Ticks (Acari: Ixodidae) transmit a wide variety of pathogens to vertebrates including viruses, bacteria, protozoa and helminthes. Tick-borne pathogens are believed to be responsible for more than 100,000 cases of illness in humans throughout the world. Ticks are considered to be second worldwide to mosquitoes as vectors of human diseases, but they are the most important vectors of disease-causing pathogens in domestic and wild animals. Infection and development of pathogens in both tick and vertebrate hosts are mediated by molecular mechanisms at the tick-pathogen interface. These mechanisms, involving traits of both ticks and pathogens, include the evolution of common and species-specific characteristics. The molecular characterization of the tick-pathogen interface is rapidly advancing and providing new avenues for the development of novel control strategies for both tick infestations and their associated pathogens.

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The genus Anaplasma is one of four distinct genera in the family Anaplasmataceae, which are obligate intracellular pathogens vectored by ticks and found exclusively within parasitophorous vacuoles in the host cell cytoplasm. The 2001 reclassification of the order Rickettsiales expanded the genus Anaplasma, which previously contained pathogens that were host specific for ruminants (A. marginale, A. centrale and A. ovis), by adding A. phagocytophilum, a unification of three organisms previously classified as Ehrlichia (E. equi, E. phagocytophila and the unnamed agent of human granulocytic ehrlichiosis). Also included in the genus Anaplasma were A. bovis (formerly E. bovis), A. platys (formerly E. platys) and Aegyptianella pullorum. Despite the genomic relatedness of the regrouped organisms, many aspects of their biology are diverse, including their host specificity, host cell preferences, major surface proteins (MSPs) and tick vectors. This review focuses on the two most important pathogens: A. marginale, which causes bovine anaplasmosis, and A. phagocytophilum, the aetiologic agent of tick-borne fever in sheep and human granulocytic anaplasmosis, an emerging tick-borne disease of humans. For both pathogens, strain diversity is much greater than previously recognised. While MSPs were found to be useful in phylogenetic studies and strain identification, highly conserved MSPs were found to affect the specificity of serologic tests. Comparison of these two important pathogens highlights the challenges and insight derived from reclassification and molecular analysis, both of which have implications for the development and evaluation of diagnosis and control strategies.

Projections show that the number of people above 60 years old will triple by 2050 in Mexico. Nevertheless, ageing is characterised by great variability in the health status. In this study, we aimed to identify trajectories of health and their associations with lifestyle factors in a national representative cohort study of older Mexicans. We used secondary data of 14,143 adults from the Mexican Health and Aging Study (MHAS). A metric of health, based on the conceptual framework of functional ability, was mapped onto four waves (2001, 2003, 2012, 2015) and created by applying Bayesian multilevel Item Response Theory (IRT). Conditional Growth Mixture Modelling (GMM) was used to identify latent classes of individuals with similar trajectories and examine the impact of physical activity, smoking and alcohol on those. Conditional on sociodemographic and lifestyle behaviour four latent classes were suggested: high-stable, moderate-stable, low-stable and decliners. Participants who did not engage in physical activity, were current or previous smokers and did not consume alcohol at baseline were more likely to be in the trajectory with the highest deterioration (i.e. decliners). This study confirms ageing heterogeneity and the positive influence of a healthy lifestyle. These results provide the ground for new policies.

The method based on the creation of a common metric of health and the use of GMM to identify similar patterns of aging, allows for the comparison of trajectories of health across longitudinal surveys. Multimorbidity, educational level, and household wealth could be considered as determinants associated to these trajectories.

Published in: De la Torre-luque A, De la Fuente J, Prina M, Sanchez-Niubo A, Haro JM, Ayuso-Mateos JL. Long-term trajectories of depressive symptoms in old age: Relationships with sociodemographic and health-related factors. Abstract Background. This study aimed at depicting the course of depression symptoms over the old age, with a special interest in a) uncovering its relationships with sociodemographic and health-related factors; b) analysing its predictive role on healthyageing outcomes later in life. Methods. The sample comprised 8317 older adults (46.02% men) from the English Longitudinal Study of Ageing. Robust structural equation modelling was used to identify symptom trajectories and their relationships with time-varying factors. Trajectory class and covariates were used to predict outcomes (quality of life, satisfaction with life, and daily living functioning) in a 2-year follow-up. Results. Three trajectory classes (so-called, normative, subclinical, chronic symptom trajectories) were identified for both sexes. Rising hearing difficulties and history of psychiatric problems were consistently associated with the chronic symptom trajectory. Lower education level, history of psychiatric problems, and increasing visual difficulties were connected with the subclinical trajectories. Finally, participants with either a subclinical or a chronic symptom trajectory showed worse outcomes than the remaining participants in the follow-up. Conclusion: This study highlighted the presence of varying courses of depression symptoms (each showing some distinctive features from other another) over the old age, pointing to some relevant implications for clinical assessment and treatment prescription.

The genus Anaplasma includes a diverse group of tick-borne pathogens found exclusively within membrane-bound vacuoles in host cells. While A. marginale, A. centrale and A. ovis, vectored by Dermacentor and Rhipicephalus ticks, are host-specific for ruminants, A. phagocytophilum, vectored by Ixodes spp., infects a wide range of hosts. In ticks Anaplasma undergoes a developmental cycle that is coordinated with the tick feeding cycle. Although research at the tick/Anaplasma interface is in its infancy, recent studies have provided evidence that Anaplasma infection and transmission is mediated by a molecular mechanism involving both tick cell and pathogen genes. Application of a growing array of molecular approaches, such as RNA interference, genomics and proteomics, are rapidly expanding our knowledge of the tick/pathogen interface. Targeting key tick cell molecules required for pathogen development in vaccine strategies may compromise the vector capacity of ticks for Anaplasma, thus reducing transmission and infection of vertebrates. Collectively, this information will likely lead to the development of dual target vaccines designed to protect vertebrates against tick infestations and prevent the transmission of pathogens.

Theories of adult cognitive development classically distinguish between fluid abilities, which require effortful processing at the time of assessment, and crystallized abilities, which require the retrieval and application of knowledge. On average, fluid abilities decline throughout adulthood, whereas crystallized abilities show gains into old age. These diverging age trends, along with marked individual differences in rates of change, have led to the proposition that individuals might compensate for fluid declines with crystallized gains. Here, using data from two large longitudinal studies, we show that rates of change are strongly correlated across fluid and crystallized abilities. Hence, individuals showing greater losses in fluid abilities tend to show smaller gains, or even losses, in crystallized abilities. This observed commonality between fluid and crystallized changes places constraints on theories of compensation and directs attention toward domain-general drivers of adult cognitive decline and maintenance.