TUESDAY, March 4 (HealthDay News) -- Oral allergy immunotherapy -- in the form of drops or tablets -- is effective at reducing asthma symptoms and the need for asthma medications in children who have what's known as allergic asthma, a new study finds.

The findings bolster hopes that these oral medications might someday replace injections, never a hit with kids.

"[Oral] immunotherapy is effective and safe, easy to administer, well-accepted by patients," said the study's senior author, Dr. Giorgio Walter Canonica, professor of allergy and respiratory disease at the Medical University of Genoa, Italy.

Commonly known as allergy shots in the United States, allergy immunotherapy works in a manner similar to vaccines -- essentially re-educating the body's immune system so that it doesn't overreact to harmless substances such as pollen or dust mites. While this therapy can be effective, it's currently only available via injections in the United States, and usually involves at least one to two shots a week for three to six months, making it a less-than-popular alternative with children.

Oral immunotherapy is available in Europe, but has yet to gain Food and Drug Administration approval in the United States.

The new study reviewed nine studies that looked at the use of so-called sublingual (oral) immunotherapy in children with asthma. A total of 441 kids between the ages of 3 and 18 who had been diagnosed with allergic asthma were included in the studies. Allergic asthma means that asthma symptoms can be triggered by exposure to an allergen, such as dust mites, pollen or mold.

Two hundred and thirty-two children received oral immunotherapy and the remaining 209 got a placebo.

The dosing schedule varied depending on the study and whether drops or tablets were used. Canonica said that during the maintenance phase of immunotherapy, drops or tablets were given three times a week. The average duration of the studies was 12 months. The most common allergen treated was dust mites. Grass mix and pollen were also included in one study each.

The researchers found that those taking sublingual immunotherapy (SLIT) had significantly fewer symptoms and needed to take less asthma medication. Not enough of the studies included measurements of lung function for the new study to assess whether SLIT affects lung function significantly.

"SLIT is highly effective in treating pediatric asthma patients, reducing both symptoms and medication use," said Canonica, who's also president of the World Allergy Organization.

Additionally, SLIT appeared to be better tolerated than allergy shots. The chances of a severe reaction are less with oral immunotherapy than with the injected type, according to Dr. Andrew MacGinnitie, an allergist/immunologist at Children's Hospital of Pittsburgh.

"There have been some rare cases of severe reactions with SLIT, but they're much less common," MacGinnitie said. Another big benefit, he added, is that "shots have to be given in the doctor's office and drops are designed to taken at home."

The results of the new study are published in the March issue of the journal Chest.

Other studies have directly compared SLIT to allergy shots and they're both equally effective, according to Canonica. And MacGinnitie said that, "immunotherapy is really the only treatment that gets to the cause of the allergic response."

"This is a potentially new and exciting treatment for kids with asthma," he concluded.

More information

To learn more about allergy immunotherapy, visit the American Academy of Allergy, Asthma and Immunology  .

TUESDAY, Feb. 19 (HealthDay News) -- New research on the spread of the 1918 influenza virus, which killed more than 50 million people worldwide, may aid research into today's potentially dangerous bird flu strain, scientists say.

MIT researchers found that the 1918 avian flu virus strain developed two mutations in a surface molecule called hemagglutinin (HA), which allowed it to bind tightly to receptors in the human upper respiratory tract. This ability to "lock in" was critical for viral transmission in humans, according to the findings, published in Feb. 18 issue of the Proceedings of the National Academy of Sciences.

"Two mutations dramatically change the HA binding affinity to receptors found in the human upper airways," said the paper's senior author Ram Sasisekharan, the Underwood Prescott Professor of Biological Engineering and Health Sciences and Technology, in a prepared statement.

Sasisekharan and colleagues previously reported in January's Nature Biotechnology that flu viruses can only bind to human respiratory cells if they match the shape of sugar (or glycan) receptors found on those cells. The receptors, known as alpha 2-6 in humans, come in two shapes -- one resembling a cone; the other an open umbrella.

In the new study, the team discovered that for avian flu viruses to transmit from birds to humans, they must gain the ability to bind tightly or with a high affinity to the umbrella-shaped receptors.

"The affinity between the influenza virus HA and the glycan receptors appears to be a critical determinant for viral transmission," Sasisekharan said.

The researchers compared the influenza virus that caused the 1918 pandemic with two similar strains (called NY18 and AV18) that differ from it by only one or two amino acids.

Using ferrets (which are susceptible to human flu strains), researchers had earlier found that the pandemic virus transmitted efficiently between ferrets, while the NY18 strain proved only slightly infectious and AV18 not at all infectious.

While slightly infectious NY18 binded to the umbrella-shaped glycan receptors, it did not do it as well as the highly infectious pandemic strain did. The non-infectious AV18 strain had no affinity for the receptors.

Another strain, TX18, proved much more infectious than NY18, and it bonded with high affinity to the umbrella-shaped receptors.

Researchers from the Centers for Disease Control and Prevention reported on the infectiousness of these strains last year, but the MIT study is the first to explain the biochemical reason causing these differences.

More information

The U.S. Centers for Disease Control and Prevention has more about influenza.