Trachoma among children in community surveys from four African countries and implications of using school surveys for evaluating prevalence

King, Jonathan D.; Odermatt, Peter; Utzinger, Jürg; Ngondi, Jeremiah; Bamani, Sanoussi; Kamissoko, Yaya; Boubicar, Kadri; Hassan, Adamou Sabo; Nwobi, Benjamin Chukwuemeka; Jip, Nimzing; Amnie, Asrat Genet; Teferi, Tesfaye; Mosher, Aryc W.; Stewart, Aisha E. P.; Cromwell, Elizabeth A.; Emerson, Paul M.

doi:10.1093/inthealth/iht027

Cited by 21 publications

(19 citation statements)

References 19 publications

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“…Published data from studies in Ethiopia [50], Niger [50], Tanzania [18], Gambia [18], Cameroon [48], Mali [51] and Brazil [52] indicate that in other trachoma-endemic populations, the highest age-specific TF prevalence is generally in those aged 3–4 years. When published age-specific TF profiles from other parts of the world are compared to the age distribution in this study (Fig 5), the peak age-specific TF prevalence in our data is shown to be in an older age group.…”

Section: Resultsmentioning

confidence: 99%

Low Prevalence of Conjunctival Infection with Chlamydia trachomatis in a Treatment-Naïve Trachoma-Endemic Region of the Solomon Islands

Butcher

Sokana²,

Jack³

et al. 2016

PLoS Negl Trop Dis

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BackgroundTrachoma is endemic in several Pacific Island states. Recent surveys across the Solomon Islands indicated that whilst trachomatous inflammation—follicular (TF) was present at levels warranting intervention, the prevalence of trachomatous trichiasis (TT) was low. We set out to determine the relationship between chlamydial infection and trachoma in this population.MethodsWe conducted a population-based trachoma prevalence survey of 3674 individuals from two Solomon Islands provinces. Participants were examined for clinical signs of trachoma. Conjunctival swabs were collected from all children aged 1–9 years. We tested swabs for Chlamydia trachomatis (Ct) DNA using droplet digital PCR. Chlamydial DNA from positive swabs was enriched and sequenced for use in phylogenetic analysis.ResultsWe observed a moderate prevalence of TF in children aged 1–9 years (n = 296/1135, 26.1%) but low prevalence of trachomatous inflammation—intense (TI) (n = 2/1135, 0.2%) and current Ct infection (n = 13/1002, 1.3%) in children aged 1–9 years, and TT in those aged 15+ years (n = 2/2061, 0.1%). Ten of 13 (76.9%) cases of infection were in persons with TF or TI (p = 0.0005). Sequence analysis of the Ct-positive samples yielded 5/13 (38%) complete (>95% coverage of reference) genome sequences, and 8/13 complete plasmid sequences. Complete sequences all aligned most closely to ocular serovar reference strains.DiscussionThe low prevalence of TT, TI and Ct infection that we observed are incongruent with the high proportion of children exhibiting signs of TF. TF is present at levels that apparently warrant intervention, but the scarcity of other signs of trachoma indicates the phenotype is mild and may not pose a significant public health threat. Our data suggest that, whilst conjunctival Ct infection appears to be present in the region, it is present at levels that are unlikely to be the dominant driving force for TF in the population. This could be one reason for the low prevalence of TT observed during the study.

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Section: Resultsmentioning

confidence: 99%

Low Prevalence of Conjunctival Infection with Chlamydia trachomatis in a Treatment-Naïve Trachoma-Endemic Region of the Solomon Islands

Butcher

Sokana²,

Jack³

et al. 2016

PLoS Negl Trop Dis

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“…Infants also cannot cooperate with the eye examination and conjunctival secretion sample collection. An African study suggested that school surveys might underestimate the prevalence because differences were found between those who attended school and those who did not; however, in Nigeria where school attendance is high the differences were not seen [38, 39]. As the rate of school attendance is high in the Shanghai migrant school aged children the prevalence in our study may be fairly accurate.…”

Section: Discussionmentioning

confidence: 54%

A Cross-Sectional Population-Based Survey of Trachoma among Migrant School Aged Children in Shanghai, China

Xue

Zhu

et al. 2016

BioMed Research International

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We investigated the prevalence of clinical trachoma in 154,265 children aged 6 to 16 years in 206 Shanghai migrant schools. Clean water availability in school, each child's facial cleanliness, eyelids, corneas, and the presenting distance visual acuities were examined. Trachoma was clinically diagnosed in accordance with the World Health Organization simplified classification. Eyes diagnosed with trachoma were swabbed to test for ocular Chlamydia trachomatis infections (OCTI) with a rapid latex immunochromatographic test. Among 153,977 students, no blindness was found related to trachoma. Trachoma was diagnosed in 8029 children (5.2%). In 87 schools clinical trachoma prevalence was higher than 5%. OCTI was confirmed in 2073 of 6823 trachoma diagnosed children (30.4%). Clinical trachoma prevalence was higher among females than males (p < 0.001), but gender comparison showed no statistical difference in the prevalence of OCTI (p = 0.077). Age and clinical trachoma (r = −0.014; p < 0.001) or OCTI (r = −0.026; p = 0.031) prevalence were negatively correlated. Clinical trachoma was different in different districts and counties (p < 0.001). Trachoma warrants close attention in Shanghai migrant children because the condition remains endemic in some schools.

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“…C. trachomatis remains an epidemic in various countries, and Canada is the only high-income country with a trachoma prevalence of >5% (Shattock et al, 2015). Active trachoma exists in a number of areas in Asia and Africa and other developing countries (Last et al, 2014;King et al, 2013;Nigusie et al, 2015;Burton et al, 2010), and a great number of studies have shown C. trachomatis serotypes differ across regions. For 8 .…”

Section: Discussionmentioning

confidence: 99%

Molecular characteristics of the ompA gene of serotype B Chlamydia trachomatis in Qinghai Tibetan primary school students

Zhang

Liang

et al. 2016

Sci. China Life Sci.

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To study the molecular characteristics of Chlamydia trachomatis, the major outer membrane protein gene (ompA) of C. trachomatis from primary school students with trachoma residing in the Qinghai Tibetan area was sequenced and compared with the same serotype in GenBank. In Jianshetang Primary School and Galeng Central Primary School in the Galeng Tibetan Township of Qinghai Haidong Sala Autonomous County, scraped samples were collected from the upper tarsal conjunctiva and lower conjunctival sac of both eyes of 45 students with trachoma, stored at 4°C, and transported to Beijing Tongren Hospital by air within 24 h. The samples were screened for C. trachomatis by real-time PCR. The ompA gene from the C. trachomatis-positive samples was amplified by nested PCR. The serotype was confirmed by National Center for Biotechnology Information (NCBI) BLAST search and homology analysis. The entire ompA gene sequence was compared with the corresponding gene sequences of serotype B strains available in GenBank. Of the 45 students aged 6-13 years with trachoma, 26 C. trachomatis-positive students were identified by the initial real-time PCR screening (average age, (9.09±1.63) years; sex ratio, 1.0), accounting for 57.78% (26/45). The cycle threshold values for real-time PCR were 16.79-37.77. Half (13/26) of C. trachomatis-positive students had a bacterial copy number of >10 5 . The compliance rate of the ompA gene sequences with the C. trachomatis serotype B strains in GenBank was up to 99%. Two novel genetic mutations were found when the ompA gene was compared with those of the 11 serotype B strains in GenBank. The two non-synonymous mutations were located at (i) position 271 in the second constant domain, an adenine (A) to guanine (G) substitution (ACTGCT), changing the amino acid at position 91 from threonine to alanine (ThrAla) in all 26 strains; and (ii) position 887 in the fourth variable domain, a cytosine (C) to thymine (T) substitution (GCAGTA), changing the amino acid at residue 296 from alanine to valine (AlaVal) in four of the 26 strains. Six mutations were identified relative to ATCC VR-573. The strains could be divided into two gene clusters according to the mutation at nucleotide position 887: CQZ-1 (China Qinghai Tibetan-1) and CQZ-2 (China Qinghai Tibetan-2). We thus detected two novel serotype B mutant strains of C. trachomatis among study subjects with trachoma.Chlamydia trachomatis, major outer membrane protein gene, sequencing, homology analysis Citation:

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Trachoma among children in community surveys from four African countries and implications of using school surveys for evaluating prevalence

Abstract: Estimating the prevalence of trachoma through examination of only school-going children risks underestimating the true prevalence.

Cited by 21 publications

References 19 publications

Low Prevalence of Conjunctival Infection with Chlamydia trachomatis in a Treatment-Naïve Trachoma-Endemic Region of the Solomon Islands

Low Prevalence of Conjunctival Infection with Chlamydia trachomatis in a Treatment-Naïve Trachoma-Endemic Region of the Solomon Islands

A Cross-Sectional Population-Based Survey of Trachoma among Migrant School Aged Children in Shanghai, China

Molecular characteristics of the ompA gene of serotype B Chlamydia trachomatis in Qinghai Tibetan primary school students

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