title: Can corneal pannus with trachomatous inflammation--follicular be used in combination as an improved specific clinical sign for current ocular Chlamydia trachomatis infection?
abstract: BACKGROUND
  Trachoma is a blinding disease caused by conjunctival infection with Chlamydia trachomatis (Ct). Mass drug administration (MDA) for trachoma control is administered based on the population prevalence of the clinical sign of trachomatis inflammation - follicular (TF). However, the prevalence of TF is often much higher than the prevalence of Ct infection. The addition of a clinical sign specific for current ocular Ct infection to TF could save resources by preventing unnecessary additional rounds of MDA.
  
  
  METHODS
  Study participants were aged between 1-9 years and resided on 7 islands of the Bijagos Archipelago, Guinea Bissau. Clinical grades for trachoma and corneal pannus and ocular swab samples were taken from 80 children with TF and from 81 matched controls without clinical evidence of trachoma. Ct infection testing was performed using droplet digital PCR.
  
  
  RESULTS
  New pannus was significantly associated with Ct infection after adjustment for TF (P = 0.009, OR = 3.65 (1.4-9.8)). Amongst individuals with TF, individuals with new pannus had significantly more Ct infection than individuals with none or old pannus (75.0% vs 45.5%, Chi(2) P = 0.01). TF and new pannus together provide a highly specific (91.7%), but a poorly sensitive (51.9%) clinical diagnostic test for Ct infection.
  
  
  CONCLUSIONS
  As we move towards trachoma elimination it may be desirable to use a combined clinical sign (new pannus in addition to TF) that is highly specific for current ocular Ct infection. This would allow national health systems to obtain a more accurate estimate of Ct population prevalence to inform further need for MDA without the expense of Ct molecular diagnostics, which are currently unaffordable in programmatic contexts.
authors.affiliation: Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. tamsyn.derrick@lshtm.ac.uk.
authors.forename: Tamsyn
authors.initials: T
authors.lastname: Derrick
authors.affiliation: Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. martin.holland@lshtm.ac.uk.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Holland
authors.affiliation: Programa Nacional de Saude de Visao, Ministerio de Saude Publica, Bissau, Guinea Bissau. eunitxsil@gmail.com.
authors.forename: Eunice
authors.initials: E
authors.lastname: Cassama
authors.affiliation: Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. rodmd@hotmail.co.uk.
authors.forename: Rod
authors.initials: R
authors.lastname: Markham-David
authors.affiliation: Programa Nacional de Saude de Visao, Ministerio de Saude Publica, Bissau, Guinea Bissau. pnlcegueira@yahoo.com.br.
authors.forename: Meno
authors.initials: M
authors.lastname: Nabicassa
authors.affiliation: Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. Michael.Marks@lshtm.ac.uk.
authors.forename: Michael
authors.initials: M
authors.lastname: Marks
authors.affiliation: Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. Robin.Bailey@lshtm.ac.uk.
authors.forename: Robin L
authors.initials: RL
authors.lastname: Bailey
authors.affiliation: Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. Anna.Last@lshtm.ac.uk.
authors.forename: Anna R
authors.initials: AR
authors.lastname: Last
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D019072:Antibiotic Prophylaxis; D002648:Child; D002675:Child, Preschool; D002690:Chlamydia Infections / Q000175:diagnosis* / Q000188:drug therapy / Q000517:prevention & control; D002692:Chlamydia trachomatis / Q000302:isolation & purification*; D003228:Conjunctiva / Q000382:microbiology; D005123:Eye / Q000382:microbiology; D005260:Female; D006169:Guinea-Bissau / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007249:Inflammation; D008297:Male; D015995:Prevalence; D014141:Trachoma / Q000175:diagnosis* / Q000188:drug therapy / Q000517:prevention & control
chemical_list: D000900:Anti-Bacterial Agents
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