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Climate and vegetation changes in China may have led to increases in sensitivity to weed pollens and molds over the past 5 years, though the number one aeroallergen remains to be house dust mites.
Sensitization rates to weed pollens (especially Humulus) and molds (Alternaria and Cladosporium) steadily rose over the previous 5 years among those with allergic rhinitis in China, according to new findings, which may reflect changes in vegetation and climate in the country.1
These findings and others regarding allergens and their effects on allergic rhinitis patients were the result of a recent retrospective study of sensitization profiles in China. The research was designed by Zhu Rongfei and Chen Hao from Tongji Hospital’s Department of Allergy at Tongji Medical College of Huazhong University.
The study’s investigators noted that in the prior 20 years, allergic rhinitis incidence has been shown to steadily increase and even led to heavy economic burden.2
“Due to the differences of climate and temperature in different countries and regions, it is of great significance to establish allergen-screening panels for the AR patients based on the spectrum of local epidemic aeroallergens,” Rongfei, Hao, and colleagues wrote. “Meanwhile, the observation that allergen sensitization patterns change over time as a result of environmental changes highlights the importance of regularly monitoring allergen panels in different regions.”
The investigators conducted an observational, cross-sectional retrospective study to assess the alteration of sensitization patterns to airborne allergens among Chinese individuals with reported allergic rhinitis over the span of 2009 - 2021. The study included people with allergic rhinitis recruited from 1 of 3 hospitals: Henan Provincial People's Hospital (located in the north), Chongqing People's Hospital (in the west), and Tongji Hospital.
Every month, the first 50 study participants exhibiting recurrent nasal symptoms (including symptoms such as sneezing, itching nose, rhinorrhea, and nasal obstruction) and suspected of having allergic rhinitis were used in the study at each center.
The suspected diagnosis of the condition was based upon symptoms and signs in accordance with the Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines. Skin prick tests were performed by the investigators on all the recruited participants with a panel of 19 airborne allergens.
In total, the research team included 16,664 participants, among whom 15.2% were shown to have concomitant asthma and allergic rhinitis, and 37.2% were children under the age of 18. Positive skin prick test results were observed by the team in 79.6% of the group, indicating sensitization to at least 1 allergen.
The investigators reported that sensitization rates of the 19 airborne allergens used in the panel demonstrated substantial changes over the period from 2009 - 2021, with distinct trends observed among all 3 centers.
Sensitization rates to house dust mites were found to have continually been stable, while sensitization rates to Artemisia, Ambrosia, and Humulus increased gradually in all of the centers used in the research. The investigators also noted a major rise in sensitization rates to animal dander, with cat and dog hair showing a notable rise from 2016 - 2021.
Center 1 was shown to have higher sensitization rates to most allergens, except house dust mites, compared to the other included centers. The mites were reported by the research team to be the most common aeroallergen in all centers, with relatively stable rates of sensitization over the past 13 years.
Sensitization rates to weed pollens (especially Humulus) and molds (Alternaria and Cladosporium) were also found to have slowly risen in the prior 5 years. The team found that Center 1 showed a higher sensitization rate to pollen, possibly due to local vegetation growth and diminished precipitation in the region.
Airborne pollen was identified as the most common seasonal allergen in the western and northern areas of China. House dust mite concentration in dust was also shown to be much lower in family homes in Northern China compared to Southern China, which may contribute to the difference in sensitization characteristics.
“Although the prevalent allergens were different in those centers, (house dust mites) are still the major allergens in Chinese AR patients, and the sensitization rates to cat, dog and Humulus pollen showed quickly increasing trends in the last decade,” they wrote.