Sheep sorrel
Summary
Sheep sorrel (Rumex acetosella) is a perennial, wind-pollinated, and invasive plant that grows to a height of around 15-40 cm. A single sheep sorrel plant can produce approximately 400 million pollen grains. This plant is predominantly found along floodplains, grasslands, open pastures, roadsides, and under forest canopies. Sheep sorrel (Rumex acetosella) is considered a cosmopolitan species as it is adaptable to a wide range of climatic conditions. The pollination period for this species initiates from late spring and extends till early summer. No allergenic proteins from sheep sorrel pollen have been identified in the IUIS database. Sheep sorrel pollen upon exposure can trigger conditions like rhino-conjunctivitis, allergic rhinitis, and bronchial asthma. Rumex spp. (sorrel) pollen has been reported to exhibit cross-reactivity with grass pollens.
Epidemiology
Worldwide distribution
Pollen from species belonging to the genus Rumex (like sheep sorrel) may induce conditions like allergic rhinitis.
A Taiwan-based study conducted on 419 patients with allergic rhinitis (AR) symptoms reported the prevalence of sheep sorrel pollen mediated positive skin test (SPT) among 9.1% (38/419) of patients from the study population.
A study conducted in the US reported sheep sorrel pollen as one of the inhalant (respiratory) allergens found in 6% (26/411) of the analyzed patient’s serum samples.
An Iran-based study conducted on 306 AR patients (12-62 years) revealed the prevalence of sheep sorrel pollen mediated positive SPT in 42.8% of the study population.
A study conducted in Poland on 1069 patients with hypersensitivity to weed pollen revealed positive SPT towards sheep sorrel pollen in 19% of the weed pollen allergic patients.
A Japanese study conducted on 151 patients reported a positive scratch test (SPT) towards sheep sorrel pollen among 9% of the study population.
Route Of Exposure
Main
The route of exposure for sheep sorrel pollen is through inhalation.
Clinical Relevance
Exposure to sheep sorrel pollen may induce conditions such as allergic rhinitis, bronchial asthma and rhino-conjunctivitis.
Allergic rhinitis (AR) and allergic rhino-conjunctivitis (ARC)
A study conducted on 419 patients with AR symptoms (itchy eyes and nose, nasal obstruction, rhinorrhea, sneezing) revealed pollen allergen sensitization in 28.2% (118/419) of the study population. Positive SPT towards sheep sorrel pollen was reported in 9.1% of the patients from the study population. Additionally, sleep impairment (moderate to severe) caused by nasal symptoms (AR-mediated) was also reported by some patients.
A study involving 306 AR patients (12-62 years) reported ARC in 74% (226/306) and a history of allergy among 60% (184/306) of the patients. A prevalence of positive SPT towards sheep sorrel pollen was revealed to be 42.8% of the study population and 44.1% among the atopic group.
Asthma
A retrospective study conducted specific-IgE testing on asthmatic patients and reported sheep sorrel allergen sensitization in 13.7% (16/117) of patients with non-fungal sensitization and 32.7% (17/53) of patients with fungal sensitization.
A study involving 1069 patients showing hypersensitivity to pollen allergens (weed) identified bronchial asthma in 9.4% (101/1069) of patients from the study population. 19% of the patients were found to exhibit positive SPT towards sheep sorrel pollen.
Prevention And Therapy
Prevention strategies
Avoidance
During pollen season, allergic patients are suggested to stay indoors or wear a mask outdoors to keep away from pollen allergens. In worsening conditions, patients may be recommended to move or live in a non-pollen area
Cross-Reactivity
Rumex spp. (sorrel) pollen allergens have been reported to be cross-reactive with grass pollens.
References
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- Weber RW. Sheep sorrel. Ann Allergy Asthma Immunol. 2004;93(2):A6.
- CABI. Rumex acetosella (Sheep's sorrel) - Invasive Species Compendium 2021 [22-January-2021]. Available from: https://www.cabi.org/isc/datasheet/48056.
- WHO/IUIS. International Union of Immunological Societies Allergen Nomenclature 2021 [21-Jan-2021]. Available from: http://www.allergen.org/search.php?allergensource=roughmarshelder&searchsource=Search.
- Weber RW. Allergen of the Month—Monk's Rhubarb. Annals of Allergy, Asthma & Immunology. 2015;115(4):A13.
- Liang K-L, Su M-C, Shiao J-Y, Wu S-H, Li Y-H, Jiang R-S. Role of pollen allergy in Taiwanese patients with allergic rhinitis. Journal of the Formosan Medical Association. 2010;109(12):879-85.
- Benninger MS, Daly T, Graffmiller K. Positivity rates of in vitro inhalant/respiratory and food allergy tests in the northern midwestern United States. Ear, Nose & Throat Journal. 2018;97(9):296.
- Fereidouni M, Hossini RF, Azad FJ, Assarezadegan MA, Varasteh A. Skin prick test reactivity to common aeroallergens among allergic rhinitis patients in Iran. Allergologia et immunopathologia. 2009;37(2):73-9.
- Gniazdowska B, Doroszewska G, Doroszewski W. [Hypersensitivity to weed pollen allergens in the region of Bygdoszcz]. Pneumonol Alergol Pol. 1993;61(7-8):367-72.
- Suzuki Y, Ohta N, Sakurai S, Aoyagi M, Fukase S. [Examination about positive ratio of pollen antigens by scratch test]. Arerugi. 2009;58(12):1619-28.
- Medrek SK, Kao CC, Yang DH, Hanania NA, Parulekar AD. Fungal sensitization is associated with increased risk of life-threatening asthma. The Journal of Allergy and Clinical Immunology: In Practice. 2017;5(4):1025-31. e2.
- Xie ZJ, Guan K, Yin J. Advances in the clinical and mechanism research of pollen induced seasonal allergic asthma. Am J Clin Exp Immunol. 2019;8(1):1-8.
- Puc M. Characterisation of pollen allergens. Annals of Agricultural and Environmental Medicine. 2003;10(2):143-50.