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Culicoides as Vectors for Disease in Livestock
For livestock producers, being aware of Culicoide activity is important
as they are vectors of several arboviral diseases such as bluetongue and
epizootic haemorrhagic disease.
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Similar to the lack of understanding
and development of treatments for allergic reactions, there is also
a lack of effective control methods against Culicoides as vectors.
Have a conversation with livestock producers about reducing
exposure. Insecticide pour-on treatments as well as vector-preventive
establishments (with openings covered by insecticide-treated nets)
are common methods of prevention.
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In one study, insecticide ear tags
reduced the number of biting midges for up to 21 days.
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While none of
these methods are guaranteed to totally remove the risk of disease, a
combination of strategies may help to reduce risk.
1. Kentucky Equine Research Staff. "Insect Bite Hypersensitivity in Horses." Kentucky Equine Research. Published June 7, 2013.
Accessed June 13, 2023. https://ker.com/equinews/insect-bite-hypersensitivity/.
2. Kentucky Equine Research Staff. "Skin Problems in Horses: Culicoides Hypersensitivity." Kentucky Equine Research.
Published May 18, 2016. Accessed June 13, 2023. https://ker.com/equinews/skin-problems-horses-culicoides-
hypersensitivity/.
3. O'Neill, W., S. McKee, and A. F. Clarke. "Flaxseed (Linum usitatissimum) Supplementation Associated with Reduced Skin
Test Lesional Area in Horses with Culicoides Hypersensitivity." Canadian Journal of Veterinary Research 66, no. 4 (October
2002): 272-277. PMID: 12418783; PMCID: PMC227015. Accessed June 13, 2023. https://www.ncbi.nlm.nih.gov/pmc/
articles/PMC227015/.
4. Schaffartzik, A., et al. "Equine Insect Bite Hypersensitivity: What Do We Know?" Veterinary Immunology and
Immunopathology 147, no. 3–4 (June 30, 2012): 113-126. Accessed June 13, 2023. https://www.sciencedirect.com/science/
article/abs/pii/S0165242712000906.
5. Marti, Eliane, et al. "Immunopathogenesis and Immunotherapy of Culicoides Hypersensitivity in Horses: An Update."
Veterinary Dermatology 32, no. 6 (December 2021): 579-e156. Special Issue: Advances in Veterinary Dermatology, Volume
9, 9th World Congress of Veterinary Dermatology, October 2020 - April 2021 (Virtual), Sydney, Australia. First published
November 18, 2021. Accessed June 13, 2023. https://onlinelibrary.wiley.com/doi/full/10.1111/vde.13042.
6. Miranda, Miguel Á. "Case Studies of Vector-Borne Diseases in Livestock: Bluetongue Virus." In Ecology and
Control of Vector-Borne Diseases, 5, 221-271. Published online August 22, 2018. Accessed June 16, 2023. www.
wageningenacademic.com/doi/pdf/10.3920/978-90-8686-863-6_9.
7. Liebisch, Gabriele, and Arndt Liebisch. "Efficacy of Flectron-eartags (cypermethrin) for control of midges (Culicoides) as the
vectors of bluetongue virus in cattle: field studies and biossays." Deutsche Tierärztliche Wochenschrift 115, no. 6 (2008):
220-230. Accessed June 16, 2023. https://pubmed.ncbi.nlm.nih.gov/18605374/.
Nutritional
Supplements for IBH
In addition to reducing exposure
to Culicoides and controlling
inflammation and itching, talk to your
clients about supplementing omega-3
fatty acids into their horses' diets.
This can help with inflammation
throughout the body and bring
some relief.
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In a study focused on
quantifying the effect of omega-3
supplements in horses with IBH, it
was found that the supplements
helped reduce the lesional area of
the skin test response and reduce
inflammation without negative side-
effects.
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Adding these supplements,
especially those with EPA and DHA,
can be a great long-term approach
for clients that have horses with
IBH. It also has the added benefit of
promoting a healthy hair coat without
having to worry about the possible
side-effects of corticosteroids.
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The Future of IBH
Treatment
Recently, a major advancement in
the understanding of the causative
allergens identified 11 Culicoides
salivary gland proteins as relevant
allergens.
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As more work is done
into characterizing the allergens
responsible for IBH and what
mechanisms induce an allergic
response to them, researchers get
closer to developing treatment
strategies such as immunotherapy.
An immunization protocol has been
developed for preventive allergen
immunotherapy, which seems to
induce a suitable immune response,
but it is too early to tell if these
advances will lead to improved
treatment and prevention of IBH.
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