Ragweed pollen concentration predicts seasonal rhino-conjunctivitis and asthma severity in patients allergic to ragweed

Global Ragweed Allergy: Molecular Allergens and Integrated Control Strategies

Originally native to North America, ragweed has become a pervasive invasive species worldwide over the past century, posing a substantial public health risk as a potent allergen. This review explores the key allergens found in common ragweed, assesses global trends in ragweed sensitization, particularly in China, and examines various therapeutic and biological control methods. There are currently 11 identified ragweed allergens, with Amb a 1 and 11 recognized as the primary triggers. Epidemiological data indicate higher rates of sensitization in North America and Europe, with a growing trend observed in China. Ragweed-induced type I hypersensitivity typically presents as seasonal allergic rhinitis, conjunctivitis, and asthma symptoms. Strategies for managing ragweed allergy include allergen avoidance, pharmacotherapy, and allergen immunotherapy (AIT). Biological control using Ophraella communa and Epiblema strenuana effectively limits ragweed proliferation. Accurate allergen identification and personalized treatment can significantly reduce the health burden associated with ragweed. An in-depth understanding of ragweed sensitization patterns and biological control measures is essential for the long-term prevention of ragweed allergies.

Prevalence of aeroallergen sensitization in a polluted and industrialized area: a pilot study in South Africa's Vaal Triangle

This pioneering study evaluates the prevalence of aeroallergens reactivity among atopic populations living in the Vaal Triangle Airshed Priority Area (VTAPA), South Africa. A total of 138 volunteers (51 males and 87 females), of African, colored, white, and Asian ethnicity, and with a mean (range) age of 22 (18-56) years were participating in the study. The study was conducted on the North-West University (NWU) campus in Vanderbijlpark/VTAPA. The International Study of Asthma and Allergies in Childhood questionnaire was utilized for pre-screening to identify individuals with probable allergic dispositions. Subsequently, skin prick testing was conducted using commercial aeroallergen extracts for all confirmed participants with allergy symptoms. One hundred six participants were clinically diagnosed with pollen and fungal spore allergies. The highest allergy prevalence was attributed to Cynodon dactylon ((L.) Pers) (Bermuda grass) (41.5%), followed by Lolium perenne (L.) (ryegrass), grass mix, and Zea mays (L.) (maize) (31.1%), respectively. Moreover, among the tree allergens, Olea (L.) (olive tree) was the most prevalent allergen (20; 18.8%), followed by Platanus (L.) (plane tree) (18; 16.9%). Among the weeds, 16 (15.1%) participants were allergic to the weed mix (Artemisia (L.) (wormwood), Chenopodium (Link) (goosefoot), Salsola (L.) (saltwort), Plantago (L.) (plantain), and 11 (10.3%) to Ambrosia (L.) (ragweed)). Regarding the fungal spores, Alternaria (Fr.) (9; 8.5%) followed by Cladosporium (Link) (5; 4.7%) had the highest skin sensitivity. In this pilot study, our findings provide insights into the prevalence of allergic responses in the study population-underlining the strong impact of allergens of exotic plants-and contribute to the existing aerobiological data in South Africa.

Quick L, Hilmer E, Van Aardt A, John J, Garland R, Finch J, Hoek W, Bamford M, Seedat RY, I. Manjra A, Peter J. Ambrosia (ragweed) pollen - A growing aeroallergen of concern in South Africa

Background

Ragweed is an invasive, highly allergenic weed predicted to expand its habitat with warming global temperatures. Several Ambrosia species have been identified in South Africa for well over a century; however, its presence remained undetected by allergists and aerobiologists until the development of an extensive aerospora monitoring system across South African urban areas since 2019. This paper presents the inventory of preliminary investigation of the Ambrosia airborne pollen and the taxonomic identification of ragweed species.

Methods

Burkard volumetric spore traps for collecting pollen samples are set up in 9 South African cities (Johannesburg, Cape Town, Pretoria, Kimberley, Durban, Potchefstroom, Ermelo, Bloemfontein, and Gqeberha). Light microscopic identification was combined with environmental DNA metabarcoding analysis to confirm the species level of airborne Ambrosia at selected monitoring stations. Ragweed sensitisation was examined in Cape Town between February 2019 and February 2024, using Allergy Xplorer (ALEX2) multicomponent allergen array.

Results

Ambrosia pollen was detected in 5 aerobiological monitoring stations over the sampling period (Durban, Kimberley, Pretoria, Potchefstroom, Johannesburg). Periods of 4 consistent pollination years were observed in Kimberley (min: 1; max: 16 p.g/m3) and Durban (min: 26; max: 66 p.g/m3). In Pretoria, ragweed pollen was detected for 2 years (2020-2021; 2022-2023) with average total annuals (5-17 p.g/m3). A peak flowering period between March and April was observed in Potchefstroom, and several ragweed pollen peaks were present between the end of December and the beginning of May in Durban. The highest number of Ambrosia pollen grains was recorded in Potchefstroom, with 308 grains, and a maximum peak of 47 p.g/m3. eDNA metabarcoding confirmed the presence of Ambrosia artemisiifolia and A.trifida species. The overall prevalence of Ambrosia-sensitisation amongst 673 tests (age range 7-72 years) was 8.2% (55/673), with no significant difference in sensitisation patterns between age groups.

Conclusion

Our study confirms the need to monitor the spread of ragweed, and an increasing awareness of Ambrosia as an allergen of concern in Southern Africa. Extension of aerobiological networks and testing for Ambrosia sensitisation across urban and rural sites will be required.

The effectiveness of pollen allergen immunotherapy on allergic rhinitis over 18 years: A national cohort study in Denmark

BACKGROUND

Because long-term effectiveness of pollen allergen immune therapy (AIT) for allergic rhinitis (AR) is not well-described, we studied effectiveness over 18 years in Denmark.

METHODS

A register-based cohort study using data on filled prescriptions, 1995-2016, Denmark. In a cohort of 1.1 million intranasal corticosteroid inhaler users (proxy for AR), we matched users treated with grass, birch or mugwort AIT 1:2 with non-treated users on baseline year and 24 characteristics in the 3 years prior to baseline. The primary outcome was the odds ratio (OR) of using anti-allergic nasal inhaler during the pollen season in the treated versus non-treated group by years since baseline.

RESULTS

Among 7760 AR patients treated with pollen AIT, the OR of using nasal inhaler 0-5 years after baseline was reduced when compared with 15,520 non-treated AR individuals (0-2 years, OR 0.84 (0.81-0.88); 3-5 years, OR 0.88 (0.84-0.92)), but was close to unity or higher thereafter (6-9 years, OR 1.03 (0.97-1.08); 10-18 years, OR 1.18 (1.11-1.26)). In post hoc analyses, results were more consistent for those who already had 3 of 3 baseline years of use, and in patients using nasal inhaler in the latest pollen season (0-2 years, OR 0.76 (0.72-0.79); 3-5 years OR 0.86 (0.81-0.93); 6-9 years, OR 0.94 (0.87-1.02); 10-18 years, OR 0.94 (0.86-1.04)) as opposed to no such use.

CONCLUSIONS

Patients treated with pollen AIT in routine care to a higher degree stopped using anti-allergic nasal inhaler 0-5 years after starting the standard 3 years of therapy, and not beyond 5 years. Post hoc analyses suggested effectiveness was more consistent among patients with persistent AR.

A temporally and spatially explicit, data-driven estimation of airborne ragweed pollen concentrations across Europe

Ongoing and future climate change driven expansion of aeroallergen-producing plant species comprise a major human health problem across Europe and elsewhere. There is an urgent need to produce accurate, temporally dynamic maps at the continental level, especially in the context of climate uncertainty. This study aimed to restore missing daily ragweed pollen data sets for Europe, to produce phenological maps of ragweed pollen, resulting in the most complete and detailed high-resolution ragweed pollen concentration maps to date. To achieve this, we have developed two statistical procedures, a Gaussian method (GM) and deep learning (DL) for restoring missing daily ragweed pollen data sets, based on the plant's reproductive and growth (phenological, pollen production and frost-related) characteristics. DL model performances were consistently better for estimating seasonal pollen integrals than those of the GM approach. These are the first published modelled maps using altitude correction and flowering phenology to recover missing pollen information. We created a web page (http://euragweedpollen.gmf.u-szeged.hu/), including daily ragweed pollen concentration data sets of the stations examined and their restored daily data, allowing one to upload newly measured or recovered daily data. Generation of these maps provides a means to track pollen impacts in the context of climatic shifts, identify geographical regions with high pollen exposure, determine areas of future vulnerability, apply spatially-explicit mitigation measures and prioritize management interventions.

Clinical efficacy in one-year treatment with Artemisia annua-SLIT drops in monosensitized and polysensitized individuals

PURPOSE

Seasonal allergic rhinoconjunctivitis (SARC) caused by Artemisia seriously affects patients' quality of life in northern China. This study aimed to estimate further the efficacy and safety of a one-year course of Artemisia annua-sublingual immunotherapy (SLIT) on SARC patients.

MATERIALS AND METHODS

This was an open-label, randomized, controlled, single-centre study involving 150 SARC patients induced by Artemisia, randomized to SLIT group (n = 75, SLIT along with pharmacotherapy) or control group (n = 75, pharmacotherapy only). According to the skin prick test (SPT) results, the SLIT group was divided into monosensitized and polysensitized groups to analyze the influence of sensitization status on the efficacy of Artemisia annua-SLIT. The clinical indicators of this study were total rhinoconjunctivitis symptom score (TRSS), total medication score (TMS), combined scores of medication and rhinoconjunctivitis symptom (CSMRS), and score of visual analog scale (VAS). Safety was evaluated by the occurrence of adverse events (AEs). Daily administration of the drops was recorded in diaries by the patients.

RESULTS

After nearly one year of treatment and follow-ups, there was a significant decline in TRSS, TMS, CSMRS, and VAS from the baseline scores in the SLIT group (p < 0.001). However, as pollen counts increased in 2022, indicators above in the control group increased significantly during the peak pollen phase (PPP) in 2022 grass pollen season (GPS) compared to the baseline. Meanwhile, we found no significant difference in TRSS, TMS, CSMRS, and VAS between the monosensitized and polysensitized groups (p > 0.05). Moreover, the result indicated that the clinical improvement in TRSS, TMS, CSMRS, and VAS was still observed in polysensitized patients who were allergic to Artemisia pollen and sensitized to house dust mite (HDM) (n = 15) in PPP of 2022, compared to the baseline value (p < 0.001).

CONCLUSION

Artemisia annua-SLIT was proven effective, tolerable and safe in patients with SARC after nearly one year of treatment, whether monosensitization or polysensitization.

[Sensitization characteristics of ragweed pollen in Beijing area]

Objective:To investigate the sensitization characteristics of ragweed pollen in patients with allergic rhinitis（AR） and（or） allergic asthma in Beijing area, and to provide basis for the prevention and treatment of ragweed pollen sensitized population. Methods:Patients with allergic rhinitis and/or asthma from January 2017 to December 2019 in the outpatient department of Allergy Department of Beijing Shijitan Hospital were retrospectively analyzed in this study. Skin prick test（SPT） was performed with ragweed pollen allergen reagents to compare different ages, genders and respiratory diseases allergen distribution, and to observe the sensitization characteristics of its population. All of the analyses were performed using SAS software version 9.4. Results:A total of 9 727 patients were enrolled in the end. The total positive rate of ragweed pollen SPT was 45.50%（4 426/9 727）, the highest positive rate was 65.54% in 13-17 years old group; The positive rate of ragweed pollen SPT was 49.79% in allergic rhinitis combined with asthma patients, followed by 46.46% in allergic rhinitis patients, and the lowest rate was 19.42% in single allergic asthma patients. There were more females than males in both ragweed pollen sensitized and non-ragweed pollen sensitized groups（P<0.05）, and the proportion was higher in 30-39 years old than in other age groups（P<0.05）. Ragweed pollen sensitization was higher than non-ragweed pollen sensitization in the allergic rhinitis group（98.49% vs 94.76%, P<0.05）. Ragweed pollen with other summer and autumn pollen allergens in patients with positive SPT, the top three were Chenopodium pollen, Humulus pollen and Artemisia grandis pollen, with positive rates of 90.42%, 89.63% and 85.40%, respectively. Ragweed combined with other pollen sensitization accounted for 99.57%（4 407/4 426）. Allergic rhinitis was the main disease in patients sensitized with ragweed pollen alone or combined with other pollens, and there was no significant difference between the two groups（94.97% vs 98.50%, P>0.05）. Conclusion:Ragweed pollen is highly sensitized in Beijing area, single ragweed pollen sensitization is rare, often combined with multiple pollen sensitization, and allergic rhinitis is the main disease.