Suggesting that the control group was reasonably representative, despite the limitations of using this recruitment method. The higher the epidemic growth rate in the source region, the greater the probability than an infected traveler will have been infected more recently. A distribution with a larger variance is appropriate when individuals vary substantially in their infectiousness. Recently, we subjected stool sample–extracted DNAs to 454 pyrosequencing, and found that nearly 20% of the reads had best hits that matched currently-reported bacterial DNA sequences. These previous results, together with our findings here, indicate that two protocols, namely direct DNA extraction for bacteria and cell/bacterial removal by centrifugation followed by RNA/DNA extraction for virus, could be used to comprehensively identify pathogenic microbes in clinical samples. Our results are conservative in the sense that they give an upper bound for the probability that an infected traveler manages to initiate an epidemic, compared to an offspring distribution with a greater variance but the same reproduction number. The nature of the next pandemic influenza virus, and particularly its reproduction number, is uncertain. If its reproduction number is low , our results indicate that at-risk countries Compound Library receiving a reasonably small number of travelers from the infected source region can expect a natural delay until importing an epidemic of the order of 2 months. This is quite variable and under favourable conditions it could be 4 months. However, the natural delay decreases rapidly as R increases. In the course of evolution, transposable elements have accumulated in the genome of eukaryotes, where they can account for up to 80% of the DNA. Most of these sequences have lost their ability to transpose. They are now stable components of the genomes. The recruitment of the patient participants from secondary care clinics rather than from primary care may have biased the sample towards those with more progressive disease. However, in the northern region of the UK, suspected cases of Parkinson’s disease are routinely referred to a secondary care physician specialising in movement disorders. These patients should, therefore, be reasonably representative of all patients presenting to primary care physicians with symptoms suggestive of PD. There is a greater likelihood of patients with AD or VAD not being referred to secondary care as dementia is often undetected, or not managed by a specialist in memory disorders. The reader should therefore bear in mind that participants in this study may have had more severe or progressive disease than those generally seen in primary care. In interpreting our results, consideration should be given to the need to stratify for dementia subtypes in univariate and multivariate analyses. Some of the predictors were not significant when analyses were stratified by dementia subtype, probably because these predictors were actually surrogate markers of a diagnosis.