Wormwood

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Code: w5
Latin name: Artemisia absinthium
Source material: Pollen
Family: Asteraceae (Compositae)
Common names: Wormwood, Common Wormwood, Absinthe, Sagewort

Not to be confused with Wormwood/Sweet Annie/Annual Wormwood (A. annua).

Allergen Exposure

The Artemisia family includes Wormwood (A. absinthum), Scoparia Wormwood (A scoparia), Tarragon syn esdragol, estragon (A. dracunculus), and the very important aeroallergen, Mugwort (A. vulgaris).

Wormwood is native to and grows wild in temperate Europe, western Asia and North Africa. It was introduced to North America in 1841 and is now naturalised across the northern United States and in Canada. The leaves and flowers, and the oil obtained from them, are used as medicine.

Artemisia absinthium is a medium-sized perennial herbaceous shrub with an aromatic sage-like odour and a very bitter taste. The plant reaches 1m tall by 0.6m wide. It grows each year from a woody base. It is often seen as one of the only surviving plants in drought areas. The light-green to olive-green leaves are 5 to 12cm long and divided two or three times into deeply lobed leaflets. The leaves and stems are covered with fine silky hairs that give the plant a greyish appearance.

Wormwood flowers from July to August. Flower stalks appear at each upper leaf node and produce numerous flower heads 2 to 3mm long and 1 to 2mm in diameter, ovoid or hemispherical and arranged in panicles. Many tiny, inconspicuous yellow flowers are produced in each head. The scented flowers are hermaphrodite (have both male and female organs) and are pollinated by wind. The fruit is an achene without a pappus. Each fruit contains one seed, which is less than 1mm long, smooth, flattened, and light grey-brown in colour. Artemisia absinthium reproduces primarily by seed and is a prolific seed producer.

Artemisia absinthium grows primarily on disturbed sites within grasslands, in pastures and perennial crops, and on land abandoned from cultivation, as well as on other wasteland, and on roadsides and rocks. It is cultivated in beds as a medicinal herb.

The flowering tops are collected during the late summer and used as a spice, in the preparation of various liqueurs and aperitifs, or in herbal medication. Artemisia absinthium yields a volatile oil containing thujone (absinthol), thujyl alcohol and iso-valeric acid. It contains, in addition, absinthin and a bitter glycoside. The plant is poisonous if used in large quantities. Even small quantities have been known to cause nervous disorders, convulsions, insomnia, etc. The scent of the plant alone has been known to cause headaches and other symptoms in some individuals.

Allergen Description

The following allergen(s) have been characterised:

Art a 1. (1)

Potential Cross-Reactivity

An extensive cross-reactivity among the different individual species of the genus could be expected, as well as to a certain degree among members of the family Asteraceae. (2) This is demonstrated by a study whose purpose was to investigate the in vitro cross-reactivity among nine Artemisia species: A. frigida, A. annua, A. biennis, A. filifolia, A. tridentata, A. californica, A. gnaphalodes, A. ludoviciana, and A. vulgaris. Results of the enzyme-linked immunosorbent assay inhibitions revealed strong cross-reactivity among all nine species, with A. biennis and A. tridentata being two of the strongest inhibitors. The polyacrylamide gel electrophoresis showed a great deal of similarity in the bands among the nine species. The nitrocellulose blots showed similar IgE binding patterns among the Artemisia species, with strong inhibition among all nine extracts. (3) Although A. absinthium was not included, one may infer that a strong degree of cross-reactivity exists between this species and other members of the Artemisia genus.

Art v 1, a defensin, an allergen from Mugwort pollen, has been shown to be cross-reactive with a pollen allergen from botanically related Asteraceae weeds (Artemisia absinthium, Helianthus annuus and Ambrosia sp.). The homologous allergens were recognised by IgE from Mugwort-sensitised patients. (1)

Clinical Experience

IgE mediated reactions

Anecdotal evidence suggests that asthma, allergic rhinitis and allergic conjunctivitis are common following exposure to pollen from Wormwood; however, few specific studies have been reported to date. (4, 5)

In a study in Poland, among 2561 patients suffering from upper airway allergy symptoms, hypersensitivity to weed pollen allergens was found in 1069 patients with pollinosis. In patients sensitised to weeds, the most prevalent allergens were Wormwood (86.2%), Mugwort (82.9%), White Goosefoot (44.3%), and Narrowleaf Plantain (28.8%). (6)

Common Wormwood is also an important aeroallergen in Japan. (4) A study in Korea reported that pollen from this plant might be considered as one of the important allergenic etiologies of atopic asthma in that country. (5)

Other reactions

Consumption of Absinthe may cause hallucinations, tremors, convulsions, and paralysis over the long term. The responsible substance for the toxicity of the drink is that Absinthe contains the compound thujone. (7, 8)

Compiled by Dr Harris Steinman, harris@allergyadvisor.com

References

  1. Gruber P, Gadermaier G, Bauer R, Weiss R, Wagner S, Leonard R, Breiteneder H, Ebner C, Ferreira F, Egger M. Role of the polypeptide backbone and post-translational modifications in cross-reactivity of Art v 1, the major mugwort pollen allergen. Biol Chem 2009 May-Jun;390(5-6):445-51.
  2. Yman L. Botanical relations and immunological cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09.
  3. Katial RK, Lin FL, Stafford WW, Ledoux RA, Westley CR, Weber RW. Mugwort and sage (Artemisia) pollen cross-reactivity: ELISA inhibition and immunoblot evaluation. Ann Allergy Asthma Immunol 1997;79(4):340-6.
  4. Iwasaki E, Baba M. Classification of allergens by positive percentage agreement and cluster analysis based on specific IgE antibodies in asthmatic children. [Japanese] Arerugi 1992;41(10):1449-58.
  5. Park HS, Lee MK, Hong CS. Bronchial challenge responses in asthmatic patients sensitized to Artemisia spp. pollen. Yonsei Med J 1989;30(2):173-9.
  6. Gniazdowska B, Doroszewska G, Doroszewski W. Hypersensitivity to weed pollen allergens in the region of Bygdoszcz. [Polish] Pneumonol Alergol Pol 1993;61(7-8):367-72.
  7. Arnold WN. Vincent van Gogh and the thujone connection. JAMA 1988;260(20):3042-4.
  8. Burkhard PR, Burkhardt K, Haenggeli CA, Landis T. Plant-induced seizures: reappearance of an old problem. J Neurol 1999;246(8):667-70.

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.