Trachoma as a leading cause of preventable blindness in the world is a neglected disease related to low socioeconomic conditions and locations without basic sanitation. Present mainly in developing countries brings great harm to public coffers in lost productivity and visual impairment. With the creation of the Alliance for the Global Elimination of Trachoma in 1997 (GET2020) the State of Pará, with support from the Ministry of Health of Brazil, held in the 2006 epidemiological survey of trachoma in school 1st to 4th grades of the official network of education in municipalities with the human development index of less than national average, to discover the prevalence of the disease. Data from the survey proved that the disease was not eradicated, revealing 35 priority municipalities in Pará and prevalence above
5%. A sub-sample of the conjunctiva of clinically positive students was collected to confirm the diagnosis by direct immunofluorescence (DIF). The present study used
52 cryopreserved samples obtained during the epidemiological survey to be analyzed by the methods of DIF and molecular biology to laboratorial identification of Chlamydia trachomatis. We found frequencies of 26.92% (14/52) and 49% (24/49) of positive results by DIF techniques and polymerase chain reaction (nested-PCR), respectively. Considering the 49 samples analyzed by two methods, the sensitivities for detection of the etiologic agent, by FAT and PCR were 28.57% (14/49) and
48.98% (24/49), respectively (p = 0,0127). The two techniques together confirmed
57.14% (n = 28) of samples with infection, where 50% (n = 14) were positive only by PCR, 35.72% (n = 10) for both technical and 14, 28% (n = 4) only by the IFD. The nucleotide sequence analysis of seven isolates showed homology to C. trachomatis genotype L1. These studies is a pioneer in Brazil, as well as confirm the presence of C. trachomatis in samples from ocular school clinically positive for trachoma, validated protocol for obtaining DNA from cryopreserved sheets DIF, showed the highest sensitivity of the molecular method front DIF and identified the genotype L1 in the sample of the conjunctiva of clinically positive students.
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