Diagnosis of latent tuberculosis infection among pediatric household contacts of Iranian tuberculosis cases using tuberculin skin test, IFN- γ release assay and IFN-γ-induced protein-10.

BACKGROUND: Although the World Health Organization has recommended the diagnosis and prophylactic treatment of latent tuberculous infection (LTBI) in child household contacts of tuberculosis (TB) cases, the national programs in high-burden TB regions rarely implement adequate screening of this high-risk group, mainly because of resource limitations. We aimed to evaluate the prevalence of LTBI among pediatric household contacts of TB cases in two high-burden provinces in Iran. METHODS: We conducted a cohort study in children who had been in household contact with a TB index. All subjects were assessed for active TB disease. For LTBI diagnosis, tuberculin skin test (TST) and QuantiFERON®-TB Gold Plus (QFT-Plus) were performed at the time of the index TB case diagnosis, as well as, 3, 12, and 18 months, if the first results were negative. In addition, interferon-γ-induced protein-10(IP-10) concentrations were measured for all participants. RESULTS: A total of 230 children were enrolled, who had contact with an index TB case. Three contacts were diagnosed with active TB. According to the TST/QFT-Plus results, 104 (45.2%) children were identified with LTBI during our study. Significantly increased IP-10 levels were found in LTBI patients compared to healthy contacts. Accordingly, more than 50% of LTBI contacts and about 10% of healthy contacts were considered as IP-10-positive. CONCLUSION: This study alarmingly illustrates a high prevalence of LTBI among Iranian children exposed to TB cases. We, therefore, emphasize that the children living in close contact with an infectious TB case should be screened effectively and receive prophylactic therapy.

Essential and toxic metals in serum of individuals with active pulmonary tuberculosis in an endemic region.

Trace elements play an important role in tuberculosis infection because their deficiencies can be associated with impaired immunity. Blood samples were collected from a total of 320 active pulmonary tuberculosis patients and healthy individuals. The serum concentrations of Zinc, Iron, Copper, Calcium, lead, Arsenic and Selenium were analyzed by atomic absorption spectrometry. The levels of trace elements were measured after 2, 4 and 6 months of anti-TB treatment initiation in TB infected groups. Compared to the control group, the concentrations of Zinc, Selenium, and Iron were significantly lower (P < 0.001) in tuberculosis patients; however, that of Arsenic, Lead, and copper was significantly higher (P < 0.001) in the serum of patients. Cu/Zn and Cu/Se ratios were also significantly higher (P < 0.001) in TB patients compared to the control group. In addition, serum concentration calcium was similar in both TB patients and healthy controls. Our results indicated that trace elements concentrations in tuberculosis patients are related to each element role in immune system. Wherever the element is essential for the pathogenesis of bacteria, its concentration will remain low; and contrariwise, when the element is toxic for the bacteria, its level will be regulated up to provide a perfect condition for bacterial growth.