report Type Number
of cases Zoonoses %
-----------------------------------------------------------------------------------------------------------------
Imported
607 212 39.93
Discovered for the
first time in
history (incl.
imported cases)
420
63 15.00
Reappeared after
3 and more years
(incl. imported cases) 329
130 30.51
===================================================================
Source: FAO/WHO/OIE Animal Health Yearbook (1980-1996)
and OIE World Animal Health yearbook (1991-2002)
Note: In 1996 special regular reporting on these
cases was abolished, i.e. later data were only ad
hoc.
Table 4
Number of animal disease introductions
through legal import (with official certificates) in Czech Republic, 1990-1996
=================================================================
Animal Imported S h
i p m
e n t s Disease Frequency
Species Animals Total Infected %
--------------------------------------------------------------------------------------------------------------
Cattle 19350 326 181 55.52
tuberculosis**** 3 x
paratuberculosis** 24 x
IBR***** 39 x
trichophytosis***** 86 x
leptospirosis 11 x
hypodermosis*** 18 x
Sheep 9880 500 31 6.20
maedi-visna* 16 x
paratuberculosis** 4 x
scrapie* 6 x
salmonellosis 1 x
mange*** 3 x
dictyocaulosis*** 1
x
Goats 315 40 2 5.00
inf.
agalactia* 1 x
tuberculosis*** 1 x
--------------------------------------------------------------------------------------------------------------
Total 29545 866 214 24.71
=================================================================
Situation before 1990: * never recorded; ** never recorded
in indigenous animals (exceptional occurrence only in some imported animals); *** eradicated; **** eliminated (free status according
to OIE Code); ***** very advanced eradication programme.
Note: Animals were imported mostly from West European
countries.
Source: State Veterinary Administration,
Address for correspondence:
Prof.MVDr Václav Kouba, DrSc.
P.B.516, 17000 Praha 7,
Tel. 42-233381088
E-mail: vaclavkouba@cbox.cz