Topic:Culicoides
Culicoides are small biting midges that are often associated with horses due to their role as vectors for various equine diseases. These insects can cause irritation and allergic reactions in horses, commonly referred to as "sweet itch" or "summer eczema," which is an allergic response to the saliva of the Culicoides. Additionally, they are known to transmit pathogens that can lead to conditions such as African horse sickness and equine encephalitis. This page aggregates peer-reviewed research studies and scholarly articles that explore the biology, behavior, and impact of Culicoides on equine health, as well as strategies for their management and control in equine environments.
Evaluation of a diagnostic ELISA for insect bite hypersensitivity in horses using recombinant Obsoletus complex allergens. 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, ...
Allergen-specific immunotherapy in horses with insect bite hypersensitivity: a double-blind, randomized, placebo-controlled study. 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 ...
Equine allergy therapy: update on the treatment of environmental, insect bite hypersensitivity, and food allergies. Allergies are common in horses. It is important to identify and correct as many factors as possible to control pruritus and make the patient comfortable. Culicoides hypersensitivity is a common component in allergic horses. The main treatment continues to be rigorous fly control and avoidance of insect bites. Environmental allergies are best addressed by early identification of the offending allergens and formulation of allergen-specific immunotherapy to decrease the need for rescue medications. Food allergy is best managed with food avoidance. Urticaria is one of the manifestations of allergi...
Evaluation of an IgE ELISA with Culicoides spp. extracts and recombinant salivary antigens for diagnosis of insect bite hypersensitivity in Warmblood horses. Insect bite hypersensitivity (IBH) in horses represents an immunoglobulin E (IgE)-mediated hypersensitivity to salivary antigens from biting midges (Culicoides spp.). The aim of this study was to evaluate and compare the performances of IgE ELISAs using recombinant Culicoides spp. Obsoletus group salivary gland antigens or crude whole body extracts ('ObsWBE'), C. nubeculosus recombinant proteins (Culn1, 3, 4, 5, 7, 8 and 10) and Obsoletus group recombinant proteins (Culo1 and 2). IgE levels were measured in plasma of 343 Warmblood horses classified as IBH-affected (n=167) and IBH-unaffected (n...
Recovery of African horse sickness virus from synthetic RNA. African horse sickness virus (AHSV) is an insect-vectored emerging pathogen of equine species. AHSV (nine serotypes) is a member of the genus Orbivirus, with a morphology and coding strategy similar to that of the type member, bluetongue virus. However, these viruses are distinct at the genetic level, in the proteins they encode and in their pathobiology. AHSV infection of horses is highly virulent with a mortality rate of up to 90 %. AHSV is transmitted by Culicoides, a common European insect, and has the potential to emerge in Europe from endemic countries of Africa. As a result, a safe an...
Where are the horses? With the sheep or cows? Uncertain host location, vector-feeding preferences and the risk of African horse sickness transmission in Great Britain. Understanding the influence of non-susceptible hosts on vector-borne disease transmission is an important epidemiological problem. However, investigation of its impact can be complicated by uncertainty in the location of the hosts. Estimating the risk of transmission of African horse sickness (AHS) in Great Britain (GB), a virus transmitted by Culicoides biting midges, provides an insightful example because: (i) the patterns of risk are expected to be influenced by the presence of non-susceptible vertebrate hosts (cattle and sheep) and (ii) incomplete information on the spatial distribution of...
Cloning and expression of candidate allergens from Culicoides obsoletus for diagnosis of insect bite hypersensitivity in horses. Insect bite hypersensitivity (IBH) is an IgE-mediated (Type I) hypersensitivity reaction induced by allergens from biting midges of the Culicoides spp. The aim of the present study was to identify, clone and express recombinant allergens from C. obsoletus, the main species found feeding on horses in the Netherlands, by sequence homology searches on the C. obsoletus specific RNA database, with previously described allergens from C. nubeculosus and C. sonorensis. BLAST searches with these described allergens resulted in similarity hits with 7 genes coding for C. obsoletus allergens. These allerg...
Seasonal differences in cytokine expression in the skin of Shetland ponies suffering from insect bite hypersensitivity. Insect bite hypersensitivity (IBH) in horses is a seasonal, IgE-mediated, pruritic skin disorder primarily caused by Culicoides spp. We hypothesize that a mixed Th2/Th1-type immune status, off season, alters into Th2-dominated immune reactivity in the skin of IBH-affected ponies in the IBH season. To study these immune response patterns Culicoides-specific IgE levels, skin histopathology and cytokine and transcription factor mRNA expression (IL4, IL10, IL13, IFNγ, FoxP3 and CD3(ζ)) in lesional and non-lesional skin of ponies affected by IBH in the IBH season were compared with those of the s...
Risk factors for insect bite hypersensitivity in Friesian horses and Shetland ponies in The Netherlands. Insect bite hypersensitivity (IBH) is an equine skin allergy caused by bites of Culicoides spp. and impacts on the welfare of affected horses. The aim of this study was to identify and quantify risk factors for IBH. Data from 3453 Friesian horse mares and 7074 Shetland pony mares scored for IBH by inspectors during obligatory foal inspections were analysed using breed-specific multivariable logistic regression models. The combined effect of month and year of scoring, Province and inspector were significantly associated with IBH in both breeds. In Shetland pony mares, withers height and coat co...
Culicoides obsoletus extract relevant for diagnostics of insect bite hypersensitivity in horses. Insect bite hypersensitivity (IBH) is an allergic dermatitis in horses caused by the bites of Culicoides species. The aim of the present study was to evaluate the applicability of whole body extracts of C. obsoletus (the main species found feeding on horses in the Netherlands), C. nubeculosus (rarely found in The Netherlands) and C. sonorensis (typical for North America) for diagnosis of IBH in horses in The Netherlands. Blood and serum samples of 10 clinically confirmed IBH affected and 10 healthy control horses were used to evaluate the IgE titers (ELISA) against the Culicoides whole body ex...
A review of African horse sickness and its implications for Ireland. African horse sickness is an economically highly important non-contagious but infectious Orbivirus disease that is transmitted by various species of Culicoides midges. The equids most severely affected by the virus are horses, ponies, and European donkeys; mules are somewhat less susceptible, and African donkeys and zebra are refractory to the devastating consequences of infection. In recent years, Bluetongue virus, an Orbivirus similar to African horse sickness, which also utilises Culicoides spp. as its vector, has drastically increased its range into previously unaffected regions in norther...
Equine insect bite hypersensitivity: what do we know? Insect bite hypersensitivity (IBH) is an allergic dermatitis of the horse caused by bites of insects of the genus Culicoides and is currently the best characterized allergic disease of horses. This article reviews knowledge of the immunopathogenesis of IBH, with a particular focus on the causative allergens. Whereas so far hardly any research has been done on the role of antigen presenting cells in the pathogenesis of IBH, recent studies suggest that IBH is characterized by an imbalance between a T helper 2 (Th2) and regulatory T cell (T(reg)) immune response, as shown both locally in the skin...
Risk of introducing African horse sickness virus into the Netherlands by international equine movements. African horse sickness (AHS) is a vector-borne viral disease of equines that is transmitted by Culicoides spp. and can have severe consequences for the horse industry in affected territories. A study was performed to assess the risk of introducing AHS virus (AHSV) into the Netherlands (P_AHS) by international equine movements. The goal of this study was to provide more insight into (a) the regions and equine species that contribute most to this risk, (b) the seasonal variation in this risk, and (c) the effectiveness of measures to prevent introduction of AHSV. Countries worldwide were grouped ...
Comparison of two trapping methods for Culicoides biting midges and determination of African horse sickness virus prevalence in midge populations at Onderstepoort, South Africa. Culicoides biting midges (Diptera: Ceratopogonidae) are vectors of a variety of pathogens including African horse sickness virus (AHSV), a member of the family Reoviridae, genus Orbivirus. AHSV causes African horse sickness (AHS), an endemic disease of equids with an extremely high mortality rate in horses in sub-Saharan Africa. Culicoides (Avaritia) imicola Kieffer is considered to be the principal vector of AHSV and is the dominant Culicoides species in South Africa. Due to the global distribution of Culicoides vectors, there is a potential risk of AHS spreading from endemic areas to areas t...
The same ELA class II risk factors confer equine insect bite hypersensitivity in two distinct populations. Insect bite hypersensitivity (IBH) is a chronic allergic dermatitis common in horses. Affected horses mainly react against antigens present in the saliva from the biting midges, Culicoides ssp, and occasionally black flies, Simulium ssp. Because of this insect dependency, the disease is clearly seasonal and prevalence varies between geographical locations. For two distinct horse breeds, we genotyped four microsatellite markers positioned within the MHC class II region and sequenced the highly polymorphic exons two from DRA and DRB3, respectively. Initially, 94 IBH-affected and 93 unaffected Sw...
Seasonal dynamics of biting midges (Diptera: Ceratopogonidae: Culicoides), the potential vectors of bluetongue virus, in Sweden. The outbreak of bluetongue (BT) in northern Europe 2006 initiated the monitoring of vectors, biting midges of the genus Culicoides in Sweden. In order to determine the diversity, distribution and seasonal dynamics of Culicoides, weekly collections were made during 2008 and during March-December 2009 using the Ondestepoort Veterinary Institute black light trap. Twenty sampling sites were selected in 12 provinces. In total of 30,704 Culicoides were collected in 2008 and 32,252 in 2009. The most abundant species were the potential vectors of BTV Culicoides obsoletus/C. scoticus that comprised of ...
Transmission and control of African horse sickness in The Netherlands: a model analysis. African horse sickness (AHS) is an equine viral disease that is spread by Culicoides spp. Since the closely related disease bluetongue established itself in The Netherlands in 2006, AHS is considered a potential threat for the Dutch horse population. A vector-host model that incorporates the current knowledge of the infection biology is used to explore the effect of different parameters on whether and how the disease will spread, and to assess the effect of control measures. The time of introduction is an important determinant whether and how the disease will spread, depending on temperature a...
Epizootic heamorragic disease. Epizootic haemorrhagic disease (EHD) is an infectious non-contagious viral disease transmitted by insects of the genus Culicoides which affects wild and domestic ruminants. The causative agent, the epizootic haemorrhagic disease virus (EHDV), belongs to the family Reoviridae, genus Orbivirus and shares many morphological and structural characteristics with the other members of the genus such as bluetongue, African horse sickness and equine encephalosis viruses. In recent years EHD outbreaks have been reported in countries bordering the European Union. They caused disease in cattle and severe r...
CD4+CD25+ T cells expressing FoxP3 in Icelandic horses affected with insect bite hypersensitivity. Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis caused by bites of midges from the genus Culicoides. We have shown previously that peripheral blood mononuclear cells (PBMC) from IBH-affected horses produce higher levels of IL-4 and lower levels of IL-10 and TGF-β1 than those from healthy horses, suggesting that IBH is associated with a reduced regulatory immune response. FoxP3 is a crucial marker of regulatory T cells (Tregs). Here we have determined the proportion of CD4(+)CD25(+)FoxP3(+) T cells by flow cytometry in PBMC directly after isolation or after stimulation with Cu...
Selective cloning, characterization, and production of the Culicoides nubeculosus salivary gland allergen repertoire associated with equine insect bite hypersensitivity. Salivary gland proteins of Culicoides spp. have been suggested to be among the main allergens inducing IgE-mediated insect bite hypersensitivity (IBH), an allergic dermatitis of the horse. The aim of our study was to identify, produce and characterize IgE-binding salivary gland proteins of Culicoides nubeculosus relevant for IBH by phage surface display technology. A cDNA library constructed with mRNA derived from C. nubeculosus salivary glands was displayed on the surface of filamentous phage M13 and enriched for clones binding serum IgE of IBH-affected horses. Ten cDNA inserts encoding putat...
The effect of a supplement containing sunflower oil, vitamins, amino acids, and peptides on the severity of symptoms in horses suffering insect bite hypersensitivity. Insect bite hypersensitivity (IBH) is most often caused by Culicoides spp., although other insect species are also thought to play a role in causing this disease. The disease has been reported to occur in most countries, with a prevalence of up to 28% in some countries in some breeds. The only truly effective therapy currently available is to prevent horses from coming into contact with Culicoides midges, which can be achieved by stabling horses during certain times of the day or by covering them with insect blankets. The effect of a new dietary supplement containing vitamins, polypeptides, an...
Intradermal testing of horses with and without insect bite hypersensitivity in The Netherlands using an extract of native Culicoides species. Intradermal tests using a Culicoides nubeculosus extract have proven unreliable for diagnosis of equine insect bite hypersensitivity (IBH) in the Netherlands. The aim of this study was to evaluate the diagnostic value of an extract derived from the Dutch species C. obsoletus and C. pulicaris. Thirteen pairs of horses were tested, each pair consisting of one horse with IBH and the other a healthy control. Each horse was injected intradermally with 0.1 mL of three concentrations of Culicoides whole body extract (1 : 1000 w/v, 1 : 10,000 w/v and 1 : 25,000 w/v), histamine solution (0.01 mg/mL, po...
Re-emergence of bluetongue, African horse sickness, and other orbivirus diseases. Arthropod-transmitted viruses (Arboviruses) are important causes of disease in humans and animals, and it is proposed that climate change will increase the distribution and severity of arboviral diseases. Orbiviruses are the cause of important and apparently emerging arboviral diseases of livestock, including bluetongue virus (BTV), African horse sickness virus (AHSV), equine encephalosis virus (EEV), and epizootic hemorrhagic disease virus (EHDV) that are all transmitted by haematophagous Culicoides insects. Recent changes in the global distribution and nature of BTV infection have been espec...
Treatment of horses with cypermethrin against the biting flies Culicoides nubeculosus, Aedes aegypti and Culex quinquefasciatus. 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...
Insect bite hypersensitivity in the horse: comparison of IgE-binding proteins in salivary gland extracts from Simulium vittatum and Culicoides nubeculosus. Insect bite hypersensitivity (IBH) is an IgE-mediated allergic dermatitis of horses caused by bites of insects such as Culicoides or Simulium spp. The aim of the present study was to compare the IgE-binding pattern of sera of IBH-affected horses to Culicoides nubeculosus and Simulium vittatum salivary gland extracts (SGE). Individual IgE responses to proteins of S. vittatum and C. nubeculosus SGEs were evaluated in 15 IBH-affected and three healthy horses on immunoblots. Fourteen out of the 15 IBH-affected but none of the healthy horses showed individual IgE binding patterns to seven and six m...
Sensitization of skin mast cells with IgE antibodies to Culicoides allergens occurs frequently in clinically healthy horses. IgE antibodies are mediators of mast cell degranulation during allergic diseases. The binding of IgE to its high-affinity IgE receptor on mast cell surfaces is called "sensitization" and precedes the development of clinical allergy. Previously, intradermal injection of anti-IgE or the anti-IgG(T) antibody CVS40 induced immediate skin reactions in horses. This suggested that both IgE and IgG(T) sensitize equine skin mast cells. Here, we investigated sensitization to allergen and with IgE or IgG(T) in clinically healthy horses of different age groups. In addition, immediate skin reactions to Cul...
Increased IL-4 and decreased regulatory cytokine production following relocation of Icelandic horses from a high to low endoparasite environment. Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis of horses caused by bites of Culicoides spp. IBH does not occur in Iceland where Culicoides are absent. However, following importation into continental Europe where Culicoides are present, >or=50% of Icelandic horses (1st generation) develop IBH but
Identification and isolation of cDNA clones encoding the abundant secreted proteins in the saliva proteome of Culicoides nubeculosus. 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...