Multidrug-resistant tuberculosis outbreak among US-bound Hmong refugees, Thailand, 2005

Molecular typing and drug sensitivity profiles of M. Tuberculosis isolated from refugees residing in Ethiopia

Background

Refugees in developing countries have poor access to Tuberculosis (TB) care and control services. The understanding of genetic diversity and drug sensitivity patterns of M. tuberculosis (MTB) is important for the TB control program. However, there is no evidence that shows the drug sensitivity profiles and genetic diversity of MTB circulating among refugees residing in Ethiopia. This study aimed to investigate the genetic diversity of MTB strains and lineages, and to identify the drug sensitivity profiles of MTB isolated from refugees residing in Ethiopia.

Methods

A cross-sectional study was conducted among 68 MTB positive cases isolated from presumptive TB refugees from February to August 2021. Data and samples were collected in the refugee camp clinics and both rapid TB Ag detection and region of difference (RD)-9 deletion typing were used to confirm the MTBs. Drug susceptibility test (DST) and molecular typing were done using Mycobacterium Growth Indicator Tube (MGIT) method and spoligotyping respectively.

Results

DST and spoligotyping results were available for all 68 isolates. The isolates were grouped into 25 spoligotype patterns, which consisted of 1-31 isolates with 36.8% strain diversity. The international shared type (SIT)25 was predominant spoligotype pattern consisting of 31 (45.6%) isolates, followed by SIT24 comprising 5 (7.4%) isolates. Further investigation showed that 64.7% (44/68) of the isolates were belonged to CAS1-Delhi family and 75% (51/68) of the isolates were belonged to lineage(L)-3. Multi-drug resistance (MDR)-TB was observed only in one isolate (1.5%) for first-line anti-TB drugs and the highest level of mono-resistance, 5.9% (4/68), was observed for PZA(Pyrazinamide). Mono-resistance was observed in 2.9 % (2/68) and while 97.0% (66/68) of the MTB positive cases were susceptible to the second-line anti-TB drugs.

Conclusion

The findings are useful evidence for the TB screening, treatment and control in refugee populations and surrounding communities in Ethiopia.

Multidrug-Resistant Tuberculosis in U.S.-Bound Immigrants and Refugees

Rationale: Approximately two-thirds of new cases of tuberculosis (TB) in the United States are among non-U.S.-born persons. Culture-based overseas TB screening in U.S.-bound immigrants and refugees has substantially reduced the importation of TB into the United States, but it is unclear to what extent this program prevents the importation of multidrug-resistant TB (MDR-TB). Objectives: To study the epidemiology of MDR-TB in U.S.-bound immigrants and refugees and to evaluate the effect of culture-based overseas TB screening in U.S.-bound immigrants and refugees on reducing the importation of MDR-TB into the United States. Methods: We analyzed data of immigrants and refugees who completed overseas treatment for culture-positive TB during 2015-2019. We also compared mean annual number of MDR-TB cases in non-U.S.-born persons within 1 year of arrival in the United States between 1996-2006 (when overseas screening followed a smear-based algorithm) and 2014-2019 (after full implementation of a culture-based algorithm). Results: Of 3,300 culture-positive TB cases identified by culture-based overseas TB screening in immigrants and refugees during 2015-2019, 122 (3.7%; 95% confidence interval [CI], 3.1-4.1) had MDR-TB, 20 (0.6%; 95% CI, 0.3-0.9) had rifampicin-resistant TB, 382 (11.6%; 95% CI, 10.5-12.7) had isoniazid-resistant TB, and 2,776 (84.1%; 95% CI, 82.9-85.4) had rifampicin- and isoniazid-susceptible TB. None were diagnosed with extensively drug-resistant TB. All 3,300 persons with culture-positive TB completed treatment overseas; of 70 and 11 persons who were treated overseas for MDR-TB and rifampicin-resistant TB, respectively, none were diagnosed with TB disease at postarrival evaluation in the United States. Culture-based overseas TB screening in U.S.-bound immigrants and refugees prevented 24.4 MDR-TB cases per year from arriving in the United States, 18.2 cases more than smear-based overseas TB screening. The mean annual number of MDR-TB cases among non-U.S.-born persons within 1 year of arrival in the United States decreased from 34.6 cases in 1996-2006 to 19.5 cases in 2014-2019 (difference of 15.1; P < 0.001). Conclusions: Culture-based overseas TB screening in U.S.-bound immigrants and refugees substantially reduced the importation of MDR-TB into the United States.

Detection of space–time clusters using a topological hierarchy for geospatial data on COVID-19 in Japan

In this paper, we detected space–time clusters using data on coronavirus disease 2019 (COVID-19) collected daily by each prefecture in Japan. COVID-19 has spread globally since the first confirmed case in China, in December 2019. Several people have to date been infected in Japan since the first confirmed case in January 2020. The outbreak of COVID-19 has had a significant impact on many people’s lives. Studies are being conducted to detect regions, called clusters, which pose a significantly higher risk of infection than their surrounding areas, based on a spatial scan statistics of COVID-19 infections. Among these studies, space–time cluster detection has to date been actively performed to gain knowledge regarding infection status. Based on the spatial scan statistic, the cylindrical scan method is a widely used space–time cluster detection method. This method enables concurrent detection of the location and time of a cluster occurrence. However, this method cannot capture spatial changes in a cluster over time. When applying the existing method to a cluster whose shape changes over time, the number of calculations required becomes extremely large, and the analysis may become difficult. In this study, we focused on the hierarchical structure of the data obtained by conducting an echelon analysis and applied the space–time cluster detection method based on this structure to enable the capture of changes in a cluster’s shape. Furthermore, we visualized the location and period of a cluster’s occurrence and considered the cause of the cluster.

Feasibility, acceptability, and effectiveness of non-pharmaceutical interventions against infectious diseases among crisis-affected populations: a scoping review

Background

Non-pharmaceutical interventions (NPIs) are a crucial suite of measures to prevent and control infectious disease outbreaks. Despite being particularly important for crisis-affected populations and those living in informal settlements, who typically reside in overcrowded and resource limited settings with inadequate access to healthcare, guidance on NPI implementation rarely takes the specific needs of such populations into account. We therefore conducted a systematic scoping review of the published evidence to describe the landscape of research and identify evidence gaps concerning the acceptability, feasibility, and effectiveness of NPIs among crisis-affected populations and informal settlements.

Methods

We systematically reviewed peer-reviewed articles published between 1970 and 2020 to collate available evidence on the feasibility, acceptability, and effectiveness of NPIs in crisis-affected populations and informal settlements. We performed quality assessments of each study using a standardised questionnaire. We analysed the data to produce descriptive summaries according to a number of categories: date of publication; geographical region of intervention; typology of crisis, shelter, modes of transmission, NPI, research design; study design; and study quality.

Results

Our review included 158 studies published in 85 peer-reviewed articles. Most research used low quality study designs. The acceptability, feasibility, and effectiveness of NPIs was highly context dependent. In general, simple and cost-effective interventions such as community-level environmental cleaning and provision of water, sanitation and hygiene services, and distribution of items for personal protection such as insecticide-treated nets, were both highly feasible and acceptable. Logistical, financial, and human resource constraints affected both the implementation and sustainability of measures. Community engagement emerged as a strong factor contributing to the effectiveness of NPIs. Conversely, measures that involve potential restriction on personal liberty such as case isolation and patient care and burial restrictions were found to be less acceptable, despite apparent effectiveness.

Conclusions

Overall, the evidence base was variable, with substantial knowledge gaps which varied between settings and pathogens. Based on the current landscape, robust evidence-based guidance is not possible, and a research agenda is urgently required that focusses on these specific vulnerable populations. Although implementation of NPIs presents unique practical challenges in these settings, it is critical that such an agenda is put in place, and that the lessons learned from historical and present experiences are documented to build a firm evidence base.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-022-00935-7.

Active and latent tuberculosis in refugees and asylum seekers: a systematic review and meta-analysis

Background

In 2018, there were 70.8 million refugees, asylum seekers and persons displaced by wars and conflicts worldwide. Many of these individuals face a high risk for tuberculosis in their country of origin, which may be accentuated by adverse conditions endured during their journey. We summarised the prevalence of active and latent tuberculosis infection in refugees and asylum seekers through a systematic literature review and meta-analyses by country of origin and host continent.

Methods

Articles published in Medline, EMBASE, Web of Science and LILACS from January 2000 to August 2017 were searched for, without language restriction. Two independent authors performed the study selection, data extraction and quality assessment. Random effect models were used to estimate average measures of active and latent tuberculosis prevalence. Sub-group meta-analyses were performed according to country of origin and host continent.

Results

Sixty-seven out of 767 identified articles were included, of which 16 entered the meta-analyses. Average prevalence of active and latent tuberculosis was 1331 per 100 thousand inhabitants [95% confidence interval (CI) = 542–2384] and 37% (95% CI = 23–52%), respectively, both with high level of heterogeneity (variation in estimative attributable to heterogeneity [I²] = 98.2 and 99.8%). Prevalence varied more according to countries of origin than host continent. Ninety-one per cent of studies reported routine screening of recently arrived immigrants in the host country; two-thirds confirmed tuberculosis bacteriologically. Many studies failed to provide relevant information.

Conclusion

Tuberculosis is a major health problem among refugees and asylum seekers and should be given special attention in any host continent. To protect this vulnerable population, ensuring access to healthcare for early detection for prevention and treatment of the disease is essential.

An outbreak of tuberculosis in a middle school in Henan, China: Epidemiology and risk factors

Background

In 2013, a tuberculosis (TB) outbreak occurred in a middle school in Henan province of China. An outbreak survey was carried out in the school.

Objectives

This study was undertaken to investigate the detection rate of TB cases and those with strong Mantoux positive (SMP), defined as tuberculin skin test (TST) indurations of 15mm or larger and/or blisters, necrosis or lymphangitis, and to identify their risk factors.

Methods

The TST, chest x-ray/radiography, and TB-suspicious symptoms interview were used to screen for TB cases. Their diagnosis was made by sputum smear microscopy, liquid culture, computed tomography (CT), and diagnostic therapy if necessary. We retrospectively analyzed the outbreak survey data of 4082 students and 278 staff in the school. Logistic regression models were used to identify the risk factors associated with SMP and TB disease.

Results

Approximately 3.55% of students and 16.55% of staff were SMP. SMP rate in students was significantly lower than that in staff (p<0.001). 55 TB cases in students and none in staff were identified in the school from February to November, 2013, with a detection rate of 1.35% for students. SMP and TB case detection rates were 20.29% and 41.77%, respectively, in the index class, both significantly higher than that in the other classes (3.26% and 0.55%, respectively; both p<0.001). In the index class, TB case detection rate over the study period in students with SMP was not significantly higher than that with TST indurations of <15mm (38.18% vs 21.43%, p = 0.24), but it was significantly higher in the other classes (7.81% vs 0.18%, p<0.001). Risk factors independently associated with SMP and TB cases shared the following with the index case: same dormitory-floor (adjusted odds ratio (AOR) 5.36, 95% CI 3.02–9.48, p<0.001 for SMP; AOR 2.67; 95% CI 1.03–6.96, p = 0.044 for TB cases), same classroom (AOR 4.01; 95% CI 1.95–8.26, p<0.001 for SMP; AOR 165.08; 95% CI 66.88–407.47, p<0.001 for TB cases), same teaching-floor in different classroom (AOR 5.41; 95% CI 3.02–9.71, p<0.001 for SMP; AOR 11.24; 95% CI 3.71–34.03, p<0.001 for TB cases) and same teaching-building on different floor (AOR 1.81; 95% CI 1.16–2.85, p = 0.009 for SMP; AOR 3.30; 95% CI 1.16–9.42, p = 0.025 for TB cases). The closer the contact was with the index case, the larger the AORs for SMP and TB cases were.

Conclusion

Same dormitory-floor, same classroom, same teaching-floor and same teaching-building with the index case were all risk factors for both TB infection and disease for students in the outbreak, and the closer the contact was with the index case, the higher the risk was observed. Attention should also be paid to students with TST indurations <15mm, as well as to those with that ≥15mm for the index class in dealing with the outbreak.

Exploration on the risk factors of pulmonary tuberculosis incidence in Wenchuan earthquake-stricken area

OBJECTIVE

To explore the risk factors of pulmonary tuberculosis incidence in Wenchuan earthquake-stricken area during a nine-year period of time.

METHODS

The incidence and socioeconomic indicators in the 181 counties of Sichuan province from 2004 to 2012 were collected, multilevel extra-Poisson model was performed for variable screening, and Bayesian spatiotemporal models were fitted.

RESULTS

The morbidity showed a downward time trend from 2004 to 2012. The spatiotemporal interaction model was applied with the smallest deviance information criterion. The risk factors included: county latitude (0.949, 95%CI 0.765 to 1.098), float proportion (0.368, 95%CI 0.354 to 0.380), per capita GDP (-0.225, 95%CI -0.235 to -0.216), population density (0.072, 95%CI 0.041 to 0.105), and minority inhabited area (0.302, 95%CI 0.241 to 0.372). The variation of posterior median and Bayesian credibility interval was small, and the spatiotemporal patterns were similar among different periods.

CONCLUSIONS

The incidence presented a smooth curve without bursting after the earthquake during 2004 to 2012, and with a tendency of decreasing from north to south in Sichuan province; PTB countermeasures should be focused on the migrating population and in the minority inhabited and economic underdeveloped regions. Geographical adjacent structure was an important factor and regional collaborative prevention and control should be strengthened.

Monitoring and managing antibiotic resistance in refugee children

INTRODUCTION

The past decade the Middle East and Southeastern Europe have witnessed an enormous movement of refugees due to the Syrian war and conflicts in Asia and Africa. Although carriage of and infections with multi-drug resistant (MDR) pathogens in refugees have been reported, pediatric data are scarce. Areas covered: MDR bacterial carriage and infections, and MDR-tuberculosis (TB) in refugee children from 2010. Expert commentary: High MDR carriage rates in refugee children are attributed to high pre-civil war MDR rates, war-damaged infrastructure and healthcare systems, and poor hygiene conditions. Currently there are no international guidelines about MDR screening in refugee children. Given the medical importance of MDRs, challenging therapeutics and risk of importation in non/low-endemic countries, we recommend routine screening and contact isolation upon hospitalization of refugees. TB, including MDR-TB, is highly-endemic in many Asian and African countries, however, current data in refugee children are lacking. TB Screening in refugees is widely implemented but there is no consensus on methods and target populations. Coordinated TB detection and treatment, use of rapid molecular tests and drug-susceptibility testing, better access to healthcare, cross border TB care collaboration, and protection from deportation while on treatment should be integrated parts of TB control and prevention.

Macro Trends and the Future of Public Health Practice

Public health practice in the twenty-first century is in a state of significant flux. Several macro trends are impacting the current practice of governmental public health and will likely have effects for many years to come. These macro trends are described as forces of change, which are changes that affect the context in which the community and its public health system operate. This article focuses on seven such forces of change: the Patient Protection and Affordable Care Act, public health agency accreditation, climate change, health in all policies, social media and informatics, demographic transitions, and globalized travel. Following the description of each of these, this article then turns to possible approaches to measuring, tracking, and understanding the impact of these forces of change on public health practice, including the use of evidence-based public health, practice-based research, and policy surveillance.

Spatial epidemiology and risk factors of pulmonary tuberculosis morbidity in Wenchuan earthquake-stricken area

OBJECTIVE

China is a country that experiences frequent earthquakes and has a high pulmonary tuberculosis burden. In this study, we aimed to explore the spatial clustering and risk factors of the reported incidence of pulmonary tuberculosis burden before and after the Wenchuan earthquake.

METHODS

Data on the location and the demographic, socioeconomic, and health service characteristics of the 181 counties of Sichuan province from 2004 to 2012 were collected. Global and local spatial autocorrelation analyses were performed to explore spatial clustering. The associated factors were screened using stepwise multiple linear regression, and a spatial lag model was fitted to explore the influence factors.

RESULTS

The incidence of pulmonary tuberculosis burden showed a global and local spatial autocorrelation relationship. The high-incidence counties shifted gradually over time from east to west and finally clustered in the "Aba-Ganzi" region. Factors influencing the incidence of pulmonary tuberculosis burden included minority areas, the proportion of the working population, county latitude, and the severity of the earthquake. The influence factors varied over time; the impact of minority regions, occupation, and health resources allocation weakened, whereas the economic development and mobility of the population became more significant.

CONCLUSION

The spatial structural relationship is an important factor related to pulmonary tuberculosis burden incidence. More attention should be paid to high-incidence areas and populations susceptible to pulmonary tuberculosis burden.

Evaluation of the user seal check on gross leakage detection of 3 different designs of N95 filtering facepiece respirators

Background

The use of N95 respirators prevents spread of respiratory infectious agents, but leakage hampers its protection. Manufacturers recommend a user seal check to identify on-site gross leakage. However, no empirical evidence is provided. Therefore, this study aims to examine validity of a user seal check on gross leakage detection in commonly used types of N95 respirators.

Methods

A convenience sample of 638 nursing students was recruited. On the wearing of 3 different designs of N95 respirators, namely 3M-1860s, 3M-1862, and Kimberly-Clark 46827, the standardized user seal check procedure was carried out to identify gross leakage. Repeated testing of leakage was followed by the use of a quantitative fit testing (QNFT) device in performing normal breathing and deep breathing exercises. Sensitivity, specificity, predictive values, and likelihood ratios were calculated accordingly.

Results

As indicated by QNFT, prevalence of actual gross leakage was 31.0%-39.2% with the 3M respirators and 65.4%-65.8% with the Kimberly-Clark respirator. Sensitivity and specificity of the user seal check for identifying actual gross leakage were approximately 27.7% and 75.5% for 3M-1860s, 22.1% and 80.5% for 3M-1862, and 26.9% and 80.2% for Kimberly-Clark 46827, respectively. Likelihood ratios were close to 1 (range, 0.89-1.51) for all types of respirators.

Conclusions

The results did not support user seal checks in detecting any actual gross leakage in the donning of N95 respirators. However, such a check might alert health care workers that donning a tight-fitting respirator should be performed carefully.

Prevalence of and risk factors for active tuberculosis in migrants screened before entry to the UK: a population-based cross-sectional study

BACKGROUND

An increasing number of countries with low incidence of tuberculosis have pre-entry screening programmes for migrants. We present the first estimates of the prevalence of and risk factors for tuberculosis in migrants from 15 high-incidence countries screened before entry to the UK.

METHODS

We did a population-based cross-sectional study of applicants for long-term visas who were screened for tuberculosis before entry to the UK in a pilot programme between Oct 1, 2005, and Dec 31, 2013. The primary outcome was prevalence of bacteriologically confirmed tuberculosis. We used Poisson regression to estimate crude prevalence and created a multivariable logistic regression model to identify risk factors for the primary outcome.

FINDINGS

476 455 visa applicants were screened, and the crude prevalence of bacteriologically confirmed tuberculosis was 92 (95% CI 84-101) per 100 000 individuals. After adjustment for age and sex, factors that were strongly associated with an increased risk of bacteriologically confirmed disease at pre-entry screening were self-report of close or household contact with an individual with tuberculosis (odds ratio 11·6, 95% CI 7·0-19·3; p<0·0001) and being an applicant for settlement and dependant visas (1·3, 1·0-1·6; p=0·0203).

INTERPRETATION

Migrants reporting contact with an individual with tuberculosis had the highest risk of tuberculosis at pre-entry screening. To tackle this disease burden in migrants, a comprehensive and collaborative approach is needed between countries with pre-entry screening programmes, health services in the countries of origin and migration, national tuberculosis control programmes, and international public health bodies.

FUNDING

Wellcome Trust, Medical Research Council, and UK National Institute for Health Research.

Genomic epidemiology of multidrug-resistant Mycobacterium tuberculosis during transcontinental spread

The transcontinental spread of multidrug-resistant (MDR) tuberculosis is poorly characterized in molecular epidemiologic studies. We used genomic sequencing to understand the establishment and dispersion of MDR Mycobacterium tuberculosis within a group of immigrants to the United States. We used a genomic epidemiology approach to study a genotypically matched (by spoligotype, IS6110 restriction fragment length polymorphism, and mycobacterial interspersed repetitive units-variable number of tandem repeat signature) lineage 2/Beijing MDR strain implicated in an outbreak of tuberculosis among refugees in Thailand and consecutive cases within California. All 46 MDR M. tuberculosis genomes from both Thailand and California were highly related, with a median difference of 10 single-nucleotide polymorphisms (SNPs). The Wat Tham Krabok (WTK) strain is a new sequence type distinguished from all known Beijing strains by 55 SNPs and a genomic deletion (Rv1267c) associated with increased fitness. Sequence data revealed a highly prevalent MDR strain that included several closely related but distinct allelic variants within Thailand, rather than the occurrence of a single outbreak. In California, sequencing data supported multiple independent introductions of WTK with subsequent transmission and reactivation within the state, as well as a potential super spreader with a prolonged infectious period. Twenty-seven drug resistance-conferring mutations and 4 putative compensatory mutations were found within WTK strains. Genomic sequencing has substantial epidemiologic value in both low- and high-burden settings in understanding transmission chains of highly prevalent MDR strains.

"Impact of and response to increased tuberculosis prevalence among Syrian refugees compared with Jordanian tuberculosis prevalence: case study of a tuberculosis public health strategy"

Introduction

By the summer of 2014, the Syrian crisis resulted in a regional humanitarian emergency with 2.9 million refugees, including 608,000 in Jordan. These refugees access United Nations High Commissioner for Refugees (UNHCR)-sponsored clinics or Jordan Ministry of Health clinics, including tuberculosis diagnosis and treatment. Tuberculosis care in Syria has deteriorated with destroyed health infrastructure and drug supply chain. Syrian refugees may have undiagnosed tuberculosis; therefore, the UNHCR, the International Organization for Migration (IOM), the National Tuberculosis Program (NTP), and the Centers for Disease Control and Prevention developed the Public Health Strategy for Tuberculosis among Syrian Refugees in Jordan. This case study presents that strategy, its impact, and recommendations for other neighboring countries.

Case description

UNHCR determined that World Health Organization (WHO) criteria for implementing a tuberculosis program in an emergency were met for the Syrian refugees in Jordan. Jordan NTP assessed their tuberculosis program and found that access to Syrian refugees was the one component of their program missing. Therefore, a strategy for tuberculosis control among Syrian refugees was developed. Since that development through work with IOM, UNHCR, and NTP, tuberculosis case detection among Syrian refugees is almost 40 % greater (74 cases/12 months or 1.01/100,000 monthly through June 2014 vs. 56 cases/16 months or 0.73/100,000 monthly through June 2013) using estimated population figures; more than two fold the 2012 Jordan tuberculosis incidence. Additionally, the WHO objective of curing ≥85 % of newly identified infectious tuberculosis cases was met among Syrian refugees.

Discussion and evaluation

Tuberculosis (TB) rates among displaced persons are high, but increased detection is possible. High TB rates were found among Syrian refugees through active screening and will probably persist as the Syrian crisis continues. Active screening can detect tuberculosis early and reduce risk for transmission. However, this strategy needs sustainable funding to continue and all activities have not been realized.

Conclusions

Initial assessment found that tuberculosis among Syrian refugees was at a high incidence rate. Through partnership, a cohesive Jordanian tuberculosis strategy was developed for Syrian refugees and it has potential to inform treatment and control efforts for other regional countries impacted by the Syrian crisis.

Effect of a culture-based screening algorithm on tuberculosis incidence in immigrants and refugees bound for the United States: a population-based cross-sectional study

BACKGROUND

Before 2007, immigrants and refugees bound for the United States were screened for tuberculosis (TB) by a smear-based algorithm that could not diagnose smear-negative/culture-positive TB. In 2007, the Centers for Disease Control and Prevention implemented a culture-based algorithm.

OBJECTIVE

To evaluate the effect of the culture-based algorithm on preventing the importation of TB to the United States by immigrants and refugees from foreign countries.

DESIGN

Population-based, cross-sectional study.

SETTING

Panel physician sites for overseas medical examination.

PATIENTS

Immigrants and refugees with TB.

MEASUREMENTS

Comparison of the increase of smear-negative/culture-positive TB cases diagnosed overseas among immigrants and refugees by the culture-based algorithm with the decline of reported cases among foreign-born persons within 1 year after arrival in the United States from 2007 to 2012.

RESULTS

Of the 3 212 421 arrivals of immigrants and refugees from 2007 to 2012, a total of 1 650 961 (51.4%) were screened by the smear-based algorithm and 1 561 460 (48.6%) were screened by the culture-based algorithm. Among the 4032 TB cases diagnosed by the culture-based algorithm, 2195 (54.4%) were smear-negative/culture-positive. Before implementation (2002 to 2006), the annual number of reported cases among foreign-born persons within 1 year after arrival was relatively constant (range, 1424 to 1626 cases; mean, 1504 cases) but decreased from 1511 to 940 cases during implementation (2007 to 2012). During the same period, the annual number of smear-negative/culture-positive TB cases diagnosed overseas among immigrants and refugees bound for the United States by the culture-based algorithm increased from 4 to 629.

LIMITATION

This analysis did not control for the decline in new arrivals of nonimmigrant visitors to the United States and the decrease of incidence of TB in their countries of origin.

CONCLUSION

Implementation of the culture-based algorithm may have substantially reduced the incidence of TB among newly arrived, foreign-born persons in the United States.

PRIMARY FUNDING SOURCE

None.

The movement of multidrug-resistant tuberculosis across borders in East Africa needs a regional and global solution

Kevin Cain and colleagues reflect on the cross border movement of people from Somalia with MDR-TB and the implications for MDR-TB programs in East Africa.

Reduced virulence of an extensively drug-resistant outbreak strain of Mycobacterium tuberculosis in a murine model

Bacterial drug resistance is often associated with a fitness cost. Large outbreaks of multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB have been described that predominately affect persons with HIV infection. We obtained four closely-related Mycobacterium tuberculosis strains (genotype F15/LAM4/KZN) from an outbreak in KwaZulu-Natal (KZN), South Africa, including drug-sensitive, MDR, and XDR clinical isolates. We compared the virulence of these strains in a murine model of aerosol M. tuberculosis infection for four phenotypes: (1) competitive in vivo growth in lung and spleen, (2) non-competitive in vivo growth in lung and spleen, (3) murine survival time, and (4) lung pathology. When mixtures of sensitive, MDR, and XDR KZN strains were aerosolized (competitive model), lung CFUs were similar at 60 days after infection, and spleen CFUs were ordered as follows: sensitive > MDR > XDR. When individual strains were aerosolized (non-competitive model), modest differences in lung and spleen CFUs were observed with the same ordering. C57BL/6, C3H/FeJ, and SCID mice all survived longer after infection with MDR as compared to sensitive strains. SCID mice infected with an XDR strain survived longer than those infected with MDR or sensitive strains. Lung pathology was reduced after XDR TB infection compared to sensitive or MDR TB infection. In summary, increasing degrees of drug resistance were associated with decreasing murine virulence in this collection of KZN strains as measured by all four virulence phenotypes. The predominance of HIV-infected patients in MDR and XDR TB outbreaks may be explained by decreased virulence of these strains in humans.

Lessons learned from earthquake-related tuberculosis exposures in a community shelter, Japan, 2011

BACKGROUND

Refugees and displaced populations after natural disasters have been vulnerable to tuberculosis. We report an active pulmonary tuberculosis case at a shelter and the subsequent contact investigation and review lessons learned from the 2011 Great East Japan Earthquake.

METHODS

The contact investigation was conducted to identify latent tuberculosis infection among a total of 95 contact persons, including 78 evacuees at the shelter, who were exposed to the index tuberculosis patient. The association between exposure time of contacts to a patient with active tuberculosis and results of interferon-γ release assay (IGRA) was also examined.

RESULTS

IGRA was positive in 9 (12.3%) of 73 evacuees at the shelter. Contacts who were exposed to active tuberculosis for more than 25 days were significantly more likely to be IGRA positive, compared with contacts exposed for less than 20 days. All of the 4 evacuees with latent tuberculosis infection who initiated treatment completed the regimen successfully.

CONCLUSION

When a disaster strikes and many people are living in shelters, it is essential for health care personnel to first suspect tuberculosis and implement prevention and control in collaboration with referral hospitals and public health centers.

Tuberculosis exposure among evacuees at a shelter after earthquake, Japan, 2011

Tuberculosis was diagnosed in a person who had stayed in a shelter after the 2011 Great East Japan Earthquake. A contact investigation showed that the prevalence of latent tuberculosis infection among other evacuees at the shelter was 20%. Our report underscores the importance of tuberculosis prevention and control after natural disasters.

Epidemiology and genetic diversity of multidrug-resistant tuberculosis in East Africa

Multidrug-resistant tuberculosis (MDR-TB) is an emerging problem in many parts of the world, and levels of MDR-TB among new TB patients are increasing in sub-Saharan Africa. We reviewed the prevalence and molecular epidemiology of MDR-TB in East Africa, including Burundi, Kenya, Rwanda, Tanzania, and Uganda. In 16 epidemiologic surveys, the prevalence of MDR among new cases ranges from 0.4% in Tanzania to 4.4% in Uganda, and among recurrent cases ranges from 3.9% in Tanzania to 17.7% in Uganda. There is a gap of 5948 cases between the estimated number of MDR-TB cases in East Africa and the number actually diagnosed. The only confirmed risk factors for MDR-TB are prior treatment for TB and refugee status. HIV has not been reported as a risk factor, and there are no reports of statistical association between spoligotype and drug resistance pattern. Increased capacity for diagnosis and treatment of MDR-TB is needed, with an emphasis on recurrent TB cases and refugees.

Burden of tuberculosis in indigenous peoples globally: a systematic review

BACKGROUND

The burden of tuberculosis (TB) in the estimated 370 million indigenous peoples worldwide is unknown.

OBJECTIVE

To conduct a literature review to summarize the TB burden in indigenous peoples, identify gaps in current knowledge, and provide the foundation for a research agenda prioritizing indigenous health within TB control.

METHODS

A systematic literature review identified articles published between January 1990 and November 2011 quantifying TB disease burden in indigenous populations worldwide.

RESULTS

Among the 91 articles from 19 countries included in the review, only 56 were from outside Australia, Canada, New Zealand and the United States. The majority of the studies showed higher TB rates among indigenous groups than non-indigenous groups. Studies from the Amazon generally reported the highest TB prevalence and incidence, but select populations from South-East Asia and Africa were found to have similarly high rates of TB. In North America, the Inuit had the highest reported TB incidence (156/100000), whereas the Metis of Canada and American Indians/Alaska Natives experienced rates of <10/100000. New Zealand's Maori and Pacific Islanders had higher TB incidence rates than Australian Aborigines, but all were at greater risk of developing TB than non-indigenous groups.

CONCLUSION

Where data exist, indigenous peoples were generally found to have higher rates of TB disease than non-indigenous peoples; however, this burden varied greatly. The paucity of published information on TB burden among indigenous peoples highlights the need to implement and improve TB surveillance to better measure and understand global disparities in TB rates.

A tuberculosis outbreak among senior high school students in China in 2011

OBJECTIVE

An outbreak of pulmonary tuberculosis (PTB) occurred in students attending Licai Training School, Gujiao City, China, in early 2011. The epidemic characteristics and possible contributory factors relating to the spread of this outbreak of PTB were studied in a field investigation and are reported here.

METHODS

Cases were detected by PTB symptom screening, tuberculin skin testing (TST), chest X-radiography, and examination of sputum smears and cultures for all students, school staff and close family contacts of patients with PTB.

RESULTS

Of the 287 students attending the school, 45 (15.7%) were diagnosed with PTB and two (0.7%) had a positive smear. No PTB was found among staff and close family contacts. Prevalence was high in Science Class 27 and the two floors of the dormitory building where the smear-positive TB patients studied and lived. The frequency of strong TST positivity was also high in Science Class 27 and among close contacts living in the same dormitories as the PTB patients.

CONCLUSIONS

Several avoidable factors likely to have enhanced disease transmission were identified and several recommendations are made to reduce the risk of future TB outbreaks in schools.

What we are watching--five top global infectious disease threats, 2012: a perspective from CDC's Global Disease Detection Operations Center

Disease outbreaks of international public health importance continue to occur regularly; detecting and tracking significant new public health threats in countries that cannot or might not report such events to the global health community is a challenge. The Centers for Disease Control and Prevention's (CDC) Global Disease Detection (GDD) Operations Center, established in early 2007, monitors infectious and non-infectious public health events to identify new or unexplained global public health threats and better position CDC to respond, if public health assistance is requested or required. At any one time, the GDD Operations Center actively monitors approximately 30-40 such public health threats; here we provide our perspective on five of the top global infectious disease threats that we were watching in 2012: 1 avian influenza A (H5N1), 2 cholera, 3 wild poliovirus, 4 enterovirus-71, and 5 extensively drug-resistant tuberculosis11†Current address: Division of Integrated Biosurveillance, Armed Forces Health Surveillance Center, US Department of Defense, Silver Spring, MD, USA.

Adverse events in healthy individuals and MDR-TB contacts treated with anti-tuberculosis drugs potentially effective for preventing development of MDR-TB: a systematic review

A recent systematic review concluded that there is insufficient evidence on the effectiveness to support or reject preventive therapy for treatment of contacts of patients with multidrug resistant tuberculosis (MDR-TB). Whether preventive therapy is favorable depends both on the effectiveness and the adverse events of the drugs used. We performed a systematic review to assess adverse events in healthy individuals and MDR-TB contacts treated with anti-tuberculosis drugs potentially effective for preventing development of MDR-TB. We searched MEDLINE, EMBASE, and other databases (August 2011). Record selection, data extraction, and study quality assessment were done in duplicate. The quality of evidence was assessed using the GRADE approach. Of 6,901 identified references, 20 studies were eligible. Among the 16 studies in healthy volunteers (a total of 87 persons on either levofloxacin, moxifloxacin, ofloxacin, or rifabutin, mostly for 1 week), serious adverse events and treatment discontinuation due to adverse events were rare (<1 and <5%, respectively), but mild adverse events frequently occurred. Due to small sample sizes of the levofloxacin and ofloxacin studies an increased frequency of mild adverse events compared to placebo could not be demonstrated or excluded. For moxifloxacin the comparative results were inconsistent. In four studies describing preventive therapy of MDR-TB contacts, therapy was stopped for 58–100% of the included persons because of the occurrence of adverse events ranging from mild adverse events such as nausea and dizziness to serious events requiring treatment. The quality of the evidence was very low. Although the number of publications and quality of evidence are low, the available evidence suggests that shortly after starting treatment the occurrence of serious adverse events is rare. Mild adverse events occur more frequently and may be of importance because these may provoke treatment interruption.

Nosocomial transmission of extensively drug-resistant tuberculosis in a rural hospital in South Africa

BACKGROUND

Extensively drug-resistant tuberculosis (XDR-tuberculosis) is a global public health threat, but few data exist elucidating factors driving this epidemic. The initial XDR-tuberculosis report from South Africa suggested transmission is an important factor, but detailed epidemiologic and molecular analyses were not available for further characterization.

METHODS

We performed a retrospective, observational study among XDR-tuberculosis patients to identify hospital-associated epidemiologic links. We used spoligotyping, IS6110-based restriction fragment-length polymorphism analysis, and sequencing of resistance-determining regions to identify clusters. Social network analysis was used to construct transmission networks among genotypically clustered patients.

RESULTS

Among 148 XDR-tuberculosis patients, 98% were infected with human immunodeficiency virus (HIV), and 59% had smear-positive tuberculosis. Nearly all (93%) were hospitalized while infectious with XDR-tuberculosis (median duration, 15 days; interquartile range: 10-25 days). Genotyping identified a predominant cluster comprising 96% of isolates. Epidemiologic links were identified for 82% of patients; social network analysis demonstrated multiple generations of transmission across a highly interconnected network.

CONCLUSIONS

The XDR-tuberculosis epidemic in Tugela Ferry, South Africa, has been highly clonal. However, the epidemic is not the result of a point-source outbreak; rather, a high degree of interconnectedness allowed multiple generations of nosocomial transmission. Similar to the outbreaks of multidrug-resistant tuberculosis in the 1990s, poor infection control, delayed diagnosis, and a high HIV prevalence facilitated transmission. Important lessons from those outbreaks must be applied to stem further expansion of this epidemic.

Mathematical models of the epidemiology and control of drug-resistant TB

Recent reports of extensively drug-resistant TB in South Africa have renewed concerns that antibiotic resistance may undermine progress in TB control. We review three major questions for which mathematical models elucidate the epidemiology and control of drug-resistant TB. How is multiple drug-resistant Mycobacterium tuberculosis selected for in individuals exposed to combination chemotherapy? What factors determine the prevalence of drug-resistant TB? Which interventions to prevent the spread of drug-resistant TB are effective and feasible? Models offer insight into the acquisition and amplification of drug resistance, reveal the importance of distinguishing the intrinsic and extrinsic determinants of the reproductive capacity of drug-resistant M. tuberculosis, and demonstrate the cost effectiveness of interventions for drug-resistant TB. These models also highlight knowledge gaps for which new research will improve our ability to project trends of drug resistance and develop more effective policies for its control.

Spatial and temporal distribution of tuberculosis in the State of Mexico, Mexico

Tuberculosis (TB) is one of the oldest human diseases that still affects large population groups. According to the World Health Organization (WHO), there were approximately 9.4 million new cases worldwide in the year 2010. In Mexico, there were 18,848 new cases of TB of all clinical variants in 2010. The identification of clusters in space-time is of great interest in epidemiological studies. The objective of this research was to identify the spatial and temporal distribution of TB during the period 2006–2010 in the State of Mexico, using geographic information system (GIS) and SCAN statistics program. Nine significant clusters (P < 0.05) were identified using spatial and space-time analysis. The conclusion is that TB in the State of Mexico is not randomly distributed but is concentrated in areas close to Mexico City.

Assessing spatiotemporal patterns of multidrug-resistant and drug-sensitive tuberculosis in a South American setting

We examined the spatiotemporal distribution of laboratory-confirmed multidrug-resistant tuberculosis (MDR TB) cases and that of other TB cases in Lima, Peru with the aim of identifying mechanisms responsible for the rise of MDR TB in an urban setting. All incident cases of TB in two districts of Lima, Peru during 2005-2007 were included. The spatiotemporal distributions of MDR cases and other TB cases were compared with Ripley's K statistic. Of 11,711 notified cases, 1187 received drug susceptibility testing and 376 were found to be MDR. Spatial aggregation of patients with confirmed MDR disease appeared similar to that of other patients in 2005 and 2006; however, in 2007, cases with confirmed MDR disease were found to be more tightly grouped. Subgroup analysis suggests the appearance of resistance may be driven by increased transmission. Interventions should aim to reduce the infectious duration for those with drug-resistant disease and improve infection control.

Determinants of multidrug-resistant tuberculosis clusters, California, USA, 2004-2007

Laboratory and epidemiologic evidence suggests that pathogen-specific factors may affect multidrug-resistant (MDR) tuberculosis (TB) transmission and pathogenesis. To identify demographic and clinical characteristics of MDR TB case clustering and to estimate the effect of specific isoniazid resistance-conferring mutations and strain lineage on genotypic clustering, we conducted a population-based cohort study of all MDR TB cases reported in California from January 1, 2004, through December 31, 2007. Of 8,899 incident culture-positive cases for which drug susceptibility information was available, 141 (2%) were MDR. Of 123 (87%) strains with genotype data, 25 (20%) were aggregated in 8 clusters; 113 (92%) of all MDR TB cases and 21 (84%) of clustered MDR TB cases occurred among foreign-born patients. In multivariate analysis, the katG S315T mutation (odds ratio 11.2, 95% confidence interval 2.2-Yen; p = 0.004), but not strain lineage, was independently associated with case clustering.

Utilizing spatiotemporal analysis of influenza-like illness and rapid tests to focus swine-origin influenza virus intervention

In the spring of 2009, a novel strain of H1N1 swine-origin influenza A virus (S-OIV) emerged in Mexico and the United States, and soon after was declared a pandemic by the World Health Organization. This work examined the ability of real-time reports of influenza-like illness (ILI) symptoms and rapid influenza diagnostic tests (RIDTs) to approximate the spatiotemporal distribution of PCR-confirmed S-OIV cases for the purposes of focusing local intervention efforts. Cluster and age adjusted relative risk patterns of ILI, RIDT, and S-OIV were assessed at a fine spatial scale at different time and space extents within Cameron County, Texas on the US-Mexico border. Space-time patterns of ILI and RIDT were found to effectively characterize the areas with highest geographical risk of S-OIV within the first two weeks of the outbreak. Based on these results, ILI and/or RIDT may prove to be acceptable indicators of the location of S-OIV hotspots. Given that S-OIV data is often difficult to obtain real-time during an outbreak; these findings may be of use to public health officials targeting prevention and response efforts during future flu outbreaks.

A scan statistic for continuous data based on the normal probability model

Temporal, spatial and space-time scan statistics are commonly used to detect and evaluate the statistical significance of temporal and/or geographical disease clusters, without any prior assumptions on the location, time period or size of those clusters. Scan statistics are mostly used for count data, such as disease incidence or mortality. Sometimes there is an interest in looking for clusters with respect to a continuous variable, such as lead levels in children or low birth weight. For such continuous data, we present a scan statistic where the likelihood is calculated using the the normal probability model. It may also be used for other distributions, while still maintaining the correct alpha level. In an application of the new method, we look for geographical clusters of low birth weight in New York City.