The multi-faceted dynamics of HIV-1 transmission in Northern Alberta: A combined analysis of virus genetic and public health data.

Molecular epidemiology has become a key tool for tracking infectious disease epidemics. Here, the spread of the most prevalent HIV-1 subtypes in Northern Alberta, Canada, was characterized with a Bayesian phylogenetic approach using 1146 HIV-1 pol sequences collected between 2007 and 2013 for routine clinical management purposes. Available patient metadata were qualitatively interpreted and correlated with onwards transmission using Fisher exact tests and logistic regression. Most infections were from subtypes A (n=36), B (n=815) and C (n=211). Africa is the dominant origin location for subtypes A and C while the subtype B epidemic was seeded from the USA and Middle America and, from the early 1990s onwards, mostly by interprovincial spread. Subtypes A (77.8%) and C (74.0%) were usually heterosexually transmitted and circulate predominantly among Blacks (61.1% and 85% respectively). Subtype B was mostly found among Caucasians (48.6%) and First Nations (36.8%), and its modes of transmission were stratified by ethnic origin. Compared to subtypes A (5.6%) and C (3.8-10.0%), a larger portion of subtype B patients were found within putative provincial transmission networks (20.3-29.5%), and this almost doubled when focusing on nationwide transmission clusters (37.9-57.5%). No clear association between cluster membership and particular patient characteristics was found. This study reveals complex and multi-faceted transmission dynamics of the HIV-1 epidemic in this otherwise low HIV prevalence population in Northern Alberta, Canada. These findings can aid public health planning.

PCR-based prevalence of a fatal reovirus of the blue crab, Callinectes sapidus (Rathbun) along the northern Atlantic coast of the USA.

There is a need for more information on the relationship between diseases and fluctuations of wild populations of marine animals. In the case of Callinectes sapidus reovirus 1 (CsRV1, also known as RLV), there is a lack of baseline information on range, prevalence and outbreaks, from which to develop an understanding of population-level impacts. An RT-qPCR assay was developed that is capable of detecting 10 copies of the CsRV1 genome. In collaboration with state, federal and academic partners, blue crabs were collected from sites throughout the north-eastern United States to assess the northern range of this pathogen. In addition, archived crab samples from the Chesapeake Bay were assessed for CsRV1 by RT-qPCR and histology. PCR-based assessments indicate that CsRV1 was present at all but one site. Prevalence of CsRV1 as assessed by RT-qPCR was highly variable between locations, and CsRV1 prevalence varied between years at a given location. Mean CsRV1 prevalence as assessed by RT-qPCR was >15% each year, and peak prevalence was 79%. The wide geographic range and highly variable prevalence of CsRV1 indicate that more study is needed to understand CsRV1 dynamics and the role the virus plays in blue crab natural mortality.

Clinical course of 161 untreated and tenofovir-treated chronic hepatitis B pregnant patients in a low hepatitis B virus endemic region.

Hepatitis B immunoprophylaxis failure is linked to high maternal viraemia. There is limited North American data on hepatitis B outcomes in pregnancy. Pregnant hepatitis B carriers were enrolled January 2011-December 2014 and offered tenofovir in the 3rd trimester if hepatitis B virus (HBV)-DNA was >7-log IU/mL. Outcomes were determined in treated vs untreated patients. In total, 161 women with 169 pregnancies (one twin, 170 infants; median age 32 years), 18% (29/161) HBeAg+ and median HBV-DNA 2.51 log IU/mL (IQR 1.66-3.65; range 0.8-8.1) were studied. 14.3% (23/161) received tenofovir due to high viral load (16/23, median 74 days, IQR 59-110) or due to liver disease (7/23). In 10/16 treated due to high viraemia, with confirmed adherence, follow-up HBV-DNA showed a 5.49 log decline (P = 0.003). In treatment naïve mothers, median alanine aminotransferase (ALT) increased from 17 IU/L (IQR 12-24) to 29 (IQR 18-36) post-partum (P = 1.5e-7). In seven highly viraemic mothers who declined therapy (HBV-DNA >8-log IU/mL); median ALT increased ~3X from baseline (P < 0.01). 26% (44/169) had Caesarean section with no difference in treated vs untreated subjects. No tenofovir-treated mothers had renal dysfunction. Data were available on 167/170 infants; in 50.8% (85/167) who completed immunoprophylaxis, 98.8% (84/85, including 12 exposed to tenofovir in utero) were HBV immune. One infant born to an HBeAg+ mother with HBV-DNA >8-log IU/mL failed immunoprophylaxis. In this prospective Canadian cohort study, most untreated mothers experienced mild HBV flares. Tenofovir in pregnancy is well tolerated and reduces viral load prior to parturition.

Surveillance for Lyme disease in Canada, 2009 to 2012.

OBJECTIVES: To summarize the first four years of national surveillance for Lyme disease in Canada from 2009 to 2012 and to conduct a preliminary comparison of presenting clinical manifestations in Canada and the United States. METHODS: The numbers and incidence of reported cases by province, month, year, age and sex were calculated. Logistic regression was used to examine trends over time. Acquisition locations were mapped and presenting clinical manifestations reported for jurisdictions where data was available. Variations by province, year, age and sex as well as presenting clinical symptoms were explored by logistic regression. An initial comparative analysis was made of presenting symptoms in Canada and the United States. RESULTS: The numbers of reported cases rose significantly from 144 in 2009 to 338 in 2012 (coefficient = 0.34, standard error = 0.07, P <0.05), mostly due to an increased incidence of infections acquired in Canada. More cases were classified as 'confirmed' (71.5%) than 'probable' (28.5%). Most cases occurred in locations where vector tick populations were known to be present. More men than women were affected (53.4% versus 46.6%), incidence was highest in adults aged 55 to 74 years and in children aged five to 14 years. Most cases (95%) were acquired from April to November. Of cases acquired in endemic areas, 39.7% presented with manifestations of early Lyme disease, while 60.3% had manifestations of disseminated Lyme disease. There were significant differences among age groups, sexes and provinces in the frequencies of reported clinical manifestations. The proportion of cases acquired in endemic areas presenting with early Lyme disease was lower than that reported in the US. CONCLUSION: Lyme disease incidence is increasing in Canada. Most cases are acquired where vector tick populations are spreading and this varies geographically within and among provinces. There is also variation in the frequency of age, season and presenting manifestations. The lower proportion of cases presenting with early Lyme disease in Canada compared with the US suggests lower awareness of early Lyme disease in Canada, but this requires further study.

Surveillance summary of hospitalized pediatric enterovirus D68 cases in Canada, September 2014.

BACKGROUND: Enterovirus D68 (EV-D68) has been detected infrequently and has not been associated with severe disease in Canada. In the early fall of 2014, following an unusual case increase in the United States, clusters of EV-D68 among children and some adults manifesting severe symptoms were reported in Canada. OBJECTIVE: To provide an initial epidemiological summary of pediatric cases hospitalized with EV-D68 in Canada. METHODS: A time-limited surveillance pilot was conducted collecting information on pediatric cases (less than 18 years of age) hospitalized with EV-D68 between September 1 and 30, 2014. RESULTS: In total, 268 cases were reported from Ontario (n=210), Alberta (n=45), and British Columbia (n=13). Of the 268 reported cases, 64.9% (n=174) were male; the sex difference was statistically significant (p<0.01). Age was reported for 255 cases, with a mean age for males of 5.4 years and for females of 5.3 years. For cases with data available, 6.8% (18/266) were admitted to an intensive care unit. Of those where clinical illness was recorded, respiratory illness alone was present in 98.3% (227/231), neurologic illness alone was present in 0.4% (n=1), and both illnesses were present in 0.9% of cases (n=2); cases with neither respiratory nor neurologic illness were rare (n=1). Of the 90 cases with additional clinical information available, 43.3% were reported as having asthma. No deaths were reported among the 268 cases. CONCLUSION: The EV-D68 outbreak in Canada in September 2014 represents the beginning of a novel outbreak associated with severe illness in children. These findings provide the first epidemiological summary of severe cases of EV-D68 as an emergent respiratory pathogen in Canada. The continued investigation of this pathogen is necessary to build on these results and capture the full spectrum of associated illness.

Weather and livestock risk factors for Escherichia coli O157 human infection in Alberta, Canada.

This study investigated the extent to which proximity to cattle and weather events in Alberta predispose human populations to E. coli O157 disease. Cases of human E. coli O157 infection in Alberta between 2004 and 2011 were obtained from the province's Communicable Disease Reporting System and Discharge Abstract Database. Regression models based on spatial area incorporated human infection data with livestock and weather covariates. A variety of regression models were applied (i.e. least squares, spatial lag/error, Poisson, negative binomial) to test the most appropriate approach. Ratios for the total number of calves, bulls and beef cows to human population were highlighted as significant cattle density variables in all final best-fitting models. Weather variables were not significant in final regression models averaged over the full study period. Our results provide evidence of a significant association between measures of cattle density and human E. coli O157 disease in Alberta.

Measles-containing vaccination rates in southern Alberta.

BACKGROUND: Southern Alberta is home to many unique homogeneous communities that typically educate their children in private schools. A number of these communities do not promote immunization as a preventive public health measure, although the reasons behind this vary. People within these communities keep themselves somewhat secluded from other populations and thus do not benefit from overall herd immunity. This has led to frequent outbreaks of vaccine-preventable diseases in private schools affiliated with these homogeneous religious communities. OBJECTIVE: To report on low immunization rates of measles, mumps, rubella (MMR) and MMR-varicella in southern Alberta communities and schools and to compare the epidemiology of immunization rates in certain vulnerable communities with those of same-age cohorts in South Zone communities. METHODS: The analysis includes immunization data at the individual level submitted to the provincial immunization repository, Immunization and Adverse Reactions to Immunization, and the Alberta Health Services Meditech module between January 1, 2013, and June 30, 2013. RESULTS: Heterogeneity of immunization status was found among communities and among schools. The status of two year old children up to date on immunizations ranged from 46.6% in Fort Macleod to 71.9% in Oyen, with a mean of 57.3 children in every 100 up to date. By age seven, the mean percentage of immunized children in southern Alberta was 77.6%, ranging from 57.8% in Picture Butte to 94.6% in Oyen. Immunization status among schools ranged from 17% to 100%, with a mean of 89.3% of children fully immunized and a median of 91% immunized. CONCLUSION: There is heterogeneity of immunization uptake for childhood measles-containing vaccine by community and by school in southern Alberta. This study highlights that the location of the school may not align with geographic community as it pertains to immunization rates. Analysis of childhood immunization data at both community and school level is important in understanding the risks of vaccine-preventable illness spread in a given geographic region, such as Alberta South Zone. Data from this study can be used to inform specific interventions required to improve immunization coverage rates in these unique homogeneous cultural communities and their respective schools, and to decrease the risk of measles transmission in Southern Alberta.

Outbreak of measles in a non-immunizing population, Alberta 2013.

BACKGROUND: An outbreak of measles was declared in southern Alberta on October 18, 2013, after a case had been reported to the local public health unit in a non-immunized teenager with recent travel to the Netherlands. The teenager had had contact with a large number of unimmunized people while infectious; therefore, the risk of spread was high. The potential for an outbreak of measles in this area had been identified by the lead Medical Officer of Health for South Zone, and planning for an outbreak had begun in August 2013. METHODS: Several public health measures were implemented to control the outbreak: mass immunization clinics; an outbreak dose of measles mumps and rubella (MMR) vaccine for infants 6-12 months old; communication within the affected and surrounding communities; a dedicated measles hotline; a Mobile Measles Assessment Team; and a Measles Assessment Centre. RESULTS: A total of 42 confirmed cases were identified during the outbreak between October 16 and November 25. Just over half the cases were male (52.4%). The average age was 12 (range < 1 to 24 years) and the median age 13 years. There was one hospitalization, and no deaths occurred. All cases were unimmunized. Cases were located in five communities immediately surrounding Lethbridge. All but two cases were epidemiologically linked within 10 households. CONCLUSION: The planning that occurred before the outbreak was essential in containing the outbreak to 10 households. To prevent future outbreaks of measles, exploring strategies for increasing immunization coverage rates in unimmunized populations is essential. When immunization acceptance is not uniform, other public health strategies should be planned for and implemented in order to prevent additional spread.

Changing epidemiology of methicillin-resistant Staphylococcus aureus in Alberta, Canada: population-based surveillance, 2005-2008.

SUMMARYIncreasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has been reported in Canada. We report the results of a prospective surveillance of MRSA infections in Alberta over a consecutive 3-year period. A total of 8910 unique clinical MRSA isolates was analysed from July 2005 to June 2008. The incidence of MRSA infection increased over the study period and was highest in males, age group ⩾85 years, and the Calgary Area. CMRSA10 (USA300) and CMRSA2 (USA100/800) were the most common PFGE strain types, representing 53·0% and 27·9% of all isolates, respectively. Significant differences were noted between MRSA strains in the source of infection and antimicrobial susceptibility. The incidence of MRSA infection in Alberta has nearly doubled in the last 3 years; this is attributed to the emergence of CMRSA10 as the predominant strain.

Teaching airway management to novices: a simulator manikin study comparing the 'sniffing position' and 'win with the chin' analogies.

BACKGROUND: The 'sniffing position' is widely promoted for teaching airway positioning before intubation, but whether this analogy results in novices placing the head and neck appropriately has not been evaluated. We compared performance following the sniffing position instructions with an alternate analogy, 'win with the chin'. We also compared performance following simple anatomic instructions and no instructions. METHODS: A randomized controlled study of medical students and PGY1 registrars in Surgery and Internal Medicine was performed. Subjects independently positioned a simulator manikin head and neck based upon their understanding of four written instructions in random order: (i) the 'sniffing position'; (ii) the 'win with the chin' analogy, (iii) anatomic instructions; and (iv) no instructions (control). Digital photographs following each instruction were analysed by two airway experts for (i) adequacy of overall positioning and (ii) the three components of airway positioning. RESULTS: Eighty-one volunteers participated. The positioning was adequate most often (43.2%) following the 'win with the chin' analogy when compared with the other instructions (37.0% anatomic instructions; 19.8% control; 14.8% 'sniffing position' analogy). Positioning following the 'sniffing position' instructions was not different from no instruction (P=0.53). The 'win with the chin' and anatomic instructions were significantly better than no instructions (P=0.002 and 0.023, respectively). CONCLUSIONS: The 'win with the chin' analogy resulted in adequate airway positioning significantly more often than the 'sniffing position' or control. It also maintained atlanto-occipital extension compared with anatomic instructions. Overall, 'win with the chin' was a superior teaching analogy and could replace the 'sniffing position' analogy.

Disruption by conophthorin of the kairomonal response of sawyer beetles to bark beetle pheromones.

Antennally active nonhost angiosperm bark volatiles were tested for their ability to reduce the response of three common species of coniferophagous wood-boring Cerambycidae to attractant-baited multiple funnel traps in the southern interior of British Columbia. Of the nonhost volatiles tested, only conophthorin was behaviorally active, disrupting the attraction of sawyer beetles, Monochamus spp., to traps baited with the host volatiles alpha-pinene and ethanol and the bark beetle pheromones ipsenol and ipsdienol. Conophthorin did not affect the attraction of sawyer beetles to the host kairomones alpha-pinene and ethanol in the absence of bark beetle pheromones, nor did it have any behavioral effect on adults of Xylotrechus longitarsis, which were not attracted to bark beetle pheromones. These results indicate that conophthorin does not act as a general repellent for coniferophagous Cerambycidae, as it seems to do for many species of Scolytidae, but has the specific activity of disrupting the kairomonal response of sawyer beetles to bark beetle pheromones.

Computational and experimental investigation of the fields generated by a 1-3 piezocomposite transducer.

Large-scale three-dimensional numerical simulations using the finite-difference time domain technique are used to compute the continuous wave fields associated with a composite transducer. The interior of the transducer is made of a periodic array of square rods. This lattice causes elastic wave Bragg diffraction similar to electrons in a periodic lattice. A low frequency mode shape is assumed for the rods. This prescribed motion includes longitudinal and transverse components. It is shown that the transverse motion in the rod gives rise to shear waves causing standing waves (lateral resonances) in the polymer regions. This is also confirmed by experimental results presented here and other independent analytical and experimental work. The full-scale numerical simulation is performed on a large parallel supercomputer and permits modeling of not only the composite transducer but the radiated pressure from near to far field. In addition, cover plates and edge effects are included, unlike analytical treatments. Although only mechanical effects are included, the wave propagation approach captures many essential features.