Impact of Emerging Antiviral Drug Resistance on Influenza Containment and Spread: Influence of Subclinical Infection and Strategic Use of a Stockpile Containing One or Two Drugs

BACKGROUND: Wide-scale use of antiviral agents in the event of an influenza pandemic is likely to promote the emergence of drug resistance, with potentially deleterious effects for outbreak control. We explored factors promoting resistance within a dynamic infection model, and considered ways in which one or two drugs might be distributed to delay the spread of resistant strains or mitigate their impact. METHODS AND FINDINGS: We have previously developed a novel deterministic model of influenza transmission that simulates treatment and targeted contact prophylaxis, using a limited stockpile of antiviral agents. This model was extended to incorporate subclinical infections, and the emergence of resistant virus strains under the selective pressure imposed by various uses of one or two antiviral agents. For a fixed clinical attack rate, R(0) rises with the proportion of subclinical infections thus reducing the number of infections amenable to treatment or prophylaxis. In consequence, outbreak control is more difficult, but emergence of drug resistance is relatively uncommon. Where an epidemic may be constrained by use of a single antiviral agent, strategies that combine treatment and prophylaxis are most effective at controlling transmission, at the cost of facilitating the spread of resistant viruses. If two drugs are available, using one drug for treatment and the other for prophylaxis is more effective at preventing propagation of mutant strains than either random allocation or drug cycling strategies. Our model is relatively straightforward, and of necessity makes a number of simplifying assumptions. Our results are, however, consistent with the wider body of work in this area and are able to place related research in context while extending the analysis of resistance emergence and optimal drug use within the constraints of a finite drug stockpile. CONCLUSIONS: Combined treatment and prophylaxis represents optimal use of antiviral agents to control transmission, at the cost of drug resistance. Where two drugs are available, allocating different drugs to cases and contacts is likely to be most effective at constraining resistance emergence in a pandemic scenario

Periodontal bone loss and risk of epithelial ovarian cancer

PURPOSE: Periodontitis, a chronic inflammatory response to pathogenic bacteria in the oral microbiome, is common among adults. It is associated with several medical conditions, including cardiovascular diseases, and potentially with esophageal, lung, oral and pancreatic cancer. One of the proposed mechanisms behind these associations is systemic inflammation, which has also been implicated in ovarian cancer etiology. The aim of this study was to evaluate association between ovarian cancer and periodontal bone loss. METHODS: The association between periodontal bone loss, a marker of periodontitis, and risk of epithelial ovarian cancer was estimated among 60,560 participants of the prospective Nurses’ Health Study using Cox proportional hazards analysis. Competing risks analysis was used to estimate association by histological subtype. RESULTS: We did not observe an increased risk of ovarian cancer among participants with periodontal bone loss (HR=0.86, 95% CI: 0.64–1.15). Among women younger than 69 years, periodontal bone loss was associated with a 40% (HR=0.60, 95% CI: 0.36–0.98) decreased ovarian cancer risk, while there was no association in women older than 69 (HR=1.09, 95% CI: 0.75–1.58), although this difference did not reach statistical significance (p-heterogeneity=0.06). We observed a suggestive decreased risk for serous tumors (HR=0.76, 95% CI: 0.53–1.09). The number of natural teeth and root canals, other metrics of oral health, were not associated with ovarian cancer risk. CONCLUSION: Our results do not support an increased ovarian cancer risk in women with periodontal bone loss, however there was a significant decrease in risk in women younger than 69. Given the unexpected association between periodontal bone loss and ovarian cancer risk in younger women, further research is warranted