Nephelometry determined serum immunoglobulin isotypes in healthy Thai children aged 2-15 years

Knowledge of what constitute normal serum immunoglobulin (Ig) concentrations are important for the diagnosis of immunologic disorders. Data on normal Ig evaluated by nephelometry are limited in healthy Asian children, none being available for Thai children. One hundred and forty-eight healthy Thai children aged 2-15 years were tested for serum immunoglobulins G, A, M, G1, G2, G3, and G4 (Ig G, A, M, G1, G2, G3, and G4) by nephelometry. Sixty-three percent were girls of median interquartile range age 6.9 (4.8-9.7) years. The geometric means for each Ig were summarized and categorized by age. Statistical analyses were used to compare Igs between sexes and age groups, and to compare IgG in this study with data from other published studies. The average ratios of IgG subclasses/IgG for Ig G1:2:3:4 were 66:22:5:7%. IgG, IgA, IgG2, and IgG3 concentrations showed a gradual increase with increasing age. There were no significant sex differences for any immunoglobulin isotype (P= 0.971). Our mean IgG concentration was lower than that measured by the radial diffusion method in healthy Thai children (P < 0.05). In all age groups, the mean IgG concentration in our study was significantly higher than that reported in Turkish and USA children, evaluated by the nephelometric and radial diffusion techniques, respectively (both P < 0.001). This study provides information about normal Ig concentrations measured by nephelometry in healthy Asian children and illustrates the importance of ascertaining normal Ig values for age- and ethnic-matched controls using the same assay to diagnose immunologic disorders correctly.     

Comparing Interferon-Gamma Release Assays to Tuberculin Skin Test in Thai Children with Tuberculosis Exposure

Background

Data on the performance of interferon-gamma release assays (IGRAs), QuantiFERON TB Gold In-tube (QFNGIT) and T-Spot.TB, in diagnosing tuberculosis (TB) are limited in Southeast Asia. This study aims to compare the performances of the two IGRAs and TST in Thai children with recent TB exposure.

Methods

This multicenter, prospective study enrolled children with recent exposure to active TB adults. Children were investigated for active TB. TST was performed and blood collected for T-Spot.TB and QFNGIT.

Results

158 children were enrolled (87% TB-exposed and 13% active TB, mean age 7.2 years). Only 3 children had HIV infection. 66.7% had TST≥10 mm, while 38.6% had TST≥15 mm. 32.5% had positive QFNGIT; 29.9% had positive T-Spot.TB. QFNGIT and T-Spot.TB positivity was higher among children with active TB compared with TB-exposed children. No indeterminate IGRA results were detected. No statistically significant differences between the performances of the IGRAs and TST at the two cut-offs with increasing TB exposure were detected. Concordance for positive IGRAs and TST ranged from 42–46% for TST≥10 mm and 62–67% for TST≥15 mm. On multivariable analyses, exposure to household primary/secondary caregiver with TB was associated with positive QFNGIT. Higher TB contact score and active TB were associated with positive T-Spot.TB.

Conclusions

Both QFNGIT and T-Spot.TB performed well in our Thai pediatric study population. No differences in the performances between tests with increasing TB exposure were found. Due to accessibility and low cost, using TST may more ideal than IGRAs in diagnosing latent and active TB in healthy children in Thailand and other similar settings.     

Fatal Balamuthia Amebic Encephalitis in a Healthy Child: A Case Report with Review of Survival Cases

Balamuthia mandrillaris is one of the 4 amebas in fresh water and soil that cause diseases in humans. Granulomatous amebic encephalitis (GAE), caused by B. mandrillaris, is a rare but life-threatening condition. A 4-year-old, previously healthy, Thai girl presented with progressive headache and ataxia for over a month. Neuroimaging studies showed an infiltrative mass at the right cerebellar hemisphere mimicking a malignant cerebellar tumor. The pathological finding after total mass removal revealed severe necrotizing inflammation, with presence of scattered amebic trophozoites. Cerebrospinal fluid (CSF) obtained from lumbar puncture showed evidence of non-specific inflammation without identifiable organisms. A combination of pentamidine, sulfasalazine, fluconazole, and clarithromycin had been initiated promptly before PCR confirmed the diagnosis of Balamuthia amebic encephalitis (BAE). The patient showed initial improvement after the surgery and combined medical treatment, but gradually deteriorated and died of multiple organ failure within 46 days upon admission despite early diagnosis and treatment. In addition to the case, 10 survivors of BAE reported in the PubMed database were briefly reviewed in an attempt to identify the possible factors leading to survival of the patients diagnosed with this rare disease.