US menace conquers Europe - ragweed

By Ernest Gill Aug 11, 2008, 3:08 GMT

Hamburg - Health authorities throughout Central Europe are issuing warnings against a virulent new menace from the United States which is advancing rapidly across the continent - ragweed.

In the style of Wild West 'wanted' posters, authorities in Germany, Austria, Switzerland and adjacent countries are posting photographs of ragweed plants on lampposts, internet websites and on television shows.

'Ragweed conquers Germany,' a headline in a Hamburg newspaper screamed this week over an article quoting Dr Beate Jessel, head of Germany's Federal Office of Nature Conservation, as saying that ragweed infestations had been reported in two-thirds of all state and local districts across Germany.

Meanwhile, physicians and hospitals are being told to be on the watch for an onslaught of patients with severe asthma and hay fever-induced allergic respiratory spasms.

Municipal governments are training their street crews in effective methods of combatting the weed, which often goes unrecognized by Europeans.

'Some gardeners naively think it is an attractive plant and give it water and fertilizer in their front gardens,' says Susanne Schwarz of Berlin's Health Department.

'They should be eradicating this menace instead,' she adds. 'Best thing to do is pull it out by the roots and burn it, since the seeds can remain fertile for up to 40 years.'

In Germany, ragweed is called 'ambrosia,' which is from the plant's botanical name, Ambrosia artemisiifolia.

'Ambrosia sounds sweet and lovely, but few people in Europe realize just how serious the ragweed threat is to their health.'

Ragweed is the leading cause of late-summer hay fever in North America. It is estimated that more than 20 per cent of all Americans suffer from ragweed allergy to some extent or other.

Ragweed pollen first found its way from the US to Europe aboard ships in the 19th century, where it found an ideal climate - warm and not too moist - along the Mediterranean coast.

But with summers becoming warmer and drier in Northern Europe, botanists say ragweed is spreading northward. The fall of the Iron Curtain has accelerated its spread, as pollen 'hitchhikes' its way through the Balkans and into Central and Northern Europe aboard trucks, trains and river barges.

This year most of Europe experienced an unusually hot and dry summer, meaning that ragweed is blossoming rampantly along the sides of motorways and city streets as far north as Denmark.

Doctors have reported an alarming increase in patients suffering from severe hay fever and asthma. Along with the combination of hot days, recent cooler temperatures and a mild wind, the allergen has Europeans coughing, sneezing and wheezing.

In many cases, people who have never suffered from hay fever in their lives have suddenly been forced to consult physicians for allergy symptoms.

'Ragweed is very potent. Any amount in the air will start people with symptoms,' says Dr Stefan Nawrath, an allergy expert at the University of Frankfurt.

'Exposure to ragweed could cause symptoms for up to six or eight hours. By that time you're probably exposed to it again,' Nawrath says.

Allergy experts say allergens can be eaten, inhaled or injected as with an insect sting. Common allergens are pollen grains, dust, mold and food, as well as animal proteins found on hair, fur and dander.

Allergens are measured by grains per cubic metre of air per day. A typical person breathes about 10 cubic metres of air per day. During a high allergy season the air will typically contain between 1,000 and 8,000 grains per cubic meters.

The annoying, cold-like symptoms (without a fever) are the body's attempt to cleanse itself of the allergens.

The most common symptoms of a ragweed allergy are itchy eyes, stuffy nose, coughing and wheezing. Sufferers may have one or all symptoms. It all comes down to genetics.

'People who are allergic do have allergic parents, one or two,' Nawrath says. 'In other words, 15 to 20 per cent of people become allergic.'

Authorities in Baden-Wuerttemberg, Bavaria, Saxony and various provinces in Austria have launched concerted campaigns to educate the public to the ragweed threat and to eradicate the plant from roadsides.

Radio and television messages urge residents to wash their hair before going to bed to get any pollen out, and not to hang clothes out on the line, to close windows and use air-conditioning when driving, and to stay indoors at peak hours, particularly first thing in the morning.

There are also a variety of over-the-counter and prescription medications available to help allergies and Europeans are being advised to consult doctors for allergy tests and possible therapies.

'We are fighting an uphill battle,' says Werner Franke, the chief noxious plants control officer for the German state of Baden-Wuerttemberg. 'Ragweed spreads like wildfire and it has the advantage of being virtually unknown in Europe. So people stop and admire its unusual green flowers and only wonder afterwards why they are sneezing.'

The health alerts in Europe coincided with headlines from Seattle, where a woman found a mammoth ragweed plant in her back garden that towered three metres tall.

The experts identified it as Ambrosia trifida, as it's known in scholarly circles, a species that can grow nearly five metres tall and is a hay fever sufferer's worst nightmare.

'If we don't act fast, ragweed will spread its way all across Europe and then there will be no stopping it,' Franke warns.