Moving Science Forward
New JAMA Study by CHORI Scientist Suggests Antibiotics Can Interfere with Protective Immunity
For the last 10 years, the World Health Organization (WHO) has been heading an ambitious project to eliminate blinding trachoma by the year 2020. No simple task, as trachoma is the second leading cause of preventable blindness in the world and already infects over 600 million people across the globe, with nearly 146 million people at risk for blindness. However, a new study just published in the Journal of the American Medical Association (JAMA) by CHORI scientist Deborah Dean, MD, MPH, has unearthed some stunning results about the WHO strategy.
“WHO’s strategy has four components called SAFE,” explains Dr. Dean. “S for surgery, A for antibiotics, F for facial cleanliness, and E for environmental improvement.”Surgery is used to treat the in-turned eyelashes, called trichiasis, that can result from scarring due to Chlamydia trachomatis infection. The eyelashes scrape the eyeball, causing scarring over the cornea and blindness, while antibiotics are used to treat the infection itself. The other elements are geared toward decreasing the transmission of the infection.
There have been no studies, however, that assessed the efficacy of antibiotic treatment beyond 1 year in populations receiving various components of the SAFE strategy - until now.
“We were very interested in determining both the risk factors for, and the rates of occurrence of, active trachoma and chlamydial infections 3 years after the first treatment,” Dr. Dean says.
The results were not what Dr. Dean expected: the unintended consequences of the SAFE strategy, at least in its current implementation, are that those treated with antibiotics are at a far greater risk for re-infection than those who have not been treated at all.
“There was a significant increase in the rates of re-infection with chlamydiae in those populations that received targeted azithromycin compared with those that did not,” Dr. Dean says of the results, which are similar to those in a study conducted in Vancouver, British Columbia, in which the risk of re-infection increased yearly (after an initial decrease) following the introduction of a control program aimed at treating chlamydial sexually active diseases with azithromycin.
“It’s unlikely that the F and E components will make it to every corner of the globe where trachoma is endemic or that the socioeconomic status will change in these developing countries,” points out Dr. Dean.
As a result, Dr. Dean’s study also emphasizes the potential need for an element of prevention not currently available to the SAFE strategists - a vaccine.
As Dr. Dean is quick to note, however, that is the very point of research. “That’s why you conduct research – to discover important findings that then lead to more questions, and more research. That’s what’s exciting about making discoveries that can move science forward - and improve people's lives.”
Monday, May 16, 2011 11:33 PM