Regional and international approaches on prevention and control of animal transboundary and emerging diseases

Transboundary animal diseases pose a serious risk to the world animal agriculture and food security and jeopardize international trade. The world has been facing devastating economic losses from major outbreaks of transboundary animal diseases (TADs) such as foot-and-mouth disease, classical swine fever, rinderpest, peste des petits ruminants (PPR), and Rift Valley fever. Lately the highly pathogenic avian influenza (HPAI) due to H5N1 virus, has become an international crisis as all regions around the world can be considered at risk. In the past decades, public health authorities within industrialized countries have been faced with an increasing number of food safety issues. The situation is equally serious in developing countries. The globalization of food (and feed) trade, facilitated by the liberalization of world trade, while offering many benefits and opportunities, also represents new risks. The GF-TADs Global Secretariat has carried out several regional consultations for the identification of priority diseases and best ways for their administration, prevention and control. In the questionnaires carried out and through the consultative process, it was noted that globally, FMD was ranked as the first and foremost priority. Rift Valley fever, and today highly pathogenic avian influenza, are defined as major animal diseases which also affect human health. PPR and CBPP, a disease which is particularly serious in Africa and finally, African swine fever (ASF) and classical swine fever (CSF) are also regionally recognised as top priorities on which the Framework is determined to work. The FAO philosophy--shared by the OIE--embraces the need to prevent and control TADs and emerging diseases at their source, which is most of the time in developing countries. Regional and international approaches have to be followed, and the FAO and OIE GF-TADs initiative provides the appropriate concepts and objectives as well as an organizational framework to link international and regional organizations at the service of their countries to better prevent and control the risks on animal and human health and the economic impact of TADs and emerging animal diseases.

Molecular epidemiology of Trichinella spp. in three Baltic countries: Lithuania, Latvia, and Estonia

Meat of domestic pigs and wild boars has been the significant source of emerged human trichinellosis in Lithuania, Latvia, and Estonia over the past two decades. However, there is very little known on the occurrence of Trichinella spp. in main wildlife reservoirs and its transmission in domestic and sylvatic cycles in these countries. The present study demonstrated considerably higher endemicity of Trichinella spp. in main sylvatic reservoirs (28.9-42% in foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) in all three countries than previously reported. Molecular identification of Trichinella larvae from more than 500 sylvatic and domestic animals revealed four Trichinella species (Trichinella spiralis, Trichinella britovi, Trichinella nativa, and Trichinella pseudospiralis) sympatric in a relatively small area and several as the first records for the respective countries. The nonencapsulating T. pseudospiralis is found for the first time in the Eastern Europe. Sylvatic T. britovi was found in domestic pigs in Lithuania and Latvia (16 and 57.1%, respectively) and only in these countries, domestic T. spiralis was detected in sylvatic animals in areas where domestic trichinellosis was registered. The study suggests that transmission of Trichinella between domestic and sylvatic cycles in Lithuania and Latvia is favored by improper human behavior, e.g., pig and slaughter waste management.

Veterinary public health activities at FAO: echinococcosis/hydatid disease

Cystic hydatidosis is a zoonotic disease that remain as a significant cause of human morbidity and mortality in many parts of the world. The disease has veterinary public health implications. FAO is involved with some activities in the control of echinococcosis/hydatid disease: within the Animal Production and Health Division the Veterinary Public Health (VHP) Programme is constituted by members of the different Services (Animal Health, Animal Production, and Livestock Policy) within the Division. FAO regular programme has also established a global network of professionals directly involved in VPH. Furthermore FAO's Technical Cooperation Projects (TCP) is a tool to assist member countries in responding to urgent and unforeseen demands.

Comparative persistent efficacy of doramectin, ivermectin and fenbendazole against natural nematode infections in cattle

A study was conducted in Argentina, to investigate the period of protection of a single injection of doramectin administered subcutaneously (s.c.) at 200 micrograms kg-1 (1 ml/50 kg) compared with single treatments of ivermectin (200 micrograms kg-1 s.c.) and fenbendazole (5 mg kg-1 p.o.), against field infections of gastrointestinal parasites of cattle. Eighty-three animals were selected and ranked on the basis of serial fecal egg counts (e.p.g.'s). From this group, three animals were slaughtered before treatment and their lungs, abomasum, small and large intestines, were processed for parasite counts and identification. The remaining 80 animals were allocated in ranked groups of four to a control or one of three treated groups. Animals of the four groups were grazed together in the same pasture for the duration of the study. Treatments were administered on Day 0. Individual fecal samples were collected at weekly intervals for the first 49 days post-treatment and twice a week from Day 52 to Day 84 (end of study). At each collection day fecal samples were pooled for coprocultures. On Day 28 and 56, two animals from each group, previously identified on Day 0, were killed and their parasite burdens determined. The duration of protection of a single injection of doramectin was longer than ivermectin or fenbendazole treatment. On Day 56, the total number of parasites found in doramectin-treated animals was significantly (P < 0.05) lower than parasite burdens found in either ivermectin- or fenbendazole-treated animals. The longer persistent activity of doramectin was expressed by the lower number of adults and L4 stages of Ostertagia ostertagi. Data from this experiment demonstrated the limitations of using fecal egg counts to evaluate the persistent efficacy of anthelmintics. The duration of activity of doramectin was demonstrated more accurately by parasite counts in cattle from each group since decreasing e.p.g.'s were seen in non-medicated animals without changes in total parasite burdens.

The prevalence of anthelmintic resistance in nematode parasites of sheep in southern Latin America: Argentina

Sixty-five sheep farms in the northern provinces of Buenos Aires, Entre Rios, Corrientes, Cordoba and Sante Fe were used in this survey on anthelmintic resistance. Anthelmintic groups tested were the benzimidazoles, levamisole, the combination levamisole + benzimidazole product and the avermectins. The overall level of resistance was 46% of properties, with resistance to the individual drug groups being 40%, 22%, 11% and 6%, respectively. On a large proportion of farms the resistance recorded was to two, or more, anthelmintic groups. Haemonchus contortus, Ostertagia spp. and Trichostrongylus spp. were the most abundant parasite species recorded. Resistance was greatest in the province of Corrientes where the frequency of treatment is generally high due to the endemic nature of H. contortus. Management practices were also important with resistance greatest on farms where frequent drenching is carried out and on farms carrying only sheep.

The prevalence of anthelmintic resistance in nematode parasites of sheep in southern Latin America: general overview

South America has a large population of small ruminants. Currents estimates are approximately 100 million sheep and 23 million goats. A large percentage of these flocks are raised in the humid tropics/sub-tropics. Nematode parasitism is singly the most important disease of these animals and typically farmers resort to frequent anthelmintic treatment in attempts to control this problem. Because of this reliance on drugs, price consideration is an important determinant in a farmer's choice of anthelmintic. In some circumstances, this has led to unethical practices of drug adulteration and substitution, or the offering to farmers of cheap, sub-standard generic products. The prevalence of anthelmintic resistance has not been investigated in any widespread sense in South America, although some of the first reports of resistance were made in southern Brazil almost 30 years ago. The following series of papers outline surveys conducted in the humid topics/sub-tropics of southern Latin America to assess the significance of resistance to the broad-spectrum anthelmintic groups in nematode parasites of sheep flocks.

Efficacy of doramectin against field nematode infections of cattle in Latin America

Two studies were conducted, one in Argentina and one in Brazil, to evaluate the therapeutic efficacy of doramectin administered subcutaneously at a dose rate of 200 micrograms kg-1 (1 ml per 50 kg) to cattle harboring mixed field infections of gastrointestinal nematodes. In each trial, 20 heifers were randomly allocated to a control or treated group of ten animals each, on the basis of fecal egg counts. Animals in the treated and control groups received an injection of doramectin or saline in the lateral midline of the neck. From 14 to 18 days post-treatment an equal number of animals from each group were slaughtered every day and the worm burdens of doramectin-treated animals were compared with those of non-treated controls. The efficacy of doramectin was at least 99.9% against adult stages of Ostertagia ostertagi, Haemonchus placei, Haemonchus contortus, Haemonchus similis, Trichostrongylus axei, Cooperia pectinata, Cooperia spatulata, Cooperia surnabada (Cooperia mcmasteri), Oesophagostomum radiatum and Dictyocaulus viviparus. Efficacy against Nematodirus helvetianus was 97.9% while efficacy against Trichuris discolor was 92.3%. Activity against inhibited larval forms of Ostertagia ostertagi, H. placei, Oesophagostomum radiatum, and Trichostrongylus axei, was at least 99.9%.

Ovicidal action of oxfendazole on sheep nematodes

Groups of five sheep naturally infested with gastrointestinal nematodes were dosed with oxfendazole at the rates of 2.5, 3.5, or 4.5 mg per kg and a similar group of five kept as controls. Frequent observations were made on worm egg output and the hatchability of the eggs passed. The first ovicidal activity was apparent five hours after treatment. Within eight hours 99.7 per cent or more of the eggs voided were sterile and by 30 hours there was a 99.9 per cent reduction in the numbers of larvae hatching compared with the controls. Within three days of dosing the faeces of the treated sheep were negative for worm eggs.