Mass dose of antibiotic reduced prevalence of trachoma for two years
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《英国医生杂志》
The prevalence and intensity of trachoma infection, a leading cause of blindness in the developing world in the developing world, fell considerably and remained low for two years after mass treatment of a population in Tanzania with a single round of azithromycin, followed by periodic use of tetracycline eye ointment for those with persistent disease.
Trachoma infection is a chronic keratoconjunctivitis caused by the Chlamydia trachomatis. When the active infection resolves, there is often scarring of the conjunctivae. Over many years, contraction of upper-lid scars that result from this scarring causes the eyelashes of some patients to deviate inwards so that they abrade the globe. This complication, termed trichiasis, leads to scarring of the cornea (New England Journal of Medicine 2004;351:1962-71).
Despite longstanding efforts to control the condition, some 84 million people have active trachoma (the infectious stage) in 55 countries in which the disease is endemic, mostly in north Africa and South Asia. About 7.6 million people have trachomatous trichiasis, the blinding stage of this infectious disease.
Researchers collected conjunctival swabs to assess the presence of the infection using polymerase chain reaction to measure viral DNA at intervals of 2, 6, 12, 18, and 24 months after mass treatment with azithromycin of a Tanzanian community in which trachoma was endemic. For ethical reasons, at 6, 12, and 18 months, the researchers gave tetracycline eye ointment to residents who had clinically active trachoma to help quash persistent infection.
At the outset, 956 of 978 residents received either one oral dose of azithromycin (917 participants) or (if azithromycin was contraindicated) a course of tetracycline eye ointment (39).
The prevalence of infection fell from 9.5% before the mass treatment to 2.1% at two months (P<0.001) and 0.1% at 24 months after treatment. The large, progressive decreases in the prevalence of infection that the researchers observed suggest that transmission was effectively halted. There are no known animal or environmental reservoirs of human C. trachomatis strains, so most of the spread is from person to person transmission.
This hypothesis is supported further by analyses of the distribution of infection. At each evaluation after treatment, more than 90% of the ocular chlamydial burden was found among participants who had had a positive result the previous time they were tested, and less than 10% was among either those who had not been tested before or those whose previous test had been negative.
The most likely explanation for the interruption in the transmission of infection, the authors wrote, is the extremely high antibiotic coverage achieved with mass treatment. "If near-complete coverage can be obtained," they wrote, "treatment with azithromycin less frequently than every 12 months may be effective" .(New York Scott Gottlieb)
Trachoma infection is a chronic keratoconjunctivitis caused by the Chlamydia trachomatis. When the active infection resolves, there is often scarring of the conjunctivae. Over many years, contraction of upper-lid scars that result from this scarring causes the eyelashes of some patients to deviate inwards so that they abrade the globe. This complication, termed trichiasis, leads to scarring of the cornea (New England Journal of Medicine 2004;351:1962-71).
Despite longstanding efforts to control the condition, some 84 million people have active trachoma (the infectious stage) in 55 countries in which the disease is endemic, mostly in north Africa and South Asia. About 7.6 million people have trachomatous trichiasis, the blinding stage of this infectious disease.
Researchers collected conjunctival swabs to assess the presence of the infection using polymerase chain reaction to measure viral DNA at intervals of 2, 6, 12, 18, and 24 months after mass treatment with azithromycin of a Tanzanian community in which trachoma was endemic. For ethical reasons, at 6, 12, and 18 months, the researchers gave tetracycline eye ointment to residents who had clinically active trachoma to help quash persistent infection.
At the outset, 956 of 978 residents received either one oral dose of azithromycin (917 participants) or (if azithromycin was contraindicated) a course of tetracycline eye ointment (39).
The prevalence of infection fell from 9.5% before the mass treatment to 2.1% at two months (P<0.001) and 0.1% at 24 months after treatment. The large, progressive decreases in the prevalence of infection that the researchers observed suggest that transmission was effectively halted. There are no known animal or environmental reservoirs of human C. trachomatis strains, so most of the spread is from person to person transmission.
This hypothesis is supported further by analyses of the distribution of infection. At each evaluation after treatment, more than 90% of the ocular chlamydial burden was found among participants who had had a positive result the previous time they were tested, and less than 10% was among either those who had not been tested before or those whose previous test had been negative.
The most likely explanation for the interruption in the transmission of infection, the authors wrote, is the extremely high antibiotic coverage achieved with mass treatment. "If near-complete coverage can be obtained," they wrote, "treatment with azithromycin less frequently than every 12 months may be effective" .(New York Scott Gottlieb)