Norio Yamada

Genome-wide association studies of tuberculosis in Asians identify distinct at-risk locus for young tuberculosis

Tuberculosis (TB) is one of the most devastating chronic infectious diseases, but the role of host genetics in disease development after infection in this disease remains unidentified. Genome-wide association studies (GWASs) in Thais and Japanese were carried out and separately analyzed, attempted replication, then, combined by meta-analysis were not yielding any convincing association evidences; these results suggested that moderate to high effect-size genetic risks are not existed for TB per se. Because of failure in replication attempt of the top 50 single-nucleotide polymorphisms (SNPs) identified form meta-analysis data, we empirically split TB cases into young TB case/control data sets (GWAS-Tyoung=137/295 and GWAS-Jyoung=60/249) and old TB case/control data sets (GWAS-Told=300/295 and GWAS-Jold=123/685), re-analyzed GWAS based on age-stratified data and replicated the significant findings in two independent replication samples (young TB; Rep-Tyoung=155/249, Rep-Jyoung=41/462 and old TB; Rep-Told=212/187, Rep-Jold=71/619). GWAS and replication studies conducted in young TB identified at-risk locus in 20q12. Although the locus is located in inter-genic region, the nearest genes (HSPEP1-MAFB) from this locus are promising candidates for TB susceptibility. This locus was also associated with anti-TNF responsiveness, drug with increased susceptibility for TB. Moreover, eight SNPs in an old TB meta-analysis and six SNPs in young TB meta-analysis provided replication evidences but did not survive genome-wide significance.These findings suggest that host genetic risks for TB are affected by age at onset of TB, and this approach may accelerate the identification of the major host factors that affect TB in human populations.

Antiretroviral therapy for HIV-infected tuberculosis patients saves lives but needs to be used more frequently in Thailand.

Descemet stripping automated endothelial keratoplasty (DSAEK), as coined by myself, is rapidly becoming the most popular method of corneal transplantation for endothelial disease. It is an evolutionary step based on the pioneering work of Melles, with further development by Terry and Price. The advantages of the keratome system to cut donor tissue have not only improved clinical outcomes but also increased the number of corneal surgeons performing endothelial transplantation by eliminating highly skilled and laborious manual dissections. The current decision for a corneal surgeon is no longer DSAEK versus PKP but purchasing a keratome system for approximately

Genome-wide SNP-based linkage analysis of tuberculosis in Thais.

30,000 versus letting the eye bank supply precut donor tissue (this scenario may change with the availability of less expensive keratome systems or Melles’ newest procedure called Descemet membrane endothelial keratoplasty). Like most expensive purchases, each surgeon must weigh many factors that include patient outcomes, convenience, and cost. This month’s edition of Cornea contains a pertinent article from the Iowa Lions eye bank on the results and surgeon satisfaction of precut donor tissue they supplied to 53 surgeons for 197 DSAEK cases. The favorable conclusions of their surgeon survey deserve further scrutiny. I would like to break down the discussion into 2 categories: clinical outcomes and financial considerations. Clinical outcomes should be the main driving force behind the evaluation of any medical procedure. Safety is the number one priority, but safety is predicated on many factors. Any increase in the number of subsequent intraocular procedures, even with ultimately good outcomes, decreases patient safety. In this survey, donor dislocations ranged from 33% to 20% depending on surgeon’s experience. The authors concluded that these numbers were in line with the previous studies and that there was no increased dislocation rate with precut tissue. I disagree with that conclusion. Although it is true that the original DSAEK papers, mine included, reported high dislocation rates consistent with the numbers in this survey, those were from seminal articles of the authors’ very first cases. Now, several years later, procedural evolution and increased numbers have reduced the present dislocation rate to single digits for experienced surgeons. One could conclude from this survey that precut tissue more than doubles the dislocation rate, which in turn decreases patient safety. To be fair, Chen and Price have reported no increased dislocation rate with precut tissue. Obviously, surgeon’s ability and technique are important factors in all aspects of DSAEK. Surgeon satisfaction should correlate with patient outcomes, especially in a retrospective survey such as the one under discussion. Ninety-eight percent of surgeons were happy with the precut tissue. Closer examination of the reported problems, however, indicates that either this group of surgeons was very easy to please or all the problems were only seen by a single surgeon. Twenty-one donor corneas (11%) required additional manual lamellar dissection by the surgeon to increase the bed size for adequate trephination size. That would make me unhappy. Fourteen cases (8%) failed, with one-third attributable to tissue-related factors. That also would not make me smile. Five donors were reported to be either totally unacceptable or too thick or too thin. I would be unhappy if I received any of those 5 donor tissues. Other annoying problems such as lack of centration mark in corneas or a free-floating anterior cap were reported. Those would be minor irritants. In totaling up all these problems, 98% of surgeons should not have been satisfied. I have never used precut tissue, but based on my discussions with both Drs Terry and Price, I believe that successful outcomes can be equally obtained with precut tissue and surgeon cut tissue. There is a level of security with precut tissue in terms of a post cut cell count and cost accountability in the rare event of an unusable donor from a poor surgeon cut. This leads us into the second half of the discussion, cost.Introduction:The impact of antiretroviral therapy (ART) on HIV-infected tuberculosis (TB) patients in public health programs in resource-limited settings is not well documented due to problems with statistical bias in observational studies. Methods:We measured the impact of ART on survival of HIV-infected TB patients in Thailand using a propensity score analysis that adjusted for factors associated with receiving ART. Results:Of 626 HIV-infected TB patients started on ART during TB treatment, 68 (11%) died compared with 295/643 (46%) of patients not prescribed ART (relative risk 0.24, 95% confidence interval: 0.19 to 0.30); in patients with very low CD4 (<10), 12/56 (21%) patients receiving ART died compared with 35/43 (81%) patients not receiving ART (relative risk 0.26, 95% confidence interval: 0.16 to 0.44). Patients treated in the private sector and in rural areas were less commonly prescribed ART. After controlling for propensity to receive ART, the hazard ratio for death among patients treated with ART was 0.17 (95% confidence interval: 0.12 to 0.24). Discussion:Patients who received ART had one sixth the risk of death of those not receiving ART. The survival benefit persisted even for those with a very low CD4 count. Expanding use of ART in HIV-infected TB patients will require increasing ART use in the private sector and rural areas.

Evaluating the potential impact of the new Global Plan to Stop TB: Thailand, 2004-2005

Tuberculosis, a potentially fatal infectious disease, affects millions of individuals annually worldwide. Human protective immunity that contains tuberculosis after infection has not been clearly defined. To gain insight into host genetic factors, nonparametric linkage analysis was performed using high-throughput microarray-based single nucleotide polymorphism (SNP) genotyping platform, a GeneChip array comprised 59 860 bi-allelic markers, in 93 Thai families with multiple siblings, 195 individuals affected with tuberculosis. Genotyping revealed a region on chromosome 5q showing suggestive evidence of linkage with tuberculosis (Z(lr) statistics=3.01, logarithm of odds (LOD) score=2.29, empirical P-value=0.0005), and two candidate regions on chromosomes 17p and 20p by an ordered subset analysis using minimum age at onset of tuberculosis as the covariate (maximum LOD score=2.57 and 3.33, permutation P-value=0.0187 and 0.0183, respectively). These results imply a new evidence of genetic risk factors for tuberculosis in the Asian population. The significance of these ordered subset results supports a clinicopathological concept that immunological impairment in the disease differs between young and old tuberculosis patients. The linkage information from a specific ethnicity may provide unique candidate regions for the identification of the susceptibility genes and further help elucidate the immunopathogenesis of tuberculosis.

Childhood TB epidemiology and treatment outcomes in Thailand: a TB active surveillance network, 2004 to 2006

OBJECTIVE WHOs new Global Plan to Stop TB 2006-2015 advises countries with a high burden of tuberculosis (TB) to expand case-finding in the private sector as well as services for patients with HIV and multidrug-resistant TB (MDR-TB). The objective of this study was to evaluate these strategies in Thailand using data from the Thailand TB Active Surveillance Network, a demonstration project begun in 2004. METHODS In October 2004, we began contacting public and private health-care facilities monthly to record data about people diagnosed with TB, assist with patient care, provide HIV counselling and testing, and obtain sputum samples for culture and susceptibility testing. The catchment area included 3.6 million people in four provinces. We compared results from October 2004-September 2005 (referred to as 2005) to baseline data from October 2002-September 2003 (referred to as 2003). FINDINGS In 2005, we ascertained 5841 TB cases (164/100 000), including 2320 new smear-positive cases (65/100 000). Compared with routine passive surveillance in 2003, active surveillance increased reporting of all TB cases by 19% and of new smear-positive cases by 13%. Private facilities diagnosed 634 (11%) of all TB cases. In 2005, 1392 (24%) cases were known to be HIV positive. The proportion of cases with an unknown HIV status decreased from 66% (3226/4904) in 2003 to 23% (1329/5841) in 2005 (P< 0.01). Of 4656 pulmonary cases, mycobacterial culture was performed in 3024 (65%) and MDR-TB diagnosed in 60 (1%). CONCLUSION In Thailand, piloting the new WHO strategy increased case-finding and collaboration with the private sector, and improved HIV services for TB patients and the diagnosis of MDR-TB. Further analysis of treatment outcomes and costs is needed to assess this programmes impact and cost effectiveness.

Social factors affecting ART adherence in rural settings in Zambia.

BackgroundOf the 9.2 million new TB cases occurring each year, about 10% are in children. Because childhood TB is usually non-infectious and non-fatal, national programs do not prioritize childhood TB diagnosis and treatment. We reviewed data from a demonstration project to learn more about the epidemiology of childhood TB in Thailand.MethodsIn four Thai provinces and one national hospital, we contacted healthcare facilities monthly to record data about persons diagnosed with TB, assist with patient care, provide HIV counseling and testing, and obtain sputum for culture and susceptibility testing. We analyzed clinical and treatment outcome data for patients age < 15 years old registered in 2005 and 2006.ResultsOnly 279 (2%) of 14,487 total cases occurred in children. The median age of children was 8 years (range: 4 months, 14 years). Of 197 children with pulmonary TB, 63 (32%) were bacteriologically-confirmed: 56 (28%) were smear-positive and 7 (4%) were smear-negative, but culture-positive. One was diagnosed with multi-drug resistant TB. HIV infection was documented in 75 (27%). Thirteen (17%) of 75 HIV-infected children died during TB treatment compared with 4 (2%) of 204 not known to be HIV-infected (p < 0.01).ConclusionChildhood TB is infrequently diagnosed in Thailand. Understanding whether this is due to absence of disease or diagnostic effort requires further research. HIV contributes substantially to the childhood TB burden in Thailand and is associated with high mortality.

Association analysis of susceptibility candidate region on chromosome 5q31 for tuberculosis

Abstract The purpose of this study was to assess the factors that influence ART adherence arising in rural settings in Zambia. A survey was conducted with face-to-face interviews using a semi-structured questionnaire and written informed consent was obtained at ART sites in Mumbwa District in rural Zambia. The questionnaire included items such as the socio-demographic characteristics of respondents, support for adherence, ways to remember when to take ARVs at scheduled times, and the current status of adherence. Valid responses were obtained from 518 research participants. The mean age of the respondents was 38.3 years and the average treatment period was 12.5 months. More than half of the respondents (51%) were farmers, about half (49%) did not own a watch, and 10% of them used the position of the sun to remember when to take ARVs. Sixteen percent of respondents experienced fear of stigma resulting from taking ARVs at work or home, and 10% felt pressured to share ARVs with someone. Eighty-eight percent of the participants reported that they had never missed ARVs in the past four days. Multivariable logistic regression analysis identified age (38 years old or less, odds ratio (OR) = 2.5, 95% confidence interval (CI): 1.3–4.8, p=0.005), “remembering when to take ARVs based on the position of the sun” (OR = 3.3, 95% CI: 1.3–8.8, p=0.016), and “feeling pressured to share ARVs with someone” (OR = 4.4, 95% CI: 1.6–12.0, p=0.004) as independent factors for low adherence. As ART services expand to rural areas, program implementers should pay more attention to more specific factors arising in rural settings since they may differ from those in urban settings.

Cross-sectional studies of tuberculosis prevalence in Cambodia between 2002 and 2011.

Chromosome 5q31 spans the T helper (Th) 2-related cytokine gene cluster, which is potentially important in Th1/Th2 immune responses. The chromosome 5q23.2–31.3 has been recently identified as a region with suggestive evidence of linkage to tuberculosis in the Asian population. With the aim of fine-mapping a putative tuberculosis susceptibility locus, we investigated a family-based association test between the dense single nucleotide polymorphism (SNP) markers within chromosome 5q31 and tuberculosis in 205 Thai trio families. Of these, 75 SNPs located within candidate genes covering SLC22A4, SLC22A5, IRF1, IL5, RAD50, IL13, IL4, KIF3A and SEPT8 were genotyped using the DigiTag2 assay. Association analysis revealed the most significant association with tuberculosis in haplotypes comprising SNPs rs274559, rs274554 and rs274553 of SLC22A5 gene (PGlobal=2.02 × 10−6), which remained significant after multiple testing correction. In addition, two haplotypes within the SLC22A4 and KIF3A region were associated with tuberculosis. Haplotypes of SLC22A5 were significantly associated with the expression levels of RAD50 and IL13. The results show that the variants carried by the haplotypes of SLC22A4, SLC22A5 and KIF3A region potentially contribute to tuberculosis susceptibility among the Thai population.

Time of highest tuberculosis death risk and associated factors: an observation of 12 years in Northern Thailand

OBJECTIVE To measure trends in the pulmonary tuberculosis burden between 2002 and 2011 and to assess the impact of the DOTS (directly observed treatment, short-course) strategy in Cambodia. METHODS Cambodias first population-based nationwide tuberculosis survey, based on multistage cluster sampling, was conducted in 2002. The second tuberculosis survey, encompassing 62 clusters, followed in 2011. Participants aged 15 years or older were screened for active pulmonary tuberculosis with chest radiography and/or for tuberculosis symptoms. For diagnostic confirmation, sputum smear and culture were conducted on those whose screening results were positive. FINDINGS Of the 40,423 eligible subjects, 37,417 (92.6%) participated in the survey; 103 smear-positive cases and 211 smear-negative, culture-positive cases were identified. The weighted prevalences of smear-positive tuberculosis and bacteriologically-positive tuberculosis were 271 (95% confidence interval, CI: 212-348) and 831 (95% CI: 707-977) per 100,000 population, respectively. Tuberculosis prevalence was higher in men than women and increased with age. A 38% decline in smear-positive tuberculosis (P = 0.0085) was observed with respect to the 2002 survey, after participants were matched by demographic and geographical characteristics. The prevalence of symptomatic, smear-positive tuberculosis decreased by 56% (P = 0.001), whereas the prevalence of asymptomatic, smear-positive tuberculosis decreased by only 7% (P = 0.7249). CONCLUSION The tuberculosis burden in Cambodia has declined significantly, most probably because of the decentralization of DOTS to health centres. To further reduce the tuberculosis burden in Cambodia, tuberculosis control should be strengthened and should focus on identifying cases without symptoms and in the middle-aged and elderly population.

Potential function of granulysin, other related effector molecules and lymphocyte subsets in patients with TB and HIV/TB coinfection.

Purpose: Northern Thailand is a tuberculosis (TB) endemic area with a high TB death rate. We aimed to establish the time of highest death risk during TB treatment, and to identify the risk factors taking place during that period of high risk. Patients and methods: We explored the TB surveillance data of the Chiang Rai province, Northern Thailand, retrospectively for 12 years. A total of 19,174 TB patients (including 5,009 deaths) were investigated from 1997 to 2008, and the proportion of deaths in each month of TB treatment was compared. Furthermore, multiple logistic regression analysis was performed to identify the characteristics of patients who died in the first month of TB treatment. A total of 5,626 TB patients from 2005 to 2008 were included in this regression analysis. Result: The numbers of deaths in the first month of TB treatment were 38%, 39%, and 46% in the years 1997–2000, 2001–2004, and 2005–2008, respectively. The first month of TB treatment is the time of the maximum number of deaths. Moreover, advancing age, HIV infection, and being a Thai citizen were significant factors contributing to these earlier deaths in the course of TB treatment. Conclusion: Our findings have pointed to the specific time period and patients at higher risk for TB death. These findings would be useful for prioritizing interventions in order to diminish TB-related deaths globally. Studies based on these findings are necessary for the introduction of newer intervention strategies.