Prueba de tamizaje simplificada para identificar a personas con visión disminuida en países en desarrollo / A simplified screening test for identifying people with low vision in developing countries

Se han creado pruebas sencillas pero útiles para el tamizaje de personas con visión disminuida en países en desarrollo. Estas pruebas, que miden la visión de lejos y de cerca y que se basan en el uso de una figura en E, fueron evaluadas y respaldadas mediante ensayos en que participaron personas de 4 a 90 años de edad, y se han puesto a prueba en los servicios de salud, educación y rehabilitación de 32 países en desarrollo. Se han calculado su sensibilidad y especificidad como instrumentos para la detección de la visión disminuída: en la prueba de visión a distancia, la sensibilidad es de 85 por ciento y la especificidad, de 96 por ciento; en la prueba de visión cercana, la sensibilidad es de 100 por ciento y la especificidad, de 84 por ciento. Se ha demostrado que el contenido y el formato de las pruebas son adecuados para países en desarrollo y se ha comprobado la utilidad de las mismas para el tamizaje de la visión disminuida

Simple but effective tests have been produced for screening subjects with low vision in developing countries. These tests of distance and near vision, based on the E test, were evaluated and validated in trials with people aged 4­90 years, and have been field tested in the health, education and rehabilitation services in 32 developing countries. Their sensitivity and specificity as screening tools for low vision have been calculated: sensitivity of 85% and specificity of 96% for the distance vision test, and sensitivity of 100% and specificity of 84% for the near vision test. The content and format of the tests have been demonstrated to be appropriate for developing countries, and their effectiveness for screening for low vision has been confirmed.

A chlamydial major outer membrane protein extract as a trachoma vaccine candidate.

PURPOSE: As shown in infected humans and in animal models of chlamydial infection, the major outer membrane protein (MOMP) of Chlamydia trachomatis is immunogenically potent. The purpose of this investigation was to test in the cynomolgus monkey model of trachoma a new extract of MOMP as a candidate vaccine against ocular chlamydial infection. METHOD: The nonionic detergent octyl-beta-D glucopyranoside (OGP) was used to extract MOMP from purified C. trachomatis (serovar C) elementary bodies. Protective immunization with OGP-MOMP by mucosal and systemic routes was compared in the cynomolgus monkey model of trachoma. All control and immunized monkeys were challenged by topical application of infectious C. trachomatis to the conjunctivae 35 days after the initiation of immunization. RESULTS: Immunization with OGP-extracted MOMP successfully induced chlamydia-specific local and systemic immunity to MOMP and to whole organism before challenge and early clearance of infection by systemically immunized monkeys. Although ocular disease was not significantly reduced in either immunized group compared to control animals, the lowest clinical and microbiologic disease scores developed in two animals in the mucosal group with the highest immunoglobulin A tear antibody titers at day 0 to 14, whereas higher tear and serum immunoglobulin G correlated with reduced disease in the systemically immunized group. CONCLUSIONS: These data demonstrate that despite evidence of vigorous MOMP-specific and other chlamydia-specific serologic and cell-mediated immunity, as well as anamnestic serologic responses to chlamydia, vaccination with OGP-MOMP was only partially protective against chlamydial ocular disease. The partial protection correlated best with tear immunoglobulin A responses after mucosal immunization and with local and systemic immunoglobulin G responses after peripheral immunization, suggesting that alternative chlamydial antigens may have to be considered in future vaccine development to induce more effective protective immunity and that evaluation of efficacy must be appropriate to route of immunization.

Epidemiology of trachoma in Bebedouro State of São Paulo, Brazil: prevalence and risk factors.

Trachoma was considered to have been 'eradicated' from the state of São Paulo, Brazil, until 1982 when a number of new cases of trachoma were reported in preschool children in Bebedouro, a small town in northwestern São Paulo. A household survey was undertaken to assess the prevalence and epidemiological characteristics of trachoma. A total of 2939 people of all ages was examined having been selected from a two-stage probalilistic household sampling frame based on census data. Overall, 7.2% of the population had evidence of one or more signs of trachoma and 2.1% had inflammatory trachoma. Inflammatory trachoma was more common in children aged one to ten years, especially in the peripheral urban and rural areas, and was more common in boys. The presence of chlamydia was confirmed by direct fluorescent antibody cytology. No cases of blindness due to trachoma were seen. A number of socioeconomic and hygiene variables were studied in order to determine the independent risk factors for trachoma in a household. Variables significantly associated with the occurrence of trachoma in the household were the number of children in the house aged one to ten years, the 'per capita' water consumption, the frequency of garbage collections, source of water, and the educational level of the head of household. Clustering of trachoma in different parts of this community was entirely explained by the concentration of households with these characteristics.

The ecology of trachoma: an epidemiological study in southern Mexico.

A total of 1097 people in two communities in Chiapas, Mexico, were examined for trachoma, and information was obtained about personal and family hygiene. Trachoma was hyperendemic; approximately 25% of those under 10 years old were found to have significant inflammatory trachoma and almost 100% of those aged over 40 years had cicatricial trachoma, although the prevalence of trachoma differed significantly between the two communities. Risk factor analysis was performed by contingency table analysis and chi(2) testing. The most important parameter associated with the occurrence and severity of inflammatory trachoma in children was the frequency of face washing. Children who washed their faces 7 or more times per week had significantly less trachoma than those who washed less often (chi(2) (2df) = 28.7; P < 0.001). This effect was independent of age, use of clean water and soap, or use of clothes to dry the face. Children who washed infrequently and who used clothes to dry the face or clean the nose were more at risk for trachoma. No parameters of family hygiene or socioeconomic status correlated with the amount of trachoma in a family.These data confirm and quantify for the first time the long-held belief that trachoma is associated with poor personal hygiene and suggest potentially effective and efficient intervention strategies.

Chemotherapy of onchocerciasis: a controlled clinical trial of topical diethylcarbamazine (DEC) in Guatemala.

A double-masked, controlled clinical trial was conducted in Guatemala to assess the safety and efficacy of diethylcarbamazine (DEC) lotion as compared to placebo lotion in the treatment of onchocerciasis. One hundred eighty-seven people were enrolled in this study and were followed for two months. Lotion was applied daily for seven days, then weekly for seven weeks. The decrease in mean microfilarial counts per skin snip was significantly greater in those receiving DEC lotion than for those receiving placebo lotion. The proportionate reduction in microfilarial counts was similar for people with light, moderate, or heavy microfilarial loads. Side effects were mainly related to skin changes, fever, and malaise, and occurred in nearly one-third of the people receiving DEC lotion. These reactions occurred almost as commonly in those people who were lightly infected as in those who had moderate or heavy infections.