One pollen replaces another. As every year at the same time, late July, early August, ragweed plants will come into bloom and release their pollen. Problem: not only is the pollen of this plant highly allergenic, but in a few decades, ragweed, which is also very invasive, has managed to colonize France.
To counter its proliferation, uprooting campaigns are regularly organized at the beginning of summer before it flowers. But is it still time to uproot it? And are these campaigns effective in reducing the health impact of ragweed and providing some respite to people with allergies?
A highly allergenic pollen
While not everyone is necessarily able to recognize a ragweed plant, many people nevertheless suffer from its pollen. According to an expert report from Anses published in 2014, “ragweed pollens are among the most problematic in France. The pollen of this plant is in fact very allergenic.” In practice, it “causes the same symptoms as other pollens in people with allergies: sneezing, nasal obstruction, conjunctivitis, redness, swelling of the eyelids,” describes the health agency.
And “a few grains per m3 of air are enough to trigger a reaction in sensitized people,” adds the Ragweed Observatory. The allergic reaction can be serious, frequently complicated by tracheitis and/or asthma, and constantly by great fatigue. Skin damage is sometimes associated: itching, hives, eczema.” For patients, “the repercussions on quality of life are considerable,” continues the Observatory, which equates ragweed with a “real biological pollutant.”
A significant health impact
However, its season is particularly long. “Ragweed causes much more severe forms of allergy than other pollens, and closes the pollen season, after tree pollen in the spring and grass pollen in the summer,” explains Isabella Annesi-Maesano, research director at Inserm and epidemiologist of allergic and respiratory diseases. Due to global warming, ragweed pollen arrives a month earlier, from the end of July to the end of October. As a result, people with allergies, who already have very damaged mucous membranes, no longer have any defenses when ragweed releases its pollen. Not to mention the cocktail effect of pollution, which makes the pollen even more violent.
In terms of figures, the health impact is already impressive: it is estimated that “between 1.1 and 3.5 million people are allergic to ragweed pollen in France”, indicates Anses. And “the prevalence of this allergy is gradually increasing. In areas of high exposure to ragweed pollen in the former Rhône-Alpes region, 21% of the population is sensitive to ragweed pollen, illustrates the Observatory. Ragweed allergy results in significant health costs”. According to Anses, “its medical coverage (medications and consultations) would cost between 59 million and 186 million euros each year” in France.
An invasive and resistant plant
Ragweed is now present almost everywhere in France, because “it is an invasive and resistant plant,” recalls Isabella Annesi-Maesano. It can be found almost everywhere: on roadsides, construction sites, wasteland or even agricultural crops.” To date, “the main allergy hotspots are located in the Rhone and Loire valleys, as well as in the South-West, particularly from Tarn-et-Garonne to Charentes, explains ANSES. Ragweed populations still seem to be, and increasingly, growing and densifying across France. The plant is now present throughout the country with varying levels of infestation.”
The health agency thus lists “the areas with high infestation/implantation including the Rhône, Isère, Drôme but also Nièvre or Cher or even Charentes and Tarn-et-Garonne”. As well as “the “front” areas located on the edge of heavily infested areas, such as Yonne, the north of Côte-d’Or or the west of Gard”. And “the areas still very little or not at all concerned such as Brittany, Normandy and Hauts-de-France”.
Uprooting to stem proliferation
To combat its proliferation, manual uprooting campaigns are organized each year. The goal: “to prevent the plant from producing pollen to limit allergies, and to produce seeds to limit the invasion, insists the Ragweed Observatory. Control actions that must be continued over several years to eradicate the plant.” On the ground, “communities, professionals and individuals: we all have a role to play in combating ragweed, by reporting or destroying plants before they flower and release their pollen,” insists ARS of Cantalwhere a day of manual uprooting was organized this Wednesday in Lacapelle-del-Fraisse.
“This is a very effective technique for completely cleaning an area,” assures the Observatory. However, it is “limited to small areas.” It has “a cost, requires a lot of work, and is a difficult task that exposes you to the plant’s pollen,” indicates Isabella Annesi-Maesano. Hence the importance of “wearing protection (mask and goggles), and of pulling out before flowering for greater efficiency and to avoid exposure to pollen,” emphasizes the Observatory.
“Manual uprooting campaigns are certainly carried out in small areas, but they are necessary and effective, according to data from the National Aerobiological Surveillance Network (RNSA), notes Isabella Annesi-Maesano. Not only because for people with allergies, there are fewer clinical manifestations: allergy is also a question of dose. But also because avoidance is the best method in allergy. So anything that reduces the presence of ragweed is very positive.”
Artificial intelligence in support
Other techniques, such as mechanical uprooting, crop rotation and soil cover with other plants complete the arsenal of control. And scientists and field workers can also count on artificial intelligence (AI) to target their actions. “AI makes it possible to monitor pollen levels in real time. But also to create predictive models using machine learning, which make it possible, from the data collected, to predict pollen concentrations in the air based on weather conditions and historical data,” explains Isabella Annesi-Maesano.
Another AI boost: “We have connected sensors that monitor pollen concentrations in the air in the field, and we are studying whether their fluctuations lead to possible variations in symptoms in allergic patients,” explains the epidemiologist. In addition, uprooting operations are carried out with the help of drones and satellite images to detect the presence of ragweed and monitor its spread.”
Finally, mobile applications are being developed “to alert people with allergies,” continues Isabella Annesi-Maesano, who participated in the development of l’appli MASK-AIRwhich supports patients in the treatment of allergic rhinitis. An app “developed by a team of world-renowned physician-researchers, indicates the RNSA, deployed in more than 20 countries and already used by more than 25,000 patients”. And if the presence of ragweed is detected, recalls the ARS of Cantal, it is possible to use “the ragweed reporting platform available on the Internet (https://signalement-ambroisie.atlasante.fr) ».
Source: www.20minutes.fr
