USDA study: Ragweed season now 16 days longer

BELTSVILLE, Md. — A U.S. Department of Agriculture study published in March in the journal Proceedings of the National Academy of Sciences has found that ragweed season is almost 16 days longer than it was in 1995 due to changes in the first frost line of the fall in North America. The first frost steadily has been creeping northward and later into the year, lead researcher Lewis Ziska wrote.

That’s 16 more days of allergy relief sales — especially good news for Chattem as it shepherds its recently switched Allegra antihistamine through its first year. “We will make very, very massive investments in terms of advertising and promotion, and we are in fact very confident, and even optimistic, that in a very, very short [time] we will reach sales levels [as high as] the two leading products in this field,” boasted Hanspeter Spek, president of global operations for Sanofi-Aventis, a few weeks before the actual launch at the beginning of March.

Though Allegra is not expected to reach the sales heights of $200 million-plus like its two second-generation antihistamine predecessors, Claritin and Zyrtec — which generated $222.5 million (up 5.4%) and $169.1 million (up 11.6%), respectively, across food, drug and mass (excluding Walmart) over the 52 weeks ended March 20, according to SymphonyIRI Group data — an incremental $100 million-plus to OTC allergy sales is not out of the question.

An extended ragweed season is advantageous for all allergy remedies, however. “For much of geographic North America, there are three distinct plant-based aeroallergen seasons,” Ziska wrote — tree pollen in the spring, grass pollen in the early summer and weed pollen, including ragweed, in the summer and fall. At least 10% of the U.S. population is ragweed sensitive, and an increase in ragweed pollen exposure could, in turn, increase allergic sensitization.

There are 17 different species of ragweed in the United States. These plants are most common in the rural areas of the East and Midwest, but are found throughout the country. A single ragweed plant can release as many as 1 billion grains of pollen over the course of a single season.

In northern areas of the United States, ragweed pollen release begins in early August and peaks by early September. An early frost in late September often shortens the ragweed season in northern areas. In the southern United States, the ragweed season begins later in August and continues through October. In Florida, there actually are some species of ragweed flowering during the winter and others that potentially flower year-round.

The study found the further north you went, the further extended the ragweed season became. In Georgetown, Texas, and Rogers, Ark., the season actually retract

ed by three to four days between 1995 and 2009. But in Papillion, Neb., which is 41 degrees north of the equator, the season extended 11 days to mid-October; in LaCrosse, Wis., which is almost 44 degrees north, the season extended 13 days (also ending now in mid-October); and in Fargo, N.D., almost 47 degrees north, the season has been extended 16 days to late September.

The USDA study found in two locations in Canada, both further north than 50 degrees latitude, the ragweed season has been extended by as many as 27 days from the 1995 season to the 2009 season.