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World animal health status
Trends in the various epizootics and the distribution of outbreaks in 1998 and early 1999
Press Release dated 21 May 1999 in Paris, France. The 67th annual General Session of the International Committee of the Office International des Epizooties (OIE), held in Paris from 17 to 21 May this year, marked the 75th anniversary of this international organisation which has been monitoring world animal health since 1924 from its headquarters in Paris.
A summary of world trends in the different diseases and epizootics was drawn up, focusing on »List A« diseases, the ones most damaging to animal, and sometimes human health, as well as to the world economy and to international trade. This year foot and mouth disease, classical swine fever and Newcastle disease were the diseases which the countries affected considered to be of greatest importance to OIE Member Countries.
The management of animal disease emergencies is becoming a primary concern. To this end, the OIE could help to define model emergency plans, working protocols and in situ practical exercises. More effective plans such as these would make it possible to take action within a much shorter time frame and so provide an appropriate response to the most sensitive situations.
Trends in the various epizootics
Diseases of most concern
Management of animal disease emergencies
Resistance of ecto- and endoparasites
New-generation vaccines for veterinary use
The 121 Heads of Veterinary Services of OIE Member Countries and 3 observers from non-member countries and territories attending the Session, as well as the representatives of 12 Inter-Governmental Organisations, including the FAO, WHO and WTO, also considered possible measures to deal with the problem of the resistance of ecto- and endoparasites to antiparasitic agents.
Finally, the field of application of the new-generation vaccines that have emerged in the past ten years is particularly promising, in particular for preventing classical swine fever, rinderpest, avian influenza, bovine herpesvirus 1 and porcine reproductive and respiratory syndrome.
The »List A« animal diseases, which pose the greatest threat to the world economy and international trade, and some, like Rift Valley fever, which seriously endanger human health, continue to occur throughout the world, affecting continents and species to varying degrees.
Rift Valley fever in East Africa and West Africa
Rift Valley fever posed a real threat to East Africa in early 1998, affecting around 89,000 people, and leading to the loss of over 200 human lives, as well as around 70 percent of the sheep and goat population, and 20 to 30 percent of the cattle and camel populations in this region. This catastrophe was related to the »El Niño« weather system, which resulted in the worst floods experienced in the Horn of Africa since 1961.
Again linked to rainfall (though not due to the »El Niño« weather system), human cases of Rift Valley fever were reported in Mauritania in September/October 1998. During the same period, numerous abortions were reported among ruminants in Mauritania.
Foot and mouth disease in Africa, Asia and South America
Foot and mouth disease is a contagious viral disease that is highly damaging to ruminant and pig farms because of the heavy economic losses which it can cause, both directly (mortality, decline in production) and indirectly (slaughter or export bans). It is either absent or under control in Oceania, North America and Central America, as well as in most European countries. It is in the process of being eradicated in South America.
With regard to Africa, Algeria, Morocco and Tunisia suffered an epizootic in early 1999. In southern Africa, foot and mouth disease broke out in Malawi, where the disease had not been observed since 1986, as well as in the Kruger National Park in South Africa (disease reported among wild animals).
With regard to Europe, the new variant of the serotype A virus, identified in Iran in 1996, was reported in Turkey, firstly in 1997 in eastern Anatolia and subsequently in several provinces of central and western Anatolia during the first half of 1998. This strain also spread into Armenia in the summer of 1998. A serological survey carried out in early 1998 in Albania, in the Former Yugoslav Republic of Macedonia and in the Federal Republic of Yugoslavia (Serbia and Montenegro) revealed no active foot and mouth disease virus in any of the three countries.
Foot and mouth disease continued to be enzootic throughout most of the Middle East. Israel reported three outbreaks in the north of the country in early 1999.
In Central Asia, outbreaks caused by the serotype O virus were reported in Kazakhstan and Kyrgyzstan in 1998. In the People's Republic of China, two districts in the Yunnan province were affected. In Taipei China, where more than 6,000 outbreaks were reported in 1997, only six farms were infected in 1998 (five during the first six months and one in December). The disease was still present in the countries of South and South-East Asia in 1998.
In South America, the disease has either been eradicated or is in the process of being eradicated in several countries and regions.
Rinderpest
Rinderpest, a viral disease which leads to a very high mortality rate in the herds affected, was not as widespread in 1998 as in the previous year. Russia is the only country to have reported the existence of this disease on its territory in 1998. A single outbreak occurred in the Amur region. Measures to control this outbreak were lifted on 1 October 1998.
Contagious bovine pleuropneumonia
In 1998, contagious bovine pleuropneumonia was still a major concern for the African continent, with the exception of North Africa. Its spread towards the south of the continent is disturbing. In February 1998, several bovines in the Northern Province of Zambia were found to be carrying specific antibodies; 15,000 bovines being reared along the border zone were vaccinated in order to counteract any further spread.
Europe progressed towards complete eradication: in Portugal, only five outbreaks were reported in 1998, compared with 64 in 1997.
Vesicular stomatitis
As in previous years, vesicular stomatitis was diagnosed only in the Americas. An epizootic, caused by the Indiana serotype, occurred in the USA from May to December 1998; the last farm to be affected was released from quarantine on 22 January 1999. Primarily Equidae were affected. In South America, the highest incidence of the disease was reported in Colombia. In Brazil, which had experienced no episode of the disease since September 1996, outbreaks were reported in four States (Mato Grosso, Minas Gerais, Parana and Santa Catarina).
African horse sickness
Unlike the previous year, outbreaks were reported in Eritrea in 1998. The incidence of the disease also increased markedly in Ethiopia (110 outbreaks in 1998, compared with 30 in 1997). In South Africa it appeared in March 1999 in the disease surveillance zone bordering the disease free zone.
African swine fever
African swine fever, which had seen a marked upsurge throughout the world in previous years, was not as prevalent in 1998. A few outbreaks were reported in Africa: a single outbreak in Senegal and another in Togo, together with 16 in Benin, compared with 104 the previous year.
The disease, which broke out in Madagascar in June 1998, led to the death of more than 107,000 pigs.
In Europe, only the Italian island of Sardinia remained infected.
»The 'List A' animal diseases, which pose the greatest threat to the world economy and international trade, and some, like Rift Valley fever, which seriously endanger human health, continue to occur throughout the world, affecting continents and species to varying degrees«.
Classical swine fever
Classical swine fever, which had seen a marked increase throughout the world in previous years, continued to occur this year.
In Europe, five outbreaks which occurred in the Netherlands during the first quarter of 1998, were quite swiftly stamped out; this country was once again able to declare itself disease-free in September 1998. In Spain, 21 outbreaks occurred between January and July 1998, and two further provinces were affected (Saragossa and Sevilla). Spain declared itself to be once again free from the disease in January 1999. In Italy, 16 outbreaks were declared on the island of Sardinia, and one in the region of Emilia-Romagna. In the Lombardy region of Italy, several boar were recognised to be carrying specific antibodies, particularly in one area close to the Swiss border. In Switzerland, where classical swine fever had not been reported since December 1993, wild boar were recognised as being affected in the canton of Tessin between May and December 1998. In Germany, several Länder were affected and around 75,000 pigs were slaughtered and carcasses then destroyed. In both Germany and th!
e CzechRepublic, the disease was also identified in boar.
In South America, Argentina reported seven outbreaks of classical swine fever (previous outbreak: April 1995). The country launched a national prevention programme. In the Dominican Republic, 232 outbreaks were declared; a national vaccination programme was implemented.
By contrast, the number of outbreaks declined in Mexico. Cuba remained free from classical swine fever in 1998, whereas it had experienced 257 outbreaks in 1996 and seven in 1997. Chile declared itself to be free from classical swine fever in April 1998 and Costa Rica in August.
Bluetongue
In Africa, Kenya reported several cases of bluetongue in early 1998, again related to the abundant rains associated with the »El Niño« weather system.
In Canada, an incursion of the bluetongue virus occurred in the Okanagan valley (province of British Colombia) during the second half of 1998, with no repercussions on the health of the valley's ruminants.
Bluetongue occurred in Greece in November and December 1998, on the islands of Kos, Rhodes and Samos.
Sheep pox
This disease, which affects small ruminants, is present in a number of countries in Africa, the Middle East and Asia. As a result of vaccination campaigns, no outbreak was reported in Morocco and the incidence of the disease declined in Algeria and Tunisia. In Greece, where only a stamping-out policy is applied, the disease also declined in 1998 and remained restricted to the most easterly region (only seven outbreaks, compared with 52 outbreaks in 1997).
Newcastle disease
In Europe, Denmark was affected (two industrial turkey farms in February 1998). Several other European countries reported the disease in amateur farms rearing pigeons, domestic poultry or ornamental birds.
In the Americas, fighting cocks were affected in the State of California in the USA in June 1998. In Venezuela, the disease broke out on a farm with nearly 100,000 meat-producing chickens (last outbreak: 1993).
In Australia, where Newcastle disease had been eradicated in 1932, three farms in the State of New South Wales were affected in August 1998. Further outbreaks occurred in early 1999. The viral strain at the origin of these outbreaks probably came from a mutation of a lentogenic strain that is enzootic in Australia.
In Africa, Botswana, which had reported only one outbreak of Newcastle disease in 1997, diagnosed several in 1998. In Ethiopia, 14 outbreaks occurred (previous outbreak: December 1996).
Avian influenza
In Italy, migratory birds were in all likelihood the origin of the episode of highly pathogenic avian influenza (between November 1997 and January 1998). The country declared itself to be once again free from the disease in August 1998.
Pakistan was the only other country to have reported the presence of the disease on its territory.
Since there were no repercussions from the episode of highly pathogenic avian influenza which occurred in Australia in late 1997, the country declared itself to be once again free from the disease in June 1998.
Nipah virus
A new zoonotic disease recently appeared in peninsular Malaysia. In humans it was at first confused with Japanese encephalitis due to the often fatal clinical signs. The virus in question was isolated by the joint research efforts of Malaysian and American researchers. The disease in humans was linked to the existence of infected pigs. Measures were taken in the four affected zones to isolate the population in order to limit human contamination, and more than 900,000 pigs were slaughtered and destroyed. Research and monitoring efforts continue, notably to identify the reservoir of the virus.
Managing animal disease emergencies
Health risk management is becoming a major concern throughout the world. The results of a questionnaire, sent to all OIE Member Countries, indicate that a large number of countries are having to deal with emergencies. In addition, growing international trade and passenger traffic mean that disease-free countries are at serious risk of contracting diseases from infected regions.
To deal with this situation, the OIE, together with other international organisations, could help to harmonise the management of animal disease emergencies world-wide, by defining model emergency plans, working protocols and in situ practical exercises. Standards would be established for managing such plans in order to provide for rapid and effective intervention. The objectives would be as follows:
to initiate the development of standards for emergency plans and practical exercises;
to help optimise the international warning system and animal disease surveillance;
to propose precise definitions of the veterinary activities that take place during an animal disease emergency;
to describe the minimum requirements for identification and information systems and help to adapt them to specific local situations.
Resistance of ecto- and endoparasites
The OIE conducted a survey to determine the world-wide scale of the problem of resistance of ecto- and endoparasites to the most commonly-used chemicals, and to propose solutions for preventing or controlling resistance.
According to the replies from 77 Member Countries, those ecto- and endoparasites with the heaviest impact on production are also those to which resistance is the most widespread throughout the world. 55% of the countries that replied reported resistance to antiparasitic agents in at least one group of parasites included in the study. 86% reported resistance to antihelmintics, 50% to ixodicides, 31% to insecticides (Diptera of veterinary importance), 19% to acaricides used against mange mites and 10% to acaricides used against lice. 24% of these same countries have more than three groups of resistant parasites (three to five) and 22% reported resistance in the two groups of parasites considered to be of greatest economic impact.
The Member Countries discussed the risk of resistance developing in species not targeted by control methods, through the systematic use of wide-spectrum antiparasitic agents.
In spite of the attention given to this problem over the past ten years, prevention and control methods have barely changed. It is seen as vital to involve all of the parties concerned - governments, the pharmaceutical industry and private and international organisations - in developing a sustainable and economically-efficient programme for controlling parasitic diseases that takes into account resistance to antiparasitic agents.
»A strategic action plan will be submitted to the International Committee following in-depth consultation with Member Countries. This plan will include an indication of the role that the OIE intends to play in the fields of animal health, public health and consumer protection«.
New-generation vaccines
Several vaccines have been genetically engineered over the past ten years. These were first used to protect pigs against Aujeszky's disease. The same principles were then applied to developing vaccines against infectious bovine rhinotracheitis and classical swine fever. Recombinant vaccines were used to protect bird species against Newcastle disease and avian influenza, and a recombinant oral vaccine was used to vaccinate wild animals against rabies.
The field of application of these vaccines could be extended to include classical swine fever, rinderpest, avian influenza and porcine reproductive and respiratory syndrome. Indeed, many of these vaccines have the advantage of allowing infected animals to be differentiated from vaccinated animals.
Action plan 2000 to 2004
Once again, this year important decisions were taken to improve the OIE recommendations concerning the sanitary conditions to be applied to international trade in animals and animal products. These improvements primarily concern the chapter on bovine spongiform encephalopathy in which many points previously under study were resolved. The conditions that a country has to fulfil to be recognised as free from the disease were established, which will allow the OIE to work on drawing up a procedure and guidelines for implementing such recognition at international level. Proposals on this subject will be submitted to the OIE International Committee in May 2000.
The OIE is preparing its action plan for the period from 2000 to 2004:
A strategic action plan will be submitted to the International Committee following in-depth consultation with Member Countries. This plan will include an indication of the role that the OIE intends to play in the fields of animal health, public health and consumer protection.
All OIE papers are available on http://www.oie.int
(billedtekst)
Presentation of OIE Honorary Awards during the opening ceremony of the 67th OIE General Session held in Paris, France, 17-21 May 1999.
From the left: Dr Nicola T. Belev, Bulgaria, for the gold medal, Dr Daan Verwoerd, South Africa, Dr Sultan Al Khalaf, Kuwait, and Professor Esko Nurmi, Finland, for the meritorious service awards.
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