Revisiting the circulation time of Plasmodium falciparum gametocytes: molecular detection methods to estimate the duration of gametocyte carriage and the effect of gametocytocidal drugs

BACKGROUND: There is renewed acknowledgement that targeting gametocytes is essential for malaria control and elimination efforts. Simple mathematical models were fitted to data from clinical trials in order to determine the mean gametocyte circulation time and duration of gametocyte carriage in treated malaria patients. METHODS: Data were used from clinical trials from East Africa. The first trial compared non-artemisinin combination therapy (non-ACT: sulphadoxine-pyrimethamine (SP) plus amodiaquine) and artemisinin-based combination therapy (ACT: SP plus artesunate (AS) or artemether-lumefantrine). The second trial compared ACT (SP+AS) with ACT in combination with a single dose of primaquine (ACT-PQ: SP+AS+PQ). Mature gametocytes were quantified in peripheral blood samples by nucleic acid sequence based amplification. A simple deterministic compartmental model was fitted to gametocyte densities to estimate the circulation time per gametocyte; a similar model was fitted to gametocyte prevalences to estimate the duration of gametocyte carriage after efficacious treatment. RESULTS: The mean circulation time of gametocytes was 4.6-6.5 days. After non-ACT treatment, patients were estimated to carry gametocytes for an average of 55 days (95% CI 28.7 - 107.7). ACT reduced the duration of gametocyte carriage fourfold to 13.4 days (95% CI 10.2-17.5). Addition of PQ to ACT resulted in a further fourfold reduction of the duration of gametocyte carriage. CONCLUSIONS: These findings confirm previous estimates of the circulation time of gametocytes, but indicate a much longer duration of (low density) gametocyte carriage after apparently successful clearance of asexual parasites. ACT shortened the period of gametocyte carriage considerably, and had the most pronounced effect on mature gametocytes when combined with PQ

Social identity change during and intergroup merger: the role of status, similarity, and identity threat

Conducted during the merger between two hospitals, this longitudinal study (N = 149) revealed that at both Time 1 (i.e., questionnaire completed 12 months prior to the merger) and Time 2 (completed 1 year after the merger had been implemented), employees from the low-status premerger organization generally reported lower adjustment to the merger. Whereas Time 2 identity threat predicted lower and decreased identification with the new merged organization and perceptions of a common in group identity, perceived similarities between the merging organizations at Time 2 predicted higher identification with the new merged organization and higher perceptions of a common in group identity

Foucault, sustainable tourism, and relationships with the environment (human and nonhuman)

Drawing on contemporary research into ethical consumption and sustainable tourism this article starts by outlining the ways in which sustainable tourism (and other forms of ethical consumption) has been understood as a means to perform class based distinctions. At this stage, it is suggested that whilst class may be one factor in understanding such a complex phenomena there might also be a need to examine the practices of sustainable tourist in a manner that takes seriously individual attempts to ‘be ethical’. Foucault’s understanding of ethics is then offered as a means through which this can be achieved. A brief account of the method used to read individuals accounts of sustainable tourism through an ethical Foucauldian lens is then presented. Following this the paper presents the analysis of interviews with sustainable tourists focusing on two key elements. Firstly, the analysis presents the emotional and reciprocal elements of interactions between sustainable tourists and the human ‘other’. Secondly the analysis examines the relationship between the sustainable tourist and non-human environments to further develop the understanding of the emotional and reciprocal elements in light of a Foucauldian ethics. In conclusion it is suggested that rather than merely representing a mode of class distinction, sustainable tourism can be understood through an appreciation of the emotional and reciprocal relationship with the other, thus taking seriously individuals attempts to engage with ethical practices

The Effects of Initial Differences in Firms' Espoused Values on their Postmerger Performance

Recent studies have concluded that most mergers and acquisitions (M&As) reduce rather than increase shareholder value for the acquiring firm, but understanding of why this occurs is limited. To date, most research has focused on issues of strategic fit, whereas this study examines the effects of organizational fit—specifically the effects of differences in firms’ pre-M&A configurations of espoused values in regards to relationships with employees versus production. The dependent variable of interest is the resulting entities’ subsequent financial performance (return on assets, adjusted for industry). The study analyzed 59 M&As between 1989 and 1996. The authors measured the espoused values of both firms in the transaction by content analyzing presidents’letters to shareholders in corporate annual reports. Using a longitudinal design, results show an inverse relationship between differences in espoused values and postmerger performance. Results and methodology are discussed in terms of their application beyond the M&A context