Study of a prevention programme for caprine arthritis-encephalitis

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1 Study of a prevention programme for caprine arthritis-encephalitis G Péretz, F Bugnard, D Calavas To cite this version: G Péretz, F Bugnard, D Calavas. Study of a prevention programme for caprine arthritis-encephalitis. Veterinary Research, BioMed Central, 1994, 25 (2-3), pp <hal > HAL Id: hal Submitted on 1 Jan 1994 HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

2 Study of a prevention programme for caprine arthritis-encephalitis G Péretz F Bugnard D Calavas Centre d Écopathologie Animale, 26, rue de la Baisse, Villeur6anne,France Summary &horbar; A prevention programme for caprine viral arthritis-encephalitis was monitored in 363 goat herds between 1988 and The level of contamination in the female kids fell from 49.5 to 25% by the end of the 2-yr period during which the programme was applied. Some 19% of the female kids that had been given substitute colostrum (cow colostrum or goat colostrum heated to 56 C for 1 h) were contaminated compared with 45% of those that had been given raw colostrum. The segregation between the animals submitted to prevention measures and those that were not are presented to illustrate the efficiency of prevention of horizontal transmission. goat / caprine arthritis-encephalitis virus / prevention Résumé &horbar; Étude d un programme de prévention de l arthrite encéphalite caprine. Un programme de prévention de l arthrite encéphalite caprine à virus a été suivi dans 363 élevages de 1988 à Le niveau de contamination des chevrettes est passé de 49,5% à 25% après 2 années d application. 19% des chevrettes qui ont bu du colostrum de remplacement (de vache ou chauffé une heure à 56 C) étaient contaminées contre 45% de celles qui ont bu du colostrum non traité. La ségrégation des animaux ayant été soumis à des mesures de prévention est commentée pour illustrer l efficacité de la prévention de la transmission horizontale. chèvre / arthrite encéphalite caprine à virus / prévention INTRODUCTION The caprine arthritis-encephalitis virus (CAEV) is an RNA virus of the family retroviridae, subfamily lentivirinae (Crawford et al, 1980; Narayan et al, 1980). It provokes arthritis, interstitial mastitis, interstitial pneumonia and encephalitis in the 2- to 4-monthold goat (Adams and Crawford, 1980; Lerondelle, 1988). Contamination occurs by transmission of infected monocytes or macrophages, which may be found in all *Correspondence and reprints types of secretions and excretions, but particularly in colostrum and milk (Adams etal, 1983). Contamination by blood has also been described. The consequences are a fall in milk production, particularly when the animal has severe arthritis (Péretz and Cimarosti, 1990) or mastitis, and changes in anticipated culling dates. This situation constitutes a real hindrance to international exchange between producers. The lack of treatment or vaccination has orientated us towards a solution based on

3 principles of sanitarian prophylaxis. Several epidemiological studies demonstrated that, in France, more than 80% of herds specialized in goat production are infected (Perrin and Polack, 1987; Monicat, 1988; Vitu and Russo, 1988). However, these goat herds had various pathological statuses, ie level of infection of animals and level of clinical expression (Monicat, 1988). It was thus impossible to propose immediate and systematic measures for eradication. A prevention programme should propose solutions allowing the improvement of all types of situations, managing risk factors specific to each herd and should be economically compatible with the size of the business involved. According to previous studies (Monicat, 1988), the massive and early contamination of the female kids was a primordial factor for the appearance of clinical signs. Therefore the rest of this article is limited to the part of the programme dealing specifically with female kids. MATERIALS AND METHODS Goat herds and animals monitored The goat herds that could be monitored were those for which the registration documents had been returned. Those documents had been supplied at the beginning of the programme. Goat herds in central and south-eastern France were monitored (363 herds) between 1988 and The data were collected and analyzed for female kids. then established. These prevention measures were applied during the next production period. Towards the end of this period, approximately 1 yr after the first assessment, a summary of disease evolution was made, highlighting the serological results for the female kids born during this production period. The comparison of these results with those from the previous production period enabled the analysis of the prevention measures, and directed the prevention programme for the next production period with the possibility of appropriate corrections or improvements. Serological analyses Each year and in each goat herd, a blood sample was taken from to 12-month-old randomly selected female kids for serological analysis, or from each kid if less than 20 were available. The method used by the laboratories was agar-gel immunodiffusion with Visna-Maedi antigen. Participant training Because of the variability of each situation, it seemed necessary that the farmer was assisted and advised by someone who had received specific training. To ensure that this assistance was well received by the farmer, it involved those individuals normally associated with the herd: the veterinarian and technicians. The training was based upon results of the study performed by the Centre d tcopathologie Animale (Villeurbanne, France) involving risk factors for arthritis in goats, the method of intervention, the significance and mechanisms of the prevention measures proposed and the consultation of the documents supplied. It involved 48 people: 28 technicians and 20 veterinarians. Study method in herds The network In each herd, the study method consisted of an assessment of the initial situation from clinical and serological results and an appraisal of the risk factors present in the goat herd before the start of parturition. According to this and the objectives and means of the farmer, a personalized programme based on prevention measures was Monitoring the progress of the prevention programme in the herds was possible owing to the establishment of a network between the farmers, the veterinarians, the technicians and the Centre d Écopathologie Animale. The circulation of information within this network enabled: (i) the collection of data (indicators of disease and a list

4 of risk factors) enabling the initial situation in the herds to be assessed and the evolution to be measured; (ii) the collection of practical information concerning the application of the prevention measures and thus suggestions for improvements to subsequent programmes; and (iii) the return of information to the farmers, allowing them to compare their results in relation to the other farmers in the programme. RESULTS AND DISCUSSION Evolution of female kid contamination A fall in the level of female kid contamination was observed in the monitored herds (table I), with 25% of the kids found to be contaminated in 1990 compared with 49.5% in This is related to the application of prevention measures in the herd at the time of birth; 74% (190 out of 257) of the herds applied the prevention measures at birth (distribution of treated colostrum) in 1990 versus 8% (25 out of 311) in This improvement also demonstrated the fact that the motivation of the farmers to apply a measure that is of proven benefit is neither systematic nor immediate. The efficiency of prevention measures To guard against vertical transmission (via colostrum and milk), the replacement of colostrum and milk with substitute products has been recommended (Adams et al, 1983). In specialized goat herds, the female kids are systematically given reconstitute powdered milk. This vector of viral transmission is thus eliminated. For colostrum, 3 solutions have been proposed: (i) to use a preparation based on lyophilized or pasteurized colostrum that can be found commercially; (ii) to use cow colostrum; or (iii) to heat goat colostrum to 56 C for 1 h in order to destroy the virus (Adams et al, 1983) without altering protein structure (a technique termed thermization ). It has been noted that since 1988 the level of contamination in female kids that received substitute colostrum was lower than the level in female kids that had received raw colostrum (table II). To fight horizontal transmission, it is recommended to separate animals that are submitted to prevention measures from animals that are not, particularly male kids devoted to meat production that have received raw goat colostrum. It has been noted (table III) that the level of segregation (between groups of female kids devoted to reproduction and groups of male kids devoted to meat production) affects the level of contamination: the more complete the segregation the lower the contamination level. The monitoring method used allowed us to verify the efficiency of certain measures of prevention of contamination in the kid. The

5 effect of these measures can only be assessed 1 yr after their application because of the often long delay between contamination and serological conversion. A 3-yr observation interval has thus allowed the efficiency of these measures to be verified only in the short term. Evaluation of impact of the programme As the objective of the programme is to propose solutions adapted to each situation, it is difficult to draw general conclusions on the development of disease. However, the noticeable reduction in the indicators of disease in the female kids demonstrates that in most of the goat herds there was a positive trend in the management of this problem. In this sense it can be said that the programme has achieved its objective. However, we have seen that the motivation of the farmers to apply the prevention measures at birth was progressively reaching 74% in the third year. However, it can be reasonably believed that only those farmers motivated by prevention remained in the survey. The situation in most of the goat herds vis-a-vis CAEV does not allow a system of prevention based on eradication. The prevention programme established, on the basis of management of risk factors has brought about a noticeable reduction in the level of contamination of the female kids and suggests solutions that are economically acceptable for French farmers.

6 REFERENCES Adams DS, Crawford TB (1980) CAE: a viral arthritis encephalitis syndrome in goats. Int Goat Sheep Res 1, Adams DS, Klevjer-Anderson P, Carlson JL, Mc Guire TC, Gorham JR (1983) Transmission and control of caprine arthritis encephalitis virus. Am J Vet Res 44, Crawford TB, Adams DS, Cheevers WD, Cork LC (1980) Chronic arthritis in goats caused by a retrovirus. Science 207, Lerondelle C (1988) L infection de la mamelle par le virus de I arthrite et de 1 enc6phalite de la chèvre (CAEV). Sci Vet Med Comp 90, Monicat F (1988) Arthrites des caprins. Compte rendu d enquete, Centre d tcopathologie Animale, Lyon, 343 p Narayan 0, Clements JE, Strandberg JD, Cork LC, Griffin DE (1980) Biological characterization of the virus causing leukoencephali- J Gen Virol50, 69- tis and arthiritis in goats. 79 Péretz G, Cimarosti I (1990) Consequences de I arthrite enc6phalite caprine sur la production laitiere. In: Resumes de la 41 e reunion de la Federation Europeenne de Zootechnie, Toulouse, Perrin G, Polack B (1987) L arthrite enc6phalite caprine (AEC). Bull Acad Vet Fr, 60, Vitu C, Russo P (1988) L arthrite enc6phalite enzootique caprine en France : recherches 6pid6miologiques et exp6rimentales. Comp Immun Microbiol Infect Dis 11, Vet Res (1994) 25, Elsevier/INRA Les contraintes spécifiques des études d écopathologie en milieu tropical PC Lefevre B Faye 1 CIRAD, département «Élevage et médecine vétérinaire des pays tropicaux», laboratoire Pathotrop, 10, rue Pierre-Curie, Maisons-Alfort 2 INRA-Theix, laboratoire d écopathologie, Saint-Genès-Champanelle, France Résumé &horbar; La mise en place d enquêtes d écopathologie dans les pays tropicaux implique des adaptations méthodologiques liées aux contraintes spécifiques de ces pays (infrastructures insuffisantes, mobilité des troupeaux, etc). Sur la base d exemples (Brésil, Sénégal, Tchad), des solutions sont proposées. méthodologie / pays tropicaux / enquête écopathologique Summary &horbar; Specific constraints to ecopathological studies in tropical areas. Development of ecopathological surveys in tropical areas implies adaptation to face the specific problems of these countries (poor substructures, mobility of herds, etc). Solutions are presented using several examples (Brasil, Senegal, Chad). methodology tropical countries l ecopathology * Correspondance et tirés à part