TABLE 7.
Published data on the correlation of qualitative laboratory tests for ocular C. trachomatis infection with clinical signs of trachoma, where signs were graded using either the modified WHO system (53) or the WHO simplified system (226)
| Country | Subjects | Prevalence of trachoma in study subjects or in population from which subjects were selected | Testa | Prevalence of positive testsb | Reference(s) |
|---|---|---|---|---|---|
| Egypt | Children 1-10 years of age with at least moderately severe active trachoma, screened at a medical clinic | “Holoendemic” | Giemsa | 13 (14%) of 91 examined | 189 |
| Nepal | All children aged 1-10 years from 6 villages examined; Giemsa staining performed on 15 children arbitrarily selected from those with active disease | 46 (6%) of 726 examined had active disease | Giemsa | 0 of 15 swabbed | 16 |
| Tunisia | Children aged 6-8 years attending schools of 4 villages screened; conjunctival scrapings collected from those with active trachoma of moderate or severe intensity (n = 162; results given for 161) | Not stated; all children from whom samples were collected had active disease of moderate or severe intensity | Giemsa | 51 (32%) of 161 | 50 |
| Mexico | All available residents of 2 villages examined; scrapings obtained from all children aged 1-10 years in every fourth family | Approximately 25% of those under 10 years had P3 and F1 OR F3 OR F2 | Giemsa | 19 (24%) of 81 children with P3 and F1, OR F3, OR F2 | 218 |
| Egypt | Children 1-10 years of age with at least moderately severe active trachoma, screened at a medical clinic | “Holoendemic” | Culture (cycloheximide-treated McCoy cells); serial passage after 96 h if negative on initial inoculation | 34 (37%) of 91 examined | 189 |
| The Gambia | All available residents (911 of 950) of 1 village examined; swabs taken from everyone with active disease and a random sample of those without active disease | 111 (12.2%) of 911 examined had active disease | Culture (cycloheximide-treated McCoy cells) | 1 (1%) of 97 without active disease; 31 (43%) of 72 with active disease (19% of those with mild active disease; 63% of those with moderate active disease; 50% of those with severe active disease) | 11, 238 |
| The Gambia | In one village (population ≈1,000), all available residents examined; in the second (population ≈600), residents of 5 randomly selected compounds examined; swabs collected from the more severely affected eye of 63 cases (31 with clinical evidence of active trachoma and 32 without) | In the first village, the prevalence of active trachoma in children under 15 yr was 22%; in the second village it was 13% | Culture (cycloheximide-treated McCoy cells) | 2 (6%) of 32 with insignificant or no active disease; 4 (40%) of 10 with mild active disease; 5 (63%) of 8 with moderate active disease; 5 (38%) of 13 with severe active disease | 126 |
| The Gambia | All residents of one village (n ≈ 900) examined twice, in 1985 and 1986; in 1985 swabs collected from a randomized, age-stratified sample of the population; in 1986 only from clinically active cases | 22% of those aged ≤15 yrs had active disease | Culture (cycloheximide-treated McCoy cells) | 3 (3%) of 90 with insignificant or no active disease, 30 (18%) of 169 with active disease | 128 |
| Nepal | All children aged ≤5 yr in three villages of Lumbini Zone, western Nepal (n = 430); specimens for 400 subjects reported | Moderate to severe intensity of inflammation in 85 (21%) of 430 examined | Culture (cycloheximide-treated McCoy cells); serial passage after 96 h on 2 duplicate plates if negative on initial inoculation | 44 (11%) of 400, ≈5% of 267 with no active disease, ≈13% of 54 with mild active disase, ≈11% of 18 with moderate active disease, ≈31% of 61 with severe active disease (read from graph) | 57 |
| Tanzania | Stratified random sample of 20 villages drawn; within each village, a cluster sample of children aged 1-7 yr and their mothers or female caretakers examined; swabs taken from all those examined in the first 9 villages (n = 1,671) | 589 (54%) of 1,090 children aged 1-7 yrs examined had active trachoma; 52 (9%) of 581 women examined had active trachoma | Culture considered inadequate if cell monolayer completely destroyed in both 1st and 2nd passages (n = 23) or if it had been completely destroyed in one and partially destroyed in the other (n = 12) | 34 (4%) of 927 with no sign of trachoma, 150 (31%) of 481 with TF only, 73 (51%) of 142 with TI, 7 (9%) of 77 with TS only, 1 (11%) of 9 with TT without TF or TI | 215 |
| USA | Students aged 12 to 21 attending the Stewart Indian School near Carson City, Nev.; all were American Indians from reservations in the southwestern U.S. | “Highly endemic” | In-house immunofluorescence of conjunctival scrapings with polyclonal fluorescein-labeled serum from a rabbit immunized with a yolk sac-grown strain of C. trachomatisb agent | 9 (53%) of 17 with clinical signs of active disease (based on severity of purulent discharge, follicular or papillary hypertrophy, pannus, and conjunctival and corneal scarring) in 1965, 8 (53%) of 15 with clinical signs of active disease in 1966, 3 (60%) of 5 with clinical signs of active disease in 1967, 5 (17%) of 29 without clinical signs of active disease in 1965, 11 (35%) of 31 without clinical signs of active disease in 1966, 15 (37%) of 41 without clinical signs of active disease in 1967 | 51, 91 |
| Egypt | Children 1-10 yr of age with at least moderately severe active trachoma screened at a medical clinic | “Holoendemic” | DFA (MicroTrak) slides considered positive if ≥10 EBs seen | 35 (38%) of 91 examined | 189 |
| The Gambia | In one village (population ≈1000), all available residents examined; in the second (population≈600), residents of 5 randomly selected compounds examined; swabs collected from the more severely affected eye of 63 cases (31 with clinical evidence of active trachoma and 32 without) | In the first village, the prevalence of active trachoma in children under 15 yr was 22%; in the second village it was 13% | DFA (MicroTrak) slides considered positive if ≥10 EBs seen | 1 (3%) of 32 with insignificant or no active disease, 2 (20%) of 10 with mild active disease, 3 (38%) of 8 with moderate active disease, 4 (31%) of 13 with severe active disease | 126 |
| Nepal | All children aged ≤5 years in three villages of Lumbini Zone, western Nepal (n = 430); specimens for 400 subjects reported | Moderate to severe intensity of inflammation in 85 (21%) of 430 examined | DFA (MicroTrak) slides considered positive if ≥10 EBs seen | 33 (8%) of 400, ≈15% of 267 with no active disease, ≈28% of 54 with mild active disease, ≈22% of 18 with moderate active disease, ≈34% of 61 with severe active disease (read from graph) | 57 |
| Tanzania | One index child from each of 234 households with children aged 1-7 yr randomly selected from a village with no previous trachoma control program | 137 (59%) of 234 examined had active disease | DFA (MicroTrak) slides considered positive if ≥5 EBs seen | 1 (1%) of 97 without TF or TI, 28 (28%) of 100 with TF but not TI, 22 (60%) of 37 with TI ± TF, | 28 |
| Tanzania | Stratified random sample of 20 villages drawn; within each village, cluster sample of children aged 1-7 yr and their mothers or female caretakers examined; swabs taken from all those examined in the first 9 villages (n = 1,671) | 589 (54%) of 1,090 children aged 1-7 yr examined had active trachoma; 52 (9%) of 581 women examined had active trachoma | DFA (MicroTrak) slides considered positive if ≥5 EBs seen; slides considered inadequate if <200 epithelial cells seen; 188 slides were inadequate but 2 of these had >10 EBs and were included | 48 (6%) of 813 with no sign of trachoma, 221 (49%) of 447 with TF only, 100 (71%) of 140 with TI, 16 (21%) of 76 with TS only, 1 (11%) of 9 with TT without TF or TI | 215 |
| The Gambia | All residents of two trachoma-endemic villages (n = 1363) examined; swabs taken from 1,348 subjects for EIA | 201 (15%) of 1,348 swabbed for EIA | EIA (Novo Nordisk) | 66 (52%) of 126 with mild active disease, 37 (79%) of 47 with moderate active disease, 22 (79%) of 28 with severe active disease, 75 (7%) of 1147 without active disease | 13 |
| The Gambia | All residents of one village (n ≈ 900) examined twice, 1985 and 1986; in 1985 swabs collected from a randomized, age-stratified sample of the population, in 1986 from the whole population | 22% of those aged ≤15 yr had active disease | EIA-PCE (Boots Celltech) | 56 (25%) of 228 with active disease, 49 (4.9%) of 997 with insignificant or no disease, 10 (20%) of 49 with severe scarring (C3) | 128 |
| Egypt | Children 1-10 yr of age with at least moderately severe active trachoma | “Holoendemic” | EIA (Chlamydiazyme) | 36 (40%) of 91 | 189 |
| The Gambia | All inhabitants of one village (n ≈ 950) examined in 1990; swabs taken from all those with active disease and from all members of 2 households, one containing substantial numbers of trachoma cases, the other free of clinical trachoma | 96 (11%) of 844 inhabitants of the village had clinically active trachoma | EIA (Novobiolabs) | 0 of 37 without active disease, 10 (83%) of 12 with severe active disease, 8 (29%) of 28 with moderate disease, 6 (11%) of 56 with mild disease | 14, 96 |
| Algeria | Children aged 3-17 yr living in 9 schools and nurseries in Saharan refugee camps (n = 527) | 13 (2.5%) of 527 examined had TF | Rapid EIA (Clearview Chlamydia MF) | 0 of 13 with TF, 2/514 (0.4%) without TF | 106 |
| The Gambia | All residents of one village (n ≈ 900) examined in 1984; swabs taken from everyone with active disease and a random sample of those without active disease | Same population as in reference 128; prevalence data provided in this paper only as a graph of prevalence against age for those 0-18 yr old (using pooled data from three studies in the village); peak prevalence of active disease (in 2-year-olds) of ≈37% | Tear MIF-ELISA for slgA | 38 (56%) of 68 with active disease, 10 (43%) of 23 without active disease but with scarring | 238 |
| Kenya | Children with abnormal ocular discharge visiting a health center after an invitation issued for families with eye problems to attend | 90% of persons in the district had “past or current findings suggestive of trachoma” in a survey performed 7-9 yr before the study | Serology (serum MIF for IgM and IgG) positive result defined as an antibody titer of ≥1:8 | 32 (82%) of 39 with 3 or more follicles, 18 (38%) of 47 with papillary hypertrophy sufficient to obscure underlying blood vessels, but 2 or fewer follicles | 31 |
| Nepal | All children aged ≤5 yr in three villages of Lumbini Zone, western Nepal (n = 430); specimens for 400 subjects reported | Moderate to severe intensity of inflammation in 85 (21%) of 430 examined | In-house DNA probe with radiolabeled cloned plasmid DNA from serovar C strain TW3 | 70 (18%) of 400, ≈10% of 267 with no active disease, ≈22% of 54 with mild active disease, ≈22% of 18 with moderate active disease, ≈46% of 61 with severe active disease (read from graph) | 57 |
| Australia | Children aged <15 yr from one Aboriginal community (n = 221) screened for trachoma; of those with follicular trachoma (n = ?), 48 had conjunctival swabs taken | Not specified; in “many Aboriginal communities in central Australia. . .20% of children (have) characteristic eyelid inflammation” | Hybridization probe (Gen-Probe PACE 2) | 0 (0%) of 48 with TF | 117, 120 |
| The Gambia | All residents of two trachoma-endemic villages (n = 1,363) examined; swabs taken from 1,332 subjects for PCR | 200 (15%) of 1,332 swabbed for PCR had active disease | In-house PCR against pCT | 83 (65%) of 128 with mild active disease, 38 (86%) of 44 with moderate active disease, 23 (82%) of 28 with severe active disease, 85 (7.5%) of 1132 without active disease | 13 |
| Algeria | Children aged 3-17 yr living in 9 schools and nurseries in Saharan refugee camps (n = 527) | 13 (2%) of 527 examined had TF | In-house PCR against pCT | 2 (15%) of 13 with TF, 10 (2%) of 514 without TF | 106 |
| The Gambia | All inhabitants of one village (n ≈ 950) examined in 1990; swabs taken from all those with active disease and from all members of two households, one containing substantial numbers of trachoma cases, the other free of clinical trachoma | 96 (11%) of 844 inhabitants of the village had clinically active trachoma | In-house PCR against MOMP | 2 (5%) of 37 without active disease, 8 (67%) of 12 with severe active disease, 16 (57%) of 28 with moderate disease, 25 (45%) of 56 with mild disease | 14, 96 |
| Tanzania | Swabs obtained from 129 individuals aged between 1 and 68 yr living in 2 trachoma-endemic villages; correlation between infection and disease reported for 50 swabs chosen by randomly selecting 24 PCR-positive swabs and 26 PCR-negative swabs and retrieving the clinical (field) information | Not stated | In-house PCR-EIA | 12 (63%) of 19 with TI, 3 (28%) of 8 with TF but not TI | 29 |
| Tanzania | One index child from each of 234 households with children aged 1-7 yr randomly selected from a village with no previous trachoma control program | 137 (59%) of 234 examined had active disease | In-house PCR-EIA against MOMP | 23 (24%) of 97 without TF or TI, 54 (54%) of 100 with TF but not TI, 35 (95%) of 37 with TI ± TF | 28 |
| Tanzania | 4,932 women aged 18 yr or older from 11 villages examined in 1989; follow-up examination planned for all women with scars living in 6 of 11 villages and a random sample of women without scars from the same villages; 523 of 745 with scars examined; 503 of 749 without scars examined | 147 (5%) of 1,014 examined had active disease | In-house PCR-EIA against MOMP | 17 (4%) of 453 without scars at baseline or active disease at F/U, 5 (31%) of 16 without scars at baseline, with TF (but not TI?) at F/U, 14 (44%) of 32 without scars at baseline, with TI at F/U, 24 (5.8%) of 414 with scars at baseline, without active disease at F/U, 2 (33%) of 6 with scars at baseline, with TF (but not TI?) at F/U, 34 (37%) of 93 with scars at baseline, with TI at F/U, 36 (7.2%) of 499 without scars at baseline, without TT at F/U, 0 (0%) of 2 without scars at baseline, with TT at F/U, 51 (11%) of 466 with scars at baseline, without TT at F/U, 9 (19%) of 47 with scars at baseline, with TT at F/U | 154 |
| Australia | Children aged <15 yr from one Aboriginal community (n = 221) screened for trachoma; of those with follicular trachoma (n = ?), 48 had conjunctival swabs taken | Not specified; in “many Aboriginal communities in central Australia. . .20% of children (have) characteristic eyelid inflammation” | PCR (in-house; target gene not specified) | 7 (15%) of 48 with TF | 117, 120 |
| Tanzania | All residents of one subvillage in Rombo district invited (956 of 978 residents examined) | 174 (18%) of 956 examined had active disease | PCR (Amplicor) | 17 (27%) of 63 with TF but not TI, 41 (37%) of 111 with TI with or without TF, 2 (2%) of 86 with TS but neither TF nor TI, 31 (4%) of 696 with no sign of trachoma | 199 |
| Tanzania | All residents of one subvillage in Kongwa district invited (874 of 1,017 residents examined; results available for 871) | 312 (36%) of 871 examined had active disease | PCR (Amplicor) | 161 (74%) of 271 with TF but not TI, 80 (84%) of 95 with TI with or without TF, 48 (52%) of 93 with TS but neither TF nor TI, 207 (44%) of 466 with no sign of trachoma | 199 |
| The Gambia | All residents of 14 trachoma-endemic villages (1,319 residents examined) | 103 (8%) of 1319 examined had active disease | PCR (Amplicor) | 14 (17%) of 84 with TF but not TI, 9 (47%) of 19 with TI with or without TF, 8 (10%) of 81 with TS but neither TF nor TI, 64 (6%) of 1135 with no sign of trachoma | 33, 199 |
| The Gambia | All residents of 14 trachoma-endemic villages (1,319 residents examined) | 103 (8%) of 1319 examined had active disease | PCR (Amplicor) | 65 (5.5%) of 1182 with P0, 10 (14%) of 69 with P1, 11 (22%) of 49 with P2, 9 (47%) of 19 with P3, 69 (6%) of 1146 with F0, 4 (5%) of 74 with F1, 6 (10%) of 62 with F2, 16 (43%) of 37 with F3 | 33 |
| Australia | Children aged <15 yr from one Aboriginal community (n = 221) screened for trachoma; of those with follicular trachoma (n = ?), 48 had conjunctival swabs taken | Not specified; in “many Aboriginal communities in central Australia. . .20% of children (have) characteristic eyelid inflammation” | PCR (Cobas Amplicor) | 3 (6%) of 48 with TF | 117, 120 |
| Egypt | All inhabitants of two trachoma-endemic villages | 46.3% of those 0-10 yr old had active disease; 3.6% of those >10 yr old had active disease | LCR (LCx) | 382 (29%) of 1,330 without active trachoma, 84 (25%) of 331 with mild follicular trachoma (F1, P1, P2), 176 (61%) of 288 with follicular trachoma only (F2, F3), 97 (81%) of 120 with severe inflammatory trachoma (P3) | 194 |
| Egypt | All children aged 1-5 yr living in two trachoma-endemic villages (an age-defined subset of the population of 194 immediately above) | 224 (62%) of 360 examined had active disease | LCR (LCx) | 45 (33%) of 136 without TF or TI, 155 (69%) of 224 with TF and/or TI | 22 |
| Egypt | All children aged 6-10 yr living in two trachoma-endemic villages (an age-defined subset of the population of 194 above) | 129 (35%) of 371 examined had active disease | LCR (LCx) | 65 (27%) of 242 without TF or TI, 90 (70%) of 129 with TF and/or TI | 22 |
| Egypt | All children aged 11-15 yr living in two trachoma-endemic villages (an age-defined subset of the population of 194 above) | 24 (7.3%) of 328 examined had active disease | LCR (LCx) | 70 (23%) of 304 without TF or TI, 15 (63%) of 24 with TF and/or TI | 22 |
| The Gambia | All inhabitants of several trachoma-endemic villages | Active disease in 34% of 0-10-yr-olds; active disease in 4.1% of >10-yr-olds | LCR (LCx) | 241 (24%) of 990 without active trachoma, 221 (46%) of 480 with mild follicular trachoma (F1, P1, P2), 81 (52%) of 155 with follicular trachoma only (F2, F3), 85 (70%) of 122 with severe inflammatory trachoma (P3) | 194 |
| Tanzania | All inhabitants of two trachoma-endemic villages | Active disease in 60.1% of 0-10-yr-olds; active disease in 17.2% of >10 yr-olds | LCR (LCx) | 22 (2%) of without active trachoma, 61 (11%) of 574 with mild follicular trachoma (F1, P1, P2), 169 (41%) of 408 with follicular trachoma only (F2, F3), 239 (55%) of 436 with severe inflammatory trachoma (P3) | 194 |
| Nepal | 17 of 18 wards in two village development committees were separated into randomization units of 1, 2, or 3 wards; 50 randomly chosen children aged 1-7 yr were chosen from each unit; LCR performed on all sampled clinically active cases (n = 117) and on a randomly chosen 118 normals | Pretreatment survey of 1,597 children aged 1-10 yr in 5 arbitrarily chosen wards showed a prevalence of active disease of 28.5% | LCR (LCx) | 29 (25%) of 117 with active disease, 5 (4%) of 118 clinically normal cases | 101 |
| Nepal | All children aged 1-10 yr from 6 villages examined; swabs taken from all those with active disease (TF or TI) and one eighth of those without active disease (selected at random) | 46 (6%) of 726 examined had active disease | LCR (LCx) | 0 of 46 with active disease (TF and/or TI in the swabbed eye), 0 of 44 without active disease | 16 |
| Egypt | All inhabitants of two villages (n = 2,067) | 408 (20%) of 2,067 examined had active disease | LCR (LCx) | 465 (28%) of 1659 without active disease, 176 (61%) of 288 with TF but not TI, 97 (81%) of 120 with TI | 48 |
| Australia | Children aged <15 yr from one Aboriginal community (n = 221) screened for trachoma; of those with follicular trachoma (n = ?), 48 had conjunctival swabs taken | Not specified; in “many Aboriginal communities in central Australia. . .20% of children (have) characteristic eyelid inflammation” | LCR (LCx) | 8 (17%) of 48 with TF | 117, 120 |
| China | All individuals (any age) with clinically active trachoma (TF or TI) in 7 villages randomly selected from Dongfang District, Hainan Province; no two cases were from the same household | Prevalence in 1-7-yr-old children 2%; sample age range 2-75 yr was though 21 of 25 swabs were from children <10 yr | LCR (LCx) | 2 (8%) of 25 swabbed (all had TF or TI) | 221 |
| Nepal | 55 children aged 1-10 yr were randomly selected from each of 4 villages in which the prevalence of active trachoma was found to be <10%; swabs taken from selected children who were clinically active | 7% in 1-10-yr-old children | LCR (LCx) | 2 (8%) of 24 swabbed (all had TF or TI) | 221 |
| Nepal | 55 children aged 1-10 yr were randomly selected from a village in which the prevalence of active trachoma was found to be >30%; swabs taken from selected children who were clinically active | 39% in 1-10-yr-old children | LCR (LCx) | 15 (63%) of 24 swabbed (all had TF or TI) | 221 |
a
DFA, direct fluorescent antibody; F/U, follow-up; EB, elementary body; EIA, enzyme immunoassay; sIgA, secretory immunoglobulin A; MIF, microimmunofluorescence; LCR, ligase chain reaction.
b
See Table 2, footnote a.