Background and Purpose-Studies on cognitive impairment without dementia (CIND) after stroke are scarce and there are no widely accepted diagnostic criteria for this condition. The purpose of this study was to determine the frequency of CIND in a hospital cohort before and after stroke during a 2-year follow up according to two alternative operational criteria. Methods-Three hundred twenty-seven consecutive stroke inpatients were prospectively evaluated with an extensive neuropsychological battery and the Informant Questionnaire of Cognitive Decline in the Elderly (IQCODE) on admission and then at 3, 12, and 24 months after discharge. CIND was established according to two alternative operational criteria: proxy information (a cutoff score of 3.35 in the IQCODE: IQ-c) or to neuropsychologic examination (a score below the sixth percentile in Ն50% of the tests exploring one cognitive domain: NPE-c). Results-A total of 12.6% patients had CIND (IQ-c) before stroke. After 3 months, the CIND frequency was 26.9% (IQ-c) or 19.6% (NPE-c); after 12 months, 39.5% or 26.8%; and after 24 months, 36.6% or 21%. The risk for developing delayed dementia was significantly higher for poststroke patients with CIND diagnosed by IQ-c (OR 8.8), NPE-c (OR 10.3), or both criteria (OR 20.8). Conclusions-Patients with CIND are frequent before and after stroke and prone to delayed dementia. Both criteria are valid for identifying CIND cases and predicting long-term conversion to dementia, but NPE-c may be more adequate for the long-term follow up and IQ-c for detecting changes from prestroke status.

The Norway or brown rat (Rattus norvegicus) is among the most ubiquitous of rodents. However, the lack of studies describing Norway rat populations from tropical areas have limited our understanding regarding their demography and seasonal dynamics. In this study, we describe seasonal pattern in the abundance, reproductive parameters, and morphometrics of Norway rat populations in Salvador, Brazil. Rodents were trapped over four seasonal trapping periods (2013–2014) from three valleys. A total of 802 Norway rats were trapped over the course of the study over 7653 trap-nights. Norway rat abundance was high, but there was no significant differences between seasons. The reproductive parameters (e.g. frequency of pregnant and lactating females) did not show statistical differences between seasons. Female rats collected in the rainy season were heavier and older than females from the dry season. Salvador rats had a high incidence of pregnancy and birth rate (estimated birth rate of 79 young per year) compared to previous studies. The information generated is critical for the understanding of the ecology of Norway rat, the main reservoir of Leptospira in Salvador. However, future studies examining the effect of rodent control programs aimed at reducing populations, and determining rates of recovery, will further clarify our understanding of population dynamics.

Norway rats (Rattus norvegicus) living in urban environments are a critical public health and economic problem, particularly in urban slums where residents are at a higher risk for rat borne diseases, yet convenient methods to quantitatively assess population sizes are lacking. We evaluated track plates as a method to determine rat distribution and relative abundance in a complex urban slum environment by correlating the presence and intensity of rat-specific marks on track plates with findings from rat infestation surveys and trapping of rats to population exhaustion. To integrate the zero-inflated track plate data we developed a two-component mixture model with one binary and one censored continuous component. Track plate mark-intensity was highly correlated with signs of rodent infestation (all coefficients between 0.61 and 0.79 and all p-values < 0.05). Moreover, the mean level of pre-trapping rat-mark intensity on plates was significantly associated with the number of rats captured subsequently (Odds ratio1.38; 95% CI 1.19-1.61) and declined significantly following trapping (Odds ratio 0.86; 95% CI 0.78-0.95). Track plates provided robust proxy measurements of rat abundance and distribution and detected rat presence even when populations appeared ‘trapped out’. Tracking plates are relatively easy and inexpensive methods that can be used to intensively sample settings such as urban slums, where traditional trapping or mark-recapture studies are impossible to implement, and therefore the results can inform and assess the impact of targeted urban rodent control campaigns.

The Norway rat (Rattus norvegicus) is a key pest species globally and responsible for seasonal outbreaks of the zoonotic bacterial disease leptospirosis in the tropics. The city of Salvador, Brazil, has seen recent and dramatic increases in human population residing in slums, where conditions foster high rat density and increasing leptospirosis infection rates. Intervention campaigns have been used to drastically reduce rat numbers. In planning these interventions, it is important to define the eradication units ‐ the spatial scale at which rats constitute continuous populations and from where rats are likely recolonizing, post‐intervention. To provide this information, we applied spatial genetic analyses to 706 rats collected across Salvador and genotyped at 16 microsatellite loci. We performed spatially explicit analyses and estimated migration levels to identify distinct genetic units and landscape features associated with genetic divergence at different spatial scales, ranging from valleys within a slum community to city‐wide analyses. Clear genetic breaks exist between rats not only across Salvador but also between valleys of slums separated by <100 m—well within the dispersal capacity of rats. The genetic data indicate that valleys may be considered separate units and identified high‐traffic roads as strong impediments to rat movement. Migration data suggest that most (71–90%) movement is contained within valleys, with no clear source population contributing to migrant rats. We use these data to recommend eradication units and discuss the importance of carrying out individual‐based analyses at different spatial scales in urban landscapes.