Use of tuberculin skin test, IFN-γ release assays and IFN-γ-induced protein-10 to identify children with TB infection.

Current tests of tuberculosis (TB) infection (tuberculin skin test (TST), interferon (IFN)-γ-release assays (IGRAs) and IFN-γ-induced protein (IP)-10) have limitations and their value when used consecutively to identify infected children has not been explored. This study describes TST, IGRA and IP-10 responses in children in contact with adults with TB, the agreement of the tests and whether using multiple tests indentifies more infected children. 330 children (aged 1-15 yrs) in contact with adults with pulmonary TB and 156 controls were studied in Ethiopia. Children exposed to adults with high bacilli grades in sputum were more likely to have positive TST, IFN-γ and IP-10 than controls. The agreement of positive tests was directly associated with the sputum bacilli grades (p<0.001 for all). The agreement of negative tests was higher in control children. The consecutive use of the tests increased the number of children classified as having at least one positive test. Using three tests increases the number of children classified as infected. This increase is associated with the bacilli load of the adults. Using only one test may underestimate the proportion of infected children, but the interpretation of the data is difficult due to the lack of reference standards.

A multi-country non-inferiority cluster randomized trial of frontloaded smear microscopy for the diagnosis of pulmonary tuberculosis.

BACKGROUND: More than 50 million people around the world are investigated for tuberculosis using sputum smear microscopy annually. This process requires repeated visits and patients often drop out. METHODS AND FINDINGS: This clinical trial of adults with cough ≥2 wk duration (in Ethiopia, Nepal, Nigeria, and Yemen) compared the sensitivity/specificity of two sputum samples collected "on the spot" during the first visit plus one sputum sample collected the following morning (spot-spot-morning [SSM]) versus the standard spot-morning-spot (SMS) scheme. Analyses were per protocol analysis (PPA) and intention to treat (ITT). A sub-analysis compared just the first two smears of each scheme, spot-spot and spot-morning. In total, 6,627 patients (3,052 SSM/3,575 SMS) were enrolled; 6,466 had culture and 1,526 were culture-positive. The sensitivity of SSM (ITT, 70.2%, 95% CI 66.5%-73.9%) was non-inferior to the sensitivity of SMS (PPA, 65.9%, 95% CI 62.3%-69.5%). Similarly, the specificity of SSM (ITT, 96.9%, 95% CI 93.2%-99.9%) was non-inferior to the specificity of SMS (ITT, 97.6%, 95% CI 94.0%-99.9%). The sensitivity of spot-spot (ITT, 63.6%, 95% CI 59.7%-67.5%) was also non-inferior to spot-morning (ITT, 64.8%, 95% CI 61.3%-68.3%), as the difference was within the selected -5% non-inferiority limit (difference ITT = 1.4%, 95% CI -3.7% to 6.6%). Patients screened using the SSM scheme were more likely to provide the first two specimens than patients screened with the SMS scheme (98% versus 94.2%, p<0.01). The PPA and ITT analysis resulted in similar results. CONCLUSIONS: The sensitivity and specificity of SSM are non-inferior to those of SMS, with a higher proportion of patients submitting specimens. The scheme identifies most smear-positive patients on the first day of consultation. TRIAL REGISTRATION: Current Controlled Trials ISRCTN53339491. Please see later in the article for the Editors' Summary.

LED fluorescence microscopy for the diagnosis of pulmonary tuberculosis: a multi-country cross-sectional evaluation.

BACKGROUND: The diagnosis of tuberculosis (TB) in resource-limited settings relies on Ziehl-Neelsen (ZN) smear microscopy. LED fluorescence microscopy (LED-FM) has many potential advantages over ZN smear microscopy, but requires evaluation in the field. The aim of this study was to assess the sensitivity/specificity of LED-FM for the diagnosis of pulmonary TB and whether its performance varies with the timing of specimen collection. METHODS AND FINDINGS: Adults with cough ≥2 wk were enrolled consecutively in Ethiopia, Nepal, Nigeria, and Yemen. Sputum specimens were examined by ZN smear microscopy and LED-FM and compared with culture as the reference standard. Specimens were collected using a spot-morning-spot (SMS) or spot-spot-morning (SSM) scheme to explore whether the collection of the first two smears at the health care facility (i.e., "on the spot") the first day of consultation followed by a morning sample the next day (SSM) would identify similar numbers of smear-positive patients as smears collected via the SMS scheme (i.e., one on-the-spot-smear the first day, followed by a morning specimen collected at home and a second on-the-spot sample the second day). In total, 529 (21.6%) culture-positive and 1,826 (74.6%) culture-negative patients were enrolled, of which 1,156 (49%) submitted SSM specimens and 1,199 (51%) submitted SMS specimens. Single LED-FM smears had higher sensitivity but lower specificity than single ZN smears. Using two LED-FM or two ZN smears per patient was 72.8% (385/529, 95% CI 68.8%-76.5%) and 65.8% (348/529, 95% CI 61.6%-69.8%) sensitive (p<0.001) and 90.9% (1,660/1,826, 95% CI 89.5%-92.2%) and 98% (1,790/1,826, 95% CI 97.3%-98.6%) specific (p<0.001). Using three LED-FM or three ZN smears per patient was 77% (408/529, 95% CI 73.3%-80.6%) and 70.5% (373/529, 95% CI 66.4%-74.4%, p<0.001) sensitive and 88.1% (95% CI 86.5%-89.6%) and 96.5% (95% CI 96.8%-98.2%, p<0.001) specific. The sensitivity/specificity of ZN smear microscopy and LED-FM did not vary between SMS and SSM. CONCLUSIONS: LED-FM had higher sensitivity but, in this study, lower specificity than ZN smear microscopy for diagnosis of pulmonary TB. Performance was independent of the scheme used for collecting specimens. The introduction of LED-FM needs to be accompanied by appropriate training, quality management, and monitoring of performance in the field. TRIAL REGISTRATION: Current Controlled Trials ISRCTN53339491. Please see later in the article for the Editors' Summary.

Frequency of the MTHFR C677T polymorphism in Yemeni children with sickle cell disease.

The frequency of the methylenetetrahydrofolate reductase enzyme (MTHFR) C677T mutation was determined using polymerase chain reaction (PCR) and with measurement of plasma total homocysteine (tHcy), folate, vitamins B6, B12 and disease severity in 102 SS children from Yemen. The homozygous TT genotype for MTHFR C677T was present in 2% (2/102), and heterozygous CT in 10.8% (11/102), giving an allele frequency of 7.35%. The T allele was not associated with raised plasma tHcy or increased disease severity. The mean [+/-SD (standard deviation)] tHcy was 2.8 +/- 1.7 micromol/L, increased with age and was highest in children >10 years (3.6 +/- 2.5 vs. 2.5 +/- 1.2 micromol/L, p <0.05). Whole blood folate and plasma vitamin B12 levels were normal or elevated, and 4% had vitamin B6 deficiency. In Yemeni children with sickle cell disease the frequency of the MTHFR C677T mutation was not higher than expected in the general population and was not associated with disease severity.

Delayed visual maturation in Karen refugee infants.

Thirty-eight babies born to Karen mothers living in camps for displaced persons in north-western Thailand have delayed visual maturation (DVM type 1) that recovers within 6 months. Vitamin A concentrations were deficient in 16% of breast-milk samples from lactating mothers and vitamin B(1) concentrations were deficient in 60% of plasma samples. Infantile beriberi was common in this population. The levels of fatty acids in plasma and milk in Karen women were excellent at birth and in the postpartum period. The degree of deficiencies in these vitamins and the concentration of essential fatty acids in cord blood and maternal breast-milk did not correlate significantly with visual impairment in the infants. DVM might be caused by nutritional deficiency or toxic effects during critical periods of gestation that lead to delayed cortical myelination or structural defects which impinge on parietal cortex function.