Reduction of trachoma in absence of a disease-control programme

Abstract

P J Dolin and colleagues (May 24, p 1511)1Dolin PJ Faal H Johnson GJ et al.Reduction of trachoma in a sub-Saharan village in absence of a disease control programme.Lancet. 1997; 349: 1511-1512Summary Full Text Full Text PDF PubMed Scopus (78) Google Scholar report a dramatic fall in trachoma without any trachoma-specific intervention in a sub-Saharan village in The Gambia. Although this fall in disease occurrence seems to have resulted from public-health improvement, the current epidemiological problems cause by Chlamydia trachomatis infections in The Gambia are unclear. C trachomatis causes trachoma and inclusion conjunctivitis. In developing countries, trachoma is a leading cause of blindness and inclusion conjunctivitis is associated with sexually transmitted disease (STD) in adults and infants. Genital infections caused by C trachomatis are the most common STD, and are one of the most important public-health problems in many industrialised countries including Japan. Inclusion conjunctivitis in adults is also associated with epithelial keratitis and small degree of corneal vascularisation. On the other hand, the clinical appearance of inclusion conjunctivitis in neonates is pseudomembraneous conjunctivitis. C trachomatis has been isolated from about 20% of patients with neonatal or adult inclusion conjunctivitis in Sapporo, Japan.2Aoki K Sato C Hashimoto N Chiba S Numazaki K Clinical and etiological studies of chlamydial conjunctivitis in Sapporo, Japan.Jpn J Ophthalmol. 1998; 32: 444-449Google Scholar The increase in cases of chlamydial conjunctivitis in Japan could result from recent advances in diagnostic and screening technology. Unlike urogenital chlamydial infection, trachoma is a household disease that has disappeared in Japan and many other parts of the world because of improved living conditions and hygiene. C trachomatis serovars of A, B, Ba and C have been predominantly associated with endemic trachoma. In Gambia, chlamydial DNA was detected in 49 (51%) of 96 cases of clinically active endemic trachoma and in 5% of clinically negative cases.3Hayes LJ Bailey RL Mabey DCW et al.Genotyping of Chlamydia trachomatis from a trachoma-endemic village in the Gambia by a nested polymerase chain reaction: identification of strain variants.J Infect Dis. 1992; 166: 1173-1177Crossref PubMed Scopus (65) Google Scholar If unrecognised and untreated, C trachomatis can remain infectious in the host for months and be readily transmitted to other people. However, in trachoma-endemic areas, severe disease leading to scarring and blindness may be the result of frequent reinfection of different serovars of C trachomatis, including urogenital-tract origin. We obtained conjunctival swabs from Japanese infants and adults, and used PCR to amply a large part of the major outer membrane protein gene and then catalogued restriction fragment length polymorphism, to determine the serotypes of C trachomatis. The serotyping of conjunctival isolates gave us the following results: D, E, F, G, H, and unclassified serovars. Although Japan used to belong to an endemic area of trachoma, the serovars that we identified were similar to those reported in other studies from non-trachoma-endemic areas.4Wagenvoort JHT Suchland RJ Stamm WE Serovar distribution of urogenital Chlamydia trachomatis strains in the Netherlands.Genitourin Med. 1988; 64: 159-161PubMed Google Scholar These serovars mainly originated from the urogenital tract. Some serovars originally associated with trachoma are occasionally detected in urogenital infections of C trachomatis. Antigenic variations of C trachomatis were also considered among the strains from endocervical and conjunctival origins. C trachomatis infections cannot be eradicated without effective disease-control programmes that focus on early diãgnosis, targeted screening, and effective treatment. Such an approach will lead to an eventual decline in the incidence of ocular and urogenital chlamydial infections.