Insect Bite Hypersensitivity (IBH) is an allergic reaction in horses caused by bites from certain insects, primarily Culicoides spp., also known as midges. It is characterized by intense itching, skin lesions, and discomfort, often leading to secondary infections due to self-trauma. The condition is seasonal and varies in severity depending on geographic location, insect prevalence, and individual horse sensitivity. IBH is a common dermatological issue in horses and serves as a model for studying allergic responses and immune regulation. This page compiles peer-reviewed research studies and scholarly articles that explore the pathophysiology, management strategies, and genetic predispositions associated with insect bite hypersensitivity in equine populations.
Schurink A, da Silva VH, Velie BD, Dibbits BW, Crooijmans RPMA, Franҫois L, Janssens S, Stinckens A, Blott S, Buys N, Lindgren G, Ducro BJ.Many common and relevant diseases affecting equine welfare have yet to be tested regarding structural variants such as copy number variations (CNVs). CNVs make up a substantial proportion of total genetic variability in populations of many species, resulting in more sequence differences between individuals than SNPs. Associations between CNVs and disease phenotypes have been established in several species, but equine CNV studies have been limited. Aim of this study was to identify CNVs and to perform a genome-wide association (GWA) study in Friesian horses to identify genomic loci associated w...
Jonsdottir S, Stefansdottir SB, Kristinarson SB, Svansson V, Bjornsson JM, Runarsdottir A, Wagner B, Marti E, Torsteinsdottir S.Insect bite hypersensitivity is an allergic dermatitis of horses caused by bites of Culicoides midges. Sufficient amount of pure, endotoxin-free allergens is a prerequisite for development and monitoring of preventive and therapeutic allergen immunotherapy. Aims of the study were to compare the Culicoides nubeculosus (Cul n) allergens Cul n 3 and Cul n 4, produced in transgenic barley grains with the corresponding E. coli or insect cells expressed proteins for measuring antibody and cytokine responses. Allergen-specific IgG responses were measured by ELISA in sera from twelve horses not expose...
Fettelschoss-Gabriel A, Fettelschoss V, Thoms F, Giese C, Daniel M, Olomski F, Kamarachev J, Birkmann K, Bühler M, Kummer M, Zeltins A, Marti E....Insect-bite hypersensitivity is the most common allergic dermatitis in horses. Excoriated skin lesions are typical symptoms of this seasonal and refractory chronic disease. On a cellular level, the skin lesions are characterized by massive eosinophil infiltration caused by an underlying allergic response. To target these cells and treat disease, we developed a therapeutic vaccine against equine IL-5 (eIL-5), the master regulator of eosinophils. The vaccine consisted of eIL-5 covalently linked to a virus-like particle derived from cucumber mosaic virus containing the tetanus toxoid universal T-...
Wilkołek P, Sitkowski W, Szczepanik M, Adamek Ł, Pluta M, Taszkun I, Gołyński M, Malinowska A.Allergic responses in humans, horses and other species are mediated by immunoglobulin E (IgE) antibodies. Serum testing to detect allergen-specific IgE antibodies has been developed for dogs, cats and horses; this allows for the identification of allergens and determination of appropriate allergen- specific immunotherapies. This study compared serum allergen-specific IgE concentrations in atopic and healthy horses. The study was performed on Malopolski breed atopic (n=21) and nonatopic (n=21) clinically healthy horses. Allergen-specific IgE serum concentrations were measured in summer seasons ...
Ahlers LRH, Goodman AG.Vector-borne diseases, including arboviruses, pose a serious threat to public health worldwide. Arboviruses of the flavivirus genus, such as Zika virus (ZIKV), dengue virus, yellow fever virus (YFV), and West Nile virus (WNV), are transmitted to humans from insect vectors and can cause serious disease. In 2017, over 2,000 reported cases of WNV virus infection occurred in the United States, with two-thirds of cases classified as neuroinvasive. WNV transmission cycles through two different animal populations: birds and mosquitoes. Mammals, particularly humans and horses, can become infected thro...
Einhorn L, Hofstetter G, Brandt S, Hainisch EK, Fukuda I, Kusano K, Scheynius A, Mittermann I, Resch-Marat Y, Vrtala S, Valenta R, Marti E, Rhyner C....Companion animals are also affected by IgE-mediated allergies, but the eliciting molecules are largely unknown. We aimed at refining an allergen microarray to explore sensitization in horses and compare it to the human IgE reactivity profiles. Methods: Custom-designed allergen microarray was produced on the basis of the ImmunoCAP ISAC technology containing 131 allergens. Sera from 51 horses derived from Europe or Japan were tested for specific IgE reactivity. The included horse patients were diagnosed for eczema due to insect bite hypersensitivity, chronic coughing, recurrent airway obstructio...
Onder Z, Duzlu O, Yildirim A, Ciloglu A, Okur M, Inci A.This study reports intense horn fly infestations of horses raised in an important wetland ecosystem, Sultan Marshes in Central Anatolia, Turkey. In total, seven horses raised together were found to be harbored over 500 flies per site of each animal. Totally, 376 fly specimens were collected from the horses by using the nets and were subjected to the laboratory for species identification. All flies were morphologically identified as the adults of Haematobia irritans. Partial fragments of mitochondrial cytochrome oxidase I (mt-COI) gene from totally 50 isolates were amplified for sequence and ph...
Lempereur L, Sohier C, Smeets F, Maréchal F, Berkvens D, Madder M, Francis F, Losson B.The dispersion potential of mechanical vectors is an important factor in the dissemination of pathogens. A mark-release-recapture experiment was implemented using two groups (unfed and partially fed) of the Tabanidae (Diptera) (Haematopota spp.) and biting Muscidae (Diptera) (Stomoxys calcitrans) most frequently collected in Belgium in order to evaluate their dispersion potential. In total, 2104 specimens of Haematopota spp. were collected directly from horses and 5396 S. calcitrans were collected in a cattle farm using hand-nets. Some of these insects were partially fed in vitro and all were ...
Lomas HR, Robinson PA.Equine insect bite hypersensitivity (IBH), commonly known as sweet itch or summer eczema, is a frustrating recurrent skin disease in the equine industry involving an immune reaction to the bites of spp. midges. To investigate the impact of IBH in the field, an exploratory pilot study was conducted with equine stakeholders in one region of central England. Nine semi-structured, face-to-face interviews were conducted with horse owners and an equine veterinarian. The aim was to gain an understanding of experiences with IBH, and to gauge opinions on the value of the various management strategies ...
Larska M, Grochowska M, Lechowski L, Żmudziński JF.The aim of the study was to estimate and compare the distribution of Culicoides biting midges species at farms with different main hosts - cattle and horse. Culicoides spp. are known vectors of arboviruses including African horse sickness virus (AHSV), bluetongue virus (BTV) and Schmallenberg virus (SBV). The latter two have been already reported in Polish ruminants recently, while AHSV remains absent, however the risk of its emergence has been increasing in the recent years. In order to establish the activity of potential AHSV vector at vicinity of horses, an OVI midge trap has been placed at...
Ziegler A, Hamza E, Jonsdottir S, Rhyner C, Wagner B, Schüpbach G, Svansson V, Torsteinsdottir S, Marti E.Insect bite hypersensitivity (IBH) is an allergic dermatitis of horses caused by bites of Culicoides spp. IBH does not occur in Iceland because of the absence of Culicoides, but the prevalence is high in horses imported from Iceland to environments where Culicoides are present. Objective: Test, in a longitudinal study before and after Culicoides exposure, whether a primary sensitizing Culicoides allergen can be identified and if an increase of allergen-specific immunoglobulin (Ig)E or IgG subclasses precedes clinical signs of IBH. Methods: Thirty two horses imported from Iceland to Europe; 16 ...
Lanz S, Brunner A, Graubner C, Marti E, Gerber V.Genetic and epidemiologic evidence suggests that in horses, as in other species, different manifestations of hypersensitivity may occur together. Objective: Horses affected with insect bite hypersensitivity (IBH) show airway hyperreactivity (AH) to inhaled histamine, even in the absence of overt clinical signs of equine asthma (EA). Methods: Twenty-two healthy controls (group C), 24 horses suffering from IBH alone (group IBH), and 23 horses suffering from IBH and EA (group IBH/EA). Methods: The clinical histories were assessed using 2 standardized questionnaires, the Horse Owner Assessed Respi...
Citek J, Vostry L, Vostra-Vydrova H, Brzakova M, Prantlova V.The objective of this study was to assess the genetic parameters of insect bite hypersensitivity (IBH) in the Old Grey Kladruber horse, an original Czech warmblood horse breed. Insect bite hypersensitivity is a recurrent allergic skin disease affecting horses worldwide. Its etiology is multifactorial. The defect is genetically controlled, and the starting impulse is a bite by midges of the spp. and less frequently spp. Knowledge about the associated genes is limited. Horses were kept by the National Stud in Kladruby (1,146 measurements) and by 10 private breeders (63 measurements). The horses ...
Kameke D, Kampen H, Walther D.Culicoides Latreille, 1809 midge species are the putative vectors of Bluetongue virus (BTV) and Schmallenberg virus (SBV) in Europe. To gain a better understanding of the epidemiology of the diseases, basic knowledge about the overwintering of the vectors is needed. Therefore, we investigated culicoid activity in relation to air temperature at livestock stables during late winter and spring season. Ceratopogonids were captured weekly indoors and outdoors on three cattle farms, three horse farms and one sheep farm in the federal state of Brandenburg, Germany between January and May, 2015 by BG-...
Jonsdottir S, Svansson V, Stefansdottir SB, Mäntylä E, Marti E, Torsteinsdottir S.Insect bite hypersensitivity is an immunoglobulin (Ig)E-mediated dermatitis of horses initiated by bites of midges of the genus Culicoides. Culicoides spp. are not indigenous to Iceland and the prevalence of insect bite hypersensitivity is much higher in horses born in Iceland and exported as compared to Icelandic horses born in a Culicoides rich environment. Immunotherapy is therefore needed. Objective: The aim of the study was to express an allergen from Culicoides in barley grain and investigate whether an immune response could be obtained in healthy Icelandic horses by oral treatment with ...
Ziegler A, Gerber V, Marti E.Insect bite hypersensitivity (IBH) is an equine allergic dermatitis to Culicoides spp. antigens. Attempts at using allergen-specific immunotherapy (AIT) as a treatment for IBH have so far proven unsuccessful. Toll-like receptor (TLR) agonists can promote a shift in the immune response from the allergy-promoting T helper cell 2 (Th2) response towards a Th1 and/or regulatory response. The aim of this study was to evaluate two immunomodulatory TLR agonists in vitro as potential vaccine adjuvants for a more efficacious AIT in IBH. Peripheral blood mononuclear cells (PBMCs) from healthy and IBH-aff...
Creton B, Pageat P, Robejean M, Lafont-Lecuelle C, Cozzi A.Hematophagous insects can be vectors of pathogens and cause significant economic loss in zootechnical production. Among biting insects, many dipteran species feed on horse blood. The black fly (Diptera: Simuliidae) group, is responsible for several disorders in horses and inflicts painful bites that lead to undesirable behaviours in horses, particularly when bites occur in sensitive areas such as the inner ear. A field study was conducted in a French equestrian center during which a semiochemical was applied on horses' ears to assess repellent efficacy against simulid infestation. During the f...
Velie BD, Shrestha M, Franҫois L, Schurink A, Tesfayonas YG, Stinckens A, Blott S, Ducro BJ, Mikko S, Thomas R, Swinburne JE, Sundqvist M....While susceptibility to hypersensitive reactions is a common problem amongst humans and animals alike, the population structure of certain animal species and breeds provides a more advantageous route to better understanding the biology underpinning these conditions. The current study uses Exmoor ponies, a highly inbred breed of horse known to frequently suffer from insect bite hypersensitivity, to identify genomic regions associated with a type I and type IV hypersensitive reaction. A total of 110 cases and 170 controls were genotyped on the 670K Axiom Equine Genotyping Array. Quality control ...
Herholz C, Kopp C, Wenger M, Mathis A, Wägeli S, Roth N.Female tabanid flies (Diptera: Tabanidae) can be a serious nuisance for horses because of their painful bites during blood feeding. They also play a primary role in mechanical transmission of a lentivirus causing Equine Infectious Anemia (EIA), a virus that has spread within Europe in recent years. According to the European law for products intended for use as a repellent on horses (recreational and sport horses), a field test is mandatory to demonstrate sufficient repellency of such a substance against the specific target fly species, but currently no agreed protocols are available for testin...
Jonsdottir S, Svansson V, Stefansdottir SB, Schüpbach G, Rhyner C, Marti E, Torsteinsdottir S.Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis of horses caused by bites of Culicoides insects, not indigenous to Iceland. Horses born in Iceland and exported to Culicoides-rich areas are frequently affected with IBH. The aims of the study were to compare immunization with recombinant allergens using the adjuvant aluminum hydroxide (Alum) alone or combined with monophosphoryl lipid A (MPLA) for development of a preventive immunization against IBH. Twelve healthy Icelandic horses were vaccinated intralymphatically three times with 10 μg each of four recombinant Culicoides nub...
Hallamaa R, Batchu K.Lipids have become an important target for searching new biomarkers typical of different autoimmune and allergic diseases. The most common allergic dermatitis of the horse is related to stings of insects and is known as insect bite hypersensitivity (IBH) or summer eczema, referring to its recurrence during the summer months. This intense pruritus has certain similarities with atopic dermatitis of humans. The treatment of IBH is difficult and therefore new strategies for therapy are needed. Autoserum therapy based on the use of serum phospholipids has recently been introduced for horses. So far...
Elbers AR, Meiswinkel R.Culicoides (Diptera: Ceratopogonidae) host preferences and attack rates were quantified in early summer at a dairy farm in the Netherlands using livestock tethered at pasture. Midges were aspirated hourly over seven consecutive hours (17:00-23:00) from a dairy cow, a Shetland pony, and a sheep and correspondingly yielded seventeen, thirteen, and nine species. Of the 14,181 midges obtained, approximately 95% belonged to the C. obsoletus complex, C. dewulfi, C. chiopterus, and C. punctatus that together include all proven or potential vectors for arboviral diseases in livestock in northwestern E...
Baker T, Carpenter S, Gubbins S, Newton R, Lo Iacono G, Wood J, Harrup LE.Biting midges of the genus Culicoides Latreille, 1809 (Diptera: Ceratopogonidae) cause a significant biting nuisance to equines and are responsible for the biological transmission of African horse sickness virus (AHSV). While currently restricted in distribution to sub-Saharan Africa, AHSV has a history of emergence into southern Europe and causes one of the most lethal diseases of horses and other species of Equidae. In the event of an outbreak of AHSV, the use of insecticide treated nets (ITNs) to screen equine accomodation is recommended by competent authorities including the Office Interna...
Meulenbroeks C, van der Meide NM, Willemse T, Rutten VP, Tijhaar E.Ponies may suffer from Insect bite hypersensitivity (IBH), an allergic IgE-mediated pruritic skin disorder, induced by allergens from biting midges of the Culicoides spp. Objective: To determine whether recombinant Culicoides obsoletus allergens are able to activate T cells of ponies exposed to C. obsoletus and whether these allergen-specific responses differ between IBH-affected and healthy ponies. Methods: Ten IBH-affected Shetland ponies and 10 age-matched healthy controls taken from the same stables, to ensure similar exposure to midges. Methods: Peripheral blood mononuclear cells (PBMC) w...
Hartmann E, Hopkins RJ, von Brömssen C, Dahlborn K.Provision of shelter for horses kept on summer pasture is rarely considered in welfare guidelines, perhaps because the benefits of shelter in warm conditions are poorly documented scientifically. For cattle, shade is a valued resource during summer and can mitigate the adverse effects of warm weather on well-being and performance. We found in a previous study that horses utilized shelters frequently in summer. A shelter with a roof and closed on three sides (shelter A) was preferred and can reduce insect pressure whereas a shelter with roof and open on three sides was not utilized. However, sh...
Peeters LM, Janssens S, Brebels M, Buys N.Genetic factors involved in susceptibility to insect bite hypersensitivity (IBH) in Belgian Warmblood horses (BWP) were investigated. Data relating to 3409 horses were collected using a questionnaire, administered to owners during sport competitions, BWP breeding days, breeder visits and after phone calls. Horses were classified as IBH-affected or unaffected, based on two 'disease classifiers': a lifetime record, based on owner information (life_status) and another based on whether or not the horse was showing clinical signs at the time of questioning (clin_status). IBH prevalence was 10% base...
Marti E, Wang X, Jambari NN, Rhyner C, Olzhausen J, Pérez-Barea JJ, Figueredo GP, Alcocer MJ.Insect bite hypersensitivity (IBH) is a seasonal recurrent skin allergy of horses caused by IgE-mediated reactions to allergens present in the saliva of biting insects of the genus Culicoides, and possibly also Simulium and Stomoxys species. In this work we show that protein microarrays containing complex extracts and pure proteins, including recombinant Culicoides allergens, can be used as a powerful technique for the diagnosis of IBH. Besides the obvious advantages such as general profiling and use of few microliters of samples, this microarray technique permits automation and allows the gen...
Shrestha M, Eriksson S, Schurink A, Andersson LS, Sundquist M, Frey R, Broström H, Bergström T, Ducro B, Lindgren G.Insect bite hypersensitivity (IBH) is the most common allergic skin disease in horses and is caused by biting midges, mainly of the genus Culicoides. The disease predominantly comprises a type I hypersensitivity reaction, causing severe itching and discomfort that reduce the welfare and commercial value of the horse. It is a multifactorial disorder influenced by both genetic and environmental factors, with heritability ranging from 0.16 to 0.27 in various horse breeds. The worldwide prevalence in different horse breeds ranges from 3% to 60%; it is more than 50% in Icelandic horses exported to ...
Liu XH, Li XY, Li K, Zhang D.Rhinoestrus purpureus (Brauer, 1858) (Diptera: Oestridae) is an economically important parasite that can cause severe nasal myiasis in equids or even attacking humans. The antennae of R. purpureus were examined using stereoscopic microscopy and scanning electron microscopy. The general morphology was provided detailedly, together with distribution, type, size, and ultrastructure of antennal sensilla. All the three antennal segments, antennal scape, pedicel, and funiculus, are interspersed by microtrichiae. Only mechanoreceptors are detected on antennal scape and pedicel. On antennal funiculus,...
Schurink A, Ducro BJ, Heuven HC, van Arendonk JA.Insect bite hypersensitivity (IBH) is a seasonal allergic skin disease in horses caused by bites of certain Culicoides spp. The aim of our study was to investigate the maternal effect on IBH and to estimate the heritability and repeatability of IBH in the Dutch Friesian horse population. Data consisted of 3,453 Dutch Friesian broodmares with 3,763 visual observations on IBH clinical symptoms scored by 12 inspectors during organized foal inspections in 2004 and 2008. Nine percent of the mares (n = 310) were scored in both years. Mares descended from 144 sires and 2,554 dams and 26.2% of the dam...
Russell CL, Heesom KJ, Arthur CJ, Helps CR, Mellor PS, Day MJ, Torsteinsdottir S, Björnsdóttir TS, Wilson AD.Culicoides spp. are vectors of several infectious diseases of veterinary importance and a major cause of allergy in horses and other livestock. Their saliva contains a number of proteins which enable blood feeding, enhance disease transmission and act as allergens. We report the construction of a novel cDNA library from Culicoides nubeculosus linked to the analysis of abundant salivary gland proteins by mass spectrometry. Fifty-four novel proteins sequences are described including those of the enzymes maltase, hyaluronidase and two serine proteases demonstrated to be present in Culicoides sali...
Robin M, Archer D, McGowan C, Garros C, Gardès L, Baylis M.African horse sickness (AHS) is a vectorborne disease spread by Culicoides biting midges. The UK's Department for Environment, Food and Rural Affairs currently suggests using topical deltamethrin for AHS control; however, no data are available regarding its efficacy in the horse. The aims of this study were to investigate the effect of topical deltamethrin on blood feeding by Culicoides on horses and to investigate which Culicoides species blood fed on horses. Three pairs of horses were placed in partially enclosed cages that allowed samples representing the Culicoides interacting with individ...
Lempereur L, Sohier C, Smeets F, Maréchal F, Berkvens D, Madder M, Francis F, Losson B.The dispersion potential of mechanical vectors is an important factor in the dissemination of pathogens. A mark-release-recapture experiment was implemented using two groups (unfed and partially fed) of the Tabanidae (Diptera) (Haematopota spp.) and biting Muscidae (Diptera) (Stomoxys calcitrans) most frequently collected in Belgium in order to evaluate their dispersion potential. In total, 2104 specimens of Haematopota spp. were collected directly from horses and 5396 S. calcitrans were collected in a cattle farm using hand-nets. Some of these insects were partially fed in vitro and all were ...
Kamyingkird K, Choocherd S, Chimnoi W, Klinkaew N, Kengradomkij C, Phoosangwalthong P, Thammasonthijarern N, Pattanatanang K, Inpankaew T, Phasuk J....African horse sickness (AHS) was reported as an outbreak in Thailand in 2020. Hematophagous insects from the genus Culicoides are the suspected vector responsible for AHS transmission. Horses in Hua Hin district, Prachuab Khiri Khan province, Thailand, were affected and died from AHS in 2020. However, the potential Culicoides species and its host preference blood meal in the affected areas are unknown. To investigate the potential vectors of AHS, Culicoides were collected using ultraviolet light traps placed near horse stables. Six horse farms, including five farms with AHS history and one far...
Baldacchino F, Cadier J, Porciani A, Buatois B, Dormont L, Jay-Robert P.Urine volatiles from different ungulates (cows, horses and sheep) were tested as bait for tabanids in southeastern France using Nzi traps during the early summer of 2011. Tabanus bromius Linnaeus, 1758 and Atylotus quadrifarius (Loew, 1874) (both: Diptera: Tabanidae) were the most captured species, respectively representing 57% and 41% of all tabanids collected (all of which were female). Horse urine significantly increased catches of T. bromius (1.6-fold) and A. quadrifarius (3.5-fold), and sheep urine significantly increased catches of A. quadrifarius (2.5-fold). In parallel, an electroanten...
How MJ, Gonzales D, Irwin A, Caro T.Of all hypotheses advanced for why zebras have stripes, avoidance of biting fly attack receives by far the most support, yet the mechanisms by which stripes thwart landings are not yet understood. A logical and popular hypothesis is that stripes interfere with optic flow patterns needed by flying insects to execute controlled landings. This could occur through disrupting the radial symmetry of optic flow via the aperture effect (i.e. generation of false motion cues by straight edges), or through spatio-temporal aliasing (i.e. misregistration of repeated features) of evenly spaced stripes. By r...
van der Meide NM, Savelkoul HF, Meulenbroeks C, Ducro BJ, Tijhaar E.Culicoides spp. of the Obsoletus complex belong to the most important species of midge, involved in causing insect bite hypersensitivity (IBH) in horses in The Netherlands. The aim of the current study was to evaluate seven different Obsoletus complex-derived recombinant allergens (Cul o 1-Cul o 7) and to compare these with Obsoletus complex whole body extract (WBE) in an IgE ELISA, using sera of 194 clinically-confirmed cases of IBH and 175 unaffected horses. The highest test accuracy was obtained with WBE, followed by Cul o 2, 3 and 5. Two ELISAs with a combination of recombinant allergens, ...
Raza F, Ivanek R, Freer H, Reiche D, Rose H, Torsteinsdóttir S, Svansson V, Björnsdóttir S, Wagner B.Culicoides hypersensitivity (CH) is induced in horses by salivary allergens of Culicoides midges. In Iceland, the causal Culicoides species for CH are not present. Previous epidemiological data indicated that Icelandic horses are more susceptible to CH when they are exported from Iceland and first exposed to Culicoides at adult age. Horses born in countries where Culicoides is endemic, develop the disease less frequently. Here, we established a longitudinal allergy model to identify predictive and diagnostic serological biomarkers of CH. Results: Sixteen adult Icelandic horses from Iceland wer...
Frey R, Bergvall K, Egenvall A.Insect bite hypersensitivity (IBH) and atopy can both be causes of pruritus in horses and are associated with allergen-specific IgE to biting insects and environmental allergens respectively. Information with respect to differences in IgE levels in diseased and healthy animals is crucial in enabling an understanding of the clinical relevance of results of allergen-specific IgE tests. The aim of this study was (i) to evaluate and compare levels of allergen-specific IgE, using an ELISA method, in Icelandic horses, with and without IBH, from Iceland and Sweden respectively; (ii) to investigate pa...
Lincoln VJ, Page PC, Kopp C, Mathis A, von Niederhäusern R, Burger D, Herholz C.Species belonging to the Culicoides complexes (Diptera, Ceratopogonidae), obsoletus and pulicaris, in Switzerland, are potential vectors of both bluetongue virus (BTV) and African horse sickness virus (AHSV). The epidemic of BTV in 2006 and 2007 in Europe has highlighted the risk of introduction and spread of vector-borne diseases in previously non-endemic areas. As a measure of prevention, as part of an integrated control programme in the event of an outbreak of African horse sickness (AHS), it is of utmost importance to prevent, or substantially reduce, contact between horses and Culicoides....
Hamza E, Akdis CA, Wagner B, Steinbach F, Marti E.Insect bite hypersensitivity (IBH) is a recurrent allergic dermatitis of horses with similarities to human atopic eczema, caused by bites of insects of the genus Culicoides. Previous studies suggested a dysregulated T cell tolerance to Culicoides allergen in IBH-affected horses. Objective: We have investigated whether the suppressive function of CD4(+) CD25(high) cells is impaired in IBH-affected horses and possible ways to restore it. Methods: CD4(+) CD25(-) cells sorted from peripheral blood mononuclear cells (PBMC) were stimulated with irradiated autologous PBMC pulsed with Culicoides or te...
Barros AT, Foil LD.Two studies evaluated the potential use of spatial barriers to reduce the mechanical transmission of disease agents by tabanids in the Pantanal region of Brazil. Tabanids at stations separated by four different distances (5, 10, 25, and 50m) were marked. In the first study, tabanids were marked and allowed to feed until engorgement or natural interruption occurred and captured if they transferred to the other horse. A total of 2847 tabanids belonging to nine different species were marked. The percentage of tabanids that moved between horses was 10.5 at 5m, 6.8 at 10m, and 4.6 at 25m. In the se...
Steinman A, Peer G, Klement E.The variations with breed, gender, age and coat colour in the prevalence of Culicoides hypersensitivity were studied in 408 horses on 18 farms in Israel. Data were gathered by means of questionnaires and the diagnoses were confirmed by direct physical examinations. The prevalence of Culicoides hypersensitivity was 28 per cent. The disease was rare on farms more than 800 m above sea level but was more prevalent at lower altitudes. The most important factors affecting the prevalence of Culicoides hypersensitivity were the farm, breed and age, but gender and colour were not significantly correlat...
Papadopoulos E, Rowlinson M, Bartram D, Carpenter S, Mellor P, Wall R.An in vitro assay was used to assess the efficacy of the proprietary pyrethroid insecticide cypermethrin applied to horses (Deosect spray, 5.0%, w/v Fort Dodge Animal Health) against the biting midge Culicoides nubeculosus (Meigen) (Diptera: Ceratopogonidae) and the mosquitoes Aedes aegypti Linneaus and Culex quinquefasciatus Say (Diptera: Culicidae). Hair was collected from the back, belly and legs of the horses immediately prior to treatment and 7, 14, 21, 28 and 35 days after treatment, and also from untreated controls. In laboratory assays groups of 10 adult female C. nubeculosus, Ae. aegy...
Anderson GS, Belton P, Kleider N.Six horses severely affected by a seasonal dermatitis similar in both histopathology and epidemiology to Culicoides hypersensitivity (CH) and six unaffected or normal horses were inoculated intradermally with an extract of Culicoides obsoletus (Meigen), the most common Culicoides in southwestern British Columbia. Affected horses developed large welts within 20 min after injection, representing an immediate (type I) reaction; welts were largest 24 h or more after challenge, indicating in addition a delayed (type IV) reaction. This reaction was discernible for greater than 3 wk in some of the af...
Hamza E, Wagner B, Jungi TW, Mirkovitch J, Marti E.Insect bite hypersensitivity (IBH) is an allergic dermatitis of horses caused by IgE-mediated reactions to bites of insects of the genus Culicoides. IBH does not occur in Iceland due to the absence of Culicoides. However, Icelandic horses exported to mainland Europe as adults (1st generation) have a > or =50% incidence of developing IBH. In contrast, their progeny (2nd generation) has a <10% incidence of IBH. Here we show that peripheral blood mononuclear cells (PBMC) from Icelandic horses born in mainland Europe and belonging either to the IBH or healthy subgroup produce less interleukin (IL)...
Anderson GS, Belton P, Kleider N.Culicoides hypersensitivity is a chronic, recurrent, seasonal dermatitis of horses that has a worldwide distribution, but has only recently been reported in Canada. It is characterized by intense pruritus resulting in lesions associated with self-induced trauma.A survey of veterinarians and horse-owners in British Columbia showed no differences in susceptibility due to the sex, color, breed, or height of the horses. The prevalence of the disease in the 209 horses surveyed was 26%. Horses sharing the same pasture could be unaffected. The disease was reported primarily from southwestern British ...
Vychodilova L, Matiasovic J, Bobrova O, Futas J, Klumplerova M, Stejskalova K, Cvanova M, Janova E, Osickova J, Vyskocil M, Sedlinska M, Dusek L....Equine insect bite hypersensitivity (IBH) is a seasonal IgE-mediated dermatosis caused by bites of insects of the genus Culicoides. A familial predisposition for the disease has been shown but, except for the MHC, the genes involved have not been identified so far. An immunogenomic analysis of IBH was performed in a model population of Old Kladruby horses, all living in the same environment. Clinical signs of IBH were used as phenotypic manifestation of IBH. Furthermore, total serum IgE levels were determined in the sera of these horses and used as an independent phenotypic marker for the immu...
Barbet JL, Bevier D, Greiner EC.Fourteen privately owned horses completed a six month, controlled, double-blind trial to assess the efficacy of immunotherapy using an aqueous extract of whole, unfed Culicoides variipennis in the treatment of Culicoides hypersensitivity. Selected horses had a history of a seasonal, pruritic dermatitis, clinical signs and distribution compatible with Culicoides hypersensitivity, failed to improve in response to ivermectin therapy, and reacted to several dilutions of Culicoides extracts without significant reactivity to other possible allergens including insects, moulds and feeds. One horse fro...
van der Haegen A, Griot-Wenk M, Welle M, Busato A, von Tscharner C, Zurbriggen A, Marti E.The aim of the present study was to investigate, with immunohistochemistry and in situ hybridisation, if immunoglobulin-E (IgE) and mast cells are involved in the pathogenesis of insect bite hypersensitivity (IBH), an allergic dermatitis of horses. In tissue sections fixed in paraformaldehyde (PFA) for <24 h, significantly more IgE protein-bearing cells were found in the dermis and epidermis of acute and chronic IBH lesions than in skin biopsies from healthy horses (medians = 466, 236 and 110 cells/mm2, respectively; P < or = 0.01). More IgE-mRNA positive (+) cells were observed in the dermis ...
Ginel PJ, Hernández E, Lucena R, Blanco B, Novales M, Mozos E.Insect bite hypersensitivity (IBH) is a common cause of pruritus in horses, but there are few controlled studies on the efficacy of allergen-specific immunotherapy (ASIT). Atopic dermatitis and IBH can present with overlapping clinical signs; multiple insect and environmental allergens could be indicated in these horses to achieve effective hyposensitization. Although the success of ASIT using Culicoides spp. whole-body extracts is controversial, there are no controlled studies published that clearly show benefit from this form of therapy. Objective: The objective was to evaluate the efficacy ...
Anderson GS, Belton P, Jahren E, Lange H, Kleider N.Immunotherapy was used to treat horses in British Columbia for Culicoides hypersensitivity. This is a severe, chronic, recurrent allergic disease of horses that results in severe irritation, large lesions, hair loss and secondary infection in the ventral midline, mane, and proximal region of the tail. A crude Culicoides extract was injected subcutaneously, in increasing doses, into 10 horses that were affected severely by the disease. Weekly doses reduced the clinical signs in 9 of the 10 horses in the 1st yr. Eight horses were treated with a maintenance dose during a 2nd yr. After the 2nd yr,...
Braverman Y, Ungar-Waron H, Frith K, Adler H, Danieli Y, Baker KP, Quinn PJ.A survey of sweet itch in horses in Israel based on a questionnaire to owners reported that 158 of 723 horses (21.8 per cent) had sweet itch lesions. The results indicated that the likelihood of a horse acquiring sweet itch decreased with increasing altitude but no definite association with rainfall zones was evident. Variation in the density of the horse population, however, obscured these observations. In the population surveyed, stallions were more sensitive than mares and pale horses appeared to be less sensitive than dark ones, but the sample size of this latter group was much smaller. In...
Shrestha M, Eriksson S, Schurink A, Andersson LS, Sundquist M, Frey R, Broström H, Bergström T, Ducro B, Lindgren G.Insect bite hypersensitivity (IBH) is the most common allergic skin disease in horses and is caused by biting midges, mainly of the genus Culicoides. The disease predominantly comprises a type I hypersensitivity reaction, causing severe itching and discomfort that reduce the welfare and commercial value of the horse. It is a multifactorial disorder influenced by both genetic and environmental factors, with heritability ranging from 0.16 to 0.27 in various horse breeds. The worldwide prevalence in different horse breeds ranges from 3% to 60%; it is more than 50% in Icelandic horses exported to ...
Marsella R, White S, Fadok VA, Wilson D, Mueller R, Outerbridge C, Rosenkrantz W.Allergic skin diseases are common in horses worldwide. The most common causes are insect bites and environmental allergens. Objective: To review the current literature and provide consensus on pathogenesis, diagnosis, treatment and prevention. Methods: The authors reviewed the literature up to November 2022. Results were presented at North America Veterinary Dermatology Forum (2021) and European Veterinary Dermatology Congress (2021). The report was available to member organisations of the World Association for Veterinary Dermatology for feedback. Conclusions: Insect bite hypersensitivity (IBH...
O'Neill W, McKee S, Clarke AF.The purpose of this study was to quantify the effect of flaxseed (Linum usitatissimum) supplementation on the skin test response of atopic horses. Six horses that displayed a positive skin test for allergy to extract from Culicoides sp. participated in the 42-day, placebo-controlled, double-blind, cross-over trial. Results showed that supplementation with flaxseed for 42 days in our experimental horses reduced the mean skin test response to Culicoides sp. This observation was concurrent with a significant decrease in the long-chain saturated fatty acids; behenic acid (22:0) and lignoceric acid...
