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      Follow-up and report on active trachoma in Zabol, Iran, prompted by Sharifi-Rad and Fallah's observations published in May 2016

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          Abstract

          Sharifi-Rad and Fallah published a paper reporting data on ocular Chlamydia trachomatis infection, determined by Amplicor PCR [1]. In June 2014, amongst 150 rural schoolchildren in Zabol, Iran (located in a zone bordering Afghanistan), they found nine girls and four boys to be positive this infection by PCR. We are grateful for their interest in an important global cause of blindness, but despite extensive communications and requests, we could not obtain further details from them, learn more about the prevalence of clinically diagnosed active trachoma in their sample of children or discover the identity of the specific communities visited in order to allow formal reassessment of the relevant population. In the absence of this guidance, in March 2017, we performed a targeted screening in primary schools of two border zone counties, Hirmand and Zehak (Fig. 1). The investigation protocol was reviewed and approved by the Zabol Deputy of Public Health (#b14541). The screening flow is depicted in Supplementary Diagram 1. Fig. 1 Geographical zone of two border counties of Hirmand and Zehak in current targeted screening. Fig. 1 Amongst 16 957 children aged 7–12 years examined, there was only one case of active trachoma (diagnosed as upper tarsal follicular conjunctivitis by a subspecialist in cornea and anterior segment of the eye (SFM) with a portable slit lamp (SK Med LS-1B, Chongqing, China). An expert ophthalmologist passed a Dacron swab firmly three times over the upper right tarsal conjunctiva of that patient, spinning 120 degrees between each pass, then placed it in a sterile microtube at 4°C, and within 10 hours of collection sent it to Bahar Medical Laboratory, Tehran, Iran, where it was stored at −80°C until processing. DNA was extracted by QIAamp DNA Blood Mini Kit (Qiagen, Hilden, Germany). Primers targeted regions of the hsp60 and hsp70 genes, which are highly conserved among Chlamydia trachomatis serovars but which vary from the corresponding human sequences. SYBR Green was used for amplicon detection. Thermal cycling was carried out using a LightCycler v.1.5 Real-Time PCR (Roche, Berlin, Germany), with C. trachomatis serovar A DNA used as a positive control. Our case's PCR test was negative. PCR is highly specific for C. trachomatis infection, but as a result of its imperfect sensitivity [2] and the kinetics of infection and disease [3], a negative PCR does not allow one to set aside a clinical diagnosis. We thus conservatively considered the case to be trachomatous. Therefore, we estimate a prevalence of active trachoma of 0.006 (Clopper-Pearson exact 95% confidence interval, 0.0001–0.03). The upper limit of the confidence interval is still far less than the 5% threshold set by the World Health Organization as the active trachoma component of ‘elimination as a public health problem’ [4] and is likewise considerably lower than the estimates reported by Sharifi-Rad and Fallah, which in any case were figures for the prevalence of ocular C. trachomatis infection rather than estimates of the prevalence of active trachoma. In recent years, the border with Afghanistan has become more tightly controlled, and one may hypothesize that this relates to the likely disparity of the earlier findings with the current ones. However, our findings are compatible with the two latest formal surveys in the region, published in 2006 and 2015 [5], [6]. Iran is in the process of seeking formal validation from the World Health Organization of trachoma's elimination as a public health problem. To keep trachoma at bay, we emphasize the importance of surveillance and of ensuring provision of clean water and environmental sanitation in border zones and in deprived and rural communities. However, for the time being, and for formal purposes, we believe that there is strong evidence to support a claim that active trachoma has been eliminated from Iran. Conflict of interest The authors alone are responsible for the views expressed in this letter and they do not necessarily represent the views, decisions or policies of the institutions with which they are affiliated.

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          Diagnosis and assessment of trachoma.

          Trachoma is caused by Chlamydia trachomatis. Clinical grading with the WHO simplified system can be highly repeatable provided graders are adequately trained and standardized. At the community level, rapid assessments are useful for confirming the absence of trachoma but do not determine the magnitude of the problem in communities where trachoma is present. New rapid assessment protocols incorporating techniques for obtaining representative population samples (without census preparation) may give better estimates of the prevalence of clinical trachoma. Clinical findings do not necessarily indicate the presence or absence of C. trachomatis infection, particularly as disease prevalence falls. The prevalence of ocular C. trachomatis infection (at the community level) is important because it is infection that is targeted when antibiotics are distributed in trachoma control campaigns. Methods to estimate infection prevalence are required. While culture is a sensitive test for the presence of viable organisms and nucleic acid amplification tests are sensitive and specific tools for the presence of chlamydial nucleic acids, the commercial assays presently available are all too expensive, too complex, or too unreliable for use in national programs. There is an urgent need for a rapid, reliable test for C. trachomatis to assist in measuring progress towards the elimination of trachoma.
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            How reliable are tests for trachoma?--a latent class approach.

            Tests for ocular Chlamydia trachomatis have not been well characterized, because there is no gold standard test. Latent class analysis (LCA) was performed to estimate the sensitivity and specificity of laboratory and clinical tests for trachoma in the absence of a gold standard. Individual data from pretreatment, hyperendemic areas in Ethiopia were used. A clustered LCA was performed for three diagnostic tests: PCR and WHO simplified criteria grades of follicular trachoma (TF) and intense trachomatous inflammation (TI). Data from 2111 subjects in 40 villages were available. TF was estimated to be 87.3% (95% CI, 83.3-90.1) sensitive and 36.6% (95% CI, 23.6-40.3) specific; TI was estimated to be 53.6% (95% CI, 46.1-88.0) sensitive and 88.3% (95% CI, 83.3-92.0) specific, and PCR was estimated to be 87.5% (95% CI, 79.9-97.2) sensitive and 100% (95% CI 69.3-100) specific. LCA allows for an estimate of test characteristics without prior assumption of their performance. TF and TI were found to act in a complementary manner: TF is a sensitive test and TI is a specific test. PCR is highly specific but lacks sensitivity. The performance of these tests may be due to the time course of ocular chlamydial infection, and for this reason, results may differ in areas of low prevalence or recent mass treatment (ClinicalTrials.gov number, NCT00221364).
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              Trachoma prevalence in rural areas of eastern Iran

              We investigated the prevalence of trachoma in rural areas of eastern Iran. We collected swabs from 150 children in three areas. Results of PCR showed presence of chlamydia in four boys (5.97%) and nine girls (10.84%). We suggest that in assessing the elimination of trachoma, WHO must consider border areas between countries.
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                Author and article information

                Contributors
                Journal
                New Microbes New Infect
                New Microbes New Infect
                New Microbes and New Infections
                Elsevier
                2052-2975
                10 August 2017
                November 2017
                10 August 2017
                : 20
                : 14-15
                Affiliations
                [1) ]Center for Communicable Diseases Control, Ministry of Health and Medical Education, Tehran, Iran
                [2) ]Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
                [3) ]Community and Preventive Medicine Department, Tehran University of Medical Sciences, Tehran, Iran
                [4) ]Iranian Blood Transfusion Organization Research Center, Tehran, Iran
                [5) ]Deputy of Public Health, Zabol University of Medical Sciences, Zabol, Iran
                [6) ]Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
                Author notes
                [] Corresponding author: E. Ashrafi, Farabi Eye Hospital, Qazvin Square, Tehran 1336616351, IranFarabi Eye HospitalQazvin SquareTehran1336616351Iran eashrafi@ 123456sina.tums.ac.ir
                Article
                S2052-2975(17)30064-1
                10.1016/j.nmni.2017.08.001
                5682883
                608bd220-d64d-4263-8f92-fc7456567250
                © 2017 The Author(s)

                This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

                History
                : 21 June 2017
                : 7 August 2017
                Categories
                Letter to the Editor

                active trachoma,elimination,iran,public health problem,zabol

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