Control of trachoma and prevention of blindness in rural communities in Burma.

Trachoma was identified as the single most important cause of blindness in central Burma in a study carried out in 1961-1962. Control measures started in 1964 considerably reduced the degree of endemicity and severity of the disease in the areas treated. According to recent simplified criteria of evaluation, the prevalence of active trachoma has been reduced by more than 60% and that of active inflammatory disease of moderate and severe intensity from 7.4% to 1.8% of the active cases. A reduction in the risk of becoming infected is evident from changes that have occurred among the younger age groups.The experience acquired by the trachoma control project in central Burma-covering a population of more than 4 million in 8000 villages-emphasizes the importance of the active participation of the community and the role of local auxiliary personnel. Most of the activities, including surgical repair of trichiasis, are the responsibility of health assistants; their training includes, in addition to the recognition and treatment of patients requiring topical application of antibiotics or surgical repair of trichiasis, the screening and referral to the general practitioner or to the eye specialist of those needing more specialized attention.The results already obtained have made possible a gradual replacement of control activities by a surveillance programme, and their integration into the basic health services. The objectives of the trachoma control programme have been expanded to include the prevention and management of other causes of preventable or curable blindness, with special emphasis on eye injuries and glaucoma.

Chlamydiae as agents of sexually transmitted diseases.

Chlamydiae are being increasingly recognized as an important cause of human disease. The known geographical distribution of lymphogranuloma venereum and the role of chlamydiae as agents of sexually transmitted diseases are reviewed. The presence of chlamydiae in the urethra and the cervix, and their etiological relationship to genital infections, first recognized in connexion with ocular infections, have been proved in a number of studies in selected populations in a few countries. Chlamydiae appear to be the most important agent of nongonococcal urethritis, which in some cases appears now to be more frequent than gonococcal urethritis. In addition to their association with cervicitis, chlamydiae appear also to be fairly frequent in the cervix of apparently normal, asymptomatic, and sexually active women. The role of chlamydiae as agents of other human diseases still requires to be clarified. The organisms have been found in association with pelvic inflammatory disease, neonatal pneumonia, pharyngitis, and otitis. There is need for additional studies in view of the fact that effective chemotherapy is available. An outline is given of laboratory methods that may be useful for the diagnosis of chlamydial infections.

Laboratory diagnosis of trachoma: a collaborative study.

A collaborative study on the laboratory diagnosis of trachoma was carried out in three laboratories. A standardized complement fixation (CF) test with chlamydial (bedsonial) group antigen was found to be highly reproducible. The results obtained by different laboratories using the method and reagents suggested by the WHO International Reference Centre for Trachoma and other Chlamydial Infections agreed in more than 95% of the tests. Similar agreement was observed between the results obtained with these reagents and those routinely used in one of these laboratories. In confirmation of previous studies, the CF test was found to give positive results in only a limited proportion of trachoma cases. However, in an area where the disease is hyperendemic the rates showed good correlation with the intensity of clinical signs. A comparison was also made between Giemsa staining and a fluorescent antibody (FA) technique for the cytological examination of conjunctival scrapings. The results obtained with the former method correlated well with clinical activity but the positivity rate was lower than that obtained by the FA technique. The FA results, however, were not an accurate indicator of clinical intensity. These results suggest that the Giemsa method may detect only the most heavily infected individuals.

Chlamydiae as agents of human and animal diseases.

A brief review is given of the properties, occurrence, and public health significance of chlamydiae in man and animals and of the diagnosis and control of chlamydial infections. Chlamydiae occur naturally in a large number of avian and mammalian species. Man is the primary host of chlamydiae causing trachoma, inclusion conjunctivitis, genito-urinary tract infection, and lymphogranuloma venereum. In animals chlamydial infections have been recognized as a cause of pneumonia, encephalitis, abortion, arthritis, diarrhoea, and conjunctivitis. Chlamydial infections have been recognized in a wide range of avian hosts. Sporadic psittacosis/ornithosis in man is associated with close exposure to birds and may occur as an occupational disease. Transmission studies suggest that mammalian chlamydial strains are not very host-specific and that diseases and even chains of infection may develop in secondary hosts. There are a few well-documented cases of human infection with chlamydiae of mammalian origin. Although various chlamydial isolates have specific antigenic components, no routine test for identifying different serotypes has been generally accepted. Further investigation of the host range of chlamydiae and of their antigenic properties is essential for a more accurate assessment of the potential danger of chlamydia-infected animals to human health. The frequent occurrence of inapparent or latent infections makes it imperative to establish adequate laboratory facilities for the effective surveillance and control of chlamydial infections.

Rickettsiae and rickettsial diseases.

This paper summarizes present knowledge on rickettsiae and rickettsial diseases, and on their epidemiological characteristics, control, and public health significance. There are many natural foci of rickettsial diseases, from where the disease may spread to other areas in the world under changing socioeconomic conditions. Because of rapid long-distance travel, sporadic cases of serious rickettsial diseases may today appear far from endemic areas where the infection occurred. Even in endemic areas the disease may be misdiagnosed and deaths may occur as a result of inadequate treatment. Rapid treatment of rickettsial infections (preferably with tetracyclines) is therefore most important. Epidemic louse-borne typhus, though no longer subject to the International Health Regulations, remains one of the diseases in the WHO epidemiological surveillance programme. This disease continues to be a major cause of morbidity and mortality in some parts of Africa and it is present also in parts of the Americas and of Asia. Scrub typhus remains a continuing and serious public health problem in areas of South-East Asia and in the Western Pacific. The annual number of reported cases of Rocky Mountain spotted fever in the USA showed an increase during the last two decades, which may be due to improved recognition as well as to increased outdoor activities and migration of people from the city centres to the suburbs. Related forms of tick-borne typhus occur in South America, the Mediterranean region, Africa, South-East Asia, the Far East, and the Western Pacific. Increasing in number, though still sporadic, are reports of serious illness from chronic Q fever infection in many parts of the world.

Growth of trachoma agent in primary cultures of rabbit corneal endothelial cells.

Primary cultures of rabbit corneal endothelial cells supported growth of trachoma agent, as evidenced by the production of inclusions and an increase of infectivity titers.

Ocular lesions induced by the trachoma agent in rabbits.

Injection of the T'ang strain of trachoma agent into the anterior chamber of the rabbit eye caused corneal opacity, characteristic microscopic lesions of the corneal endothelium, varying degrees of neovascularization of the cornea, and uveitis. These ocular changes were agent-specific. The experimental data showed that the microorganism developed in the ocular tissues. The results of this study suggest the possibility of using the rabbit eye as an experimental model for the study of trachoma.

Studies on trachoma. 11. Evaluation of laboratory diagnostic methods under field conditions.

The severity of trachoma in endemic areas has, in general, a tendency to decrease as a consequence of control measures and gradual improvements in sanitation and living conditions. The number of mild cases seen where the disease is prevalent is thus increasing and it is becoming more difficult to establish a differential diagnosis in certain cases, and to determine the degree of endemicity of the disease in a given area or community.In order to ascertain whether available laboratory methods could contribute useful data from this point of view, a clinical and laboratory study was carried out on the school population of the island of Djerba, off the south coast of Tunisia, during the school year 1963-64.The ophthalmological findings confirmed that, notwithstanding the large-scale treatment campaigns which had been in operation for 10 years, trachoma was then still highly endemic in the island, but relatively mild.The laboratory studies included microscopical examination of conjunctival scrapings for inclusion bodies, complement-fixation tests on serum specimens and-on a subsample of the populations studied-attempts to isolate the trachoma agent. The results indicated that the tests are more likely to be positive when the clinical signs are more pronounced. In individual cases, laboratory tests can at best confirm an already established clinical diagnosis and contribute little to the differential diagnosis of borderline cases.However, this study also indicated that the laboratory tests may provide useful quantitative indications on the endemicity of the disease in a community or in an area, from the point of view of the density of the agent and of the response to its presence. The techniques used must obviously be uniform enough to allow for a comparison with results obtained elsewhere or at different times.