Attempted transmission of Ehrlichia chaffeensis among white-tailed deer by Amblyomma maculatum

Tick-Borne Bacterial Diseases in Europe: Threats to public health

BACKGROUND

Tick-borne diseases, caused by bacterial pathogens, pose a growing threat to public health in Europe. This paper provides an overview of the historical context of the discovery of the most impactful pathogens transmitted by ticks, including Borrelia burgdorferi sensu lato, Rickettsia spp., Anaplasma spp., Francisella spp., Ehrlichia spp., and Neoehrlichia mikurensis. Understanding the historical context of their discovery provides insight into the evolution of our understanding of these pathogens.

METHODS AND RESULTS

Systematic investigation of the prevalence and transmission dynamics of these bacterial pathogens is provided, highlighting the intricate relationships among ticks, host organisms, and the environment. Epidemiology is explored, providing an in-depth analysis of clinical features associated with infections. Diagnostic methodologies undergo critical examination, with a spotlight on technological advancements that enhance detection capabilities. Additionally, the paper discusses available treatment options, addressing existing therapeutic strategies and considering future aspects.

CONCLUSIONS

By integrating various pieces of information on these bacterial species, the paper aims to provide a comprehensive resource for researchers and healthcare professionals addressing the impact of bacterial tick-borne diseases in Europe. This review underscores the importance of understanding the complex details influencing bacterial prevalence and transmission dynamics to better combat these emerging public health threats.

Artificial infestation of white-tailed deer with ticks (Acari: Ixodidae) to study tick-host interactions

White-tailed deer (Odocoileus virginianus) are a main host for the adult life stages of tick species of medical and veterinary importance. Since white-tailed deer play a vital role in tick ecology, research has been conducted to understand this tick-host relationship. To date, research involving captive white-tailed deer and artificial infestation of these animals with ticks has focused on host suitability, the role of white-tailed deer in tick-borne diseases, and anti-tick vaccine research. The methodology reported for these studies was at times not descriptive and inconsistent regarding how and what region of the white-tailed deer was infested with ticks. Here, we propose a standardized method to artificially infest captive white-tailed deer with ticks for research purposes. The protocol describes a method proven effective to experimentally infest captive white-tailed deer with blacklegged ticks (Ixodes scapularis) to study tick-host interactions. The methods can be reliably transferred for experimental infestation of white-tailed deer by other multi-host and one-host tick species.

Effect of Urbanization on Presence, Abundance, and Coinfection of Bacteria and Protozoa in Ticks in the US Great Plains

Urbanization alters components of natural ecosystems which can affect tick abundance and tick-borne disease prevalence. Likely due to these changes, tick-borne pathogen prevalence has increased in many U.S. urban areas. Despite the growing public health importance of tick-borne diseases, little is known about how they are influenced by urbanization in North America, especially in the central U.S. where several pathogens occur at or near their highest levels of incidence nationally. To determine whether urban development influences tick infection with bacteria and protozoa, we collected ticks at 16 parks across a gradient of urbanization intensity in Oklahoma City, Oklahoma, USA and tested them using a variety of PCR assays. Adult ticks tested positive for Rickettsia parkeri, R. amblyommatis, R. rhiphicephali, 'Candidatus R. andeanae', Ehrlichia chaffeensis, E. ewingii, Panola Mountain Ehrlichia, 'Borrelia lonestari', Theileria cervi, Babesia spp. Coco, and Cytauxzoon felis. These results indicate the presence of a high diversity of tick-borne bacteria and protozoa across an expanding urban area in the U.S. Great Plains. Although there appeared to be some risk of encountering tick-borne microorganisms across the entire urbanization gradient, E. chaffeensis, E. ewingii, and T. cervi-infected ticks and microbe diversity decreased with increasing urbanization intensity. We identified a low rate of coinfection between different microorganisms, with coinfected ticks mainly collected from sites in the least-urbanized areas. This study suggests the need for awareness of tick-borne disease risk throughout urban areas in the central U.S., and highlights a need for studies of tick host habitat use and movement in cities.

Ehrlichia chaffeensis: a prototypical emerging pathogen

Ehrlichia chaffeensis is an obligately intracellular, tick-transmitted bacterium that is maintained in nature in a cycle involving at least one and perhaps several vertebrate reservoir hosts. The moderate to severe disease caused by E. chaffeensis in humans, first identified in 1986 and reported for more than 1,000 patients through 2000, represents a prototypical "emerging infection." Knowledge of the biology and natural history of E. chaffeensis, and of the epidemiology, clinical features, and laboratory diagnosis of the zoonotic disease it causes (commonly referred to as human monocytic ehrlichiosis [HME]) has expanded considerably in the period since its discovery. In this review, we summarize briefly the current understanding of the microbiology, pathogenesis, and clinical manifestations associated with this pathogen but focus primarily on discussing various ecological factors responsible for the recent recognition of this important and potentially life-threatening tick-borne disease. Perhaps the most pivotal element in the emergence of HME has been the staggering increases in white-tailed deer populations in the eastern United States during the 20th century. This animal serves as a keystone host for all life stages of the principal tick vector (Amblyomma americanum) and is perhaps the most important vertebrate reservoir host for E. chaffeensis. The contributions of other components, including expansion of susceptible human populations, growth and broadening geographical distributions of other potential reservoir species and A. americanum, and improvements in confirmatory diagnostic methods, are also explored.