Background Ehrlichia chaffeensis is an emerging tick-borne rickettsial pathogen responsible for human monocytic ehrlichiosis. Despite the induction of an active host immune response, the pathogen has evolved to persist in its vertebrate and tick hosts. Understanding how the organism progresses in tick and vertebrate host cells is critical in identifying effective strategies to block the pathogen transmission. Our recent molecular and proteomic studies revealed differences in numerous expressed proteins of the organism during its growth in different host environments.Methodology/Principal FindingsTransmission electron microscopy analysis was performed to assess morphological changes in the bacterium within macrophages and tick cells. The stages of pathogen progression observed included the attachment of the organism to the host cells, its engulfment and replication within a morulae by binary fission and release of the organisms from infected host cells by complete host cell lysis or by exocytosis. E. chaffeensis grown in tick cells was highly pleomorphic and appears to replicate by both binary fission and filamentous type cell divisions. The presence of Ehrlichia-like inclusions was also observed within the nucleus of both macrophages and tick cells. This observation was confirmed by confocal microscopy and immunoblot analysis.Conclusions/SignificanceMorphological differences in the pathogen’s progression, replication, and processing within macrophages and tick cells provide further evidence that E. chaffeensis employs unique host-cell specific strategies in support of adaptation to vertebrate and tick cell environments.

PurposeThe purpose of the present study was to observe the preparation practices of both adult and young consumers using frozen, uncooked, breaded chicken products, which were previously involved in outbreaks linked to consumer mishandling. The study also sought to observe behaviors of adolescents as home food preparers. Finally, the study aimed to compare food handler behaviors with those prescribed on product labels.Design/methodology/approachThe study sought, through video observation and self‐report surveys, to determine if differences exist between consumers' intent and actual behavior.FindingsA survey study of consumer reactions to safe food‐handling labels on raw meat and poultry products suggested that instructions for safe handling found on labels had only limited influence on consumer practices. The labels studied by these researchers were found on the packaging of chicken products examined in the current study alongside step‐by‐step cooking instructions. Observational techniques, as mentioned above, provide a different perception of consumer behaviors.Originality/valueThis paper finds areas that have not been studied in previous observational research and is an excellent addition to existing literature.

Several tick-transmitted Anaplasmataceae family rickettsiales of the genera Ehrlichia and Anaplasma have been discovered in recent years. Some are classified as pathogens responsible for emerging diseases and are a growing health concern for people. These illnesses include human monocytic ehrlichiosis, human granulocytic ewingii ehrlichiosis and human granulocytic anaplasmosis which are caused by Ehrlichia chaffeensis, E. ewingii and Anaplasma phagocytophilum, respectively. Despite the complex cellular environments of arthropod and vertebrate hosts with sophisticated defense systems, rickettsial pathogens have evolved strategies to evade host clearance and persist in vertebrate and tick hosts. For example, E. chaffeensis growing in vertebrate macrophages has distinct patterns of host cell-specific protein expression, assessed by large scale proteome analysis, and also differs considerably in its morphology compared with when it is growing in tick cells. Immunological studies suggest that host-cell-specific differences in E. chaffeensis gene expression aid the pathogen, extending its survival. Bacteria isolated from tick cells persist longer when injected into mice compared with mammalian macrophage-grown bacteria, and the host response is also significantly different. This review presents the current understanding of tick-Ehrlichia interactions at the molecular level and implications for future research in devising effective control methods.