TUESDAY, March 2 (HealthDay News) -- Asthma rates are increasing across the United States, a new government study shows, but certain states have significantly lower rates of the respiratory disease.

The overall rate of asthma is currently estimated to be 7.85 percent of the population, an increase of about 0.5 percent every three years. But, the report also found that some states have dramatically lower rates of asthma. For example, the study found that while almost 11 percent of people in Rhode Island had asthma, just 5 percent of those living in Louisiana had the illness.

"Asthma is a very common condition," said study author Dr. Teresa Ann Morrison, a medical officer in the Air Pollution and Respiratory Health Branch of the National Center for Environmental Health, in Atlanta.

"Our findings indicated wide differences in geographic prevalence among adults across the state level and an overall increased prevalence," she added.

Results of the study were to be presented Tuesday at the American Academy of Allergy, Asthma & Immunology annual meeting, in New Orleans.

For the study, Morrison and her colleagues culled data on adults with asthma from the Behavioral Risk Factor Surveillance System from 2000 to 2008. They broke the data into three-year increments (2000-2002, 2003-2005 and 2006 to 2008) so they could average the incidence of asthma over three years.

National three-year averages rose consistently by 0.5 percent. Overall, the incidence of asthma in adults was 7.85 percent, the study found.

Only one state -- Nevada -- experienced a decline in asthma incidence, but the difference wasn't statistically significant.

The prevalence of asthma varied significantly from state to state, with Louisiana reporting the lowest incidence at 5.04 percent and Rhode Island posting the highest incidence at 10.68 percent.

Nineteen states had larger-than-average increases, and the states with the two highest increases were Oklahoma with a 2.03 percent increase and Alabama with a 1.91 percent increase.

Morrison said there are a lot of theories as to why these geographic differences exist, but her study wasn't designed to tease out the reasons, only to identify the disparity.

"Asthma is very multi-factorial, and these differences can be due to a lot of different things. These findings are a call to engage further studies because these differences may help us understand the causes of asthma, help manage the disease and design state-specific interventions," she explained.

Dr. Jennifer Appleyard, chief of allergy and immunology at St. John Hospital and Medical Center in Detroit, said: "The fact that rates are consistently going up jibes with my clinical impression that prevalence is increasing. But, it's hard to tell what's causing the differences among the states. Because asthma is so complicated, I don't know if it's just one thing. It's probably a whole host of reasons, such as geography and who seeks health care."

If you already have asthma, Morrison said, it's important to make sure you have a "medical provider that understands asthma, [and] works with you to develop an asthma action plan to help you control your asthma exacerbations. You need to be followed up routinely, so make sure you have a good medical home."

More information

The American Academy of Allergy, Asthma & Immunology offers suggestions on potentially preventing asthma and allergies in children  .

SUNDAY, Feb. 28 (HealthDay News) -- A carbohydrate in meat called alpha-gal may be the unrecognized cause of recurring severe allergic reactions in some patients, a new study suggests.

The study included 60 people in Australia and the United States who experienced the recurrent severe allergic reaction known as anaphylaxis with no known cause. Allergy tests revealed that 25 of the 60 patients had positive responses to alpha-gal. A positive response was considered a level of greater than 1.0 international units per milliliter of immunoglobulin E (IgE).

The tests did not identify any other allergens that would explain the cause of anaphylaxis in the 25 patients who were positive for alpha-gal or in the other 35 patients, the study authors noted.

The findings were scheduled to be presented Sunday at the American Academy of Allergy, Asthma & Immunology annual meeting, in New Orleans.

"These studies continue to suggest not only that IgE to a carbohydrate has important clinical implications in food allergy and anaphylaxis, but that the presence of this antibody may well have been under-appreciated in terms of the number of patients affected and the geographical scope," study author Dr. Scott P. Commins, of the University of Virginia, said in an academy news release.

A person who suffers an anaphylactic reaction to something unknown is at increased risk for recurring anaphylaxis if the trigger isn't identified.

More information

The Food Allergy & Anaphylaxis Network has more about anaphylaxis  .

SATURDAY, Feb. 27 (HealthDay News) -- A blood test may help identify children with milk allergy who can tolerate baked-milk products and those who may have a serious allergic reaction to any form of cow's milk, a new study shows.

Previous research found that up to 75 percent of children with milk allergy can tolerate heated milk.

This new study found that immunoglobulin E (IgE) antibodies from children who reacted to both baked milk and unheated milk bound to more epitopes than IgE antibodies from children who had an allergic reaction only to unheated milk. There was a direct link between the severity of the allergic reaction and the number of epitopes recognized by IgE antibodies from a child.

"IgE antibodies can travel to a type of cell that releases chemicals and causes an allergic reaction. Each type of IgE has specific 'radar' for each type of allergen, such as cow's milk. An epitope is a site on a particular molecule, such as a milk protein, that stimulates specific immune responses," according to a news release from the American Academy of Allergy, Asthma & Immunology.

"With this blood test, we hope to be able to tell which cow's milk-allergic children will be able to tolerate milk in baked products without having to resort to oral food challenges. It may also provide some insight into the severity of allergic reaction that a patient might experience," study co-author Dr. Hugh Sampson, a professor of pediatrics, allergy and immunology at Mount Sinai School of Medicine in New York City, said in the news release.

The research was to be presented Saturday at the academy's annual meeting in New Orleans.

More information

The U.S. National Institute of Allergy and Infectious Diseases has more about food allergy.