The transmission dynamics of Tuberculosis (TB) involve complex epidemiological and socio-economical interactions between individuals living in highly distinct regional conditions. The level of exogenous reinfection and first time infection rates within high-incidence settings may influence the impact of control programs on TB prevalence. The impact that effective population size and the distribution of individuals’ residence times in different patches have on TB transmission and control are studied using selected scenarios where risk is defined by the estimated or perceive first time infection and/or exogenous re-infection rates.
Methods
This study aims at enhancing the understanding of TB dynamics, within simplified, two patch, risk-defined environments, in the presence of short term mobility and variations in reinfection and infection rates via a mathematical model. The modeling framework captures the role of individuals’ ‘daily’ dynamics within and between places of residency, work or business via the average proportion of time spent in residence and as visitors to TB-risk environments (patches). As a result, the effective population size of Patch i (home of i-residents) at time t must account for visitors and residents of Patch i, at time t.
Results
The study identifies critical social behaviors mechanisms that can facilitate or eliminate TB infection in vulnerable populations. The results suggest that short-term mobility between heterogeneous patches contributes to significant overall increases in TB prevalence when risk is considered only in terms of direct new infection transmission, compared to the effect of exogenous reinfection. Although, the role of exogenous reinfection increases the risk that come from large movement of individuals, due to catastrophes or conflict, to TB-free areas.
Conclusions
The study highlights that allowing infected individuals to move from high to low TB prevalence areas (for example via the sharing of treatment and isolation facilities) may lead to a reduction in the total TB prevalence in the overall population. The higher the population size heterogeneity between distinct risk patches, the larger the benefit (low overall prevalence) under the same “traveling” patterns. Policies need to account for population specific factors (such as risks that are inherent with high levels of migration, local and regional mobility patterns, and first time infection rates) in order to be long lasting, effective and results in low number of drug resistant cases.
The maintenance of chromosomal integrity is an essential task of every living organism and cellular repair mechanisms exist to guard against insults to DNA. Given the importance of this process, it is expected that DNA repair proteins would be evolutionarily conserved, exhibiting very minimal sequence change over time. However, BRCA1, an essential gene involved in DNA repair, has been reported to be evolving rapidly despite the fact that many protein-altering mutations within this gene convey a significantly elevated risk for breast and ovarian cancers.
Results
To obtain a deeper understanding of the evolutionary trajectory of BRCA1, we analyzed complete BRCA1 gene sequences from 23 primate species. We show that specific amino acid sites have experienced repeated selection for amino acid replacement over primate evolution. This selection has been focused specifically on humans and our closest living relatives, chimpanzees (Pan troglodytes) and bonobos (Pan paniscus). After examining BRCA1 polymorphisms in 7 bonobo, 44 chimpanzee, and 44 rhesus macaque (Macaca mulatta) individuals, we find considerable variation within each of these species and evidence for recent selection in chimpanzee populations. Finally, we also sequenced and analyzed BRCA2 from 24 primate species and find that this gene has also evolved under positive selection.
Conclusions
While mutations leading to truncated forms of BRCA1 are clearly linked to cancer phenotypes in humans, there is also an underlying selective pressure in favor of amino acid-altering substitutions in this gene. A hypothesis where viruses are the drivers of this natural selection is discussed.
U.S. border colonias, otherwise known as Disadvantaged Unincorporated Communities, are rural settlements along the U.S. Mexico border with substandard housing conditions. Colonia residents often face inadequate access to necessities such as appropriate shelter, septic and sewer systems, and potable water. Water insecurity in colonias poses a particularly difficult challenge for residents who require clean water not only for consumption, but also household use in sanitation and hygienic practices. As of 2015, an estimated 30% of over five million US colonia residents lack access to clean drinking water, resulting in health complications and unsanitary living conditions. Preliminary health data collected indicates that due to water insecurity, colonia residents are more likely to contract gastrointestinal disease, be exposed to carcinogenic compounds from contaminated water, and experience psychosocial distress. Yet more comprehensive research needs to be conducted to understand the full breadth of the public health issue. A scoping review on water insecurity in colonias has not been completed before and could be beneficial in informing policymakers and other stakeholders on the severity of the situation while advising possible solutions.
Climate change is a threat to food security and food system stability, especially towards small islands. Climate change is increasing the frequency of extreme weather events, further putting island rural farming communities at greater risk for reduced crop yields and food insecurity. Puerto Rico’s dependence on food imports exacerbates vulnerabilities during natural disasters including reduced food quality, rural impoverishment, and periodic food insecurity. Despite these vulnerabilities, Puerto Rican farmers serve as cultural emblems within their community, providing fresh foods in times of disaster when federal aid was not available. There is very limited research focusing on how the informal social structures of these rural communities contribute to community-level disaster preparedness and mitigation strategies. Since the devastating Hurricane Maria in 2017, there has been little literature focusing on increasing rural farming community resilience against natural disasters like hurricanes in Puerto Rico. Using literature mapping software, this scoping review identifies a very limited existing set of research concerning adaptive capacity strategies in rural farming communities in Puerto Rico since 2017, discusses the strengths and weaknesses of aid organizations like the Southern Sustainable Agricultural Research and Education grant in Utuado, Puerto Rico, and suggests value in additional focused research specific to identifying how communities implement disaster preparedness and mitigation strategies.
In the Southwestern United States, climate change poses challenges to reliable water access due to droughts, wildfires, and urban development. Arizonan farmers are faced with unpredictable precipitation, muddled legal water rights, and outdated equipment to irrigate their land. Located in Northern Arizona, Verde Valley residents and stakeholders are challenging the way the Verde River water is managed through collaboration, partnerships, and technical changes to water infrastructure. Through interviews conducted with various stakeholders involved in the Verde River ditch irrigation system, ranging from water users to nonprofit organizations, this paper identifies sociotechnical tinkering as an important aspect of maintaining agricultural operations along the river amid political tensions, social relations, and climate change. Through interviews and analysis, this paper further contributes to the relatively new discourse on the concept of sociotechnical tinkering by proving its existence and its subsequent effectiveness in the Verde Valley. Using statements made by respondents, the paper argues that sociotechnical tinkering helps manage resources through political and social relations.