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Ovine Echinococcus granulosus transmission dynamics in the province of Rio Negro, Argentina, 1980–1999
- Source :
- Veterinary Parasitology. 98:263-272
- Publication Year :
- 2001
- Publisher :
- Elsevier BV, 2001.
-
Abstract
- In this work, the impact of a hydatidosis control programme for dogs on the intermediate ovine host was specifically analysed to determine the levels of prevalence achieved and the dynamics of parasite transmission, as well as to evaluate the quality of diagnostic systems in slaughterhouses. A field study was conducted in four slaughterhouses (Valcheta, Los Menucos, Jacobacci, Bariloche) that process animals coming from all the departments within the work area. The control programme for dogs entailed treating dogs with 5 mg/kg praziquantel at 2-month intervals for 20 years. Sample size was determined with a 10% error margin and a 95% significance level. Harvested viscera (liver, lungs, kidneys) were preserved in 5% formaldehyde and sent to the laboratory for diagnostic confirmation of both positive and negative specimens. The 61% initial prevalence dropped to 18.3% at the end of the 10-year period, observed differences proving significant (Chi-square=15.454, P=0.00). There were statistically significant increases in infection prevalence with age (Pearson’s Chi-square=133.61, P=0.00). Overall, 37.2% of hydatidosis cases diagnosed in slaughterhouses were considered non-hydatid by histological study. On the other hand, 1.1% of those diagnosed as healthy were found to be infected with hydatidosis. The number of hydatid cysts per animal increased with age: 0.04 in lambs and 1.22 in adults (linear regression equation, −0.0539+0.0127×age), whereas the average for the whole period was 3.7% in lambs and 20.5% in adults. Viability studies indicated that 63.8% of parasitised animals had viable cysts, out of which 53.3% were fertile. Diagnosis of infection in sheep made by means of an adjusted statistical design and with histological confirmation of the presumptive diagnosis made in slaughterhouses demonstrated the flaws of the official systems for epidemic surveillance of hydatidosis. However, there was no overall significant difference in slaughterhouse and laboratory data. Ro was 0.53 and could imply a decrease in reproductive capacity of the parasite and steady state extinction.
- Subjects :
- Veterinary medicine
Argentina
Sheep Diseases
Praziquantel
law.invention
Random Allocation
Dogs
Echinococcosis
law
Statistical significance
Prevalence
medicine
Animals
Parasite hosting
Parasite transmission
Dog Diseases
Longitudinal Studies
Echinococcus granulosus
Anthelmintics
Sheep
General Veterinary
biology
business.industry
Infection prevalence
Significant difference
General Medicine
biology.organism_classification
Echinococcus
Transmission (mechanics)
Parasitology
business
Abattoirs
medicine.drug
Subjects
Details
- ISSN :
- 03044017
- Volume :
- 98
- Database :
- OpenAIRE
- Journal :
- Veterinary Parasitology
- Accession number :
- edsair.doi.dedup.....a130de46e889e777c3d08fb2cada54ba