***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: This study was undertaken to vali date a WHO methodology for the rapid assessment of trachoma . Fourteen villages were chosen by r and om sampling in two counties in Hainan Province , China . For the rapid assessment , trichiasis patients were identified , 50 children ages 1–10 years were examined for active trachoma , and information was collected on community access to services and community risk factors . To vali date the methodology , a prevalence survey was undertaken simultaneously in the same villages . For the prevalence survey , 2428 people from 1606 households in the 14 villages were chosen by r and om sampling . Very little active trachoma was found by either method , although the rates of trichiasis were more substantial . Ranking of the villages by the two methods for trichiasis was highly corre-lated ( Spearman 's correlation coefficient = 0.60 , p = 0.02 ) . For active trachoma , the Spearman 's correlation coefficient for the ranking of villages by the two methods was 0.40 and not significant ( p = 0.14 ) , suggesting that a correlation this close may have been seen by chance alone . The observational data showed all the villages to be at risk of active trachoma ( due to poor environmental hygiene conditions ) , suggesting that this aspect of the WHO methodology overestimates the risk for active trachoma . We conclude that , with the exception of the community assessment of risk , this rapid assessment methodology is a valid tool for the assessment of trichiasis and possibly of active trachoma in rural communities , although the level of active trachoma in this study was too low to effectively vali date that aspect of the methodology In February 1995 , single-dose azithromycin was given to children with trachoma and their household contacts who were children . For children with trachoma , rates of carriage of pneumococci immediately before treatment with azithromycin and 2 - 3 weeks , 2 months , and 6 months after treatment were 68 % ( 54 of 79 ) , 29 % ( 11 of 38 ) , 78 % ( 29 of 37 ) , and 87 % ( 34 of 39 ) , respectively . The proportion of carriage-positive children with  azithromycin-resistant  Streptococcus pneumoniae strains was 1 of 54 ( 1.9 % ) before treatment and then 6 of 11 ( 54.5 % ) , 10 of 29 ( 34.5 % ) , and 2 of 34 ( 5.9 % ) at follow-up visits . The profile of pneumococcal serotypes changed after azithromycin treatment . Azithromycin-resistant  strains ( serotypes 10F , 23A , and 45 ) were isolated from 1 ( 1.3 % ) of 79 pretreatment swab specimens , from 16 ( 21.3 % ) of 75 swab specimens collected up to 2 months after treatment , and from 2 ( 6 % ) of 32 obtained 6 months after treatment . Mathematical modeling showed a more rapid appearance of azithromycin-resistant pneumococcal strains in previously colonized children than in previously noncolonized children . Thus , it appears that the selective effect of azithromycin allowed the growth and transmission of preexisting azithromycin-resistant strains . More research is needed to clarify the clinical relevance and implication s of azithromycin use Background Antibiotics are a major tool in the WHO 's trachoma control program . Even a single mass distribution reduces the prevalence of the ocular chlamydia that causes trachoma . Unfortunately , infection returns after a single treatment , at least in severely affected areas . Here , we test whether additional scheduled treatments further reduce infection , and whether infection returns after distributions are discontinued . Methods Sixteen communities in Ethiopia were r and omly selected . Ocular chlamydial infection in 1- to 5-year-old children was monitored over four biannual azithromycin distributions and for 24 months after the last treatment . Findings The average prevalence of infection in 1- to 5-year-old children was reduced from 63.5 % pre-treatment to 11.5 % six months after the first distribution ( P<0.0001 ) . It further decreased to 2.6 % six months after the fourth and final treatment ( P = 0.0004 ) . In the next 18 months , infection returned to 25.2 % , a significant increase from six months after the last treatment ( P = 0.008 ) , but still far lower than baseline ( P<0.0001 ) . Although the prevalence of infection in any particular village fluctuated , the mean prevalence of the 16 villages steadily decreased with each treatment and steadily returned after treatments were discontinued . Conclusion In some of the most severely affected communities ever studied , we demonstrate that repeated mass oral azithromycin distributions progressively reduce ocular chlamydial infection in a community , as long as these distributions are given frequently enough and at a high enough coverage . However , infection returns into the communities after the last treatment . Sustainable changes or complete local elimination of infection will be necessary . Trial Registration Clinical Trials.gov Background Blindness due to trachoma is avoidable through Surgery , Antibiotics , Facial hygiene and Environmental improvements ( SAFE ) . Recent surveys have shown trachoma to be a serious cause of blindness in Southern Sudan . We conducted this survey in Ayod County of Jonglei State to estimate the need for intervention activities to eliminate blinding trachoma . Methodology and Findings A cross-sectional two-stage cluster r and om survey was conducted in November 2006 . All residents of selected households were clinical ly assessed for trachoma using the World Health Organization ( WHO ) simplified grading scheme . A total of 2,335 people from 392 households were examined , of whom 1,107 were over 14 years of age . Prevalence of signs of active trachoma in children 1–9 years of age was : trachomatous inflammation follicular ( TF ) = 80.1 % ( 95 % confidence interval [ CI ] , 73.9–86.3 ) ; trachomatous inflammation intense ( TI ) = 60.7 % ( 95 % CI , 54.6–66.8 ) ; and TF and /or TI ( active trachoma ) = 88.3 % ( 95 % CI , 83.7–92.9 ) . Prevalence of trachomatous trichiasis ( TT ) was 14.6 % ( 95 % CI , 10.9–18.3 ) in adults over 14 years of age ; 2.9 % ( 95 % CI , 0.4–5.3 ) in children 1–14 years of age ; and 8.4 % ( 95 % CI , 5.5–11.3 ) overall . The prevalence of corneal opacity in persons over 14 years of age with TT was 6.4 % ( 95 % CI , 4.5–8.3 ) . No statistically significant difference was observed in the prevalence of trachoma signs between genders . Trachoma affected almost all households surveyed : 384/392 ( 98.0 % ) had at least one person with active trachoma and 130 ( 33.2 % ) had at least one person with trichiasis . Conclusions Trachoma is an unnecessary public health problem in Ayod . The high prevalence of active trachoma and trichiasis confirms the severe burden of blinding trachoma found in other post-conflict areas of Southern Sudan . Based on WHO recommended thresholds , all aspects of the SAFE strategy are indicated to eliminate blinding trachoma in Ayod Mass administration of azithromycin to eliminate blindness due to trachoma has raised concerns regarding the emergence of antimicrobial resistance . During 2000 , we compared the antimicrobial resistance of nasopharyngeal pneumococcal isolates recovered from and the prevalence of impetigo , respiratory symptoms , and diarrhea among 458 children in Nepal before and after mass administration of azithromycin .  No azithromycin-resistant  pneumococci were isolated except from 4.3 % of children who had received azithromycin during 2 previous mass treatments ( P<.001 ) . There were decreases in the prevalence of impetigo ( from 14 % to 6 % of subjects ; adjusted odds ratio [ OR ] , 0.41 ; 95 % confidence interval [ CI ] , 0.21 - 0.80 ) and diarrhea ( from 32 % to 11 % ; adjusted OR , 0.26 ; 95 % CI , 0.14 - 0.43 ) 10 days after azithromycin treatment . The absence of macrolide-resistant isolates after 1 mass treatment with azithromycin is encouraging , although the recovery of azithromycin-resistant isolates after 2 mass treatments suggests the need for resistance monitoring when multiple rounds of antimicrobial treatment are given CONTEXT Treatment recommendations assume that repeated mass antibiotic distributions can control , but not eradicate or even locally eliminate , the ocular strains of chlamydia that cause trachoma . Elimination may be an important end point because of concern that infection will return to communities that have lost immunity to chlamydia after antibiotics are discontinued . OBJECTIVE To determine whether biannual treatment can eliminate ocular chlamydial infection from preschool children and to compare results with the World Health Organization-recommended annual treatment . DESIGN , SETTING , AND PARTICIPANTS A cluster-r and omized clinical trial of biannual vs annual mass azithromycin administrations to all residents of 16 rural villages in the Gurage Zone , Ethiopia , from March 2003 to April 2005 . INTERVENTIONS At scheduled treatments , all individuals aged 1 year or older were offered a single dose of oral azithromycin either annually or biannually . MAIN OUTCOME MEASURE Village prevalence of ocular chlamydial infection and presence of elimination at 24 months in preschool children determined by polymerase chain reaction , correcting for baseline prevalence . Antibiotic treatments were performed after sample collection s. RESULTS Overall , 14,897 of 16,403 eligible individuals ( 90.8 % ) received their scheduled treatment . In the villages in which residents were treated annually , the prevalence of infection in preschool children  was reduced from a mean of 42.6 % ( range , 14.7%-56.4 % ) to 6.8 % ( range , 0.0%-22.0 % ) at 24 months . In the villages in which residents were treated biannually , infection was reduced from 31.6 % pretreatment ( range , 6.1%-48.6 % ) to 0.9 % ( range , 0.0%-4.8 % ) at 24 months . Biannual treatment was associated with a lower prevalence at 24 months ( P = .03 , adjusting for baseline prevalence ) . At 24 months , no infection could be identified in 6 of 8 of those treated biannually and in 1 of 8 of those treated annually ( P = .049 , adjusting for baseline prevalence ) . CONCLUSION Local elimination of ocular chlamydial infection appears feasible even in the most severely affected areas , although it may require biannual mass antibiotic distributions at a high coverage level . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00221364 The objective of this study was to confirm whether the combination of a health education programme with a mass treatment campaign was able to improve the effectiveness of trachoma control . An open controlled clinical trial with a 2 x 2 factorial design was carried out . Four villages , matched for size and epidemiological , economic and social conditions , were included in the study . The first village received mass treatment with 1 % oxytetracycline eye drops combined with a specific health education programme . The second village received only a health education programme . The third village received only mass treatment and the fourth village did not receive any intervention during the study ( control village ) . 1810 subjects were enrolled of whom 76 % were successfully followed for 6 months . The incidence of new cases ranged between 1.6 % and 14.2 % . In this study the combination of a health education programme with mass treatment failed to increase the cure rate . There was even a negative interaction ( P = 0.03 ) . The best results were obtained in the village where antibiotic treatment was used alone , both in terms of cure rate ( 82 % ) and reduction of C trachomatis transmission . These results suggest that the addition of a health education programme does not systematic ally improve the performances of a mass treatment campaign . The efficacy of this combination depends essentially on the capacity of the community to modify its hygiene behaviour Background Trachoma is a leading cause of preventable blindness . Reports from eye surgery camps and anecdotal data indicated that blinding trachoma is a serious cause of visual impairment in Mankien payam ( district ) of southern Sudan . We conducted this study to estimate the prevalence of trachoma , estimate targets for interventions , and establish a baseline for monitoring and evaluation . Methods and Findings A population -based cross-sectional survey was conducted in May 2005 . A two-stage cluster r and om sampling with probability proportional to size was used to select the sample population . Participants were examined for trachoma  by experienced grade rs using the World Health Organization simplified grading scheme . A total of 3,567 persons were examined ( 89.7 % of those enumerated ) of whom 2,017 were children aged less than 15 y and 1,550 were aged 15 y and above . Prevalence of signs of active trachoma in children aged 1–9 y was : tra 
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This has been associated with significant reductions in the prevalence of active disease over the past 20 years , but there remain a large number of people with trichiasis who are at risk of blindness