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Crimean-Congo hemorrhagic fever (CCHF), caused by Crimean-Congo hemorrhagic fever virus (CCHFV), is endemic in Africa, Asia, and Europe, but CCHF epidemiology and epizootiology is only rudimentarily defined for most regions. Here we summarize what is known about CCHF in Central, Eastern, and South-eastern Asia. Searching multiple international and country-specific databases using a One Health approach, we defined disease risk and burden through identification of CCHF cases, anti-CCHFV antibody prevalence, and CCHFV isolation from vector ticks. We identified 2313 CCHF cases that occurred in 1944-2021 in the three examined regions. Central Asian countries reported the majority of cases (2,026). In Eastern Asia, China was the only country that reported CCHF cases (287). In South-eastern Asia, no cases were reported. Next, we leveraged our previously established classification scheme to assign countries to five CCHF evidence levels. Six countries (China, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan) were assigned to level 1 or level 2 based on CCHF case reports and the maturity of the countries' surveillance systems. Two countries (Mongolia and Myanmar) were assigned to level 3 due to evidence of CCHFV circulation in the absence of reported CCHF cases. Thirteen countries in Eastern and South-eastern Asia were categorized in levels 4 and 5 based on prevalence of CCHFV vector ticks. Collectively, this paper describes the past and present status of CCHF reporting to inform international and local public-health agencies to strengthen or establish CCHFV surveillance systems and address shortcomings., Competing Interests: Conflict of interest The authors declare no relevant financial or non-financial conflict of interests., (Copyright © 2023 The Authors. Publishing services by Elsevier B.V. All rights reserved.)

Haemaphysalis Koch, 1844, is the largest genus of ticks in Southeast Asia, but little information is available concerning the species present in Laos. Recent research has yielded records for 10 Haemaphysalis species in Laos, including 5 new records, as well as 3 morphological entities of uncertain status. Further morphological and molecular studies are needed to clarify our taxonomic understanding of this genus in Southeast Asia., (© The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The genus Haemaphysalis Koch, 1844 (Acari: Ixodidae) is the second-largest genus, with more than 170 described species that primarily parasitize mammals and birds (Guglielmone et al. 2014, Guglielmone et al. 2020). Haemaphysalis species are three-host ticks, mainly distributed in southern and southeastern Asia and tropical Africa (Guglielmone et al. 2014). The present study identified a tick, Haemaphysalis hoodi Warburton & Nuttall, 1909, collected from a human in Yaoundé, Cameroon. This tick species feed on birds in sub-Saharan Africa. To the best of our knowledge, this is the second record of H. hoodi from humans. In addition, 16S ribosomal RNA and cytochrome oxidase I sequences were generated for this species for the first time. Screening pan-Rickettsia-PCR infection gave a negative result., (© 2022. The Author(s).)

The tick genus Amblyomma Koch, 1844 (Acari: Ixodidae) has received little attention in Malaysia; therefore, its associated hosts and distribution records are poorly known. In this study, we collected six Amblyomma sp. individuals (two larvae and four adults) that infested a common treeshrew, Tupaia glis (Diard, 1820) (Scandentia: Tupaiidae) caught in a recreational area in Sungai Lembing, Pahang (West Malaysia). The adult female ticks were morphologically identified according to taxonomic keys prior to molecular identification using cytochrome oxidase subunit I (COI) and 16S rDNA genes. The ticks were genetically verified as Amblyomma geoemydae (Cantor, 1847) with 98%-99% similarity to the available GenBank sequences. Neighbor-joining (NJ) trees indicated that A. geoemydae was clearly distinguished from other Amblyomma ticks and this was supported with high bootstrap values. This paper is the first to report A. geoemydae ticks infesting T. glis and provides a new tick-host record from West Malaysia. This information is significant for further investigation, specifically on this tick species as potential vector of tick-borne disease (TBD) agents., (© The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Crimean-Congo hemorrhagic fever (CCHF) is endemic in Africa, but the epidemiology remains to be defined. Using a broad database search, we reviewed the literature to better define CCHF evidence in Africa. We used a One Health approach to define the impact of CCHF by reviewing case reports, human and animal serology, and records of CCHF virus (CCHFV) isolations (1956-mid-2020). In addition, published and unpublished collection data were used to estimate the geographic distribution of Hyalomma ticks and infection vectors. We implemented a previously proposed classification scheme for organizing countries into five categories by the level of evidence. From January 1, 1956 to July 25, 2020, 494 CCHF cases (115 lethal) were reported in Africa. Since 2000, nine countries (Kenya, Mali, Mozambique, Nigeria, Senegal, Sierra Leone, South Sudan, Sudan, and Tunisia) have reported their first CCHF cases. Nineteen countries reported CCHF cases and were assigned level 1 or level 2 based on maturity of their surveillance system. Thirty countries with evidence of CCHFV circulation in the absence of CCHF cases were assigned level 3 or level 4. Twelve countries for which no data were available were assigned level 5. The goal of this review is to inform international organizations, local governments, and healthcare professionals about shortcomings in CCHF surveillance in Africa to assist in a movement toward strengthening policy to improve CCHF surveillance.

Background: Ticks are important ectoparasites of horses that can affect animal welfare and vector several infectious, including zoonotic, diseases. In order to investigate the species distribution, epidemiology and seasonal dynamics of ticks infesting horses in Israel, 3267 ticks were collected from 396 horses in 24 farms across the country from July 2014 to June 2015., Results: Ticks were found on 50% of the farms and on 25% of the horses, with Hyalomma being the most prevalent genus (70% of ticks). Pasture was the most prominent risk factor for tick infestation (99% of ticks, P < 0.001), and is represented here by two areas with a Mediterranean climate that differ in their environmental characteristics: the Golan Heights (GH, 74% of ticks); and the Carmel mountain ridge (CMR, 24%). Although these two sites are less than 100 km apart, the composition of the tick populations infesting horses differed significantly between them. In GH the most abundant tick species was Hyalomma excavatum (P < 0.001), while in CMR it was Hyalomma marginatum (P < 0.001). The GH also hosted a more diverse tick fauna than the CMR, including Haemaphysalis parva (peaking in the autumn, P < 0.001) and Rhipicephalus turanicus (peaking in the spring, P < 0.001), which were not found at the other sites. A few Rhipicephalus bursa, Hyalomma rufipes and Hyalomma turanicum were also found on horses., Conclusions: The current findings can be used in epidemiological studies assessing the risk of tick-borne equine diseases in the area. Further analysis is needed to determine the specific distribution and habitat preferences of each tick species.

Background: The controversy surrounding the potential impact of birds in spirochete transmission dynamics and their capacity to serve as a reservoir has existed for a long time. The majority of analyzed bird species are able to infect larval ticks with Borrelia. Dispersal of infected ticks due to bird migration is a key to the establishment of new foci of Lyme borreliosis. The dynamics of infection in birds supports the mixing of different species, the horizontal exchange of genetic information, and appearance of recombinant genotypes., Methods: Four Borrelia burgdorferi sensu lato strains were cultured from Ixodes minor larvae and four strains were isolated from Ixodes minor nymphs collected from a single Carolina Wren (Thryothorus ludovicianus). A multilocus sequence analysis that included 16S rRNA, a 5S-23S intergenic spacer region, a 16S-23S internal transcribed spacer, flagellin, p66, and ospC separated 8 strains into 3 distinct groups. Additional multilocus sequence typing of 8 housekeeping genes, clpA, clpX, nifS, pepX, pyrG, recG, rplB, and uvrA was used to resolve the taxonomic status of bird-associated strains., Results: Results of analysis of 14 genes confirmed that the level of divergence among strains is significantly higher than what would be expected for strains within a single species. The presence of cross-species recombination was revealed: Borrelia burgdorferi sensu stricto housekeeping gene nifS was incorporated into homologous locus of strain, previously assigned to B. americana., Conclusions: Genetically diverse Borrelia strains are often found within the same tick or same vertebrate host, presenting a wide opportunity for genetic exchange. We report the cross-species recombination that led to incorporation of a housekeeping gene from the B. burgdorferi sensu stricto strain into a homologous locus of another bird-associated strain. Our results support the hypothesis that recombination maintains a majority of sequence polymorphism within Borrelia populations because of the re-assortment of pre-existing sequence variants. Even if our findings of broad genetic diversity among 8 strains cultured from ticks that fed on a single bird could be the exception rather than the rule, they support the theory that the diversity and evolution of LB spirochetes is driven mainly by the host.

Borrelia burgdorferi sensu lato (s.l.) complex is a diverse group of worldwide distributed bacteria that includes 18 named spirochete species and a still not named group proposed as genomospecies 2. Descriptions of new species and variants continue to be recognized, so the current number of described species is probably not final. Most of known spirochete species are considered to have a limited distribution. Eleven species from the B. burgdorferi s.l. complex were identified in and strictly associated with Eurasia (B. afzelii, B. bavariensis, B. garinii, B. japonica, B. lusitaniae, B. sinica, B. spielmanii, B. tanukii, B. turdi, B. valaisiana, and B. yangtze), while another 5 (B. americana, B. andersonii, B. californiensis, B. carolinensis, and B. kurtenbachii) were previously believed to be restricted to the USA only. B. burgdorferi sensu stricto (s.s.), B. bissettii, and B. carolinensis share the distinction of being present in both the Old and the New World. Out of the 18 genospecies, 3 commonly and 4 occasionally infect humans, causing Lyme borreliosis (LB) - a multisystem disease that is often referred to as the 'great imitator' due to diversity of its clinical manifestations. Among the genospecies that commonly infect people, i.e. B. burgdorferi s.s., B. afzelii, and B. garinii, only B. burgdorferi s.s. causes LB both in the USA and in Europe, with a wide spectrum of clinical conditions ranging from minor cutaneous erythema migrans (EM) to severe arthritis or neurological manifestations. The epidemiological data from many European countries and the USA show a dramatic increase of the diagnosed cases of LB due to the development of new progressive diagnostic methods during the last decades (Hubálek, 2009). Recently, the definition of the disease has also changed. What was not considered Lyme borreliosis before might be now., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

Antimicrobial peptides are major components of host innate immunity, a well-conserved, evolutionarily ancient defensive mechanism. Infectious disease-bearing vector ticks are thought to possess specific defense molecules against the transmitted pathogens that have been acquired during their evolution. We found in the tick Haemaphysalis longicornis a novel parasiticidal peptide named longicin that may have evolved from a common ancestral peptide resembling spider and scorpion toxins. H. longicornis is the primary vector for Babesia sp. parasites in Japan. Longicin also displayed bactericidal and fungicidal properties that resemble those of defensin homologues from invertebrates and vertebrates. Longicin showed a remarkable ability to inhibit the proliferation of merozoites, an erythrocyte blood stage of equine Babesia equi, by killing the parasites. Longicin was localized at the surface of the Babesia sp. parasites, as demonstrated by confocal microscopic analysis. In an in vivo experiment, longicin induced significant reduction of parasitemia in animals infected with the zoonotic and murine B. microti. Moreover, RNA interference data demonstrated that endogenous longicin is able to directly kill the canine B. gibsoni, thus indicating that it may play a role in regulating the vectorial capacity in the vector tick H. longicornis. Theoretically, longicin may serve as a model for the development of chemotherapeutic compounds against tick-borne disease organisms.

Lyme borreliosis, or Lyme disease (LD), is a tick-borne zoonotic infection of biomedical significance, caused by Borrelia burgdorferi sensu lato (s.l.) spirochetes and transmitted by Ixodes species ticks. It usually circulates among wildlife vertebrate reservoirs and vector ticks but may infect humans, causing multisystem problems. In far western and northern North America, the host reservoirs, tick vectors, and genospecies of Borrelia are well known but not so in the southern U.S., where there is controversy as to the presence of "true" LD. Here we report the presence of the LD spirochete B. burgdorferi sensu stricto (s.s.) and Borrelia bissettii, three main reservoir hosts, and two enzootic tick vectors in the southeastern U.S. The two enzootic tick vectors, Ixodes affinis and Ixodes minor, rarely bite humans but are more important than the human biting "bridge" vector, Ixodes scapularis, in maintaining the enzootic spirochete cycle in nature. We also report extraordinary longevities and infections in the reservoir rodents Peromyscus gossypinus, Sigmodon hispidus, and Neotoma floridana.

Tissues of rodents and host-seeking adult ticks collected in the Piedmont, Sandhills, Coastal Plain, and Coastal Zone of South Carolina were cultured in attempts to isolate Borrelia burgdorferi (Johnson, Schmid, Hyde, Steigerwalt & Brenner), the etiologic agent of Lyme disease. An exploratory, tree-based statistical analysis was used to identify ecological variables that were associated with spirochete infection among rodents and ticks. Spirochetes were isolated from tissues of 71 rodents: 22 (69%) of 32 eastern woodrats, 39 (53%) of 74 cotton mice, and 11(25%) of 44 hispid cotton rats. Rodent infection prevalences were significantly higher in the Coastal Zone than in other regions. Spirochetes were also cultured from 31 (2.6%) of 1,193 questing ticks. Prevalence of spirochetes in Ixodes affinis Neumann (19/74, 26%) was significantly higher than in I. scapularis Say (12/864, 1.3%) and other species (0/255) of ticks tested. In addition, two (9%) of 23 adult I. minor Neumann removed from woodrats contained spirochetes. Isolates from rodents and ticks were analyzed immunologically by indirect immunofluorescence and Western blots, and further characterized by polymerase chain reaction assays and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. All were determined to be B. burgdorferi sensu lato. Results of this study confirmed that B. burgdorferi is endemic in South Carolina, and that enzootic transmission cycles exist at foci in the Coastal Zone. These findings add additional evidence that I. affinis and I. minor are potentially significant maintenance vectors of the spirochete.

From June 1993 through June 1996, 2,260 adult, 4,426 nymphal, and 2,178 larval lone star ticks Amblyomma americanum (L.) were collected in Missouri from vertebrate hosts and by dragging a cloth over vegetation. Prevalence, mean intensity, and relative abundance of each stage varied among hosts. The relative abundance of adult lone star ticks was highest on white-tailed deer, but this stage was also collected from raccoons, opossum, red fox, coyotes, and wild turkey. Nymphs were collected from gray squirrels, eastern cottontail rabbits, opossums, red fox, Carolina wren, and bobwhite quail, but the highest relative abundance occurred on wild turkey, white-tailed deer, and raccoons. Eastern cottontail rabbits, white-tailed deer, raccoons, and squirrels had the highest relative abundance of larval lone star ticks, but they were also found on opossums and wild turkey. The activity of adult lone star ticks was greatest from May through July. The activity for nymphs was highest from May through August, and for larvae, July through September.

Human monocytic ehrlichiosis is an emerging zoonosis caused by infection with Ehrlichia chaffeensis Anderson, Dawson, Jones & Wilson, which is transmitted to mammals by ixodid ticks. Prevalence of infected ticks and distribution of infection foci indicate relative risk of human exposure to ehrlichiosis and may be influenced by factors such as geographic isolation, human disturbance, and the availability of suitable mammalian reservoir hosts. To test, this, individual and pooled lone star ticks, Amblyomma americanum (L.), were collected from three populations from the Georgia coast (1 mainland site and two barrier islands) and screened for E. chaffeensis. A species-specific, nested polymerase chain reaction (PCR) assay was used to amplify a 572 bp fragment of the E. chaffeensis 16S rRNA gene from infected ticks. PCR product specificity was confirmed by nucleotide sequencing. Our results showed the prevalence of infected ticks to be 0.0% (n = 151), 0.9% (n = 111), and 9.3% (n = 129) for Sapelo Island, St. Catherine's Island, and Fort McAllister, respectively.

Results of a survey for ixodid ticks and/or serum antibodies to Borrelia burgdorferi from 14 species of small to large mammals from eastern coastal areas of the United States are presented. Most samples were obtained from July 1987 through June 1989 (excluding December-March) at 3 locales: Assateague Is. National Seashore, Worcester Co., MD., and Accomack Co., VA. (approximately 38 degrees 05' N 75 degrees 10' W), and Cape Hatteras National Seashore, Dare Co., NC (approximately 35 degrees 30' N 76 degrees 35' W). Hosts sampled included opossums (Didelphis virginiana), least shrews (Cryptotis parva), gray foxes (Urocyon cinereoargenteus), red foxes (Vulpes vulpes), raccoons (Procyon lotor), feral cats (Felis sylvestris), feral horses (Equus caballus), sika deer (Cervus nippon), rice rats (Oryzomys palustris), white-footed mice (Peromyscus leucopus), meadow voles (Microtus pennsylvanicus), house mice (Mus musculus), norway rats (Rattus norvegicus) and jumping mice (Zapus hudsonius). An indirect fluorescent antibody test was used for testing sera from opossums, raccoons, and feral cats; enzyme-linked immunosorbent assays were used for sera from foxes, horses, deer, and house and white-footed mice. Antibodies to B. burgdorferi were found in all species tested from each locale. Seasonal data reinforce the contention that P. leucopus is a suitable sentinel species for B. burgdorferi. Ticks on hosts included Ixodes scapularis Say, I. texanus Banks, Dermacentor variabilis (Say), D. albipictus (Packard), and Amblyomma americanum (L.). Males comprised approximately 0-22 and 60-81% of Ixodes sp. and Amblyomma-Dermacentor adults collected from hosts, respectively. All stages of A. americanum, adult D. variabilis, and larval I. scapularis were collected from vegetation. The highest seropositivity rate (67%) was recorded for 45 P. leucopus at Assateague during July, approximately 1 mo. after peak nymphal I. scapularis intensity. Borrelia burgdorferi was isolated from 6 nymphal and 12 female I. scapularis collected from P. leucopus and C. nippon, respectively, on Assateague.

Ixodid ticks were collected from live-trapped rodents and by flagging vegetation at sites in the Piedmont, Sandhills, Coastal Plain, and Coastal Zone of South Carolina from May 1994 through December 1995. A total of 1,514 ticks was recovered from 237 live-trapped rodents. Host-attached species included Ixodes minor Neumann (n = 818), Dermacentor variabilis (Say) (n = 346), Amblyomma maculatum Koch (n = 209), Ixodes affinis Neumann (n = 89), and Ixodes scapularis Say (n = 52). Species of questing adult ticks collected from vegetation were Ix. scapularis (n = 1,627), Amblyomma americanum L. (n = 1,052), D. variabilis (n = 649), A. maculatum (n = 134), Ix. affinis (n = 70), and Dermacentor albipictus (Packard) (n = 3). Geographic distribution and seasonal activities of most stages and species are presented. This report includes the first detailed description of the seasonal activities of all active stages of Ix. minor in the United States, and documents that this tick is well established in the southern Coastal Zone of South Carolina.

Five Borrelia burgdorferi sensu lato isolates from Missouri are described. This represents the first report and characterization of such isolates from that state. The isolates were obtained from either Ixodes dentatus or Amblyomma americanum ticks that had been feeding on cottontail rabbits (Sylvilagus floridanus) from a farm in Bollinger County, Mo., where a human case of Lyme disease had been reported. All isolates were screened immunologically by indirect immunofluorescence by using monoclonal antibodies to B. burgdorferi-specific outer surface protein A (OspA) (antibodies H3TS and H5332), B. burgdorferi-specific OspB (antibody H6831), Borrelia (genus)-specific antiflagellin (antibody H9724), and Borrelia hermsii-specific antibody (antibody H9826). Analysis of the isolates also involved a comparison of their protein profiles by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Finally, the isolates were analyzed by PCR with six pairs of primers known to amplify selected DNA target sequences specifically found in the reference strain B. burgdorferi B-31. Although some genetic variability was detected among the five isolates as well as between them and the B-31 strain, enough similarities were found to classify them as B. burgdorferi sensu lato.

A total of 5,669 ticks of 4 species was collected from 515 hunter killed, white-tailed deer. Odocoileus virginianus (Zimmerman), in southeastern Missouri from 1993 through 1995. The American dog tick, Dermacentor variabilis (Say) (4 adults), the lone star tick, Amblyomma americanum (L.) (57 adults, 2 nymphs), the blacklegged tick, Ixodes scapularis (Say) (3,120 adults), and the winter tick, Dermacentor albipictus (Packard) (2.059 adults, 436 nymphs, 1 larva) were collected. Patterns of adult D. albipictus and I. scapularies infesting deer were analyzed with respect to upland versus lowland habitat, county, and host sex. Prevalence and intensity of infestation by D. albipictus were higher on bucks than does, and a higher infestation prevalence was recorded for this tick on deer from upland than from lowland habitats. Mean intensities for D. albipictus were not significantly different between counties. Prevalence and mean intensity of infestation for I. scapularis were significantly higher on deer from uplands than lowlands and on bucks than does; mean intensities also differed between counties for this tick. Because adjacent populations, as well as the sex of the host, can differ in infestation rates, differences between local populations of I. scapularis should be recognized to optimize tick surveys and population models.

From 1990 through 1995, 913 ticks removed from 460 human patients in Georgia or South Carolina were identified and recorded. The majority of these specimens (758, 83.0%) were lone star ticks, Amblyomma americanum. One hundred and four (11.4%) American dog ticks Dermacentor variabilis, 36 (3.9%) blacklegged ticks Ixodes scapularis, 9 (1.0%) Gulf coast ticks Amblyomma maculatum, and 6 (0.7%) brown dog ticks Rhipicephalus sanguineus were also recovered. All active stages (larvae, nymphs, and adults) of A. americanum were represented, whereas nymphs and adults of D. variabilis and I. scapularis and only adults of A. maculatum and R. sanguineus were recorded. Compared with data published for other regions in the U.S.A., A. americanum was a much more prevalent parasite of humans in the current survey. Only 1 (3%) of the I. scapularis collected was a nymph. Because these tick species are vectors of zoonotic pathogens or cause tick paralysis in humans, the data have epidemiological significance.

An 18-mo study was conducted in Bulloch County, Georgia, to determine tick species composition, seasonal activity of individual tick species, and host-tick associations. The following 7 methods of tick collection were included: (1) live trapping of potential host animals, (2) checking wild game, (3) drag sampling, (4) carbon dioxide attraction, (5) checking livestock, road kills, nests, and burrows, (6) samples submitted from veterinarians, and (7) ticks collected by local residents and submitted for identification. Twelve tick species (Ixodidae) were identified. Blacklegged tick, Ixodes scapularis Say, and American dog tick, Dermacentor variabilis (Say), had the widest host ranges and were the most numerous. White-tailed deer, Odocoileus virginianus (Zimmermann), supported 5 tick species, the greatest number on any host. Of 55 animal species examined, 16 mammal, 5 bird, and 3 reptile species were parasitized by ticks. Opossums, Didelphis virginiana Kerr, and cotton mice, Peromyscus gossypinus (LeConte), were the most commonly examined wild animals.

Evolutionary patterns in ticks have traditionally been cast in terms of host associations. Largely untested assumptions of cospeciation and observations of current host associations are used to estimate the age of different taxa. Several recent phylogenetic studies of supraspecific relationships in ticks, based on both morphological and DNA-sequence data, allow the first rigorous testing of these assumptions. Reanalysis of patterns of tick-host associations suggests that the perception of host specificity in ticks may be an artifact of incomplete sampling. An analysis of tick-host and -habitat associations and biogeographical patterns, in the context of the newly derived phylogenies, suggests that much of the existing host-association patterns may be explained as artifacts of biogeography and ecological specificity.

A morphological study of postlarval stages of the blacklegged tick, Ixodes scapularis Say, was conducted to examine congruence between northern (formerly I. dammini Spielman, Clifford, Piesman & Corwin) and southern morphotypes. The character set totaled 17 for females, 25 for males, and 28 for nymphs. Populations from 6 geographic areas, F1 progeny from reciprocal crosses between I. scapularis from Massachusetts and Georgia, and I. pacificus Cooley & Kohls from California were measured. Characters, except cornua length in nymphs, were positively correlated with PC1, indicating it was a general-size eigenvector. Characters used previously by others to distinguish northern and southern forms had a highly positive allometric relationship to general size. In canonical variate analysis (CVA) of nymphs, canonical score 1 (CAN1) discriminated I. pacificus from all other groups, canonical score 2 (CAN2) discriminated the remaining groups in a pattern that correlated with latitude, and canonical score 3 (CAN3) separated the western (Minnesota and Missouri) from the eastern groups. Size-free CVA indicated that north-south discrimination was size dependent, but that variation between Missouri and all other groups was not size related. Mahalanobis distances between groups within stages were significant with the exception of the 2 groups of female progeny of reciprocal crosses (Massachusetts x Georgia). Analysis of variance and Student-Newman-Keuls tests revealed that each geographic population differed from all other groups in at least 1 nymphal character. Nymphs from northern areas (Minnesota, Massachusetts, Maryland) differed from those from southern areas (Missouri, North Carolina, Georgia) in characters associated with the basis capitulum (longer intercornua and interauricular distances, basis capituli, and hypostome internal files, larger auriculae, but shorter cornua). Western populations (Minnesota, Missouri) differed from eastern populations in idiosomal characters (broader scutum, larger coxae III and IV). Frequency polygons of characters with the greatest differences indicated that data are continuous and geographic variation is overlapping. Thus, the data support the previous contention of conspecificity of I. scapularis and I. dammini. I. scapularis appears to be a polytypic species with a widespread geographic distribution exhibiting north-south and east-west morphological clines in eastern North America.

Evolution of the rDNA spacer, ITS 2, is examined by comparing 17 DNA sequences of the ticks, Ixodes scapularis and I. pacificus. The distribution of fixed interspecific differences and the relative frequency of base changes vs. insertions/deletions (indels) matches the distribution and relative frequency for intraspecifically variable sites. This suggests that most intraspecific variation is not effectively selected against. The base composition of the ITS 2 transcript is G- and U-biased. But, 5-base regions enriched (> 80 per cent) for A or U occur more frequently than expected while G- and C-enriched regions occur less frequently than expected. Enriched sequences may be prone to replication slippage, accounting for the A/T bias in insertions. Slippage-mediated gains and losses of A/T-rich tandem repeats apparently account for most indels. Minimum-energy conformations of the two species' folded transcripts share major structural features. Structural inertia arises from intramolecular base pairing within stems that allows most mutations to be absorbed as new bulges off stems. Yet, there is evidence of selection to maintain the conformation. First, intraspecifically variable sites are concentrated at the ends of stems in loops and intersections, structures that do not contribute to intramolecular base pairing. Moreover, some indels that have become fixed in one species compensate for the presence of conformation-destabilizing indels. However, high rates of sequence evolution within stems and absence of compensatory base evolution contraindicates selective constraint. Degenerate dispersed and tandem copies of two subrepeats, each approximately 20 bases long, may account for much of the ITS 2 sequence. These are approximately inverses of each other and are, consequently, capable of significant intramolecular hydrogen bonding to produce folded transcripts of low energy. Evolution of the ITS 2 sequence may largely entail replication slippage-mediated gains and losses of these repeats or their composite subrepeats.

The ability of three common tick species from Georgia to maintain and transmit the causative agent of Lyme disease, Borrelia burgdorferi, was compared under laboratory conditions. A B. burgdorferi cotton rat isolate (MI-6) from Florida was selected as a strain from the south, and the SH2-82 isolate from New York was used as a positive control. Amblyomma americanum (L.) and Dermacentor variabilis (Say) did not transmit the MI-6 isolate from inoculated hamsters to naive laboratory mice, and nymphal ticks did not maintain this isolate transstadially. Ixodes scapularis Say transmitted both isolates to laboratory mice. There was a significant difference in the percentage of transmission of the two isolates. I. scapularis also transmitted the MI-6 isolate to two of three cotton rats. This study adds support to the premise that I. scapularis is probably the main tick vector of B. burgdorferi in the southeastern United States.

The base sequence of the internal transcribed spacer 1 (ITS 1) of ribosomal DNA of the tick Ixodes scapularis Say (= I. dammini Spielman, Clifford, Piesman & Corwin) was determined to assess genetic divergence between populations along the eastern (Atlantic) seaboard of the United States. Twenty sequences were obtained from localities down the eastern margin of the species's range: 10 from the southeast (Georgia and Florida), seven from the middle east (North Carolina, Maryland), and three from the northeast (Massachusetts, New Jersey, New York). Both the neighbor-joining and parsimony methods cluster most of the southeastern sequences together and most of the middle eastern sequences together but fail to cluster those from the northeast. In addition, an F ratio test revealed significant between-region sequence variation. Thus, there appears to be genetic structuring on at least a macrogeographic scale. Only 23% (SEM = 6.4%) of the sequence variation occurs between regions, with the vast majority of variation, 77% (SEM = 6.4%), being within region. These data, plus other published data, indicate that I. scapularis constitutes a single species. However, the pattern of variation is consistent with restricted gene flow between regions or, alternatively, with recent introgression between northern and southern types in the middle-eastern part of the species's range.

Nymphal and adult Dermacentor variabilis (Say) molting from larvae and nymphs, respectively, that fed on a Holtzman strain of Rattus norvegicus demonstrated reduced longevity compared with those from immature stages that fed on albino laboratory mice, Mus musculus. The decrease in survivorship did not appear to be caused by host-acquired resistance; lower feeding weights, longer feeding times, and reduced molting were not observed. In addition, reduced survivorship was not limited to ticks fed on Holtzman rats. It was also demonstrated in adult D. variabilis molting from nymphs that fed on Wistar strain rats, but the effect was not as severe as with Holtzman rats. Moreover, reduced survivorship occurred in Ixodes scapularis Say that fed on rats, but, again, the effect as less severe than on D. variabilis. Nymphal feeding on mice appeared to counteract the negative effect of larval feeding on rats in both adult D. variabilis and I. scapularis.

FMRFamide-like immunoreactivity was studied in the argasid tick Ornithodoros parkeri and the ixodid tick Dermacentor variabilis using immunocytochemistry based on the peroxidase-antiperoxidase method. FMRFamide-like immunoreactive cells are widely distributed in various regions of the tick synganglion including protocerebral, cheliceral, stomodeal, palpal, pedal I-IV, and opisthosomal regions in both species. However, there is one layer of immunoreactive cells located on the dorsal surface of the postoesophageal part of the synganglion that is found only in D. variabilis. Besides the immunoreactivity within the cell body and its axons, the neuropile and the neural lamella (the extracellular sheath of the synganglion) are rich in immunoreactive materials. Some coxal muscles are innervated by the FMRFamide-like immunoreactive processes of the nerve from the pedal ganglion.

Ecdysteroids and cuticulogenesis were studied in third-instar nymphs of the tick Ornithodoros parkeri Cooley. Ecdysteroid titer increases slightly during the postfeeding intermolt period, which correlates with the deposition of additional procuticle lamellae. The titer increases at the time of apolysis, peaks at the time of epicuticle deposition, and then drops to a low but detectable level from the time of procuticle deposition until after ecdysis. Ecdysone and 20-hydroxyecdysone are the two major ecdysteroids present during the postfeeding intermolt period and the period of epicuticle deposition. After ecdysis, the ecdysteroid immunoreactive material is composed principally of an unknown compound more polar than 20,26-dihydroxyecdysone and is found only in the midgut. This compound is possibly a metabolite of ecdysteroids left over from the previous instar.

The male of Amblyomma rotundatum is described for the first time, and the nymph and larva are redescribed. This tick is a parthenogenetically reproducing species parasitic on amphibians and reptiles in the warmer areas of the New World. Attempts to mate male and female A. rotundatum under laboratory conditions were unsuccessful.

Preserved museum specimens of 13 lizard and 3 snake species common in the southeastern U.S.A. were examined for immature Ixodes scapularis Say ticks. Five Eumeces and 4 Ophisaurus lizard species yielded an infestation prevalence of 17.8% for species of Eumeces and 29.0% for species of Ophisaurus. Mean intensity of larvae and nymphs was 7.1 and 2.7, respectively, for species of Eumeces, and 6.3 and 1.4, respectively, for species of Ophisaurus. Collection dates of the lizards ranged from January through December, but most were collected from March through October. The maximum number of immatures found on a single specimen was 193 larvae and 11 nymphs on a specimen of Eumeces and 75 larvae and 7 nymphs on a specimen of Ophisaurus. For species of Eumeces, 75.2% of all nymphs observed were attached in the shoulder area. Larvae were most abundant on the rear legs (53.3%), followed by the front legs (26.3%) and shoulders (12.9%). Larvae and nymphs on species of Ophisaurus were found almost exclusively in the lateral groove area (84.0% and 94.4%, respectively). Three other lizard species (Anolis carolinensis, Sceloporus undulatus, Scincella lateralis) had only a few ticks or none. A fourth species, Cnemidophorus sexlineatus, hosted a total of 3 larvae on 3 specimens (infestation prevalence, 10.7%). Three snake species (Diadophis punctatus, Virginia striatula, Crotalus adamanteus) had none.

The parthenogenetic tick Amblyomma rotundatum, a Central and South American species, has become established in southern Florida. The date of introduction is unknown, but it is suspected to be either during the 1930s, when 1 of its natural hosts, the giant or marine toad, Bufo marinus, was introduced to southern Florida as a potential biological control of pest beetles in sugar cane fields, or between 1955 and 1964 when specimens of B. marinus were accidentally or deliberately released in the greater Miami area. Several museum specimens of this toad collected in the Miami area 25 April 1979 had nymphal and adult A. rotundatum attached. Subsequent examination of living giant toads collected at another Miami area site from 1983 through 1985 revealed larval, nymphal, and adult A. rotundatum and confirmed colonization of this tick. Under laboratory conditions, another neotropical amphibian and reptile tick, Amblyomma dissimile, is capable of transmitting Cowdria ruminantium, the causative agent of heartwater, a disease present in the Caribbean area. Therefore, we suggest that A. rotundatum should also be tested for vectorial competence.

The structure of Haller's organ in all major groups of soft ticks, family Argasidae, is reexamined, and hypotheses of setal homology are proposed based on a comparative study of developmental patterns. The larvae of most taxa have 7 setae in the anterior pit (1 serrate, 1 conical, 2 fine, 2 porose, 1 grooved) and 4 porose setae in the capsule. The postlarval stages add up to 3 setae to the anterior pit (1 serrate, 1 porose, 1 grooved) and up to 3 porose setae to the capsule. Preliminary hypotheses of polarity, distinguishing ancestral from derived character states, are generated for most characters examined by comparisons with results obtained for the other major family of ticks, Ixodidae, and (where possible) other members of Parasitiformes. Most of the variability in the setal complement of the anterior pit and capsule results from paedomorphosis, and nearly all the observed changes in the setal complement (both modifications of addition patterns and changes in fundamental numbers) are restricted to single species or small species groups. A correlation between changes in Haller's organ structure and changes in life history patterns is suggested but cannot be confirmed based on presently available data.

Reciprocal crosses between Ixodes dammini Spielman, Clifford, Piesman & Corwin from Massachusetts and Ixodes scapularis Say from Georgia produced offspring through the F3 generation when the experiment was discontinued. Reciprocal I. dammini x Ixodes pacificus Cooley & Kohls (California) and I. scapularis x I. pacificus crosses produced F1 progeny; however, all progeny were sterile. Assortative mating experiments between I. dammini and I. scapularis indicated that males and females of both species mated with the opposite sex of heterospecific or conspecific ticks when there was a choice. Conventional discriminant analysis of morphometric measurements of ticks from Georgia, North Carolina, Maryland, Massachusetts, and two populations of F1 hybrids indicated that there were recognizable differences. However, size-free (sheared) discriminant analysis indicated that these differences were largely size-dependent, with much overlap of the four eastern and two hybrid populations but no overlap with I. pacificus from California. Analysis of chromosomes (morphology and C band) indicated no differences between the Georgia and Massachusetts populations but showed a difference between them and the California population of I. pacificus. Analysis of isozymes showed that the genetic identity value for the Georgia and Massachusetts populations was within the normal range for conspecific populations, whereas the California population indicated congeneric but not conspecific relatedness to the Georgia and Massachusetts populations. Life cycle data collected under similar laboratory conditions showed no differences in length of feeding and molting periods among Georgia, Massachusetts, and California populations. These data and results of the work of other authors on tick host preferences and vector competence indicate that I. dammini is not a valid species separate from I. scapularis. Because the name Ixodes scapularis Say, 1821, has priority over the name Ixodes dammini Spielman, Clifford, Piesman & Corwin, 1979, I. dammini is relegated to a junior subjective synonym of I. scapularis (based on Article 23 of the International Code of Zoological Nomenclature).

Larvae and nymphs of Ixodes dammini Spielman, Piesman, Clifford & Corwin from a laboratory colony were fed on two white-tailed deer, Odocoileus virginianus (Zimmerman) inoculated with either the SH2-82 or JD-1 strains of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner. Ticks were exposed to one deer 43 and 69 d after inoculation of the spirochete and to a second deer 35 and 61 d after inoculation. Polymerase chain reaction assays amplified the 158 bp OspA DNA target sequence in 11.1% (n = 9) of fed larvae and 3.3% (n = 30) of nymphs from the deer inoculated with the SH2-82 strain, and 22.7% (n = 22) of larvae and 0% (n = 21) of nymphs from a second deer inoculated with the JD-1 strain of B. burgdorferi. One of three females derived from nymphs fed on one of the inoculated deer showed presence of B. burgdorferi DNA, but none of four males was positive. Experimentally inoculated deer can serve as a source of at least two geographic strains of B. burgdorferi to I. dammini larvae and nymphs for at least several weeks.

A method for detection and identification of mammalian DNA in the gut of alcohol-preserved ticks has been developed. Successful amplification and sequencing of host cytochrome b is reported from ticks preserved in 70% alcohol for more than 40 yr. The method described shows promise for determination of unknown tick hosts.

The house mouse (laboratory strain), Mus musculus (L.), the cotton mouse, Peromyscus gossypinus (LeConte), the broad-headed skink, Eumeces laticeps (Schneider), and the guinea pig, Cavia porcellus (L.), were successively infested five times with larvae of the blacklegged tick, Ixodes scapularis Say. Tick feeding success, engorgement weight, and subsequent molting success were measured after each infestation. A greater percentage of ticks (P less than 0.05) fed on M. musculus and E. laticeps than on P. gossypinus or C. porcellus. P. gossypinus expressed a transitory partial resistance, measured in percentage of ticks feeding, during the third infestation but showed increased tolerance during the fourth and fifth infestations. Ticks fed on E. laticeps were heavier than those fed on any other host (P less than 0.05). Those fed on M. musculus were heavier than those fed on P. gossypinus, but the difference was not statistically significant. On C. porcellus, only 1.6% of larvae from the third infestation and none thereafter engorged; weights of larvae from first and second infestations were higher (P less than 0.05) than those fed on M. musculus and P. gossypinus and lower (P less than 0.05) than those fed on E. laticeps. A greater percentage of larvae from E. latticeps and M. musculus (P less than 0.05) molted to nymphs compared with those from P. gossypinus and C. porcellus. Molting success was the same for ticks fed on P. gossypinus and on C. porcellus during the first and second infestations. M. musculus, P. gossypinus, and E. laticeps expressed no resistance (measured as percentage feeding, engorgement weight, and molting) to feeding by I. scapularis larvae after five infestations. Host serum was tested using an ELISA for detection of antibodies against I. scapularis salivary gland antigens before and after each infestation. Antibodies were detected after the second infestation and thereafter in C. porcellus, the only species to show antibodies or to express and maintain an acquired resistance to tick feeding throughout five infestations.

The central nervous system of Ixodes scapularis is fused into a single compact synganglion. The esophagus runs through the synganglion and divides it into supraesophageal and subesophageal parts. The supraesophageal portion contains a single protocerebrum with four pairs of glomeruli, paired optic lobes and cheliceral ganglia, and a single stomodeal bridge. The subesophageal portion contains a centrally located network of commissures and connectives, a pair of palpal ganglia, paired olfactory lobes of the first pedal ganglia, four pairs of pedal ganglia, and a single opisthosomal ganglion. A retrocerebral organ complex (ROC) in close vicinity of the digestive tract, as described in some other tick species, apparently is lacking. Perhaps the function of the ROC is performed by the paired, large, ganglion-like bodies that lie anterolaterad to the cheliceral ganglia. The rind, which is formed from the neuronal somata and glial cells, surrounds the central fibrous core or neuropile. Neurosecretory cells (NSC) are distinct among rind cells due to their large size and concentration of cytoplasmic neurosecretions. NSC are present throughout the synganglion, although the subesophageal portion contains larger groups of these cells. Histological serial sections, stained with Meola's (Trans Am Microsc Soc 89:66-71, '70) paraldehyde fuchsin (PAF) procedure revealed 24 PAF-stained, putative neurosecretory regions in the synganglion of virgin, unfed females. All of these regions appear to be connected and associated with the nearest ganglion and are correspondingly named. Eighteen PAF-positive regions occur in the synganglion. In addition, PAF-negative (green-stained) cells occupy 6 distinct regions in the synganglion of unfed, unmated females.

Ornithodoros (Alectorobius) capensis Neumann, an ectoparasite of seabirds found circumglobally in the tropics and subtropics, has become established along the southeastern seacoast of the United States. The tick has been found feeding primarily on brown pelicans, Pelecanus occidentalis, but also has been found on the laughing gull, Larus atricilla, and the American oystercatcher, Haematopus palliatus. We report here the presence of O. (A.) capensis from New Hanover and Brunswick counties (near the mouth of the Cape Fear River) in North Carolina, to the Charleston Harbor area of South Carolina and thence south to Cumberland Island (a barrier island) in Camden County, Georgia, just north of the Florida state line.

The role of the synganglion in oocyte development in Ornithodoros parkeri was investigated by ligation and transplantation experiments. Ligation between legs 2 and 3 to isolate the synganglion from the ovary and ligation between legs 1 and 2 to keep both the synganglion and the ovary in the posterior ends were performed on mated females on different days after feeding. Results show that vitellogenesis was inhibited significantly if the synganglion was separated from the ovary within the first few days after feeding. However, transplantation of synganglia from 3 kinds of donors (unfed virgin, fed virgin, and fed mated females) into the synganglionless posterior portions induced vitellogenesis and oocyte development to final maturation. The supra- and subesophageal parts of the synganglion showed a similar gonadotropic activity after each was transplanted separately into the ligated synganglionless posterior portions. These results indicate that the synganglion produces an egg development stimulation factor (EDSF) that possibly is present in a storage form in unfed and/or fed virgin females in which vitellogenesis has not progressed and is released in females after feeding and mating. However, the characterization of EDSF and precise sites of production and storage await further investigation.

Immunocytochemical staining based on the peroxidase-antiperoxidase method has shown that some neurosecretory cells (NSC) in the synganglion of the adult female tick Ornithodoros parkeri react with an antibody to bovine insulin. There are 18 regions of paraldehyde fuchsin-positive NSC of which three regions showed specific insulin-like immunoreactivity: anterolateral cheliceral, anteromedial stomodeal and posterior opisthosomal. Immunoreactivity can also be found in the extracellular surface of the neurilemma of the synganglion. This suggests a possible neurohemal site and release of neurohormone in a diffuse manner.

Various tissues excised from nymphs of the tick Ornithodoros parkeri at the time of epicuticle deposition were incubated in vitro. The medium from the incubation of salivary glands, coxal glands, synganglion, testis, midgut, and fat body associated with tracheal trunk showed little or no ecdysteroid immunoreactivity. Only medium from incubated integument contained ecdysteroids. The following evidence indicated that epidermal cells are the source of ecdysone: (i) when dorsal and/or ventral integuments were incubated separately, both produced ecdysteroid immunoreactive material during the course of incubation. As compared with the ecdysteroid content in the integument before incubation, the amount of ecdysteroids produced after a 24-h incubation increased 4- to 7-fold; (ii) enzymatic hydrolysis showed that neither highly polar ecdysteroid conjugates nor apolar conjugates were stored in the integument; (iii) histological and scanning electron microscope observations demonstrated that these excised integuments consisted of newly deposited epicuticle and epidermis as well as some fat body cells; (iv) HPLC RIA showed that the integument with associated fat body produced ecdysone and 20-hydroxyecdysone, while the integument produced only ecdysone after removing fat body. Presumably, ecdysone secreted by epidermis was converted into 20-hydroxyecdysone by fat body.

A comparative study of feeding and host preference was made among immatures of Ixodes dammini Spielman, Clifford, Piesman & Corwin, I. scapularis Say, and I. pacificus Cooley & Kohls, using white laboratory mice, Eumeces lizards, and chickens (3-4 d old) as hosts. Larval feeding of each species when placed on hosts was greater (P less than 0.05) on mice than on chickens and lizards and higher on lizards than on chickens (P less than 0.05). When larvae of the three species were given a choice between mouse and lizard and mouse and chicken, they preferred mice (except no statistical difference was found between mice and chickens for I. pacificus larvae). When given a choice between lizard and chicken, no significant difference in host preference was seen. Nymphs of I. dammini, I. scapularis, and I. pacificus displayed no statistical difference in feeding ability between mice and lizards when placed on these hosts, but more ticks fed on mice and lizards than on chickens. Nymphs of all three species also showed no preference between mice and lizards but preferred either of these hosts to chickens (however, no statistical difference was found between mice and chickens for I. dammini nymphs or between lizards and chickens for I. pacificus nymphs).

Lyme disease spirochetes (Borrelia burgdorferi) multiplied rapidly in larval Ixodes dammini, reaching a mean density of 2,735 spirochetes/tick on day 15 post-repletion. A 5-fold drop in spirochete levels occurred during the subsequent premolting period. Recently molted nymphs contained a mean of less than 300 spirochetes/tick. Following nymphal repletion, spirochete multiplication renewed, reaching a mean abundance of 61,275 spirochetes/nymph on day 75 post-repletion. A 10-fold drop in spirochete abundance occurred again when ticks molted to the adult stage. Tick-derived spirochetes proved to be infectious when greater than 10(4) spirochetes were inoculated ip into hamsters (4 of 4 animals infected). Inocula of 10(3-4) spirochetes were not always infectious (8 of 23 animals infected), and inocula of less than 10(3) spirochetes were insufficient for establishing infection (0 of 8 animals infected).

The effects of metepa on the cytology and fertility of male Dermacentor variabilis treated as unfed adults are determined. Evidence of cellular damage is found in testicular areas where actively dividing cells and some enlarging spermatocytes are found. The amount of cellular damage correlates positively to the concentration of the chemosterilant and results in decreases numbers of spermatids. In crosses of treated males to untreated females, resulting egg masses hatch normally; however, the percentage of females producing egg masses that hatch is reduced.

Log-log plots of unfed and fed tick weight on corresponding values of the scutal index (SI = scutal length x scutal width) show similar slopes for female D. variabilis from two laboratory populations. As derived from these plots, the relative engorgement state of a tick at any time during feeding can be expressed as the ratio of the cube roote of weight to the square root of the scutal index (RES = W1/3 divided by SI 1/2), where SI serves as an independent measure of tick size. After feeding for specified periods, mean population fed-weights are not statistically different, but differences between mean population RES ratios are highly significant. When SI is used as a covariate, differences between mean population fed-weights are also highly significant. Tests of mean log-fed-weight and mean RES values show that the effects of individual rabbit hosts on feeding performance are highly significant, but the statistic associated with differences between RES means is higher than that between log-fed-weight means. We conclude that differences in tick engorgement behaviors are measured more sensitively by RES ratios than by engorgement weights.

Morphological characters are measured from each tick specimen from samples of 10 "populations" of Haemaphysalis longicornis. The 10 populations consist of 6 diploid bisexual and 4 triploid parthenogenetic populations from Australia, Japan, and Korea. Statistical analyses (univariate and multivariate) of differential morphological variation are made among sex, method of reproduction, and chromosome ploidy level in attempts to determine the effects of these parameters on overall variation. In general, laboratory-reared thelytokous females (3n = 33y are least variable, laboratory-reared bisexual females and males (2n = 22 female; 21 male) are intermediate in variation, and field-collected bisexual males and females are most variable. However, the only field-collected thelytokous "population" (3n = 33) in the analyses is more variable than even the field-collected bisexual ticks.

The peripheral nervous system of an ixodid and an argasid tick include the following components: (1) paired optic, cheliceral and pedipalpal nerves and unpaired stomodeal nerve arising from the pre-esophageal portion of the central nervous system (synganglion); (2) 4 pairs of pedal nerve trunks (each with appendicular and hemal branches) and 4 major pairs of opisthosomal nerves (including the paraspiracular, genital, postlateral-myosomal, and ano-myosomal nerves); and (3) the lateral "sympathetic" plexuses formed by contributions of hemal nerves arising from pedal ganglia and from the paraspiracular nerves. The salivary glands are multiply innervated by 4 pairs of nerves. The 1st pair arise from the pedipalpal nerves, the 2nd and 3rd from the lateral sympathetic plexuses, and the 4th from the paraspiracular nerves. Portions of the integument and the majority of non-appendicular muscles are innervated by various fine nerves arising from the lateral sympathetic plexuses and from the 4 pairs of opisthosomal nerves.