Code | w3 |
LOINC | 6124-2 |
Family | Asteraceae (Compositae) |
Genus | Ambrosia |
Species | A. trifida |
Route of Exposure | Inhalation |
Source Material | Giant ragweed pollen |
Latin Name | Ambrosia trifida |
Other Names | Great ragweed, giant ragweed, tall ragweed, blood ragweed, Texan great ragweed |
Categories | Weed Pollens |
Giant ragweed (Ambrosia trifida) is an herbaceous annual weed, native to North America and introduced to many countries in Europe and Asia. It is associated with allergic rhinitis, conjunctivitis and asthma as well as contact dermatitis. Giant ragweed shows high levels of cross-reactivity with other ragweeds (Ambrosia species) and mugwort (Artemisia species).
Giant ragweed (Ambrosia trifida) is an herbaceous annual weed native to North America and Mexico. It has been introduced to many countries in Europe and Asia and is the most prevalent ragweed species in northern China (1-3). Giant ragweed is often one of the earliest plants to emerge during the spring and is mainly wind-pollinated. It is estimated that a single plant can produce up to 10 million pollen grains per day and one billion pollen grains in its lifetime (1, 3).
The ragweed (Ambrosia spp) pollen season has become significantly longer over the last 20 years, possibly due to climate change influences on plant distribution, flowering season, pollen load and allergenicity. Weed pollen and grass pollen seasons overlap in most parts of Europe, as do ragweed and mugwort pollen seasons (4).
Taxonomic tree of Ambrosia trifida (1) |
|
Domain |
Eukaryota |
Kingdom |
Plantae |
Phylum |
Spermatophyta |
Subphylum |
Angiospermae |
Class |
Dicotyledonae |
Family |
Asteraceae |
Genus |
Ambrosia. |
Weed pollen
Ragweed pollen is an important allergen source: Ambrosia species (of which short ragweed, giant ragweed and western ragweed are the most widespread) are major elicitors of pollen allergy in North America. In a study of 50 Chinese patients (aged 8–54 years) with weed pollen-induced allergic rhinitis, 34 % had specific IgE to giant ragweed allergen, Amb t (2)
Climate change modelling suggests there will be an impact on the giant ragweed distribution area, although whether this will potentially increase or decrease depends on the climate scenario (5).
Giant ragweed is an aggressive weed that prefers disturbed ground, including cultivated land, pasture, roadsides, riverbanks and grasslands, especially flood plains. This enables it to dominate the growing season, leading to poor yields and reduced biodiversity of native species (1).
The main route of exposure is inhalation.
Giant ragweed pollen causes seasonal allergic rhinitis, asthma and conjunctivitis in sensitized patients as well as contact dermatitis (3, 6).
Giant ragweed pollen can rupture osmotically in the atmosphere, producing sub-pollen particles that penetrate deeper into the respiratory tract than intact pollen grains, potentially triggering severe asthma
Allergenic cross-reactivity exists between Amb a (short or common ragweed), Amb p (western ragweed) and Amb t (giant ragweed), and given the effective Amb b inhibition of Amb p and Amb t suggests that an Amb a-based, single-species allergen immunotherapy may be successful in patients allergic to diverse ragweed pollens, although species-specific immunotherapy may be required given the allergen diversity (7, 8)
Allergen |
Class |
Amb t 5 |
4.4 kDa basic protein |
Amb t 5.0101 |
Isoform of Amb t 5 |
Amb t 8 |
Profilin |
Amb t 5 (a secreted basic protein) is an identified allergen from giant ragweed. Amb t 5 is homologous to Amb a 5 from short or common ragweed (A. artemisiifolia), although their sequence homology is relatively low at 45 % (6). In a proteomic study of other proteins were identified including some pectate lyases (Amb a 1.2, 1.4, and Amb a 2) as well as a profilin and profilin-3 (9).
The presence of homologous allergens leads to extensive IgE cross-reactivity between the pollen extracts Amb t from giant ragweed, Amb p from western ragweed (A. psilostachya) and Amb a from short or common ragweed (A. artemisiifolia) (6, 8)
A high degree of IgE cross-reactivity is seen among different species of ragweed (Ambrosia spp) and mugwort (Artemisia) and to other allergenic plants of the Asteraceae family. (4).
Author: RubyDuke Communications
Reviewer: Dr. Michael Thorpe
Last reviewed:February 2022