Ecotyping of Anaplasma phagocytophilum from Wild Ungulates and Ticks Shows Circulation of Zoonotic Strains in Northeastern Italy

The Presence of Bacterial and Protozoan Pathogens in Wild Fallow Deer (Dama dama) from a Protected Area in Central Italy

Wild ruminants often harbor pathogens transmissible to other animals and humans, but their epidemiological role is not always defined for all microorganisms. In this survey, spleens, kidneys, and hearts sampled from 162 fallow deer (Dama dama) were subjected to molecular analyses to detect bacterial (Anaplasma phagocytophilum, Borrelia burgdorferi s.l., Brucella spp., Chlamydia abortus, Coxiella burnetii, Francisella tularensis, Leptospira spp.) and protozoan (piroplasms, Neospora caninum, Toxoplasma gondii) pathogens. Five (3.08%) spleens were positive for A. phagocytophilum, and twelve (7.40%) spleens were positive for Theileria cervi. The remaining pathogens investigated were not detected, and no coinfections were found. The analyzed animals do not seem to have a relevant role in the spreading of these pathogens; however, monitoring is pivotal to understand the epidemiological scenarios and take appropriate preventive measures in areas frequently visited by people.

Tick-Borne Diseases in Sub-Saharan Africa: A Systematic Review of Pathogens, Research Focus, and Implications for Public Health

Sub-Saharan Africa, with its hot and humid climate, is a conducive zone for tick proliferation. These vectors pose a major challenge to both animal and human health in the region. However, despite the relevance of emerging diseases and evidence of tick-borne disease emergence, very few studies have been dedicated to investigating zoonotic pathogens transmitted by ticks in this area. To raise awareness of the risks of tick-borne zoonotic diseases in sub-Saharan Africa, and to define a direction for future research, this systematic review considers the trends of research on tick-borne bacteria, parasites, and viruses from 2012 to 2023, aiming to highlight the circulation of these pathogens in ticks, cattle, sheep, goats, and humans. For this purpose, three international databases were screened to select 159 papers fitting designed inclusion criteria and used for qualitative analyses. Analysis of these studies revealed a high diversity of tick-borne pathogens in sub-Saharan Africa, with a total of 37 bacterial species, 27 parasite species, and 14 viruses identified. Among these, 27% were zoonotic pathogens, yet only 11 studies investigated their presence in humans. Furthermore, there is growing interest in the investigation of bacteria and parasites in both ticks and ruminants. However, research into viruses is limited and has only received notable interest from 2021 onwards. While studies on the detection of bacteria, including those of medical interest, have focused on ticks, little consideration has been given to these vectors in studies of parasites circulation. Regarding the limited focus on zoonotic pathogens transmitted by ticks, particularly in humans, despite documented cases of emerging zoonoses and the notable 27% proportion reported, further efforts should be made to fill these gaps. Future studies should prioritize the investigation of zoonotic pathogens, especially viruses, which represent the primary emerging threats, by adopting a One Health approach. This will enhance the understanding of their circulation and impact on both human and animal health. In addition, more attention should be given to the risk factors/drivers associated to their emergence as well as the perception of the population at risk of infection from these zoonotic pathogens.

Zoonotic Tick-Borne Pathogens in Ticks from Vegetation and Alpine Ibex (Capra ibex) in the Maritime Alps, Italy

In the Maritime Alps (northwestern Italy), we collected ticks from vegetation and Alpine ibex (Capra ibex). Ixodes ricinus was the most abundant species in the study area, questing up to 1824 m a.s.l. and infesting 28 out of 72 ibexes. Haemaphysalis punctata, H. sulcata and Dermacentor marginatus were also collected. The abundance of questing ticks significantly decreased with altitude, with beechwoods being the preferred habitat. By PCR, we identified Borrelia burgdorferi s.l. in questing I. ricinus (28.3%; 95%CI: 19.4-38.6) but not in specimens collected from animals. Rickettsia spp. infected both questing (20.6%; 95%CI: 12.9-30.3) and on-host (30.2%; 95%CI: 21.2-40.4) I. ricinus. Anaplasma phagocytophilum was detected in 4.3% (95%CI: 1.2-10.8) of questing I. ricinus and in 45.3% (95%CI: 34.6-56.4) of I. ricinus collected from ibex. Female I. ricinus collected on animals were significantly more infected with A. phagocytophilum than females collected from vegetation (OR = 11.7; 95%CI: 3.8-48.1). By amplifying and sequencing a fragment of the groEL gene, we identified 13 groEL haplotypes, clustering with ecotypes I and II; ecotype I, prevalent in our sample, is considered zoonotic. Our study demonstrates the presence of different tick-borne zoonotic agents in the study area, encompassing a wide altitudinal range, as confirmed by the ticks found on ibex, a typical mountain-dwelling mammal. The results also confirm the altitudinal range expansion of ticks and associated pathogens in the Alps and suggest that Alpine ibex may act as a reservoir for A. phagocytophilum, as do other wild ungulate species.

Detection of Anaplasma spp. and Ehrlichia spp. in dogs from a veterinary teaching hospital in Italy: a retrospective study 2012-2020

Anaplasma phagocytophilum, Anaplasma platys and Ehrlichia canis, responsible of diseases in dogs, are tick-borne pathogens with a proven or potential zoonotic role that have shown increasing prevalence worldwide. The aims of this retrospective study were to assess the frequency of Anaplasma spp. and Ehrlichia spp. exposure in dogs tested in a veterinary teaching hospital in Italy over a 9-year period, to compare the performance of the diagnostic tests used, to evaluate correlations with clinical data, and to genetically analyse the identified bacteria. During the study period, 1322 dogs tested by at least one of the rapid immunoenzymatic test, indirect immunofluorescent antibody test or end-point PCR assay for Anaplasmataceae detection were included. Dogs were tested if they had clinical signs or clinicopathological alteration or risk factors related to infection, and if they were potential blood-donor animals. Ninety-four of 1322 (7.1%) dogs tested positive for at least one pathogen: 53 (4.3%) for A. phagocytophilum, one (0.1%) for A. platys and 63 (4.6%) for E. canis. The number of dogs tested increased and the positivity rate progressively declined over the years. Comparison of tests showed a near-perfect agreement between serological tests and a poor agreement between PCR and indirect assays. A breed predisposition has been highlighted for A. phagocytophilum infection in hunting breed dogs and for E. canis infection in mixed breed dogs. Phylogeny confirmed potential zoonotic implications for A. phagocytophilum and showed no correlation of the identified bacteria with the geographical origin. Our study provides new insights into possible risk factors in dogs and evidenced discordant results between different tests, suggesting that a combination of serological and molecular assays is preferable for a correct diagnosis.

Helminth Prevalence in European Deer with a Focus on Abomasal Nematodes and the Influence of Livestock Pasture Contact: A Meta-Analysis

Deer are susceptible to infection with parasitic helminths, including species which are of increasing economic concern to the livestock industry due to anthelmintic drug resistance. This paper systematically collates helminth prevalence data from deer across Europe and explores patterns in relation to host and parasite species, as well as landscape factors. A livestock pasture contact index (LPCI) is developed to predict epidemiological overlap between deer and livestock, and hence to examine deer helminth fauna in the context of their surrounding environment. Fifty-eight studies comprising fallow (Dama dama), red (Cervus elaphus), roe (Capreolus capreolus) and sika (Cervus nippon) deer were identified. Deer populations in "likely" contact with livestock pasture had a higher mean prevalence of the abomasal nematodes Haemonchus contortus, Ostertagia ostertagi, Teladorsagia circumcincta and Trichostrongylus axei (p = 0.01), which are common in livestock and not primarily associated with deer. Roe deer populations had a higher prevalence of T. circumcincta (p = 0.02) and T. axei (p = 0.01) than fallow deer and a higher prevalence of H. contortus than both red (p = 0.01) and fallow deer (p = 0.02). Liver fluke and lungworm species were present sporadically at low prevalence, while the abomasal nematode Ashworthius sidemi occurred locally at high prevalence. Insights from this research suggest that deer helminth fauna is reflective of their surrounding environment, including the livestock species which inhabit areas of shared grazing. This is explored from an epidemiological perspective, and the prospect of helminth transmission between wild and domestic hosts is discussed, including drug-resistant strains, alongside the role of helminths as indicators relevant to the transmission of other pathogens at the wildlife-livestock interface.

Diversity of Anaplasma phagocytophilum Strains from Roe Deer (Capreolus capreolus) and Red Deer (Cervus elaphus) in Poland

BACKGROUND

The Gram-negative bacterium Anaplasma phagocytophilum is an intracellular pathogen and an etiological agent of human and animal anaplasmosis. Its natural reservoir comprises free-ranging ungulates, including roe deer (Capreolus capreolus) and red deer (Cervus elaphus). These two species of deer also constitute the largest group of game animals in Poland. The aim of the study was to genotype and perform a phylogenetic analysis of A. phagocytophilum strains from roe deer and red deer.

METHODS

Samples were subjected to PCR amplification, sequencing, and phylogenetic analysis of strain-specific genetic markers (groEL, ankA).

RESULTS

Five haplotypes of the groEL gene from A. phagocytophilum and seven haplotypes of ankA were obtained. The phylogenetic analysis classified the groEL into ecotypes I and II. Sequences of the ankA gene were classified into clusters I, II, and III.

CONCLUSIONS

Strains of A. phagocytophilum from red deer were in the same ecotype and cluster as strains isolated from humans. Strains of A. phagocytophilum from roe deer represented ecotypes (I, II) and clusters (II, III) that were different from those isolated from red deer, and these strains did not show similarity to bacteria from humans. However, roe deer can harbor nonspecific strains of A. phagocytophilum more characteristic to red deer. It appears that the genetic variants from red deer can be pathogenic to humans, but the significance of the variants from roe deer requires more study.

Survey of Tick-Borne Zoonotic Agents in Ixodes Ticks Carried by Wild Passerines during Postbreeding Migration through Italy

Recently, increasing attention has been posed on the role of migrating birds in the spread of ticks and indirectly of tick-borne pathogens (TBPs). Despite, Italy is considered a bridge between continental Europe and North Africa and a necessary path to connect Mediterranean countries, few studies have been conducted on ticks collected from birds migrating through this country and associated TBPs. The aims of this research were to estimate the infestation burden and identify tick species feeding on migratory birds, and perform a molecular screening for TBPs. During autumn migration (2019-2020), birds were inspected for ticks in a ringing station located in north-east Italy. Ticks were identified and screened for tick-borne encephalitis virus (TBEV), Borrelia burgdorferi sensu latu, Rickettsia spp., Ehrlichia spp., Neoehrlichia spp., Anaplasma phagocytophilum, and Bartonella spp. Ixodes ticks (n = 209) were feeding on 2.6% of passerines (88/3411). Most of these (208/209) were Ixodes ricinus, except one Ixodes frontalis. Eight bird species were infested: common blackbird, redwing, brambling, song thrush, common chaffinch, European robin, water pipit, and coal tit. Rickettsiales showed a low prevalence, from 1.4% of Ehrlichia spp., 4.3% of A. phagocytophilum, up to 7.2% of Rickettsia spp.. Borrelia burgdorferi s.l. had the highest prevalence, 54.6%, and several zoonotic genotypes were identified: B. garinii, B. valaisiana, B. afzeli, B. burgdorferi sensu stricto, and B. miyamotoi. All specimens were negative for TBEV and Bartonella spp.. Although the tick burden was generally low, most of the vectors (>60%) were positive for at least one pathogen, highlighting the relevance of a continuous monitoring of migrating birds as potential sources of pathogen dispersal.

Wild ungulates as sentinels of flaviviruses and tick-borne zoonotic pathogen circulation: an Italian perspective

BACKGROUND

Vector-borne zoonotic diseases are a concerning issue in Europe. Lyme disease and tick-borne encephalitis virus (TBEV) have been reported in several countries with a large impact on public health; other emerging pathogens, such as Rickettsiales, and mosquito-borne flaviviruses have been increasingly reported. All these pathogens are linked to wild ungulates playing roles as tick feeders, spreaders, and sentinels for pathogen circulation. This study evaluated the prevalence of TBEV, Borrelia burgdorferi sensu lato, Rickettsia spp., Ehrlichia spp., and Coxiella spp. by biomolecular screening of blood samples and ticks collected from wild ungulates. Ungulates were also screened by ELISA and virus neutralization tests for flaviviral antibody detection.

RESULTS

A total of 274 blood samples were collected from several wild ungulate species, as well as 406 Ixodes ricinus, which were feeding on them. Blood samples tested positive for B. burgdorferi s.l. (1.1%; 0-2.3%) and Rickettsia spp. (1.1%; 0-2.3%) and showed an overall flaviviral seroprevalence of 30.6% (22.1-39.2%): 26.1% (17.9-34.3%) for TBEV, 3.6% (0.1-7.1%) for Usutu virus and 0.9% (0-2.7%) for West Nile virus. Ticks were pooled when possible and yielded 331 tick samples that tested positive for B. burgdorferi s.l. (8.8%; 5.8-11.8%), Rickettsia spp. (26.6%; 21.8-31.2%) and Neoehrlichia mikurensis (1.2%; 0-2.4%). TBEV and Coxiella spp. were not detected in either blood or tick samples.

CONCLUSIONS

This research highlighted a high prevalence of several tick-borne zoonotic pathogens and high seroprevalence for flaviviruses in both hilly and alpine areas. For the first time, an alpine chamois tested positive for anti-TBEV antibodies. Ungulate species are of particular interest due to their sentinel role in flavivirus circulation and their indirect role in tick-borne diseases and maintenance as Ixodes feeders and spreaders.

Anaplasma phagocytophilum Ecotype Analysis in Cattle from Great Britain

Anaplasma phagocytophilum (A. phagocytophilum) is the aetiological agent of tick-borne fever in cattle and sheep, and granulocytic anaplasmosis in human and dogs. Livestock, companion animal and human infections with A. phagocytophilum have been reported globally. Across England and Wales, two isolates (called ecotypes) have been reported in ticks. This study examined A. phagocytophilum isolates present in livestock and wildlife in Great Britain (GB), with a particular focus on cattle. Clinical submissions (EDTA blood) from cattle (n = 21) and sheep (n = 3) were received by APHA for tick-borne disease testing and the animals were confirmed to be infected with A. phagocytophilum using a PCR targeting the Msp2 gene. Further submissions from roe deer (n = 2), red deer (n = 2) and Ixodes ricinus ticks (n = 22) were also shown to be infected with A. phagocytophilum. Subsequent analysis using a nested PCR targeting the groEL gene and sequencing confirmed the presence of ecotype I in cattle, sheep, red deer and Ixodes ricinus, and ecotype II in roe deer and I. ricinus removed from deer carcasses. Despite the presence of two ecotypes, widely distributed in ticks from England and Wales, only ecotype I was detected in cattle in this study.

Presence of Anaplasma phagocytophilum Ecotype I in UK Ruminants and Associated Zoonotic Risk

Anaplasma phagocytophilum is the causative agent of tick-borne fever in sheep, pasture fever in cattle, and granulocytic anaplasmosis in humans. The increasing prevalence and transboundary spread of A. phagocytophilum in livestock, ticks, and wildlife in the UK poses a potential zoonotic risk that has yet to be estimated. Several ecotypes of A. phagocytophilum show variable zoonotic potential. To evaluate the possible risk associated with the transmission of A. phagocytophilum from ruminants to humans, the ecotype was determined by sequencing the groEL gene from 71 positive blood and tissue samples from UK ruminants. Thirty-four groEL sequences were obtained, fourteen of which were identified in multiple samples. Of the 13 nucleotide polymorphisms identified through pairwise comparison, all corresponded to synonymous substitutions. The subsequent phylogenetic estimation of the relationship with other European/world isolates indicated that all the groEL sequences clustered with other ecotype I sequences. The presence of ecotype I closely reflects that observed in ruminants in continental Europe and suggests a lower risk of zoonotic transmission from this reservoir.

Molecular survey on the presence of arthropod-borne bacteria and protozoans in roe deer (Capreolus capreolus) and ticks from Central Italy

Environmental changes, due to climatic emergency and to anthropogenic activities severely impact on the epidemiology of vector borne diseases, mostly when transmitted by ticks. The data about the distribution of microorganisms responsible for them in roe deer (Capreolus capreolus) population living in Italy are scanty and completely lacking in Tuscany, so a molecular survey was carried out to estimate the prevalence of some zoonotic tick-borne pathogens in roe deer, and ticks removed from them, living in areas of Central Italy with high risk of arthropod exposure. Spleen samples from 72 roe deer were tested by PCR for Anaplasma phagocytophilum, Borrelia burgdorferi s.l., Francisella tularensis and piroplasms. Moreover, 345 ticks were removed from 65 roe deer, morphologically or molecularly identified and grouped into 162 pools that were submitted to PCR for detecting the same pathogens. Forty-six (63.88%) roe deer were positive for at least one investigated pathogen: 43 (59.72%) for A. phagocytophilum, 2 (2.78%) for Babesia capreoli, 1 (1.39%) for B. burgdorferi, and 1 (1.39%) for Babesia sp.. No animals were PCR positive for F. tularensis. All ticks were identified as Ixodes ricinus. Seventy-six (46.91%) tick pools showed DNA of one or more pathogens: 66 (40.74%) were positive for A. phagocytophilum, 22 (13.58%) for B. burgodorferi s.l., 6 (3.70%) for B. venatorum and 3 (1.85%) for B. capreoli. No pools were positive for F. tularensis. Two or three pathogens were detected in 23 (14.19%) pools.

Molecular Survey of Babesia spp. and Anaplasma phagocytophilum in Roe Deer from a Wildlife Rescue Center in Italy

Simple Summary

Roe deer, whose populations are increasing and expanding throughout Europe, are suitable hosts for the maintenance of a variety of infectious tick-vectored microorganisms, that can infect both animals and humans. In this study the presence of tick-transmitted pathogens was investigated in roe deer recovered by a wildlife rescue center based in Italy. This kind of samples represents a convenient material for investigations under several aspects for both animals and researchers. Notably, no live trapping or killing are required to obtain samples, as they are collected in the context of the rescue activities and aimed to frame the health status of the animal. The investigated blood samples showed high positive rates to typical roe deer-related microorganisms (such as Babesia capreoli), and to the zoonotic agent Babesia venatorum. Roe deer were also positive to Anaplasma phagocytophilum strains mainly considered apathogenic or limited to wild ungulates. The obtained results underline the importance of a constant investigation on circulating tick-borne pathogens in roe deer, and generally speaking, in wild animal species, due to their potential role as a key factor in the endemic cycle of important infectious agents for domestic and wild animals, as well as humans.

Abstract

Babesia ssp. and Anaplasma spp. are tick-borne microorganisms representing a possible health risk for domestic and wild animals, as well as humans. Roe deer serve as a suitable reservoir host for some species ascribed to Babesia spp. and Anaplasma phagocytophilum taxa, also due to its important role in the maintenance of large populations of Ixodes ricinus, the main tick vector of these pathogens in Europe. Roe deer populations have been recently expanding throughout Europe, namely in Italy. However, the collection of samples from free-ranging wild animals for diagnostic investigations often includes several practical issues. This problem can be overcome using samples provided by wildlife rescue centers making them available for investigations following routine analyses. The presence of Babesia spp. and Anaplasma spp. in blood samples of 43 roe deer rescued by a wildlife rescue center in Emilia-Romagna region (Italy) was molecularly investigated. PCR screening revealed the presence of at least one pathogen in 86.05% of the animals, while co-infection occurred in 18.92% of the tested individuals. Zoonotic Babesia venatorum was found in 6.98% of the samples, while Babesia capreoli and Anaplasma phagocytophilum were detected in 74.42% and in 20.93%, respectively. No hematological signs compatible with clinical anaplasmosis or piroplasmosis, as well as absence of intracellular circulating microorganisms in blood smears, were observed, suggesting asymptomatic infection in the tested animals. These results confirm the usefulness of wild rescued animals as convenient source of biological samples for tick-borne pathogens investigation and the role of roe deer as a key factor in the endemic cycle of Babesia species and A. phagocytophilum.

Tick-Borne Pathogens in Ticks Collected from Wild Ungulates in North-Eastern Poland

This study was carried out in north-eastern Poland during two hunting seasons between 2018 and 2020. Ticks (Ixodes ricinus and Dermacentor reticulatus) were removed from wild cervids and boars and examined for the presence of Borrelia spirochetes and Rickettsiales members: Rickettsia spp. and Anaplasma phagocytophilum. The present study contributes to the knowledge of even-toed ungulates, which are an important reservoir of the above-mentioned pathogens and a potential source of infections for humans through ticks as vectors. Almost 40% of the collected ticks (191 out of 484) were infected with the following pathogens: 3.3% with Borrelia spp., 19.2% with A. phagocytophilum and 26.9% with Rickettsia spp. Only the ticks collected from cervids carried Borrelia. Typing of the species DNA confirmed the presence of B. afzelii, B. garinii, B. lusitaniae and B. miyamotoi. An analysis of Rickettsia spp. sequences using the GenBank data revealed the presence of R. helvetica, R. raoultii and R. monacensis. Monoinfections (79.1%) dominated over co-infections (20.9%). Among co-infections, the most frequent was A. phagocytophilum/Rickettsia spp. (70%), however co-infections, including B. afzelii/A. phagocytophilum, B. afzelii/Rickettsia spp., B. miyamotoi/A. phagocytophilum and B. afzelii/B. garinii/B. lusitaniae, were also noted. Significant differences were observed in the affinity of some pathogens to their vectors. Thus, Borrelia spp. and A. phagocytophilum were more frequently detected in I. ricinus (5.3% and 23.1%) than in D. reticulatus (1.2% and 15.3%). Infection frequency with Rickettsia spp. was similar (approximately 25–29%) in both tick species. The prevalence of A. phagocytophilum and Rickettsia spp. in ticks removed from cervids was 19.8% and 27.1%, and in ticks from wild boars it was 13.3% and 24.4%, respectively.