Chest Radiograph Screening for Detecting Subclinical Tuberculosis in Asymptomatic Household Contacts, Peru.

The World Health Organization's end TB strategy promotes the use of symptom and chest radiograph screening for tuberculosis (TB) disease. However, asymptomatic early states of TB beyond latent TB infection and active disease can go unrecognized using current screening criteria. We conducted a longitudinal cohort study enrolling household contacts initially free of TB disease and followed them for the occurrence of incident TB over 1 year. Among 1,747 screened contacts, 27 (52%) of the 52 persons in whom TB subsequently developed during follow-up had a baseline abnormal radiograph. Of contacts without TB symptoms, persons with an abnormal radiograph were at higher risk for subsequent TB than persons with an unremarkable radiograph (adjusted hazard ratio 15.62 [95% CI 7.74-31.54]). In young adults, we found a strong linear relationship between radiograph severity and time to TB diagnosis. Our findings suggest chest radiograph screening can extend to detecting early TB states, thereby enabling timely intervention.

Comparison of interferon-γ release assay to two cut-off points of tuberculin skin test to detect latent Mycobacterium tuberculosis infection in primary health care workers.

BACKGROUND: An interferon-γ release assay, QuantiFERON-TB (QFT) test, has been introduced an alternative test for the diagnosis of latent Mycobacterium tuberculosis infection (LTBI). Here, we compared the performance of QFT with tuberculin skin test (TST) measured at two different cut-off points among primary health care work (HCW) in Brazil. METHODS: A cross-sectional study was carried out among HCWs in four Brazilian cities with a known history of high incidence of TB. Results of the QFT were compared to TST results based on both ≥5 mm and ≥10 mm as cut-off points. RESULTS: We enrolled 632 HCWs. When the cut-off value of ≥10 mm was used, agreement between QFT and TST was 69% (k = 0.31), and when the cut-off of ≥5 mm was chosen, the agreement was 57% (k = 0.22). We investigated possible factors of discordance of TST vs QFT. Compared to the TST-/QFT- group, risk factors for discordance in the TST+/QFT- group with TST cut-off of ≥5 mm included age between 41-45 years [OR = 2.70; CI 95%: 1.32-5.51] and 46-64 years [OR = 2.04; CI 95%: 1.05-3.93], BCG scar [OR = 2.72; CI 95%: 1.40-5.25], and having worked only in primary health care [OR = 2.30; CI 95%: 1.09-4.86]. On the other hand, for the cut-off of ≥10 mm, BCG scar [OR = 2.26; CI 95%: 1.03-4.91], being a household contact of a TB patient [OR = 1.72; CI 95%: 1.01-2.92] and having had a previous TST [OR = 1.66; CI 95%: 1.05-2.62], were significantly associated with the TST+/QFT- group. No statistically significant associations were found among the TST-/QFT+ discordant group with either TST cut-off value. CONCLUSIONS: Although we identified BCG vaccination to contribute to the discordance at both TST cut-off measures, the current Brazilian recommendation for the initiation of LTBI treatment, based on information gathered from medical history, TST, chest radiograph and physical examination, should not be changed.

[Clinical and radiological study of Suruí indigenous children and adolescents, Amazon Region, Brazil]. / Estudo clínico-radiológico de crianças e adolescentes indígenas Suruí, Região Amazônica.

INTRODUCTION: The average incidence coefficient of tuberculosis in Suruí Indians from Rondônia was 2.500/100.000 inhabitants in 1991-2002. About 50% of these cases were reported in children < 15 years-old. METHODS: This study aimed to describe the clinical and radiological characteristics of children and adolescents identified as TB case contacts. A score system for the diagnosis of childhood TB was used and the procedures adopted by local health services were in accordance with national guidelines. RESULTS: 52 chest X-rays of 37 indigenous subjects were analyzed; of these, 51.9% were abnormal. Some X-rays showed more than two lesions, making a total of 36 independent events. Infiltrates (38.9%), calcifications (38.9%), cavitations (11.1%) and atelectasis/pleural effusion (11.1%) were observed. Among the abnormal images, 22.2% were probably indicated active TB and 33.3% showed sequelae. Confrontation with the guidelines revealed 52.6% of divergent procedures. CONCLUSIONS: The presence of latent tuberculosis infection (LTBI) and active TB between children and adolescents are indicators of active and progressive transmission of Mycobacterium tuberculosis. The X-rays showed high frequencies of infiltrates and calcifications, which are compatible with primary infection in early childhood. However, these lesions are not different from those observed among other groups and do not suggest immune deficiencies. The divergences presented show that the best moment for the treatment of LTBI went unnoticed by local personnel. In conclusion, the use of a score system is fundamental for the correct diagnosis of TB in childhood, as is conducting bacilloscopy and sputum culture in adolescents able to expectorate.