A prospective study on insect bite hypersensitivity in horses exported from Iceland into Switzerland.

Torsteinsdottir, Sigurbjörg; Scheidegger, Stephan; Baselgia, Silvia; Jonsdottir, Sigridur; Svansson, Vilhjalmur; Björnsdottir, Sigridur; Marti, Eliane Isabelle (2018). A prospective study on insect bite hypersensitivity in horses exported from Iceland into Switzerland. Acta Veterinaria Scandinavica, 60(1), p. 69. BioMed Central Ltd. 10.1186/s13028-018-0425-1

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BACKGROUND Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis caused by bites of Culicoides spp., which occurs frequently in horses imported from Iceland to continental Europe. IBH does not occur in Iceland because Culicoides species that bite horses are not present. However, Simulium vittatum (S. vittatum) are found in Iceland. In Europe, blood basophils from IBH-affected horses release significantly more sulfidoleukotrienes (sLT) than those from healthy controls after in vitro stimulation with Culicoides nubeculosus (C. nubeculosus) and S. vittatum. Aims of the study were: (I) using the sLT release assay, to test if horses living in Iceland were sensitized to S. vittatum and (II) to determine in a longitudinal study in horses imported from Iceland to Switzerland whether the sLT release assay would allow to predict which horses would develop IBH. RESULTS Horses in Iceland, even when living in high S. vittatum areas, were usually not sensitized to S. vittatum or C. nubeculosus. Incidence of IBH in the 145 horses from the longitudinal study was 51% and mean time until IBH developed was 2.5 ± 1 year. Before import and after the first summer following import, there were no significant differences in sLT release between the endpoint healthy (H) and IBH groups. After the 2nd summer, when the number of clinically affected horses increased in the endpoint IBH group, a significantly higher sLT release after stimulation with C. nubeculosus but not with S. vittatum was observed. After the 3rd and 4th summer, the endpoint IBH group had a significantly higher sLT release with C. nubeculosus and S. vittatum than the endpoint H group. Some of the horses that remained healthy became transiently positive in the sLT release assay upon stimulation of their peripheral blood leucocytes with C. nubeculosus. CONCLUSIONS Horses in Iceland are not sensitized to S. vittatum. In horses that develop IBH, sensitization to S. vittatum is secondary to sensitization to C. nubeculosus and probably a result of an immunological cross-reactivity. A sLT release assay cannot be used to predict which horses will develop IBH. A transient positive reaction in the sLT release assay observed in horses that remained healthy suggests that immunoregulatory mechanisms may control an initial sensitization of the healthy horses.

Item Type:

Journal Article (Original Article)

Division/Institute:

05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH) > Experimental Clinical Research
05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH)

UniBE Contributor:

Jonsdottir, Sigridur and Marti, Eliane Isabelle

Subjects:

600 Technology > 630 Agriculture

ISSN:

1751-0147

Publisher:

BioMed Central Ltd.

Language:

English

Submitter:

Eliane Isabelle Marti Schalch

Date Deposited:

06 Feb 2019 10:00

Last Modified:

02 Nov 2019 12:36

Publisher DOI:

10.1186/s13028-018-0425-1

PubMed ID:

30390694

Uncontrolled Keywords:

Culicoides Icelandic horses Insect bite hypersensitivity Simulium Sulfidoleukotriene release assay

BORIS DOI:

10.7892/boris.125678

URI:

https://boris.unibe.ch/id/eprint/125678

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