Experimental and Field Studies on the Suitability of Raccoons (Procyon lotor) as Hosts for Tick-Borne Pathogens

Vector-Borne Disease in Wild Mammals Impacted by Urban Expansion and Climate Change

Ecologies of zoonotic vector-borne diseases may shift with climate and land use change. As many urban-adapted mammals can host ectoparasites and pathogens of human and animal health concern, our goal was to compare patterns of arthropod-borne disease among medium-sized mammals across gradients of rural to urban landscapes in multiple regions of California. DNA of Anaplasma phagocytophilum was found in 1-5% of raccoons, coyotes, and San Joaquin kit foxes; Borrelia burgdorferi in one coyote, rickettsiae in two desert kit foxes, and Yersinia pestis in two coyotes. There was serological evidence of rickettsiae in 14-37% of coyotes, Virginia opossums, and foxes; and A. phagocytophilum in 6-40% of coyotes, raccoons, Virginia opossums, and foxes. Of six flea species, one Ctenocephalides felis from a raccoon was positive for Y. pestis, and Ct. felis and Pulex simulans fleas tested positive for Rickettsia felis and R. senegalensis. A Dermacentor similis tick off a San Joaquin kit fox was PCR-positive for A. phagocytophilum. There were three statistically significant risk factors: risk of A. phagocytophilum PCR-positivity was threefold greater in fall vs the other three seasons; hosts adjacent to urban areas had sevenfold increased A. phagocytophilum seropositivity compared with urban and rural areas; and there was a significant spatial cluster of rickettsiae within greater Los Angeles. Animals in areas where urban and rural habitats interconnect can serve as sentinels during times of change in disease risk.

Multi-Locus Sequencing Reveals Putative Novel Anaplasmataceae Agents, 'Candidatus Ehrlichia dumleri' and Anaplasma sp., in Ring-Tailed Coatis (Carnivora: Nasua nasua) from Urban Forested Fragments at Midwestern Brazil

The Anaplasmataceae family encompasses obligate intracellular α-proteobacteria of human and veterinary medicine importance. This study performed multi-locus sequencing to characterize Ehrlichia and Anaplasma in coati's blood samples in Midwestern Brazil. Twenty-five samples (25/165-15.1%) were positive in the screening PCR based on the dsb gene of Ehrlichia spp. and were characterized using 16S rRNA, sodB, groEL, and gltA genes and the 23S-5S intergenic space region (ITS). Phylogenetic analyses based on all six molecular markers positioned the sequences into a new clade, with a common origin of Ehrlichia ruminantium. Haplotype analyses of 16S RNA sequences revealed the presence of two distinct Ehrlichia genotypes. Six samples (6/165, 3.6%) were positive in the screening nPCR for the 16S rRNA gene of Anaplasma spp. and were submitted to an additional PCR targeting the ITS for molecular characterization. Phylogenetic analyses based on both 16S rRNA gene and ITS positioned the Anaplasma sp. detected in the present study in a large clade with other Anaplasma sp. previously detected in ticks and wild animals and in a clade with 'Candidatus Anaplasma brasiliensis', respectively. Based on distinct molecular markers, the present work described a putative novel Anaplasmataceae agent, namely 'Candidatus Ehrlichia dumleri', and Anaplasma sp. closely related to the previously described 'Candidatus Anaplasma brasiliensis'.

Invasive raccoon (Procyon lotor) and raccoon dog (Nyctereutes procyonoides) as potential reservoirs of tick-borne pathogens: data review from native and introduced areas

In recent decades, populations of the raccoon (Procyon lotor) and the raccoon dog (Nyctereutes procyonides) have increased and adapted to peri-urban and urban environments in many parts of the world. Their ability to rapidly colonize new territories, high plasticity and behavioral adaptation has enabled these two species to be considered two of the most successful invasive alien species. One of the major threats arising from continually growing and expanding populations is their relevant role in maintaining and transmitting various vector-borne pathogens among wildlife, domestic animals and humans. According to the WHO, over 17% of infectious diseases are vector-borne diseases, including those transmitted by ticks. Every year tick-borne pathogens (TBPs) create new public health challenges. Some of the emerging diseases, such as Lyme borreliosis, anaplasmosis, ehrlichiosis, babesiosis and rickettsiosis, have been described in recent years as posing important threats to global health. In this review we summarize current molecular and serological data on the occurrence, diversity and prevalence of some of the TBPs, namely Babesia, Theileria, Hepatozoon, Borrelia, Rickettsia, Bartonella, Anaplasma and Ehrlichia, that have been detected in raccoons and raccoon dogs that inhabit their native habitats and introduced areas. We draw attention to the limited data currently available on these invasive carnivores as potential reservoirs of TBPs in different parts of the world. Simultaneously we indicate the need for more research in order to better understand the epidemiology of these TBPs and to assess the future risk originating from wildlife.

Incompetence of the Asian Longhorned Tick (Acari: Ixodidae) in Transmitting the Agent of Human Granulocytic Anaplasmosis in the United States

The Asian longhorned tick, Haemaphysalis longicornis Neumann (Acari: Ixodidae), was recently introduced into the United States and is now established in at least 15 states. Considering its ability for parthenogenetic propagation and propensity for creating high-density populations, there is concern that this tick may become involved in transmission cycles of endemic tick-borne human pathogens. Human granulocytic anaplasmosis (HGA) caused by Anaplasma phagocytophilum is one of the more common tick-borne diseases in the United States, especially in the northeastern and midwestern states. There is considerable geographical overlap between HGA cases and the currently known distribution of H. longicornis, which creates a potential for this tick to encounter A. phagocytophilum while feeding on naturally infected vertebrate hosts. Therefore, we evaluated the ability of H. longicornis to acquire and transmit the agent of HGA under laboratory conditions and compared it to the vector competence of I. scapularis. Haemaphysalis longicornis nymphs acquired the pathogen with the bloodmeal while feeding on infected domestic goats, but transstadial transmission was inefficient and PCR-positive adult ticks were unable to transmit the pathogen to naïve goats. Results of this study indicate that the Asian longhorned tick is not likely to play a significant role in the epidemiology of HGA in the United States.

Prevalence, distribution, and diversity of cryptic piroplasm infections in raccoons from selected areas of the United States and Canada

The order Piroplasmida contains a diverse group of intracellular parasites, many of which can cause significant disease in humans, domestic animals, and wildlife. Two piroplasm species have been reported from raccoons (Procyon lotor), Babesia lotori (Babesia sensu stricto clade) and a species related to Babesia microti (called B. microti-like sp.). The goal of this study was to investigate prevalence, distribution, and diversity of Babesia in raccoons. We tested raccoons from selected regions in the United States and Canada for the presence of Babesia sensu stricto and Babesia microti-like sp. piroplasms. Infections of Babesia microti-like sp. were found in nearly all locations sampled, often with high prevalence, while Babesia sensu stricto infections had higher prevalence in the Southeastern United States (20–45% prevalence). Co-infections with both Babesia sp. were common. Sequencing of the partial 18S rRNA and cytochrome oxidase subunit 1 (cox1) genes led to the discovery of two new Babesia species, both found in several locations in the eastern and western United States. One novel Babesia sensu stricto sp. was most similar to Babesia gibsoni while the other Babesia species was present in the ‘western piroplasm’ group and was related to Babesia conradae. Phylogenetic analysis of the cox1 sequences indicated possible eastern and western genetic variants for the three Babesia sensu stricto species. Additional analyses are needed to characterize these novel species; however, this study indicates there are now at least four species of piroplasms infecting raccoons in the United States and Canada (Babesia microti-like sp., Babesia lotori, a novel Babesia sensu stricto sp., a novel western Babesia sp.) and a possible fifth species (Babesia sensu stricto) in raccoons in Japan.

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Raccoons in all locations tested were infected with piroplasms.

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Babesia microti-like sp. was commonly found in raccoons throughout North America.

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Babesia sensu stricto spp. were less common throughout North America.

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Four, possibly five, distinct species of piroplasms in raccoons.

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Possible spatial genetic variation within the two raccoon piroplasm species.

Diversity of Anaplasma and Ehrlichia/Neoehrlichia Agents in Terrestrial Wild Carnivores Worldwide: Implications for Human and Domestic Animal Health and Wildlife Conservation

Recently, the incidence and awareness of tick-borne diseases in humans and animals have increased due to several factors, which in association favor the chances of contact among wild animals and their ectoparasites, domestic animals and humans. Wild and domestic carnivores are considered the primary source of tick-borne zoonotic agents to humans. Among emergent tick-borne pathogens, agents belonging to family Anaplasmataceae (Order Rickettsiales) agents stand out due their worldwide distribution and zoonotic potential. In this review we aimed to review the genetic diversity of the tick-transmitted genera Ehrlichia, Anaplasma and "Candidatus Neoehrlichia sp." in wild carnivores Caniformia (Canidae, Mustelidae and Ursidae) and Feliformia (Felidae, Hyanidae, Procyonidae and Viverridae) worldwide, discussing the implications for human and domestic animal health and wildlife conservation. Red foxes (Vulpes vulpes) have been identified as hosts for Anaplasma spp. (A. phagocytophilum, Anaplasma ovis, A. platys), Ehrlichia canis and "Candidatus Neoehrlichia sp." (FU98 strain) and may contribute to the maintaenance of A. phagocytophilum in Europe. Raccoons (Procyon lotor) have been reported as hosts for E. canis, A. bovis, "Candidatus Neoehrlichia lotoris" and A. phagocytophilum, and play a role in the maintenance of A. phagocytophilum in the USA. Raccoon dogs (Nyctereutes procyonoides) may play a role as hosts for A. bovis and A. phagocytophilum. New Ehrlichia and/or Anaplasma genotypes circulate in wild canids and felids from South America and Africa. While Ehrlichia sp. closely related to E. canis has been reported in wild felids from Brazil and Japan, Anaplasma sp. closely related to A. phagocytophilum has been detected in wild felids from Brazil and Africa. Red foxes and mustelids (otters) are exposed to E. canis in countries located in the Mediaterranean basin, probably as a consequence of spillover from domestic dogs. Similarly, E. canis occurs in procyonids in North (raccoons in USA, Spain) and South (Nasua nasua in Brazil) Hemispheres, in areas where E. canis is frequent in dogs. While "Candidatus Neoehrlichia lotoris" seems to be a common and specific agent of raccoons in the USA, "Candidatus Neoehrlichia sp." (FU98 strain) seems to show a broader range of hosts, since it has been detected in red fox, golden jackal (Canis aureus) and badger (Meles meles) in Europe so far. Brown (Ursus arctos) and black (Ursus americanus) bears seem to play a role as hosts for A. phagocytophilum in the North Hemisphere. Anaplasma bovis has been detected in wild Procyonidae, Canidae and Felidae in Asia and Brazil. In order to assess the real identity of the involved agents, future works should benefit from the application of MLST (Multi Locus Sequence Typing), WGS (Whole Genome Sequencing) and NGS (Next Generation Sequencing) technologies aiming at shedding some light on the role of wild carnivores in the epidemiology of Anaplasmataceae agents.

Prevalence and diversity of piroplasms and ticks in young raccoons and an association of Babesia sensu stricto infections with splenomegaly

Piroplasms are intraerythrocytic parasites that are often transmitted by ixodid ticks, but vertical transmission is an alternative route for some species. In the USA, raccoons (Procyon lotor) are hosts for two known species, a Babesia microti-like sp. and Babesia lotori (in Babesia sensu stricto group). To better understand the natural history of Babesia in raccoons, we tested young raccoons from Minnesota and Colorado for Babesia spp., examined them for ticks, and assessing for splenomegaly as a sign of clinical disease. Raccoons from both states were infected with B. microti-like sp. and Babesia sensu stricto spp. Infections of B. microti-like were common, even in 1-week-old raccoons, suggesting vertical transmission. Babesia sensu stricto infections were more common in older raccoons. Raccoons infected with Babesia sensu stricto had significantly higher spleen:body weight ratios compared with uninfected or B. microti-like sp.-infected raccoons. Ticks were only found on raccoons from Minnesota. The most common and abundant tick was Ixodes texanus but Ixodes scapularis and Dermacentor variabilis were also found on raccoons. We report piroplasm infections and infestations with several tick species in very young raccoons. Young raccoons infected with Babesia sensu stricto spp. had higher spleen:body weight ratios, suggesting a disease risk.

The occurrence of Anaplasmataceae in European populations of invasive carnivores

The raccoon (Procyon lotor) and the raccoon dog (Nyctereutes procyonoides) belong to a group of the invasive species. The introduced species as potential reservoirs for vector-borne pathogens have been the subject of recent research, though there are still no data with reference to the European population of the raccoon, and few studies concern only the raccoon dog. This study shows the occurrence of Anaplasmataceae representatives in raccoons and a sympatric population of the raccoon dogs obtained from the area of Poland and Germany. During the study, the occurrence of Anaplasma phagocytophilum ecotype I in the introduced raccoon in northwestern Poland was revealed. Additionally, Candidatus Neoehrlichia sp. (FU98) was identified for the first time in the raccoon dog in Central Europe and thereby the raccoon dog is a new host for this pathogen.

Epidemiological study of relapsing fever borreliae detected in Haemaphysalis ticks and wild animals in the western part of Japan

The genus Borrelia comprises arthropod-borne bacteria, which are infectious agents in vertebrates. They are mainly transmitted by ixodid or argasid ticks. In Hokkaido, Japan, Borrelia spp. were found in deer and Haemaphysalis ticks between 2011 and 2013; however, the study was limited to a particular area. Therefore, in the present study, we conducted large-scale surveillance of ticks and wild animals in the western part of the main island of Japan. We collected 6,407 host-seeking ticks from two regions and 1,598 larvae obtained from 32 engorged female ticks and examined them to elucidate transovarial transmission. In addition, we examined whole blood samples from 190 wild boars and 276 sika deer, as well as sera from 120 wild raccoons. We detected Borrelia spp. in Haemaphysalis flava, Haemaphysalis megaspinosa, Haemaphysalis kitaokai, Haemaphysalis longicornis, and Haemaphysalis formosensis. In addition, we isolated a strain from H. megaspinosa using Barbour-Stoenner-Kelly medium. The minimum infection rate of ticks was less than 5%. Transovarial transmission was observed in H. kitaokai. Phylogenetic analysis of the isolated strain and DNA fragments amplified from ticks identified at least four bacterial genotypes, which corresponded to the tick species detected. Bacteria were detected in 8.4%, 15%, and 0.8% of wild boars, sika deer, and raccoons, respectively. In this study, we found seasonal differences in the prevalence of bacterial genotypes in sika deer during the winter and summer. The tick activity season corresponds to the season with a high prevalence of animals. The present study suggests that a particular bacterial genotype detected in this study are defined by a particular tick species in which they are present.

Opening the black box of Anaplasma phagocytophilum diversity: current situation and future perspectives

Anaplasma phagocytophilum is a zoonotic obligate intracellular bacterium known to be transmitted by ticks belonging to the Ixodes persulcatus complex. This bacterium can infect several mammalian species, and is known to cause diseases with variable symptoms in many domestic animals. Specifically, it is the causative agent of tick-borne fever (TBF), a disease of important economic impact in European domestic ruminants, and human granulocytic anaplasmosis (HGA), an emerging zoonotic disease in Asia, USA and Europe. A. phagocytophilum epidemiological cycles are complex and involve different ecotypes, vectors, and mammalian host species. Moreover, the epidemiology of A. phagocytophilum infection differs greatly between Europe and the USA. These different epidemiological contexts are associated with considerable variations in bacterial strains. Until recently, few A. phagocytophilum molecular typing tools were available, generating difficulties in completely elucidating the epidemiological cycles of this bacterium. Over the last few years, many A. phagocytophilum typing techniques have been developed, permitting in-depth epidemiological exploration. Here, we review the current knowledge and future perspectives regarding A. phagocytophilum epidemiology and phylogeny, and then focus on the molecular typing tools available for studying A. phagocytophilum genetic diversity.

White-nosed coatis (Nasua narica) are a potential reservoir of Trypanosoma cruzi and other potentially zoonotic pathogens in Monteverde, Costa Rica

We studied white-nosed coatis (Nasua narica) in Monteverde, Costa Rica to evaluate their potential as a reservoir for the vector-borne zoonotic parasite Trypanosoma cruzi and other selected microorganisms. We live-trapped 20 coatis in July and August 2011 and tested them for T. cruzi by blood smear, molecular analysis of blood, culture of blood and anal gland secretions, and serology. Seven coatis (35%) were polymerase-chain-reaction-positive for T. cruzi and one coati was also culture positive. We did not detect T. cruzi in anal gland secretions. All coatis were positive for Mycoplasma and Babesia, but were negative for Baylisascaris, Anaplasma, Candidatus Neoehrlichia lotoris, Ehrlichia, Bartonella, and several apicomplexan parasites. The possible pathogenicity of T. cruzi, Babesia, and Mycoplasma in coatis and their transmission potential to humans and domestic animals warrants further investigation.

Anaplasma phagocytophilum--a widespread multi-host pathogen with highly adaptive strategies

The bacterium Anaplasma phagocytophilum has for decades been known to cause the disease tick-borne fever (TBF) in domestic ruminants in Ixodes ricinus-infested areas in northern Europe. In recent years, the bacterium has been found associated with Ixodes-tick species more or less worldwide on the northern hemisphere. A. phagocytophilum has a broad host range and may cause severe disease in several mammalian species, including humans. However, the clinical symptoms vary from subclinical to fatal conditions, and considerable underreporting of clinical incidents is suspected in both human and veterinary medicine. Several variants of A. phagocytophilum have been genetically characterized. Identification and stratification into phylogenetic subfamilies has been based on cell culturing, experimental infections, PCR, and sequencing techniques. However, few genome sequences have been completed so far, thus observations on biological, ecological, and pathological differences between genotypes of the bacterium, have yet to be elucidated by molecular and experimental infection studies. The natural transmission cycles of various A. phagocytophilum variants, the involvement of their respective hosts and vectors involved, in particular the zoonotic potential, have to be unraveled. A. phagocytophilum is able to persist between seasons of tick activity in several mammalian species and movement of hosts and infected ticks on migrating animals or birds may spread the bacterium. In the present review, we focus on the ecology and epidemiology of A. phagocytophilum, especially the role of wildlife in contribution to the spread and sustainability of the infection in domestic livestock and humans.

Molecular survey of Anaplasma and Ehrlichia infections of feral raccoons (Procyon lotor) in Hokkaido, Japan

Infection by Anaplasma and Ehrlichia in feral raccoons (Procyon lotor) in Hokkaido, Japan, was examined by molecular methods. A polymerase chain reaction (PCR) screen for Anaplasmataceae, based on 16S rRNA, showed that 38 (5.4%) of 699 raccoons examined were positive. These 38 positive samples were examined for Anaplasma phagocytophilum, Anaplasma bovis, Ehrlichia chaffeensis, and Ehrlichia canis infection by species-specific nested PCR. Nested PCR results indicated that 36 of the 38 samples were positive for A. bovis. All 38 samples were PCR negative for A. phagocytophilum, E. chaffeensis, and E. canis. This is the first report of the detection of A. bovis in the peripheral blood of raccoons. A total of 124 raccoons were infested with ticks, including Ixodes ovatus, Ixodes persulcatus, and Haemaphysalis spp. The rate of A. bovis infection in raccoons infested with Haemaphysalis spp. (46.7%, 7/15) was significantly higher than that in raccoons without Haemaphysalis spp. infestation (3.7%, 4/109, p < 0.001). No significant differences were observed in A. bovis infection rates between raccoons infested with I. ovatus or I. persulcatus and those not so infested. A total of four ticks (two males and two nymphs) and one larval pools from four raccoons showed positive for A. bovis-specific nested PCR. This results support the correlation between the A. bovis infection of raccoons and Haemaphysalis infestation. In conclusion, raccoons could be possible reservoir animals for A. bovis, and A. bovis infection in raccoons may be related to infestation with Haemaphysalis spp.

Prevalence of Ehrlichia chaffeensis and Ehrlichia ewingii in ticks from Tennessee

Human ehrlichiosis is the second most common tick-borne disease reported in Tennessee after Rocky Mountain spotted fever. Two closely related ehrlichiae, Ehrlichia chaffeensis and Ehrlichia ewingii, are both causative agents of human disease and are transmitted by Amblyomma americanum, the lone star tick. Prevalence rates and distribution patterns of these pathogens among ticks in Tennessee are currently unknown. To understand prevalence and exposure risk of Ehrlichia spp., we tested 616 ticks (309 Amblyomma americanum (L.), 277 Dermacentor variabilis (Say), 17 Ixodes texanus (Banks), 7 Ixodes cookei Packard, 4 Ixodes scapularis (Say), and 2 Amblyomma maculatum Koch) from 46 counties for E. chaffeensis and 324 ticks (238 A. americanum and 86 D. variabilis) from 29 counties for E. ewingii. Overall, E. chaffeensis was detected in 2.6% (8/309) of A. americanum and E. ewingii in 0.8% (2/238). Ehrlichia spp. DNA was not detected in any tick species other than A. americanum. Although sample sizes were low in many counties, all positive ticks were identified in the Interior Plateau and Southeastern Plains ecoregions which is where the majority of human ehrlichiosis cases are reported from Tennessee (e.g., 66.3% of the human cases in 2008 are from the Interior Plateau ecoregion). The data from this pathogen survey combined with frequent human case reports from certain areas indicate potential "hot spots" for ehrlichiosis infection. Targeted vector control interventions in these areas may help decrease human ehrlichiosis transmission.

Tick-borne disease agents in various wildlife from Mississippi

Because tick-borne diseases are becoming increasingly important throughout the world, monitoring their causative agents in wildlife may serve as a useful indicator of potential human exposure. We assessed the presence of known and putative zoonotic, tick-borne agents in four wildlife species in Mississippi. Animals were tested for exposure to or infection with Ehrlichia chaffeensis, Ehrlichia ewingii, Borrelia lonestari, Rickettsia spp., Anaplasma phagocytophilum, and Francisella tularensis. Whole blood and serum were tested from white-tailed deer (WTD; Odocoileus virginianus) and feral swine (Sus scrofa); serum was tested from raccoons (Procyon lotor) and opossums (Didelphis virginiana). We used polymerase chain reaction to detect all agents in blood, whereas an indirect fluorescent antibody assay was used to detect antibodies to E. chaffeensis, B. lonestari, and Rickettsia parkeri (spotted fever group rickettsiae) antigens in serum. Molecular evidence of infection with E. chaffeensis, B. lonestari, and An. phagocytophilum was detected only in WTD. Antibodies to E. chaffeensis antigen were detected in 43.9% of WTD, 32.8% of swine, 42.1% of raccoons, and 15.8% of opossums. Serologic evidence of exposure to B. lonestari antigen was found in 19.3% of WTD, 6.9% of swine, and 5.3% of raccoons, but not in opossums. Interestingly, the percent of animals with antibodies reactive to spotted fever group rickettsiae (R. parkeri antigen) was highest in raccoons (73.7%) and opossums (57.9%). These results support the role of WTD as reservoirs for E. chaffeensis, B. lonestari, and An. phagocytophilum, as well as provide additional evidence for exposure of raccoons and opossums to E. chaffeensis. Finally, we provide new data that feral swine may have antibodies to these agents. Thus, in general, these four wildlife species are exposed to tick-borne disease agents in Mississippi, suggesting that ticks carry and have the potential to transmit the agents to humans in the state.

Distribution, prevalence, and genetic characterization of Baylisascaris procyonis in selected areas of Georgia

Baylisascaris procyonis is an intestinal nematode of raccoons (Procyon lotor) that can cause fatal larval migrans in numerous species of birds and mammals, including humans. Although this parasite has historically been absent in the southeastern United States, it has been found in isolated regions in the Appalachian Mountains and was recently documented in DeKalb County, Georgia. The first objective of the current study was to investigate the distribution and prevalence of B. procyonis in selected populations of raccoons in Georgia. Intestinal tracts of 312 raccoons from 25 Georgia counties were examined for B. procyonis. The only county where B. procyonis was detected was Clarke County, where 12 of 116 (10.3%) raccoons were infected. In Clarke County, significantly more juveniles (P  =  0.049) were infected compared with adults, and no differences in prevalence were noted by sex, season of capture, or land use (rural vs. urban); however, significantly (P  =  0.0370) higher worm burdens were found in infected raccoons from urban/suburban locations compared with rural areas. In addition, Toxascaris leonina , a morphologically similar ascarid, was found in 3 raccoons from Clarke County (n  =  2) and Morgan County (n  =  1). A second objective was to determine if sequence polymorphisms were associated with B. procyonis from different geographic regions. Because sequences from a single worm from Japan had been entered into GenBank, we obtained nematodes from Kentucky and Texas for comparison with our samples from Georgia. Sequence analysis of the 18S and 5.8S rRNA genes and the internal transcribed spacer (ITS) -1 and ITS-2 regions confirmed Georgia samples were B. procyonis. Although several polymorphic bases were observed within both ITS regions, none was associated with a particular geographic location. These data indicate that the distribution of B. procyonis within Georgia is increasing and only limited genetic variation is present in the rRNA and ITS gene regions among B. procyonis from the southern United States and introduced populations in Japan.

Host associations of Dermacentor, Amblyomma, and Ixodes (Acari: Ixodidae) ticks in Tennessee

From April 2007 to September 2008, 1,793 adult and nymphal ixodid ticks were collected from 49 counties in Tennessee. Six species were identified, including Dermacentor variabilis (Say), Amblyomma americanum (L.), Ixodes texanus (Banks), Ixodes cookei Packard, Ixodes scapularis (Say), and Amblyomma maculatum Koch, from 13 medium- to large-sized mammalian hosts and dragging through vegetation. Raccoons were the most common vertebrate source (198 captures), accounting for 60% of ticks collected. Dermacentor variabilis was the predominant species from raccoons with a prevalence of 92% and mean intensity of 5.3. A. americanum was predominated in white-tailed deer and drags with respective mean intensities of 3.1 and 14.1 and prevalence values of 94%. All tick species were identified between April and August, coinciding with the majority of animal captures. Only A. americanum, I. texanus, and I. cookei were identified from 22 animal captures from November to March. I. texanus and I. cookei were more common in the eastern portions of the state, but this may be a result of higher raccoon captures in those areas. Only four specimens of I. scapularis were collected in this study, which may reflect the absence of small mammal or reptile captures. Two A. maculatum were collected, and we report new distribution records in Tennessee for this species. Despite unequal sampling among ecoregions, the large numbers of D. variabilis and A. americanum from multiple host species suggest their widespread distribution throughout the state. These species of ticks can transmit multiple pathogens, including spotted fever group rickettsiae and ehrlichiae.

Natural history of Ehrlichia chaffeensis: vertebrate hosts and tick vectors from the United States and evidence for endemic transmission in other countries

Ehrlichia chaffeensis, an intracellular gram-negative zoonotic bacterium, is the causative agent of human monocytotropic ehrlichiosis (HME). In humans, the disease can range from a mild, non-specific illness with few to no clinical signs to a moderately severe to fatal disease, especially those with compromised immune systems. E. chaffeensis is maintained in a complex cycle involving white-tailed deer (WTD; Odocoileus virginianus) as a primary reservoir and the lone star tick (LST; Amblyomma americanum) as a primary vector. Numerous other species are naturally exposed to E. chaffeensis and disease has been documented in some domestic animals and wildlife including domestic dogs and ring-tailed lemurs. The organism has been found throughout the natural range of the LST and as the tick continues to expand its range, the geographic range of risk for E. chaffeensis infections will likely continue to expand. Recent data have indicated that E. chaffeensis, or a closely related organism, has been found in many species of ticks and vertebrate hosts in numerous countries.

Characterization of 'Candidatus Neoehrlichia lotoris' (family Anaplasmataceae) from raccoons (Procyon lotor)

Recently, a novel ehrlichial organism was isolated from a raccoon (Procyon lotor) and the isolate (RAC413) was infectious to two naïve raccoons but not laboratory mice, rats or rabbits. In this study, amplification and sequencing of four gene targets (16S rRNA gene, groESL, gltA and rpoB) confirmed that the novel ehrlichial organism was a member of the family Anaplasmataceae and was most closely related to, but distinct from, 'Candidatus Neoehrlichia mikurensis' TK4456(R) and IS58. RAC413 shared the highest sequence similarity with members of the genus Ehrlichia (94.2-95.1, 80.9-83.1, 67.9-71.9 and 39.9-40.7 % similarity for the 16S rRNA gene, groESL, gltA and rpoB, respectively). No sequence variation in three sequences (16S rRNA gene, groESL and gltA) was observed between the RAC413 isolate and five additional sequences amplified from blood of naturally infected raccoons from several geographically isolated populations in the south-eastern USA. Serum samples from four experimentally infected raccoons did not react to Ehrlichia canis, Ehrlichia chaffeensis, Anaplasma marginale or Anaplasma phagocytophilum antigens in an immunofluorescence assay or an Ehrlichia ewingii peptide in an ELISA format. On the basis of the distinctive molecular and serological characteristics and apparent host specificity of this ehrlichial organism, it is proposed that this organism be designated 'Candidatus Neoehrlichia lotoris' (reference strain RAC413).

Role of the lone star tick, Amblyomma americanum (L.), in human and animal diseases

We reviewed scientific literature pertaining to known and putative disease agents associated with the lone star tick, Amblyomma americanum. Reports in the literature concerning the role of the lone star tick in the transmission of pathogens of human and animal diseases have sometimes been unclear and even contradictory. This overview has indicated that A. americanum is involved in the ecology of several disease agents of humans and other animals, and the role of this tick as a vector of these diseases ranges from incidental to significant. Probably the clearest relationship is that of Ehrlichia chaffeensis and A. americanum. Also, there is a definite association between A. americanum and tularemia, as well as between the lone star tick and Theileria cervi to white-tailed deer. Evidence of Babesia cervi (= odocoilei) being transmitted to deer by A. americanum is largely circumstantial at this time. The role of A. americanum in cases of southern tick-associated rash illness (STARI) is currently a subject of intensive investigations with important implications. The lone star tick has been historically reported to be a vector of Rocky Mountain spotted fever rickettsiae, but current opinions are to the contrary. Evidence incriminated A. americanum as the vector of Bullis fever in the 1940s, but the disease apparently has disappeared. Q fever virus has been found in unfed A. americanum, but the vector potential, if any, is poorly understood at this time. Typhus fever and toxoplasmosis have been studied in the lone star tick, and several non-pathogenic organisms have been recovered. Implications of these tick-disease relationships are discussed.