Bad Bug, Good Bug - Common Germ Causes Ulcers, Cancer But May Protect Children From Asthma

Main Category: Infectious Diseases / Bacteria / Viruses
Also Included In: Respiratory / Asthma;  Pediatrics / Children's Health
Article Date: 08 Oct 2007 - 4:00 PST

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The bacteria that cause ulcers and stomach cancer also appear to protect children from asthma, suggests research being presented at the 45th Annual Meeting of the Infectious Diseases Society of America (IDSA).

Helicobacter pylori (H. pylori) bacteria occur naturally and have been the dominant organism in human stomachs for thousands of years, but have nearly disappeared from our systems, most likely due to our modern lifestyle and the high use of antibiotics, according to the researchers. Fifty years ago, more than half of American children had H. pylori in their stomachs, but today, fewer than one in 10 children ages 13 and younger have the organism.

"It's clear that there is a biological cost to having H. pylori in an increased risk for getting ulcers and stomach cancer, but these typically occur relatively late in life," said Martin J. Blaser, MD, chairman of the department of medicine and professor of medicine and microbiology at the New York University School of Medicine, New York City. "Meanwhile, asthma is a serious diagnosis especially in young children, and can be deadly."

Children ages 3 to 13 who had H. pylori in their stomachs were 53 percent less likely to ever have had asthma than those who did not have the bug, according to the study, which involved an analysis of 3,327 children and teens who had participated in the National Health and Nutrition Examination Survey (NHANES).

While H. pylori have been on the decline, asthma has increased and has become a major health problem. More than 9 million children younger than 18 (13 percent of all children) have ever been diagnosed with the chronic disease, according to the Centers for Disease Control and Prevention (CDC), Atlanta. Asthma is a chronic inflammation of the lung airways that causes coughing, chest tightness, wheezing, or shortness of breath. Asthma is the third leading cause of hospitalization among children younger than 15 and occasionally is fatal - 154 children under 15 died from asthma in 2003.

The study was based on the results of NHANES 1999-2000, which was the most recent version of the survey to test for H. pylori. Researchers compared study participants ages 3 to 19 who were tested for H. pylori with those who had ever been diagnosed with asthma. The study found that overall, those with H. pylori in their stomachs were 35 percent less likely to have ever had asthma and 44 percent less likely to have early-onset asthma, before age 5.

H. pylori could protect against asthma by priming the immune system, said Dr. Blaser. "H. pylori could be beneficial in other ways. For instance, we found that people with the bacteria were less likely to have had recent bouts of wheezing, allergic rhinitis, dermatitis, eczema, or rash," said Yu Chen, PhD, MPH, co-author of the study and assistant professor for the department of environmental medicine and department of medicine at New York University School of Medicine. "And other studies have shown that it may protect against gastroesophageal reflux disease (GERD) and esophageal cancer."

More research must be done, but there may be treatment implications, Dr. Blaser noted. The next step would be to determine the actual mechanisms that could lead to H. pylori being protective against asthma.

"If future studies confirm and extend our findings, one concept to consider is introducing H. pylori or something similar into the system to provide a protective effect," Dr. Blaser said.

H. pylori bacteria are transmitted from person to person, so once it has become diminished in the population, it is also less likely to be passed on.

Although it's not proven, the relatively quick disappearance of H. pylori from our systems is consistent with the idea that widespread antibiotic use is changing human microbiology, which has a consequence, said Dr. Blaser. Other factors in the decline of H. pylori include improvements in childhood living conditions and smaller family size.

"Many studies show that early childhood use of antibiotics is associated with an increased risk of asthma," said Dr. Chen.

In this study, more than one in 10 children under the age of 10 (11 percent) had taken antibiotics in the prior month. Prior studies have shown that by 15, the average child has received three or four courses of antibiotics just for ear infections.

"That translates on an annual basis to an extremely high rate of antibiotic use in childhood," she said.

"Sure, your child's ears may seem a little better after antibiotic treatment for an ear infection, but an increased risk for asthma may be one of the costs," said Dr. Blaser, who is the immediate past president of the IDSA.

A prior report published by Drs. Chen and Blaser based on the adults who participated in an earlier NHANES study suggested a childhood link between lack of asthma and H. pylori in the stomach, and this study confirms and extends it by analyzing the data in children, Dr. Chen said.

IDSA is an organization of physicians, scientists, and other health care professionals dedicated to promoting human health through excellence in infectious diseases research, education, prevention, and patient care. Major programs of IDSA include publication of two journals, The Journal of Infectious Diseases and Clinical Infectious Diseases, an Annual Meeting, awards and fellowships, public policy and advocacy, practice guidelines, and other membership services. The Society, which has about 8,000 members, was founded in 1963 and is headquartered in Arlington, Va.

http://www.idsociety.org