Bayesian estimation of the sensitivity and specificity of coprological and serological diagnostic tests for the detection of Ascaris suum infection on pig farms

• Published in: International journal for parasitology Vol. 54; no. 10; pp. 523 - 533
• Main Authors: Delsart, Maxime, Répérant, Jean-Michel, Benoit, Chantal, Boudin, Edouard, Da-Costa, Jean-François, Dorenlor, Virginie, Eono, Florent, Eveno, Eric, Kerphérique, Stéphane, Poulain, Gilles, Souquière, Marie, Thomas-Hénaff, Martine, Pol, Françoise, Dufour, Barbara, Rose, Nicolas, Fablet, Christelle
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-08-2024; Elsevier
• Subjects: Animals; Antibodies, Helminth - blood; Ascariasis - diagnosis; Ascariasis - parasitology; Ascariasis - veterinary; Ascaris suum - immunology; Ascaris suum - isolation & purification; Bayes Theorem; Coprology; Diagnostic performance; Enzyme-Linked Immunosorbent Assay - methods; Enzyme-Linked Immunosorbent Assay - veterinary; Farms; Feces - chemistry; Feces - parasitology; France; Life Sciences; Parasitism; Pig; Sensitivity and Specificity; Serologic Tests - methods; Serologic Tests - veterinary; Serology; Swine; Swine Diseases - diagnosis; Swine Diseases - parasitology; France; Diagnostic performance; Parasitism; Coprology; Serology; Pig; Diagnostic; performance
• ISSN: 0020-7519; 1879-0135; 1879-0135
• DOI: 10.1016/j.ijpara.2024.04.010

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•Ascaris suum is the most widespread and common nematode in pigs.•Ascaris suum eggs were detected in 18% of the alternative farms included in the study.•At least 20% of pigs over 22 weeks of age were seropositive for A. suum on 80% of farms.•The coprological test has very good specificity but very low sensitivity.•The serological diagnostic test seems better suited to defining a farm’s status.
Coprological and serological diagnostic tests were compared to define the status of a pig farm with regard to Ascaris suum. On each of the 100 farms in France visited for the study, 10 blood samples were taken from pigs at the end of fattening (at least 22 weeks old) and 20 to 30 faecal samples were taken, depending on the category of animals present on the farm (10 sows, 10 piglets aged 10 to 12 weeks and 10 pigs at the end of fattening, aged at least 22 weeks). A SERASCA® ELISA test (Laboratory of Parasitology, Ghent University) was performed on each blood sample (cut-off 0.5) and a coprological analysis on each faecal sample. A Bayesian approach was used to estimate the sensitivity and specificity of the coprological and serological tests. A farm was considered positive if at least one A. suum egg was observed in the faecal samples. With regard to the serological test, various hypotheses were tested in order to define the number of seropositive animals required to consider a farm positive for A. suum. The coprological test has very good specificity in the search for A. suum, whether 20 or 30 samples are taken per farm. However, even with an increase in the number of samples, the sensitivity of this diagnostic approach is very low (less than 30%). On the other hand, the serological diagnostic method, which consists of taking blood samples from 10 animals at the end of fattening, has good sensitivity and seems better suited to defining the status of a farm with regard to A. suum, provided that a farm is considered seropositive only if two out of 10 samples are positive.