Plasmonic gratings with nano-protrusions made by glancing angle deposition for single-molecule super-resolution imaging

Super-resolution imaging has been advantageous in studying biological and chemical systems, but the required equipment and platforms are expensive and unable to observe single-molecules at the high (μM) fluorophore concentrations required to study protein interaction and enzymatic activity. Here, a plasmonic platform was designed that utilized an inexpensively fabricated plasmonic grating in combination with a scalable glancing angle deposition (GLAD) technique using physical vapor deposition. The GLAD creates an abundance of plasmonic nano-protrusion probes that combine the surface plasmon resonance (SPR) from the periodic gratings with the localized SPR of these nano-protrusions. The resulting platform enables simultaneous imaging of a large area without point-by-point scanning or bulk averaging for the detection of single Cyanine-5 molecules in dye concentrations ranging from 50 pM to 10 μM using epifluorescence microscopy. Combining the near-field plasmonic nano-protrusion probes and super-resolution technique using localization microscopy, we demonstrate the ability to resolve grain sizes down to 65 nm. This plasmonic GLAD grating is a cost-effective super-resolution imaging substrate with potential applications in high-speed biomedical imaging over a wide range of fluorescent concentrations.

Epilepsy in patients with primary brain tumors: The impact on mood, cognition, and HRQOL

BACKGROUND

A primary brain tumor (PBT) is often a fatal disease of the nervous system and has a serious impact on health-related quality of life (HRQOL). Presence of epilepsy and adverse reactions from tumor and epilepsy treatments may cause additional decline in HRQOL.

OBJECTIVES

We aimed to study the impact of epileptic seizures on cognition, mood, and HRQOL in patients with brain tumor-related epilepsy.

MATERIALS AND METHOD

Patients were grouped on an ordinal scale according to epilepsy burden from none to severe based on the presence of epileptic seizures and seizure frequency: L1, no epilepsy; L2, with epilepsy, seizure-free in the last 6 months with antiepileptic drugs; and L3, with epilepsy, at least one seizure in the last 6 months with AEDs. Health-related quality of life was measured by Functional Assessment of Cancer Therapy-Brain (FACT-Br) and Quality of Life in Epilepsy-31 (QOLIE-31) tools, cognition by the Montreal Cognitive Assessment (MoCA) tool and Frontal Assessment Battery (FAB), mood by the Hospital Anxiety and Depression Scale (HADS), activities of daily living (ADLs) by the Barthel Index (BI), and performance status by the Karnofsky Performance Status (KPS) scale in patients with primary brain tumors at least one month following neurosurgery with or without radiotherapy and chemotherapy.

RESULTS

Eighty-one patients with a diagnosis of primary brain tumors were recruited. Sixty-eight percent of patients were diagnosed with primary brain tumor-related epilepsy, 50.61% patients had cognitive impairment, 33% had abnormal scores in the anxiety scale, and 34% had abnormal scores in the depression scale. There were no statistically significant differences in these scores among L1, L2, and L3 groups. There were statistically significant differences in duration of disease and KPS and BI scores between L1 and L3 groups. The L3 group has significantly longer duration of disease and scored low in both the BI and KPS scale when compared to the L1 group. All patients with primary brain tumors scored significantly low in FACT-Br 'physical well-being' (PWB) and 'emotional well-being' (EWB) and high in 'social well-being' (SWB) when compared to healthy controls. When scores of each group were individually compared to healthy controls, the L3 group showed the lowest scores in PWB, EWB, and 'functional well-being'. In SWB, L1 and L2 groups showed statistically significantly high scores when compared to normative data. The QOLIE-31 applied to groups with epilepsy showed statistically significantly lower scores in the L3 group when compared to the L2 group in 'cognitive' and 'social functioning' domains. On multivariate analysis, both poor performance status and frequency of seizures were found to be independent risk factors for poor HRQOL when FACT-Br mean scores were compared. Level of seizures was found to be an independent risk factor for poor HRQOL when QOLIE-31 scores were compared between L2 and L3 groups.

DISCUSSION

Presence of brain tumors could be attributed to cognitive impairment irrespective of the presence of epilepsy in our cohort. High seizure burden is an independent risk factor for poor HRQOL in patients with primary brain tumors. The QOLIE-31 is a more sensitive tool than the FACT-Br because of the presence of a seizure-related questionnaire.

Treatment of symptomatic coral reef aorta with an uncovered stent graft

Coral reef aorta is a rare condition characterised by extreme calcific growths affecting the juxta and suprarenal aorta. It can cause symptoms due to visceral ischaemia, lower limb hypoperfusion, and distal embolisation. We present a case of a 61-year-old man with unresponsive hypertension, who was found to have an occluded right renal artery, and an extensive coral reef aorta with a marked pressure gradient across the lesion. Renal hypoperfusion secondary to aortic coral reef aorta was thought to be the cause for his hypertension. Endovascular placement of a balloon expandable uncovered stent resolved his hypertension within one month, with no adverse effects noted at subsequent follow-up. Endovascular treatment of coral reef aorta is technically possible and avoids a major vascular procedure.

A comparative study of the iron status of patients with oesophageal adenocarcinoma to determine suitability for a clinical trial of iron chelation therapy

INTRODUCTION

The incidence of oesophageal adenocarcinoma (OAC) is rising dramatically and overall survival remains extremely poor. Iron has been shown to potentiate tumourigenesis in OAC, and iron chelation therapy demonstrates promise in vivo as an adjunct to neoadjuvant and palliative chemotherapy. OAC, however, has traditionally been associated with iron deficiency anaemia. The aim of this study was therefore to formally quantify the iron status of OAC patients in order to guide the design of future clinical trials involving iron chelation therapy.

METHODS

Demographic and cancer specific data were collected prospectively from all patients presenting with OAC and gastric adenocarcinoma (GAC). Patients had haemoglobin, serum iron, serum ferritin and serum transferrin receptor (sTfR) levels measured to assess systemic iron status. In addition, the sTfR/log ferritin (sTfR-F) index was calculated.

RESULTS

Average haemoglobin, serum iron, serum ferritin, sTfR and sTfR-F index values for all patients presenting with OAC were within normal sex specific reference ranges. No statistical difference in iron status was observed between OAC patients presenting with resectable and advanced OAC. Patients with OAC are relatively iron replete compared with those presenting with GAC. Iron parameters were not significantly altered by standard neoadjuvant chemotherapy.

CONCLUSIONS

Patients presenting with resectable or advanced OAC could be considered as candidates for a clinical trial of iron chelation therapy as an addition to standard neoadjuvant or palliative treatments.

Progress on obesity prevention over 20 years in Australia and New Zealand

The lessons learned from over 20 years of obesity prevention efforts in Australia and New Zealand are presented. The obesity epidemic started in the 1980s but poor monitoring systems meant the rise in obesity prevalence initially went undetected. In the 1990 s, experts started advocating for government action; however, it was the rapid increase in media reports on obesity in the early 2000s which created the pressure for action. Several, comprehensive reports produced some programme investment but no regulatory policies were implemented. The powerful food industry lobby ensured this lack of policies on front-of-pack food labelling, restrictions on unhealthy food marketing to children, or taxes on unhealthy foods. The New Zealand government even backpedalled by rescinding healthy school food guidelines and withdrawing funding for the comprehensive national obesity strategy. In 2007, Australian Governments started a major long term-investment in preventive health in order to improve economic productivity. Other positive initiatives, especially in Australia, were: the establishment of several advocacy organizations; successful, long-term, whole-of-community projects reducing childhood obesity; a national knowledge exchange system for practitioners; and some innovative programmes and social marketing. However, despite multiple reports and strong advocacy, key recommended regulatory policies remain unimplemented, largely due to the private sector interests dominating public policy development.

Monitoring the health-related labelling of foods and non-alcoholic beverages in retail settings

Food labelling on food packaging has the potential to have both positive and negative effects on diets. Monitoring different aspects of food labelling would help to identify priority policy options to help people make healthier food choices. A taxonomy of the elements of health-related food labelling is proposed. A systematic review of studies that assessed the nature and extent of health-related food labelling has been conducted to identify approaches to monitoring food labelling. A step-wise approach has been developed for independently assessing the nature and extent of health-related food labelling in different countries and over time. Procedures for sampling the food supply, and collecting and analysing data are proposed, as well as quantifiable measurement indicators and benchmarks for health-related food labelling.

Review of Eastern coral snake (Micrurus fulvius fulvius) exposures managed by the Florida Poison Information Center Network: 1998-2010

CONTEXT

Envenomation by the Eastern coral snake is rare but may be associated with significant morbidity. While effective, acquisition of North American Coral Snake Antivenin (NACSAV) is difficult because production was discontinued for many years.

OBJECTIVE

The purpose of this study is to characterize coral snake exposures in Florida and determine the effects of varying treatment paradigms on patient outcomes.

METHODS

This study is an observational case series of cases received at Florida poison centers. Included cases were Eastern coral snake exposures occurring between January 1, 1998 and October 31, 2010. Excluded cases included those found to be unrelated or those not followed for at least 24 h post envenomation. Case comments were reviewed to obtain data. Comparisons were made between asymptomatic patients receiving empiric antivenom therapy (empiric group) and those asymptomatic patients who received antivenom upon developing signs of systemic envenomation (withhold group).

RESULTS

Of the 553 cases identified, 387 were included in the final analysis. According to case comments, 56.3% of patients had no reported systemic symptoms. Most commonly, patients were reported to have pain (40.6%), paresthesias (28.4%), nausea (12.7%), and emesis (11.4%). NACSAV was administered to 252 patients (65%). Of those patients receiving NACSAV, 18.25% were reported to have had an adverse reaction. Patients in the withhold group (n = 106) had significantly fewer minor, moderate, and major outcomes than patients in the empiric group (n = 134, p < 0.01).

DISCUSSION

While patients in the withhold group had favorable outcomes compared with those in the empiric group, this strategy cannot be applied to all patients presenting asymptomatic to healthcare facilities due to study limitations.

CONCLUSION

Further studies are needed to determine what treatment strategy is most appropriate for asymptomatic patients presenting to healthcare facilities.

Long-lasting neuroprotection and neurological improvement in stroke models with new, potent and brain permeable inhibitors of poly(ADP-ribose) polymerase

BACKGROUND AND PURPOSES

Thienyl-isoquinolone (TIQ-A) is a relatively potent PARP inhibitor able to reduce post-ischaemic neuronal death in vitro. Here we have studied, in different stroke models in vivo, the neuroprotective properties of DAMTIQ and HYDAMTIQ, two TIQ-A derivatives able to reach the brain and to inhibit PARP-1 and PARP-2.

EXPERIMENTAL APPROACH

Studies were carried out in (i) transient (2 h) middle cerebral artery occlusion (tMCAO), (ii) permanent MCAO (pMCAO) and (iii) electrocoagulation of the distal portion of MCA in conjunction with transient (90 min) bilateral carotid occlusion (focal cortical ischaemia).

KEY RESULTS

In male rats with tMCAO, HYDAMTIQ (0.1-10 mg·kg(-1)) injected i.p. three times, starting 4 h after MCAO, reduced infarct volumes by up to 70%, reduced the loss of body weight by up to 60% and attenuated the neurological impairment by up to 40%. In age-matched female rats, HYDAMTIQ also reduced brain damage. Protection, however, was less pronounced than in the male rats. In animals with pMCAO, HYDAMTIQ administered 30 min after MCAO reduced infarct volumes by approximately 40%. In animals with focal cortical ischaemia, HYDAMTIQ treatment decreased post-ischaemic accumulation of PAR (the product of PARP activity) and the presence of OX42-positive inflammatory cells in the ischaemic cortex. It also reduced sensorimotor deficits for up to 90 days after MCAO.

CONCLUSION AND IMPLICATIONS

Our results show that HYDAMTIQ is a potent PARP inhibitor that conferred robust neuroprotection and long-lasting improvement of post-stroke neurological deficits.

Differences in hepatitis B infection rate between ethnic groups in antenatal women in Birmingham, United Kingdom, May 2004 to December 2008

Hepatitis B virus (HBV) is a major cause of morbidity and mortality worldwide. Although the United Kingdom (UK) prevalence of HBV is low, it is increasing. There is some evidence that the rate of infection is much higher in some populations living in Britain of non-white ethnicity or who were not born in Britain, compared with the British-born white population. We examined the prevalence of HBV infection in pregnant women through hepatitis B surface antigen (HBsAg) or e-antigen (HBeAg) in Birmingham UK between May 2004 and December 2008 and the effect of ethnicity on the relative risk of infection. There was a significant increase in the number of antenatal HBV infections detected over the study period from 106 cases in 2005 to 161 cases in 2008 (p=0.037). Women who define themselves as of black African, non-British white and Pakistani ethnicity had a markedly elevated rate of HBV infection (relative risk (RR): 11.25, 5.87 and 2.33 respectively) compared to the England average. Health organisations that serve populations with a high or increasing proportion of women originating from intermediate and high HBV prevalence areas of the world such as Africa, some parts of Europe and Asia, should anticipate a need for perinatal and postnatal prophylaxis to children born to HBV infected mothers.

Differences in hepatitis B infection rate between ethnic groups in antenatal women in Birmingham, United Kingdom, May 2004 to December 2008

Hepatitis B virus (HBV) is a major cause of morbidity and mortality worldwide. Although the United Kingdom (UK) prevalence of HBV is low, it is increasing. There is some evidence that the rate of infection is much higher in some populations living in Britain of non-white ethnicity or who were not born in Britain, compared with the British-born white population. We examined the prevalence of HBV infection in pregnant women through hepatitis B surface antigen (HBsAg) or e-antigen (HBeAg) in Birmingham UK between May 2004 and December 2008 and the effect of ethnicity on the relative risk of infection. There was a significant increase in the number of antenatal HBV infections detected over the study period from 106 cases in 2005 to 161 cases in 2008 (p=0.037). Women who define themselves as of black African, non-British white and Pakistani ethnicity had a markedly elevated rate of HBV infection (relative risk (RR): 11.25, 5.87 and 2.33 respectively) compared to the England average. Health organisations that serve populations with a high or increasing proportion of women originating from intermediate and high HBV prevalence areas of the world such as Africa, some parts of Europe and Asia, should anticipate a need for perinatal and postnatal prophylaxis to children born to HBV infected mothers.

Expression of fat mobilizing genes in human epicardial adipose tissue

BACKGROUND

Epicardial adipose tissue (EAT) mass correlates with metabolic syndrome and coronary artery disease (CAD). However, little is known about the expression of genes involved in triglyceride (TG) storage and mobilization in EAT. We therefore analyzed the expression of genes involved in fat mobilization in EAT in comparison to subcutaneous abdominal adipose tissue (AAT) in CAD patients and in controls.

METHODS

EAT and AAT were obtained during coronary artery bypass graft (CABG) surgery from 16 CAD patients and from 14 non-CAD patients presenting for valve surgery. The state of atherosclerosis was assessed by angiography. RNA from tissues were extracted, reversibly transcribed and quantified by real time polymerase chain reaction (RT-PCR). The following genes were analyzed: perilipin-1 and -5 (PLIN1, PLIN5), lipoprotein lipase (LPL), hormone sensitive lipase (HSL), adipose triglyceride lipase (ATGL), comparative gene identification-58 (CIG-58), angiopoietin like protein 4 (ANGPTL4), in addition to interleukine-6 (IL-6), leptin (LEP) and adiponectin (ADPN).

RESULTS

A significant expression of all listed genes could be observed in EAT. The relative expression pattern of the 10 genes in EAT was comparable to the expression in AAT, yet there was a significantly higher overall expression in AAT. The expression of the listed genes was not different between CAD patients and controls.

CONCLUSION

It is suggested that the postulated difference in EAT volume between CAD patients and non-CAD patients is not caused by a differential mRNA expression of fat mobilizing genes. Further work on protein levels and enzyme activities will be necessary to get a complete picture.

Size and shape of the corpus callosum in adult Niemann-Pick type C reflects state and trait illness variables

BACKGROUND AND PURPOSE

Variable alterations to the structure of the corpus callosum have been described in adults with NPC, a neurometabolic disorder known to result in both white and gray matter pathology. This study sought to examine the structure of the callosum in a group of adult patients with NPC and compared callosal structure with a group of matched controls, and to relate callosal structure with state and trait illness variables.

MATERIALS AND METHODS

Nine adult patients with NPC were matched to control subjects (n = 26) on age and sex. The corpus callosum was segmented from the midsagittal section of T1-weighted images on all subjects, and total area, length, bending angle, and mean thickness were calculated. In addition, 39 regional thickness measures were derived by using a previously published method. All measures were compared between groups, and analyzed alongside symptom measures, biochemical parameters, and ocular-motor measures.

RESULTS

The callosal area and mean thickness were significantly reduced in the patient group, and regional thickness differences were greatest in the genu, posterior body, isthmus, and anterior splenium. Global callosal measures correlated significantly with duration of illness and symptom score, and at trend level with degree of filipin staining. Measures of reflexive saccadic peak velocity and gain, and self-paced saccades, correlated strongly with total callosal area.

CONCLUSIONS

Callosal structure and size reflect both state and trait markers in adult NPC, and they may be useful biomarkers to index both white and gray matter changes that reflect illness severity and progression.

Prevalence and nature of anaemia in a prospective, population-based sample of people with diabetes: Teesside anaemia in diabetes (TAD) study

AIMS

Anaemia occurs in 25% of people attending hospital diabetes clinics, but this may not be representative of all people with diabetes. We aimed to determine the prevalence of anaemia in a prospective population-based sample stratified by estimated glomerular filtration rate (eGFR) using the 4-point Modification of Diet in Renal Disease (MDRD) formula.

METHODS

All 7331 patients on our district register were stratified by eGFR. Seven hundred and thirty were approached by letter on two occasions. Two hundred and thirty-four (32%) returned questionnaires and blood samples. Responders (R), non-responders (NR) and the whole cohort (C) were similar: mean +/- sd age R 61.7 +/- 12.7 years; NR 61.3 +/- 15.1 years; C 61.8 +/- 14.2 years; diabetes duration R 8.8 +/- 8.6 years; NR 8.2 +/- 7.9 years; C 7.5 +/- 7.8 years, Type 1 diabetes R 10.1%, NR 10.8%, C 9.4%. Anaemia was defined using World Health Organization criteria: haemoglobin < 13 g/dl for men, < 12 g/dl for women.

RESULTS

Previously undiagnosed anaemia was present in 15% of the whole group, 36% with eGFR < 60 ml/min per 1.73 m(2) and 9% of those with eGFR > 60 ml/min per 1.73 m(2). Anaemia was as a result of erythropoietin deficiency in 34%, abnormal haematinics in 40% and was unexplained in 26% of patients. Five per cent of the patients had anaemia below the treatment threshold of 11 g/dl.

CONCLUSIONS

The prevalence of unrecognized anaemia in population-based cohorts is lower than that in hospital-based studies. Current clinical surveillance in the UK is failing to detect anaemia in stage 3-5 chronic kidney disease (eGFR < 60 ml/min per 1.73 m(2)) and current guidelines will not detect 9% of diabetic patients with anaemia and an eGFR > 60 ml/min per 1.73 m(2).

White and gray matter alterations in adults with Niemann-Pick disease type C: a cross-sectional study

OBJECTIVE

Niemann-Pick disease type C (NPC) is a progressive neurovisceral disorder with disrupted intracellular cholesterol metabolism that results in significant alterations to neuronal and axonal structure. Adult patients present with ataxia, gaze palsy, impaired cognition, and neuropsychiatric illness, but the neural substrate has not been well-characterized in vivo. Our aim was to investigate a well-characterized sample of adults with confirmed NPC for gray and white matter abnormalities.

METHODS

We utilized a combination of optimized voxel-based morphometry of T1-weighted images and tract-based spatial statistics of diffusion tensor images to examine gray matter volume and white matter structural differences in 6 adult patients with NPC and 18 gender- and age-matched controls.

RESULTS

Patients with NPC demonstrated bilateral gray matter reductions in large clusters in bilateral hippocampus, thalamus, superior cerebellum, and insula, in addition to smaller regions of inferoposterior cortex. Patients demonstrated widespread reductions in fractional anisotropy in major white matter tracts. Subsequent analysis of measures of axial and radial diffusivity suggest that these changes are contributed to by both impaired myelination and altered axonal structure.

CONCLUSIONS

Findings in gray matter areas are broadly consistent with human and animal studies of selective vulnerability of neuronal populations to the neuropathology of NPC, whereas more widespread white matter changes are consistent with the hypothesis that disrupted myelination and axonal structure predate changes to the neuronal cell body. These findings suggest that volumetric analysis of gray matter and diffusion tensor imaging may be useful modalities for indexing illness stage and monitoring response to emerging treatment.

First Report of Leaf Rust of Blueberry Caused by Thekopsora minima on Vaccinium corymbosum in the Western Cape, South Africa

Southern highbush blueberry plants (Vaccinium corymbosum interspecific hybrids) showing rust-like symptoms were observed in July 2006 in Porterville in the Western Cape (WC), South Africa. Diseased plants were also found in Villiersdorp and George in the WC in 2007. In 2008, symptoms were observed in George, and in 2009, in all the previous reported areas. Cvs. Bluecrisp, Emerald, Jewel, Sharpblue, and Star were infected. Reddish-to-brown spots appeared on the adaxial surface of leaves and developed into yellow-to-orange erumpent uredinia with pulverulent urediniospores. Uredinia were hypophyllous, dome shaped, 113 to 750 μm wide, and occasionally coalescing. Urediniospores were broadly obovate, sometimes ellipsoidal or pyriform, with yellowish orange content, and measured 19 to 27 × 12 to 20 μm (average 24 × 15 μm, n = 30). Spore walls were echinulate, hyaline, 1 to 1.5 μm thick, and with obscure germ pores. No telia or teliospores were observed. Voucher specimens were lodged in the South African National Fungus Collection in Pretoria (PREM 60245). The isolate was initially identified as Thekopsora minima P. Syd. & Syd., based primarily on the absence of conspicuous ostiolar cells characteristic of Naohidemyces spp. (3). Genomic DNA was extracted from urediniospores. Approximately 1,400 bp were amplified spanning the 5.8S, ITS2, and 28S large subunit of the ribosomal DNA (1). The sequence (GU355675) shared 96% (907 of 942 bp; GenBank AF522180) and 94% (1,014 of 1,047 bp; GenBank DQ354563) similarities in the 28S portion, respectively, to those of Naohidemyces vaccinii (Wint.) Sato, Katsuya et Y. Hiratsuka and Pucciniastrum geoppertianum (Kuehn) Kleb, two of the three known rust species of blueberry (2). Although no sequences of T. minima were available for direct comparison, phylogenetic analyses of the 28S region strongly supported the South African blueberry rust as congeneric with T. guttata (J. Schröt.) P. Syd. & Syd. (GenBank AF426231) and T. symphyti (Bubák) Berndt (GenBank AF26230) (data not shown). Four 6-month-old cv. Sharpblue plants were inoculated with a suspension (approximate final concentration of 1 × 10⁵ spores per ml) of fresh urediniospores in a water solution with 0.05% Tween 20. After incubation at 20°C for 48 h under continuous fluorescent lighting, the plants were grown in a glasshouse (18/25°C night/day temperatures). Identical uredinia and symptoms developed approximately 3 weeks after inoculation on the inoculated plants, but not on two control plants of cv. Sharpblue sprayed with distilled water and kept at the same conditions. The alternate host hemlock (Tsuga spp.) is not endemic to South Africa and not sold as an ornamental plant according to a large conifer nursery. Hosts of T. minima include Gaylussacia baccata, G. frondosa, Lyonia neziki, Menziesia pilosa, Rhododendron canadense, R. canescens, R. lutescens R. ponticum, R. prunifolium, R. viscosum, V. angustifolium var. laevifolium, V. corumbosum, and V. erythrocarpon (3). Visual inspection of possible hosts in the gardens in close proximity of Vaccinium production areas did not show any rust symptoms. To our knowledge, this is the first report of T. minima on blueberries outside of Asia and the United States (2). References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. USDA-ARS, 2009. (3) S. Sato et al. Trans. Mycol. Soc. Jpn. 34:47, 1993.

Risk of developing tuberculosis from a school contact: retrospective cohort study, United Kingdom, 2009

To quantify the risk of developing tuberculosis (TB) following school contact with a student with smear positive respiratory TB in a population with a high background rate of tuberculosis, a retrospective cohort study was conducted. This study included all students and staff (n=1,065) at an inner city secondary school in Birmingham, United Kingdom (UK). Being in the same school year as the index case resulted in a significantly higher risk of being diagnosed with active TB (odds ratio (OR) 6.11) and either active or latent TB (OR 10.52) compared to the risk for pupils in other school years. Neither lower level classroom exposure in tutoring groups nor being a staff member resulted in significantly increased risk of infection. The number of cases detected in the school was significantly higher than compared with the TB notification rate for the respective age groups in the population in the area. This study is consistent with the small body of evidence that already exists suggesting that greater levels of classroom contact with a student with smear positive active TB significantly increases the risk of contracting active and latent TB. It also suggests that staff may be at a lower risk of active TB than students. It does not appear that being in an area with high TB incidence substantially alters the epidemiology of the outbreak or risk of transmission between students in comparison to other populations.