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T Lietman

Publications and source records attributed to T Lietman.

At least 19 recordsLinked to original sources
PubMed2003

The SAFE strategy for the elimination of trachoma by 2020: will it work?

WHO has recently launched a programme (GET 2020) for the elimination of trachoma, the leading cause of preventable blindness. GET 2020 has adopted the SAFE strategy, a comprehensive set of control measures (Surgery for entropion/trichiasis; Antibiotics for infectious trachoma; Facial cleanliness to reduce transmission; Environmental improvements such as control of disease-spreading flies and access to clean water). The present article reviews the strengths and weaknesses of each component of the strategy. Although significant hurdles remain to be overcome there is every reason to hope that GET 2020 will be successful.

Anti-Bacterial Agents↗
PubMed2003

Community treatment with azithromycin for trachoma is not associated with antibiotic resistance in Streptococcus pneumoniae at 1 year.

AIMS: To determine if macrolide resistant Streptococcus pneumoniae will be a major concern in areas that receive annual mass azithromycin distributions for trachoma. METHODS: A cross sectional survey was conducted of nasopharyngeal S pneumoniae isolates for susceptibility to azithromycin 1 year after administering a single dose of azithromycin to treat trachoma in a village in Nepal. RESULTS: S pneumoniae was isolated from 50 (86%) of 57 nasopharyngeal cultures and no resistance to azithromycin was detected. CONCLUSION: The authors were unable to demonstrate that mass azithromycin therapy for trachoma produced macrolide resistant S pneumoniae that persists until the next scheduled annual treatment.

Anti-Bacterial Agents↗
PubMed2002

Biotypes and serotypes of Haemophilus influenzae ocular isolates.

AIM: To determine which subtypes of Haemophilus influenzae are most commonly associated with ocular disease, and whether the site of ocular H influenzae infection is correlated with specific subtypes of the organism. METHODS: The biotypes and serotypes of ocular H influenzae isolates collected at the Francis I Proctor Foundation between March 1989 and January 2000 were examined. A total of 62 ocular isolates were retrieved from frozen storage and plated on chocolate agar. Biotypes were assigned based upon the ability of the isolates to produce indole, urease, and ornithine decarboxylase. Capsular subtypes a-f were determined by slide agglutination using commercially available subtype specific antisera. Identified biotypes and serotypes were then analysed with regard to site of infection. RESULTS: Patient age ranged from 1 to 92 years with a median age of 45 years. 38 (61%) of the isolates were biotype II, 23 (37%) were biotype III, and one (2%) was biotype VII. All of the isolates were non-encapsulated and thus serologically non-typable. H influenzae biotype II was found in 28 of 48 (58%) conjunctivitis cases, five of eight (63%) keratitis cases, and two of two (100%) endophthalmitis cases. Biotype III was found in 20 of 48 (42%) conjunctivitis cases, two of eight (25%) keratitis cases, and a single case of dacryocystitis. Biotype VII was associated with one of eight (13%) keratitis cases. CONCLUSION: Most ocular H influenzae isolates appear to be serologically non-typable strains from biotypes II and III, less virulent subtypes that frequently colonise the nasopharynx. In addition, the site of ocular H influenzae infections appears to be largely independent of species subtype.

Adolescent↗
PubMed2001

Chlamydial genovar distribution after community wide antibiotic treatment.

Major outer membrane protein sequences, determined from Chlamydia-positive eye swab samples collected in 2 Egyptian villages, were used to analyze the epidemiology of trachoma in an endemic setting. Samples were collected during the 1999 Azithromycin in Control of Trachoma trial, in which residents of villages were mass treated with either oral azithromycin or topical tetracycline and were followed up for nearly 2 years. Three genovar families (A, Ba, and C) and 12 genovars were detected, with 2 genovars (A1 and Ba1) comprising almost 75% of the samples. The presence of >1 genovar within households was common, with > or =24% of households having >1 genovar. Evidence consistent with reinfection and persistence as mechanisms of communitywide continued presence of trachoma was provided by data for individuals infected with rare genovars.

Anti-Bacterial Agents↗
PubMed2001

Pooling of Chlamydia laboratory tests to determine the prevalence of ocular Chlamydia trachomatis infection.

With the Global Elimination of Trachoma by 2020 program underway, it has become increasingly important to identify the prevalence of ocular chlamydia infection in communities. DNA amplification tests are the gold standard, but are prohibitively expensive. In the present paper, we investigate whether pooling multiple specimens into a single test is feasible. The conjunctivae of 170 children in western Nepal were examined and swabbed. The prevalence of chlamydial infection was estimated in two ways using the ligase chain reaction: by testing all 170 specimens individually, and by testing 34 pools of 5 specimens each. We show that the confidence interval for 34 pooled specimens approaches that of doing all 170 specimens as the prevalence decreases. We also determine the optimal number of specimens to pool into a single test to minimize the confidence interval of the estimate. If the population prevalence is expected to be around 10%, then 14 specimens should be pooled per test. Even at 50% prevalence, costs can be reduced by pooling two samples per test.

Child↗
PubMed2001

Evaluating the human optical system: corneal topography and wavefront analysis.

In this article we review three different systems for evaluating the human optical system: placido-disc based corneal topography, scanning slit topography, and wavefront sensors. We briefly describe the principles of each system, and discuss the strengths and weakness. We suspect all three will be used by ophthalmologists in the coming decade.

Cornea↗
PubMed2000

Potential impact of tuberculosis vaccines as epidemic control agents.

We use 2 simple mathematical models (one a preexposure vaccine model and the other a postexposure vaccine model) to provide general insight into the effects of vaccination on tuberculosis epidemics. We discuss how these models can be used as health policy tools: to identify which vaccines are "equivalent," to design control strategies, and to predict the epidemiological impact of different vaccination strategies. Our results show that even moderately effective vaccines could have a significant effect on reducing tuberculosis epidemics if they can be coupled with moderate to high treatment rates. We suggest that both preexposure and postexposure tuberculosis vaccines can be used to help eliminate tuberculosis in developing countries. In developed countries, only a preexposure vaccine (used in combination with a high level of treatment) would be necessary to eliminate tuberculosis.

BCG Vaccine↗
PubMed1999

Mooren ulcer in South India: serology and clinical risk factors.

PURPOSE: To investigate the rate of undiagnosed rheumatologic diseases and hepatitis C infection among patients with the clinical diagnosis of Mooren ulcer seen at Aravind Eye Hospital, Madurai, South India. METHODS: Twenty-one patients with the clinical diagnosis of Mooren ulcer and 44 control patients underwent a complete ophthalmic history and examination, as well as serologic testing for antinuclear antibodies, rheumatoid factor, antineutrophil cytoplasmic antibodies, herpes simplex virus 1 antibodies, and hepatitis C virus antibodies. RESULTS: There were no statistically significant differences in the rates of seropositivity for antinuclear antibodies, rheumatoid factor, antineutrophil cytoplasmic antibodies, herpes simplex virus 1 antibodies, and hepatitis C virus antibodies between patients with Mooren ulcer and control patients. Two patients with Mooren ulcer and four control patients were found to have a rheumatoid factor titer of greater than 1:20. One of the control patients, but none of the patients with Mooren ulcer, was found to have serologic evidence of hepatitis C infection. A history of corneal trauma, surgery, or infection was reported by 68% of patients with Mooren ulcer, compared with 20% of control patients (P < .001). Among patients with Mooren ulcer, bilateral disease occurred in 37% of patients, visual acuity was reduced to light perception in 15% of eyes, and perforation occurred in 19% of eyes. CONCLUSIONS: Nineteen (90%) of 21 patients with the clinical diagnosis of Mooren ulcer were found to have no evidence of an underlying rheumatologic disease by history, examination, or serologic testing, and none was seropositive for hepatitis C. However, patients with Mooren ulcer were more likely than control patients to report a history of corneal trauma, surgery, or infection.

Adolescent↗
PubMed1999

Global elimination of trachoma: how frequently should we administer mass chemotherapy?

The World Health Organization has recommended repeat mass drug administration as part of their global initiative to eliminate blinding trachoma by the year 2020. The efficacy of repeat treatment will be tested empirically, but the results will not be available for many years, and recommendations for the necessary frequency of treatment are needed immediately. We have developed a mathematical model that uses available epidemiological data from a variety of countries. We recommend, based on our analysis, that in areas where trachoma is moderately prevalent (<35% in children), it should be treated annually, but hyperendemic areas (>50% in children), it should be treated biannually.

Anti-Bacterial Agents↗
PubMed1999

Neural networks for visual field analysis: how do they compare with other algorithms?

PURPOSE: To compare the performance of a neural network in identifying visual field defects with the performance of other available algorithms. METHODS: A feed-forward neural network with a single hidden layer was trained to recognize visual field defects previously collected in a longitudinal follow-up glaucoma study, and then tested on fields taken from the same study but not used in the training. The receiver operating characteristics of the network then were compared with the previously determined performance of other algorithms on the same data set. RESULTS: At a specificity greater than 90%, the neural network was more sensitive than any of the available algorithms (although only the global indices were available for comparison, as the cluster and cross-meridional algorithms did not achieve such high specificity at their current settings). At a lower specificity (80-85%), the neural network was unable to attain the high sensitivity of the cluster or cross-meridional algorithms; in fact, the cluster algorithm from the Low-Tension Glaucoma study was significantly more sensitive. CONCLUSION: The receiver operating characteristics of a feed-forward neural network designed to detect visual field defects were explored. At a very high specificity (90-95%) a neural network performed better than the global indices. However, at a lower specificity (78%-88%), the neural network performed worse than cluster and cross-meridional algorithms.

Algorithms↗
PubMed1999

Reliability of clinical diagnosis in identifying infectious trachoma in a low-prevalence area of Nepal.

The WHO Alliance for Global Elimination of Trachoma by 2020 has increased the need to identify ocular chlamydial infections by clinical examination in areas of both high and low prevalence. The relationship between clinically active trachoma (as defined by clinical examination) and chlamydial infection is known for areas with hyperendemic trachoma, but not for areas with a low prevalence of the clinical disease. In the present study, we examined, photographed, and DNA tested the conjunctivae of children in the Surkhet district of mid-western Nepal, an area known to have a low prevalence of clinically active trachoma. Although 6% of the children aged 10 years and under were found to have clinically active trachoma, none were found to have chlamydia infection by the most sensitive DNA amplification tests available. A very low prevalence of clinically active trachoma is not necessarily evidence of the presence of chlamydial infection. Therefore, the WHO policy of not recommending an intensive trachoma control effort when the prevalence of clinically active trachoma is less than 10% in children is appropriate for this area of Nepal.

Child↗
PubMed1998

Chronic follicular conjunctivitis associated with Chlamydia psittaci or Chlamydia pneumoniae.

We determined whether patients with chronic conjunctivitis in whom direct fluorescent antibody (DFA) tests revealed genus-specific chlamydial antigens (but not species-specific Chlamydia trachomatis antigens) were infected with Chlamydia psittaci or Chlamydia pneumoniae. Patients were divided into a case group of possible non-trachomatis chlamydial conjunctivitis and a control group of nonchlamydial conjunctivitis on the basis of examination and DFA testing. Species-specific primers were used to amplify C. trachomatis, C. psittaci, and C. pneumoniae DNA with polymerase chain reaction (PCR). Four (27%) of 15 samples from the case group were positive for C. psittaci or C. pneumoniae DNA, whereas none of 24 control samples were positive. Sequencing revealed a C. pneumoniae, an avian C. psittaci, and two mammalian C. psittaci strains. A short course of oral antibiotic treatment appears to be inadequate for patients with non-trachomatis chlamydial conjunctivitis. Ocular infections due to C. pneumoniae and C. psittaci may be more common than previously recognized and can be identified by DFA and PCR.

Adult↗