Constant Ocular Infection with Chlamydia trachomatis Predicts Risk of Scarring in Children in Tanzania
Received 20 June 2008; received in revised form 18 August 2008; accepted 5 September 2008. published online 16 December 2008.
Objective
Clinically, constant severe trachoma predicts an increased risk of scarring in children. There are no data on the risk of scarring associated with constant infection with Chlamydia trachomatis, regardless of clinical manifestation. We propose to determine the 5-year incidence of scarring in children with a history of constant severe trachoma, constant infection, or both compared with children who had a history of neither.
Design
A 5-year, longitudinal observational study.
Participants
Children aged less than 10 years with data on trachoma and infection for 3 of the 5 visits in the first 18 months, and follow-up 5-year data on scarring.
Methods
Data were collected on clinical trachoma, and ocular swabs were taken to determine the presence of C. trachomatis in children in a hyperendemic village in Tanzania. Images were graded for scarring. Data were collected at baseline; 2, 6, 12, and 18 months; and 5 years from baseline. Severe trachoma was defined as the presence of 10 or more follicles, or trachoma intense. A child had constant infection (severe trachoma) if infection (severe trachoma) was present on at least 3 visits before the 5-year survey.
Main Outcome Measures
Five-year risk of scarring.
Results
Of the 189 children, 22 (11.6%) had constant severe trachoma, but not constant infection. Nine children (4.8%) had constant infection but not constant severe trachoma. Both constant severe trachoma and constant infection were present in 16 children (8.5%). The 5-year incidence of scarring was similar in all 3 groups; children with constant severe trachoma only, with constant infection only, and with both were most likely to develop scars (35.0%, 44.4%, 31.2%, respectively) compared with those with sporadic trachoma or infection (15.2%) or neither (6.8%) (P = 0.0002).
Conclusions
Children with constant infection are also likely to have constant severe trachoma, and their 5-year risk of scarring is high compared with children with sporadic severe trachoma or infection. These data further support the presence of a subgroup of children who cannot clear infection with C. trachomatis, who may manifest a severe immunologic response to infection, and who are at increased risk of scarring sequelae.
Financial Disclosure(s)
Proprietary or commercial disclosure may be found after the references.
Available online: December 16, 2008.
1Dana Center for Preventive Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland
Correspondence: Sheila K. West, PhD, Wilmer Eye Institute, Room 129, 600 North Wolfe Street, Baltimore, MD 21287
Manuscript no. 2008-760.
Financial Disclosure(s): The authors have no proprietary or commercial interest in any materials discussed in this article.
Support for the study came from National Eye Institute grant number EY01387. The sponsor or funding organization had no role in the design or conduct of this research.
Pfizer International provided azithromycin for the study, as part of its donation to the Tanzania National Trachoma Control Program. Dr Sheila West has a senior scientific award of unrestricted funds from Research to Prevent Blindness.
ABSTRACT