Fly control may not be needed for trachoma control

NEW ORLEANS — Treating children at risk of trachoma with antibiotics may be a more effective approach to control the disease than “swatting flies,” according to a speaker here.

Trachoma is the world’s leading cause of infectious blindness, said Scott Lee, MD, at the Ocular Microbiology and Immunology Group meeting. He noted that the World Health Organization is currently expending “tremendous efforts” in endemic areas to control the flies that spread the chlamydial infection that causes trachoma. But he said a study he and colleagues conducted suggests this may not be the best strategy for disease control.

Dr. Lee and others at the University of California, San Francisco, performed the study with colleagues from Orbis International, Ethiopia.

The study was done in the Gurage region of Ethiopia, a remote area in the horn of Africa. The researchers collected 120 flies from the faces of children in three villages where mass distribution of oral azithromycin had been administered 6 months previously. They gathered the same number of flies from three other villages in the same region that had not had azithromycin treatment. The flies were tested in a masked fashion for the presence of chlamydial DNA. Conjunctival swabs taken from the children in the villages were also tested for the presence of Chlamydia.

The researchers found Chlamydia trachomatis on 23% of the flies in the untreated villages and only 0.3% of the flies in the treated villages. This correlated highly with the prevalence of trachoma in the children in the treated and untreated villages, Dr. Lee said.

He said that, while it is true that the flies carry the trachoma infection, treatment of children with azithromycin greatly reduces the role of the flies as a vector for spread of the disease. He suggested that it may be more cost effective to treat children “with a simple pill” than to undertake massive public projects to control the flies that spread trachoma.

At the end of the meeting, the Leiter Award was given to Kevin Miller, MD, also of the University of California, San Francisco, for a paper on a related subject delivered at last year’s OMIG meeting. In that paper, the UCSF/Proctor researchers showed that flies do indeed carry the Chlamydia organisms. The Leiter Award for the best paper is sponsored by Leiter’s Pharmacy. John P. Whitcher, PhD, head of the Proctor Foundation, accepted the award for Dr. Miller.