Risk Factors For Tuberculosis Transmission Research Articles

Transmission dynamics of tuberculosis in a high-burden area of China: An 8-year population-based study using whole genome sequencing

ObjectivesThis study investigated the transmission patterns of tuberculosis (TB) and its associated risk factors in Hunan province to inform the development of prevention and control strategies in the region. MethodsAn 8-year retrospective population-based genomic epidemiological study was conducted. Genomic clusters were defined using distance thresholds of 12-single-nucletide-polymorphisms. Risk factors associated with TB transmission were analyzed using logistic regression model. Kernel Density analysis was used to locate hotspots where transmission occurred. ResultsAmong 2649 TB cases included in this study, 275 clusters were identified, with an overall clustering rate of 24.7% (654/2649). Nearly 95% (620/654) of clustered strains were isolated from the same county. Of the 275 clusters, 23 (8.4%, 23/275) had differences in drug-resistant profiles, with FQs resistance mutations occurring most frequently (52.2%, 12/23). Multivariate analysis identified male TB patients, those aged 30-60 years, ethnic minorities, nonfarmers, retreated TB patients, and individuals infected with MDR/RR-TB as independent risk factors for TB transmission (P < 0.05). Kernel density analysis showed that among the 5 drug-resistant surveillance sites, Leiyang had the highest clustering rate, followed by Yongshun, Qidong, Hecheng, and Taojiang. ConclusionRecent transmission in the region is predominantly occurring within counties. The risk factors related to TB transmission and the hotspots where transmission occurs can provide a scientific basis for the formulation of targeted TB prevention and control strategies.

Association of Mycobacterium tuberculosis infection test results with risk factors for tuberculosis transmission

BackgroundClose contacts infected with Mycobacterium tuberculosis are at high risk of tuberculosis (TB) disease and a priority for preventive treatment. Three tests measure infection: two interferon-gamma release assays (IGRAs) and the tuberculin skin test (TST). The objective of our study was to assess the association of positive test results in contacts with infectiousness of the presumed TB source case. MethodsContacts in a cohort study at 10 United States sites received both IGRAs (QuantiFERON-TB Gold In-Tube (QFT-GIT) and T-SPOT.TB (T-SPOT)) and TST. We defined test conversion as negative for all tests at baseline and positive for at least one on retest. Risk ratios (RR) and 95% confidence intervals (CI) assessed association of positive test results with increased infectiousness of the TB case—defined as acid-fast bacilli (AFB) on sputum microscopy or cavities on chest radiographs— and contact demographics. ResultsAdjusted for contacts’ age, nativity, sex, and race, IGRAs (QFT-GIT RR = 6.1, 95% CI 1.7–22.2; T-SPOT RR = 9.4, 95% CI 1.1–79.1), but not TST (RR = 1.7, 95% CI 0.8–3.7), were more likely to convert among contacts exposed to persons with cavitary TB disease. ConclusionsBecause IGRA conversions in contacts are associated with infectiousness of the TB case, their use may improve efficiency of health department contact investigations by focusing efforts on those likely to benefit from preventive treatment in the United States.

Risk-adjusted active tuberculosis case finding strategy in central Ethiopia

BackgroundThe World Health Organization recommends active case finding for tuberculosis (TB). Our study evaluated the targeted screening of household contacts (HHCs) of patients with contagious pulmonary tuberculosis (PTB) in Central Ethiopia. MethodsThe HHCs of patients with microbiologically confirmed PTB were screened for TB symptoms and risk factors for TB transmission. Symptomatic HHCs were subjected to secondary investigation. Antimicrobial resistance was investigated among study participants. ResultsOverall, 112 index patients with TB were included, and 289 HHCs from 89 households were screened. Multidrug-resistant-TB was detected in 2.7% (n=3) of index patients. The routine public health system process did not identify any TB suspects among HHCs. In total, 23.9% (n=69) of HHCs reported ≥1 TB symptom and PTB was confirmed in 2.1% (n=6). Reporting >1 TB symptom (relative risk [RR] 29.4, 95% CI 3.5−245.5, P<0.001) and night sweats (RR 27.1, 95% CI 3.2−226.6, P<0.001) were associated with the greatest relative risk. Regular alcohol consumption was identified as an individual risk factor for TB among HHCs (P=0.022). ConclusionThe MDR-TB rate among our patients was higher than recently reported for Ethiopia. Enhanced contact tracing using a risk-adjusted approach seems feasible and increases the case detection rate among HHCs of confirmed TB cases.

What Can Genetic Relatedness Tell Us About Risk Factors for Tuberculosis Transmission?

To stop tuberculosis (TB), the leading infectious cause of death globally, we need to better understand transmission risk factors. Although many studies have identified associations between individual-level covariates and pathogen genetic relatedness, few have identified characteristics of transmission pairs or explored how closely covariates associated with genetic relatedness mirror those associated with transmission. We simulated a TB-like outbreak with pathogen genetic data and estimated odds ratios (ORs) to correlate each covariate and genetic relatedness. We used a naive Bayes approach to modify the genetic links and nonlinks to resemble the true links and nonlinks more closely and estimated modified ORs with this approach. We compared these two sets of ORs with the true ORs for transmission. Finally, we applied this method to TB data in Hamburg, Germany, and Massachusetts, USA, to find pair-level covariates associated with transmission. Using simulations, we found that associations between covariates and genetic relatedness had the same relative magnitudes and directions as the true associations with transmission, but biased absolute magnitudes. Modifying the genetic links and nonlinks reduced the bias and increased the confidence interval widths, more accurately capturing error. In Hamburg and Massachusetts, pairs were more likely to be probable transmission links if they lived in closer proximity, had a shorter time between observations, or had shared ethnicity, social risk factors, drug resistance, or genotypes. We developed a method to improve the use of genetic relatedness as a proxy for transmission, and aid in understanding TB transmission dynamics in low-burden settings.

Knowledge and transmission risk awareness of tuberculosis among the pilgrims attending a religious mass gathering in India: a cross-sectional study

BackgroundTuberculosis infection accounts for more annual deaths than any other single infectious disease, except the Corona Virus infection. It is a significant global issue and India is one of the most affected countries. Religious mass gatherings congregate millions of pilgrims at one place. Over-crowding is a high-risk factor for the transmission of tuberculosis. Knowledge and awareness of the disease are proven prerequisites for the spread-prevention and early diagnosis of tuberculosis. The present study was designed to explore the knowledge of tuberculosis and awareness of disease transmission risk among pilgrims attending a religious mass gathering, the Kumbh Mela (2016) in Ujjain, India.MethodsSelf-reported data on the pilgrims’ tuberculosis-knowledge were collected using a cross-sectional study design. A contextual, pre-tested questionnaire was used, using the convenience sampling method. In addition to the anonymous descriptive analyses, a composite knowledge-score was developed to enable comparisons between demographic groups.ResultsIn total, 1665 pilgrims participated in the study with 38.8 years of mean age and 59% literacy rate. The most recognized symptoms of tuberculosis were “Cough for more than 15 days with sputum” (94%) and “Blood in sputum” (81%). Most participants knew that tuberculosis is an infectious disease (93%) and not hereditary (91%). Additionally, 84% considered it is a potentially lethal disease that requires extensive treatment. However, vaccine awareness was poor (4%). “Direct contact with tuberculosis patient” (78%) and “To be in a crowded area” (4%) were considered as the most important risk factors for tuberculosis transmission. For the composite knowledge-score, a significantly higher mean score was seen among those with at least ten years of schooling compared with illiterates (p < 0.001). Occupation and residency also affected the mean score.ConclusionMost pilgrims attending the Kumbh Mela had basic knowledge of the characteristics of tuberculosis, but some important knowledge gaps concerning the transmission risks associated with crowded situations existed. These gaps need to be addressed in future policies to enable safer mass gatherings and to end the TB epidemic, globally.

Hubungan faktor lingkungan fisik, sosial dan ekonomi dengan kejadian Tuberkulosis Paru di Kecamatan Tambang Kabupaten Kampar

Pulmonary tuberculosis is an infectious disease caused by Mycobacterium tuberculosis which mostly attacks the lungs and can also attack other organs. Tuberculosis is transmitted by smear positive tuberculosis patients, Tuberculosis germs are transmitted through the air when the patient coughs and sneezes so that the germs spread in the air in the form of droplets (sputum sparks), so people can become infected if they inhale the droplet into the respiratory tract (Ministry of Health Republic of Indonesia, 2014 ). According to Achmadi (2010) risk factors for tuberculosis transmission are environmental and behavioral factors. Environmental factors include ventilation, occupancy density, temperature, lighting and humidity. Whereas behavioral factors include smoking, spitting or sputum in any place, coughing or sneezing not closing the mouth and habit of not opening the window. Based on the results of a survey in Indonesia by the Directorate General of Communicable Disease Eradication and Environmental Health (2011), the high incidence of pulmonary TB is caused by a lack of knowledge. Knowledge of tuberculosis sufferers will affect the attitude and behavior such as throwing up spit or sputum that can be carelessly a source of transmission for people around him. Prabu in Fitriani (2013) explained that family heads who have an income below the regional minimum wage (UMR) will consume foods with nutrient levels that are not in accordance with the needs of each family member so that they have an nutritional status that is lacking and will make it easier to contract infectious diseases including Lung TB. According to WHO the number of cases of tuberculosis is ranked above HIV / AIDS. In 2016 there were an estimated 10.4 million new cases of tuberculosis or 142 cases / 100,000 population, 60% of new cases occurred in 6 (six) countries namely India, Indonesia, China, Nigeria, Pakistan and South Africa, and Indonesia ranked second (WHO Global Tuberculosis Report, 2017). Based on data on Indonesia's health profile in 2018 the number of tuberculosis cases in Indonesia in 2017 was 420,994 cases and increased in 2018 to reach 511,873 cases (Ministry of Health Republic of Indonesia, 2018). The number of pulmonary tuberculosis in Riau Province in 2018 is 11,135 cases (Ministry of Health of the Republic of Indonesia, 2018). Based on data on the health profile of Kampar Regency in 2017, tuberculosis is an environmentally-based direct infectious disease that ranks second with a total of 1,071 cases after diarrheal disease with a total of 1,076 cases. The number of positive AFB cases in 2017 in Kampar District reached 1071 cases, with the highest number of sufferers found in Tambang District, 78 cases. In 2018 the number of TB cases was 1079 cases, with the highest cases also occurring at the Tambang Health Center with a total of 67 cases and 43 new cases, followed by the Siak Hulu I Health Center with a total of 57 cases (Dinkes District Health Office, 2018). Based on this, this study aims to analyze and the risk of the relationship between the physical, social and economic environment with the incidence of pulmonary tuberculosis in Tambang District, Kampar Regency.

Baseline Assessment of Risk Factors of Presumptive Tuberculosis among under Five Children Living with an Index Client under Treatment in Mbale District, Eastern Uganda.

Background and Aims:Children in contact with adults having pulmonary Tuberculosis (TB) are vulnerable to TB infection and hence contact tracing and screening is important for early detection of infection. However, there are few contacts traced and the prevalence and risk factors for transmission are not well studied. The objective of this study was to determine the prevalence of infection and risk factors associated with TB transmission among under five children in household contact with adult pulmonary TB patients.Materials and Methods:A cross sectional study was carried out in three health facilities with a high TB burden in Mbale District, Eastern Uganda involving all under five household contacts of adults with pulmonary tuberculosis recorded in the TB register from October 2018 to March 2019 and still on treatment. Structured questionnaires were administered to the index clients to obtain their demographic and clinical data about TB, HIV as well as information on the children. Children were screened using the intensive case finding forms to identify presumptive cases.Results:The total number of index TB Clients line listed were 70. Number of clients traced was 38, 21 (%) of whom had children under five years and a total of 33 children were identified. The number of presumptive cases was 9/33 (27.27%). 77.8% of the presumptive cases were living in poorly ventilated houses.Conclusion:The study identified children with presumptive TB and various risk factors for TB transmission. Intensive contact tracing can therefore help reduce TB transmission within the communities. It is recommended to undertake studies aiming at improving contact tracing and strategies to eliminate the risk factors to TB transmission.

Using Reports of Latent Tuberculosis Infection Among Young Children to Identify Tuberculosis Transmission in New York City, 2006-2012.

The presence of latent tuberculosis infection (LTBI) in young children indicates recent tuberculosis (TB) transmission. We reviewed surveillance reports of children with LTBI to assess whether more follow-up is needed to prevent TB in this high-risk population. Data on all children under 5 years of age who were reported by health-care providers or laboratories to the New York City Department of Health during 2006-2012 were abstracted from the TB surveillance and case management system, and those with LTBI were identified. Potential source cases, defined as any infectious TB case diagnosed in the 2 years before a child was reported and whose residence was within 0.5 miles (0.8 km) of the child's residence, were identified. Neighborhood risk factors for TB transmission were examined. Among 3,511 reports of children under age 5 years, 1,722 (49%) had LTBI. The children were aged 2.9 years, on average, and most (64%) had been born in the United States. A potential source case was identified for 92% of the children; 27 children lived in the same building as a TB patient. Children with potential source cases were more likely to reside in neighborhoods with high TB incidence, poverty, and population density. The high proportion of children born in the United States and the young average age of the cases imply that undetected TB transmission occurred. Monitoring reports could be used to identify places where transmission occurred, and additional investigation is needed to prevent TB disease.

Mycobacterium tuberculosis complex transmission is not associated with recent immigration (≤ 5 years) in Florida

As tuberculosis (TB) incidence decreases in the US, foreign-born persons continue to account for a larger proportion of the burden. In these cross-sectional analyses of 1149 culture-confirmed TB cases genotyped using spoligotyping and 24-locus MIRU, we show that over a quarter of cases among the foreign-born population in Florida resulted from recent transmission of the Mycobacterium tuberculosis complex. In addition, over a third of these cases occurred among persons who had immigrated 5years or less prior to their diagnosis. Although recent immigration was not a significant predictor of TB transmission, younger age, birthplace in the Americas, homelessness, drug use and TB lineage are risk factors for TB transmission among the foreign-born population in Florida. These data provide actionable insights into TB transmission among the foreign-born population in Florida.

A four-year nationwide molecular epidemiological study in Estonia: Risk factors for tuberculosis transmission

A four-year nationwide molecular epidemiological study in Estonia: Risk factors for tuberculosis transmission

A four-year nationwide molecular epidemiological study in Estonia: risk factors for tuberculosis transmission.

Estonia has a high proportion of multidrug-resistant tuberculosis (MDR-TB). It is important to link molecular and epidemiological data to understand TB transmission patterns. To use 24-locus variable numbers of tandem repeat (VNTR) typing and national TB registry data in Estonia from 2009 to 2012 to identify the distribution of drug resistance patterns, Mycobacterium tuberculosis isolate clustering as an index for recent transmission, socio-demographic and clinical characteristics associated with recent transmission, and the distribution of transmission between index and secondary cases. A retrospective nationwide cross-sectional study. Of 912 cases with isolate and patient information, 39.1% of isolates were from the Beijing lineage. Cluster analysis identified 87 clusters encompassing 69.1% of isolates. The largest cluster comprised 178 isolates from the Beijing lineage, of which 92.1% were MDR- or extensively drug-resistant TB (XDR-TB). Factors associated with recent transmission were polyresistant TB, MDR- and XDR-TB, human immunodeficiency virus positivity, Russian ethnicity, non-permanent living situation, alcohol abuse and detention. XDR-TB cases had the highest risk of recent transmission. The majority of transmission cases involved individuals aged 30-39 years. Recent TB transmission in Estonia is high and is particularly associated with MDR- and XDR-TB and the Beijing lineage.

Three-Year Population-Based Evaluation of Standardized Mycobacterial Interspersed Repetitive-Unit-Variable-Number Tandem-Repeat Typing ofMycobacterium tuberculosis

Standardized mycobacterial interspersed repetitive-unit-variable-number tandem repeat (MIRU-VNTR) typing based on 15 and 24 loci recently has been proposed for Mycobacterium tuberculosis genotyping. So far, this optimized system has been assessed in a single, 1-year population-based study performed in Germany (M. C. Oelemann, R. Diel, V. Vatin, W. Haas, S. Rusch-Gerdes, C. Locht, S. Niemann, and P. Supply, J. Clin. Microbiol. 45:691-697, 2007). Here, we evaluated these optimized formats in a much larger population-based study conducted during 39 months in the Brussels capital region of Belgium. Isolates from 807 patients were genotyped. The resolution power, cluster, and lineage identification by the standardized MIRU-VNTR sets were compared to those obtained using standardized IS6110-restriction fragment length polymorphism (RFLP), spoligotyping, and a previous 12-MIRU-VNTR-locus set. On a subset representing 77% of the cases during a 16-month period, a high concordance was observed between unique isolates or strain clusters as defined by standardized MIRU-VNTR and IS6110-RFLP (i.e., more than five IS6110 bands). When extended to the entire population-based collection, the discriminatory subset of 15 loci decreased the strain-clustering rate by almost twofold compared to that of the old 12-locus set. The addition of the nine ancillary MIRU-VNTR loci and/or spoligotyping only slightly further decreased this strain-clustering rate. Familial, social, and/or geographic proximity links were found in 48% of the clusters identified, and well-known risk factors for tuberculosis transmission were identified. Finally, an excellent correspondence was determined between our MIRU-VNTR-spoligotyping strain identifications and external reference strain lineages included in the MIRU-VNTRplus database and identified by, e.g., large sequence polymorphisms. Our results reinforce the proposal of standardized MIRU-VNTR typing as a new reference genotyping method for the epidemiological and phylogenetic screening of M. tuberculosis strains.

Typing of Mycobacterium tuberculosis strains isolated in Community Health Centers of Rio de Janeiro City, Brazil

Fingerprinting of Mycobacterium tuberculosis strains from tuberculosis (TB) patients attended in Community Health Centers (CHCs) of Rio de Janeiro was performed to verify possible risk factors for TB transmission. A prospective community-based study was performed during the period of July 1996 to December 1996 by collecting sputum samples of 489 patients in 11 different CHCs in four different planning areas (APs) of the city. Bacteriological, clinical, and epidemiological information was collected and M. tuberculosis genotypes defined after restriction fragment length polymorphism (IS6110-RFLP) and double repetitive element (DRE) fingerprinting of RFLP-clustered cases. Risk factors for TB transmission were looked for using three levels of cluster stringency. Among 349 (71%) positive cultures obtained, IS6110-RFLP typing could be performed on strains from 153 different patients. When using identity of RFLP patterns as cluster definition, 49 (32%) of the strains belonged to a cluster and none of the clinical or epidemiologic characteristics was associated with higher clustering levels. However, higher clustering level was observed in the AP including the central region of the city when compared to others. This strongly suggests that more recent transmission occurs in that area and this may be related with higher incidence of TB and HIV in this region.

Molecular epidemiology of tuberculosis in a rural area of high prevalence in South India: implications for disease control and prevention.

Molecular and conventional epidemiologic techniques were used to study the mechanisms and risk factors for tuberculosis transmission in a rural area with high prevalence in south India. Restriction fragment length polymorphism analysis with IS6110 and direct repeat probes was performed with 378 Mycobacterium tuberculosis isolates from patients. Forty-one percent of M. tuberculosis isolates harbored a single copy of IS6110. Of 378 patients, 236 had distinct strains; 142 (38%) shared a strain with other patients, indicating recent infection. Older patients, those detected by a house-to-house community survey, and those hospitalized in a sanatorium were more likely to have had a recent infection. These findings suggest that the majority of the tuberculosis cases in south India were due to reactivation; therefore, efforts to control tuberculosis should be sustained.

Molecular fingerprinting of Mycobacterium tuberculosis and risk factors for tuberculosis transmission in Paris, France, and surrounding area.

Forty-three percent of the tuberculosis cases reported in France are from the Ile de France region. The incidence of tuberculosis in this region is 33 cases per 100,000 inhabitants, twice the national average. A restriction fragment length polymorphism (RFLP) analysis was performed with clinical isolates of Mycobacterium tuberculosis isolated during 1995 in 10 hospitals in Paris and surrounding areas to detect tuberculosis transmission and define the factors associated with clustering in this population. The molecular markers used were the insertion sequence IS6110 and the direct repeat (DR) sequence. Social, demographic, and clinical data were collected from the patients' medical files. Ten patients with isolates with a single copy of IS6110 were excluded from further analysis. Twenty-four patients with false-positive cultures due to laboratory contamination (based on RFLP analysis with IS6110 and examination of patient data) were also excluded. The study was then conducted with 272 strains isolated from 272 patients. Further fingerprinting was performed by using the DR element with strains with patterns by RFLP analysis with IS6110 that differed by one band only and strains with identical patterns by RFLP analysis with IS6110 and with low numbers of copies of IS6110. The combined use of both markers identified unique patterns for 177 strains and clustered 95 (35.7%) strains in 26 groups, each containing isolates from 2 to 12 patients. The clustering was strongly associated with homelessness and the male sex. It was not associated with age, birth in a foreign country, human immunodeficiency virus positivity, or residence in hostels or prison. Isolates from homeless people were often included in large clusters, and homeless people could be the source of tuberculosis transmission for more than 50% of the clustered patients. These results suggest that homeless people play a key role in the spread of M. tuberculosis in the community and that poor socioeconomic conditions are the main risk factors associated with active tuberculosis transmission.