Accelerated deactivation of Myxobolus cerebralis myxospores by susceptible and non-susceptible Tubifex tubifex.

In the 1990s, the Tubifex tubifex aquatic oligochaete species complex was parsed into 6 separate lineages differing in susceptibility to Myxobolus cerebralis, the myxozoan parasite that can cause whirling disease (WD). Lineage III T. tubifex oligochaetes are highly susceptible to M. cerebralis infection. Lineage I, IV, V and VI oligochaetes are highly resistant or refractory to infection and may function as biological filters by deactivating M. cerebralis myxospores. We designed a 2-phased laboratory experiment using triactinomyxon (TAM) production as the response variable to test that hypothesis. A separate study conducted concurrently demonstrated that M. cerebralis myxospores held in sand and water at temperatures ≤15°C degrade rapidly, becoming almost completely non-viable after 180 d. Those results provided the baseline to assess deactivation of M. cerebralis myxospores by replicates of mixed lineage (I, III, V and VI) and refractory lineage (V and VI) oligochaetes. TAM production was zero among 7 of 8 Lineage V and Lineage VI T. tubifex oligochaete groups exposed to 12500 M. cerebralis myxospores for 15, 45, 90 and 135 d. Among 4 mixed lineage exposure groups, TAM production averaged 14641 compared with 2202495 among 12 groups of Lineage III oligochaetes. Among the 6 unexposed Lineage III experimental groups seeded into original Phase 1 substrates for the 45, 90 and 135 d treatments during the Phase 2 portion of the study, TAM production was reduced by 98.9, 99.9 and 99.9%, respectively, compared with the average for the 15 d exposure groups. These results are congruent with the hypothesis that Lineage V and Lineage VI T. tubifex oligochaetes can deactivate and destroy M. cerebralis myxospores.

Assessment of the Long-Term Viability of the Myxospores of Myxobolus cerebralis as Determined by Production of the actinospores by Tubifex tubifex.

While whirling disease was first observed in Rainbow Trout Oncorhynchus mykiss in 1893, the complete life cycle of Myxobolus cerebralis (Mc), the causative agent of the disease, was not understood until 1984, when it was shown to involve two obligate hosts, a salmonid fish and the aquatic oligochaete Tubifex tubifex (Tt). The viability of the triactinomyxon (TAM) actinospores produced by Tt has been well studied, and is known to be temperature dependent and measured in days and weeks. Assertions that Mc myxospores produced by infected fish remain viable for years or even decades were made during the mid-20th century, decades before the Mc life cycle was described. Moreover, the duration of myxospore viability has not been well studied since the life cycle was elucidated. In a series of time-delay treatments, we assessed the long-term viability of Mc myxospores by exposure to Mc-susceptible Tt oligochaetes and quantified TAM production. As the time delay between inoculation and incubation of Mc myxospores in sand and water and exposure to Tt oligochaetes increased, TAM production decreased exponentially. Production among the 15-d time-delay replicates was reduced 74.7% compared with the 0-d treatment. Likewise, total TAM production was reduced 94.5, 99.4, and 99.9%, respectively, in the 90-, 120-, and 180-d time-delay treatments. Linear regression analysis of our data and the absence of TAM production among replicates of Mc myxospores held at 5°C for 365 d prior to exposure to Mc-susceptible Tt oligochaetes indicate that the long-term viability of Mc myxospores is less than 1 year under the conditions of this study.

Is Canadian women's breast cancer screening behaviour associated with having a family doctor?

OBJECTIVE: To assess whether regular care from a family physician is associated with regular participation in screening mammography. DESIGN: Secondary analysis of the 2006 Canadian Community Health Survey data. SETTING: Canada. PARTICIPANTS: Cross-sectional sample of 15 195 Canadian women aged 50 to 69 years. MAIN OUTCOME MEASURES: The outcome of interest was screening mammography within the past 2 years; the key explanatory factor was active interaction with a family physician. Control factors included sociodemographic characteristics, other cancer screening behaviour, and other cancer risk habits. RESULTS: Active interaction with a regular family doctor doubled the odds that a woman had received a recent screening mammogram. Other cancer screening and preventive measures were also strongly associated with that outcome. A woman who had had a recent Papanicolaou test was more than 3 times as likely to have had a recent mammogram; nonsmokers were much more likely to have had a recent mammogram than smokers. CONCLUSION: Adults who receive regular care from family physicians are more likely to participate in screening mammography within the recommended time frames.

Conceptual and practical challenges for implementing the communities of practice model on a national scale--a Canadian cancer control initiative.

BACKGROUND: Cancer program delivery, like the rest of health care in Canada, faces two ongoing challenges: to coordinate a pan-Canadian approach across complex provincial jurisdictions, and to facilitate the rapid translation of knowledge into clinical practice. Communities of practice, or CoPs, which have been described by Etienne Wenger as a collaborative learning platform, represent a promising solution to these challenges because they rely on bottom-up rather than top-down social structures for integrating knowledge and practice across regions and agencies. The communities of practice model has been realized in the corporate (e.g., Royal Dutch Shell, Xerox, IBM, etc) and development (e.g., World Bank) sectors, but its application to health care is relatively new. The Canadian Partnership Against Cancer (CPAC) is exploring the potential of Wenger's concept in the Canadian health care context. This paper provides an in-depth analysis of Wenger's concept with a focus on its applicability to the health care sector. DISCUSSION: Empirical studies and social science theory are used to examine the utility of Wenger's concept. Its value lies in emphasizing learning from peers and through practice in settings where innovation is valued. Yet the communities of practice concept lacks conceptual clarity because Wenger defines it so broadly and sidelines issues of decision making within CoPs. We consider the implications of his broad definition to establishing an informed nomenclature around this specific type of collaborative group. The CoP Project under CPAC and communities of practice in Canadian health care are discussed. SUMMARY: The use of communities of practice in Canadian health care has been shown in some instances to facilitate quality improvements, encourage buy in among participants, and generate high levels of satisfaction with clinical leadership and knowledge translation among participating physicians. Despite these individual success stories, more information is required on how group decisions are made and applied to the practice world in order to leverage the potential of Wenger's concept more fully, and advance the science of knowledge translation within an accountability framework.

Facilitated "fast track" referral reduces time from abnormal screening mammogram to diagnosis.

BACKGROUND: The Screening Mammography Program of British Columbia (SMPBC) implemented voluntary, facilitated referral to diagnostic imaging ("Fast Track") after testing 5 interventions to reduce time from an abnormal screening mammogram to diagnosis. The purpose of this study was to compare time intervals for patients evaluated through the Fast Track process with patients who were not. METHODS: Data were extracted from the SMPBC database for women with abnormal screens conducted from January 1, 2003 to June 30, 2005 (N = 40,292). After exclusions, 39,607 screens were analyzed. Median and 90th percentile times were calculated from abnormal screen to diagnosis and for three subintervals: abnormal screen to notification, notification to first assessment, and first assessment to diagnosis. RESULTS: One third of abnormal screens were investigated through Fast Track imaging facilities. Overall, the median time from abnormal screen to diagnosis was 8 days faster for Fast Track compared with non-Fast Track. There was no clinically significant difference in time from abnormal screen to notification. The median time from notification to first assessment was 1.1 weeks (Fast Track) compared with 2.4 weeks (non-Fast Track), a reduction of 9 days or 54% in the interval targeted by the Fast Track strategy. The time interval distribution from first assessment to diagnosis was significantly different only for those having a core biopsy (average 3 days faster for Fast Track). INTERPRETATION: Facilitated referral to diagnostic imaging reduces average time from notification of abnormal screen to first assessment by more than half. Additional strategies are needed to address diagnostic investigation beyond initial imaging procedures.

Where there is a will, there is a way: networks as a means of cancer control.

A key challenge in cancer control is the need for translational research to link discovery research with improved health outcomes. In British Columbia, we have built upon the idea of communities of practice to develop networks that will meet our cancer-control mandate.