News in brief - March 28, 2005

Stroke warnings mean treatment needed - Childhood asthma and cockroaches - Norovirus causes most traveler's diarrhea - Experts work to better define anaphylaxis - MS drug withdrawn - Celiac screening and osteoporosis

Stroke warnings mean treatment needed

Warning signs of an ischemic stroke could be evident as early as seven days before an attack and require urgent treatment to prevent serious brain damage, according to a study of stroke patients published in the March 8 Neurology.

Eighty percent of strokes are ischemic and often are preceded by a transient ischemic attack that typically lasts less than five minutes and doesn't cause injury.

The Neurology study examined 2,416 people who had experienced an ischemic stroke.

In 549 patients, TIAs were experienced before the ischemic stroke and, in most cases, occurred within the preceding seven days: 17% occurring on the day of the stroke, 9% on the previous day and 43% at some point in the previous seven days.

"We have known for some time that TIAs are often a precursor to a major stroke," said study author Peter M. Rothwell, MD, PhD, of Radcliffe Infirmary in Oxford, England. "What we haven't been able to determine is how urgently patients must be assessed following a TIA in order to receive the most effective preventive treatment."

The study indicates that treatments should be initiated within hours of a TIA to prevent a major attack and that clinical guidelines should be amended accordingly.

Childhood asthma and cockroaches

Cockroach allergen was found to worsen asthma symptoms among inner-city children more than either dust mite or pet allergens, according to findings from a nationwide study published in the March Journal of Allergy and Clinical Immunology.

Cockroach allergens come from saliva, fecal material, secretions and cast-off exoskeletons as well as from dead roaches.

The study also showed marked geographic differences in allergen exposure. Researchers found that a majority of homes in Chicago and New York City had cockroach allergen levels high enough to trigger asthma symptoms, while a majority of homes in Dallas and Seattle had dust mite allergen levels above the asthma symptom threshold.

Norovirus causes most traveler's diarrhea

The majority of diarrhea in travelers to Mexico and Guatemala is caused by the Norovirus, states a study published in the March Journal of Clinical Microbiology.

Researchers at Johns Hopkins University Bloomberg School of Public Health in Baltimore recruited nearly 1,500 students traveling to these countries to submit stool samples if they developed problems. Scientists used molecular detection methods to determine that about 65% tested positive for the bug. The longer the traveler stayed abroad, the more likely they were to contract it. Also, 32% were co-infected with Escherichia coli.

Norovirus long has been implicated in the stomach troubles that so many international travelers develop, but only recently has the technology to determine the true prevalence been available. Authors wrote that the high prevalence found in this study suggest the need for further research into the possible mechanisms of action and treatments.

Experts work to better define anaphylaxis

Epinephrine is the universally accepted treatment for anaphylaxis, but the lack of a clearly defined set of symptoms that would help physicians arrive at the diagnosis is jeopardizing patients, according to a report published in this month's Journal of Allergy and Clinical Immunology.

The paper, written by an expert panel convened by the National Institute of Allergy and Infectious Disease and the Food Allergy and Anaphylaxis Network, advocated that physicians improve their understanding of the condition and that medical facilities have an established anaphylaxis protocol. Patients with a history of anaphylaxis also should be educated on self-treatment.

MS drug withdrawn

Tysabri, or natalizumab, approved last fall to treat multiple sclerosis, was taken off the market on Feb. 28 after one patient died and another possibly developed progressive multifocal leukoencephalopathy.

Tysabri had been granted accelerated approval by the Food and Drug Administration based on promising first-year results from a two-year trial. The drug had shown signs of being effective in treating relapsing MS, the most common form. About 400,000 people have been diagnosed with MS.

The patient death and possible illness occurred during a clinical trial using Tysabri in combination with Avonex, or interferon beta-1a. Both patients had received more than two years of treatment with Tysabri and Avonex. A total of 3,000 patients have been treated with Tysabri in clinical trials of MS, Crohn's disease and rheumatoid arthritis.

Manufacturer Biogen Idec sent out Dear Doctor letters recommending that patients be evaluated for signs and symptoms of PML and that any potential cases be reported.

Celiac screening and osteoporosis

The higher prevalence of celiac disease in people with osteoporosis could justify screening patients with osteoporosis for celiac, according to an article in the Feb. 28 Archives of Internal Medicine.

Although adults diagnosed with celiac disease commonly have a low bone mineral density that improves with a gluten-free diet, there had not been clear evidence of the benefit of screening everyone with osteoporosis for celiac disease.

But the researchers found that the prevalence of celiac among osteoporotic patients was high enough to justify a recommendation that all individuals with osteoporosis undergo serologic screening for celiac disease.

In an editorial accompanying the study, Alan L. Buchman, MD, MPH, of the Feinberg School of Medicine at Northwestern University in Chicago, wrote that the cost to prevent a single fracture in a patient with celiac disease and osteoporosis would be $43,000, similar to the cost of screening mammography.

Because not all studies have found an increased prevalence of celiac disease in individuals with osteoporosis or an increased fracture risk in patients with celiac disease, Dr. Buchman advises holding off on a screening recommendation until additional studies are conducted.