Potential for Lyme disease in Maine: deer survey of distribution of Ixodes dammini, the tick vector.

A survey of deer brought to tagging stations at 24 sites in Main revealed the presence of the deer tick, Ixodes dammini, on 5.1 percent of deer. Ticks were found almost exclusively on deer from southwest coastal sites in the state. The potential for endemic Lyme disease in coastal Maine merits further study.     

Prevalence of tick-borne encephalitis virus and Borrelia burgdorferi sensu lato in Ixodes ricinus ticks in Lower Bavaria and Upper Palatinate,Germany

Lyme borreliosis and tick-borne encephalitis (TBE) are the most common tick-borne diseases in Germany. We collected Ixodes ricinus ticks from 16 high-risk and four low-risk sites distributed in Lower Bavaria and Upper Palatinate based on the number of human TBE cases recorded at the Robert Koch Institute from 2001 to 2009. A total of 8805 questing ticks (8203 nymphs, 602 adults) were collected in 2010 and examined in pools for the presence of tick-borne encephalitis virus (TBEV) using real-time RT–PCR. Overall TBEV prevalence evaluated as the minimum infection rate (MIR) was 0.26 % (23 positive pools/8805 ticks in 1029 pools). TBEV was detected at seven of the 16 high-risk sites, where MIR ranged from 0.16 to 2.86 %. A total of 3969 ticks were examined by PCR for infection with Borrelia burgdorferi sensu lato (s.l.) targeting the 5 S–23 S rRNA intergenic spacer (IGS) region. IGS nucleotide sequences were used to determine genospecies. Selected positive Borrelia samples were subjected to PCR and sequencing targeting the OspA gene, providing 46 sequences for molecular phylogenetic analysis. Of the 3969 questing ticks, 506 (12.7 %) were positive for B. burgdorferi s.l. Seven B. burgdorferi s.l. genospecies were identified: B. afzelii (41.3 %), B. garinii (19 %), B. valaisiana (13.8 %), B. burgdorferi sensu stricto (11.1 %), B. spielmanii (0.4 %), B. lusitaniae (0.2 %), and Candidatus B. finlandensis (0.6 %). Mixed infections were identified in 13.6 % of the ticks. The rate of infection in questing ticks varied among sites from 5.6 % (72 examined, four positive) to 29.5 % (88 examined, 26 positive). B. burgdorferi s.l. occurred at all 20 sites, whereas TBEV was detected only at the high-risk sites where more human TBE cases were reported compared to low-risk sites.     

Roe deer as sentinels for endemicity of tick-borne encephalitis virus.

The suitability of serological surveys of roe deer (Capreolus capreolus) in determining the spread of tick-borne encephalitis virus (TBEV) was tested in a south German area with a low risk of TBEV infection to humans. Sera obtained from 192 hunted roe were screened by an haemagglutination-inhibition test (HAI) and in an ELISA developed in our laboratory. Those found positive were tested in a neutralization test (NT). Fifty (26.0%) sera reacted positive by ELISA and 43 (86.0%) of these were confirmed by HAI or NT. Forty-seven (24.5%) samples were positive by HAI, 44 (93.6%) of which were also positive in NT or ELISA. Only insignificant increase of the antibody prevalence with age (P = 0.17 for HAI antibodies) suggests that most infections occur at an early age in scattered natural foci. The antibody prevalence in females was lower than in males (OR = 0.63; P = 0.02 for HAI antibodies). In determining the distribution of seropositive roe we increased the sample size to 235 sera. No antibodies were detected in 56 (23.8%) sera collected in the eastern third of the county. The areas of high antibody prevalence in roe match those in which humans have been infected. We conclude that serosurveys of roe deer are useful in marking out areas in which humans face the risk of infection, provided that an adequate number of sera, preferably from males, is available.     

Prevalence of tick-borne pathogens in Ixodes scapularis in a rural New Jersey County.

To assess the potential risk for other tick-borne diseases, we collected 100 adult Ixodes scapularis in Hunterdon County, a rapidly developing rural county in Lyme disease endemic western New Jersey. We tested the ticks by polymerase chain reaction for Borrelia burgdorferi, Babesia microti, and the rickettsial agent of human granulocytic ehrlichiosis (HGE). Fifty-five ticks were infected with at least one of the three pathogens: 43 with B. burgdorferi, five with B. microti, and 17 with the HGE agent. Ten ticks were coinfected with two of the pathogens. The results suggest that county residents are at considerable risk for infection by a tick-borne pathogen after an I. scapularis bite.     

Virus meningo-encephalitis in Slovenia. 4. Isolation of the virus from the ticks Ixodes ricinus

This article describes the steps taken to verify that the tick Ixodes ricinus is the main vector of Slovenian meningo-encephalitis.In 1954, several unsuccessful attempts were made to isolate the virus from unengorged ticks collected at random, but in the following year this system was abandoned, and instead the search for specimens was carried out on the basis of evidence supplied by meningo-encephalitis patients with a tick-bite case history.In June-the peak endemic period-140 unengorged ticks were collected from a part of a forest in central Slovenia where one of these patients had been working. The ticks were washed in alcohol, finely ground, and centrifuged, and the supernatant was inoculated intracerebrally into suckling mice, and intraperitoneally into adult mice and guinea-pigs. The infected suckling mice died between the fourteenth and eighteenth day after inoculation; a suspension of their brains was inoculated intracerebrally into a further batch of suckling and adult mice, which subsequently fell ill, showing signs in the central nervous system.The virus strain obtained was subjected to neutralization and complement-fixation tests, in order to identify the infective agent.     

Prevalence of Ixodes dammini near the homes of Lyme disease patients in Westchester County, New York

Cases of Lyme disease that occurred in Westchester County, an affluent suburb north of New York City, in 1983 were investigated in 1983 and 1984 to determine the presence of Ixodes dammini (Acari: Ixodidae) in the vicinity of the patients' homes. Small mammal trapping, drag cloth, and carbon dioxide-baited tick traps were used to sample ticks. In all but one of 11 cases investigated, I. dammini was found on or near well-maintained lawns in the immediate vicinity of the residences. A mark-release-recapture experiment to determine tick abundance in one 700 m2 lawn resulted in an estimate of 6800 adult ticks (approximately 1 per m2). Dark-field microscopic examination of tick midgut tissues revealed that 33% of nymphs and 55% of adult ticks from this lawn contained spirochetes. These data suggest that many cases of Lyme disease in Westchester County, New York, may be acquired at home as a result of activities on the lawn.     

Detection of four species of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks collected from roe deer (Capreolus capreolus) in The Netherlands.

Roe deer (Capreolus capreolus) were investigated for their value as sentinel animals for Lyme borreliosis in the Netherlands. Serum was obtained from 114 roe deer, and 513 Ixodes ricinus, predominantly females (72%), were obtained from 47 animals (41%). The polymerase chain reaction was used to detect DNA of Borrelia burgdorferi sensu lato in a total of 190 ticks, comprising 106 engorged ticks and 84 non-engorged ticks. Borrelia DNA was detected in 24 engorged ticks (23%) and 26 non-engorged ticks (31%). This difference was not significant (P = 0.25). Four species of B. burgdorferi sensu lato were identified in the ticks. B. burgdorferi sensu stricto, Borrelia garinii, Borrelia afzelii and group VS116. B. afzelii was most commonly found and present in 13 mixed infections, and in 28 single infections. Fifteen sera (13%) contained antibodies to Borrelia spp. Ticks are more appropriate sentinel animals for Lyme borreliosis than roe deer, an important host for I. ricinus. Although the viability of borrelia spirochaetes in engorged ticks collected from roe deer was not assessed, a bloodmeal taken from roe deer did not eliminate borrelia spirochaetes from the tick. The relevance of this finding for transovarial transmission of borrelia spirochaetes in ticks is discussed.     

Occurrence and genetic variability of Kemerovo virus in Ixodes ticks from different regions of Western Siberia,Russia and Kazakhstan

Kemerovo virus (KEMV), a member of the Reoviridae family, Orbivirus genus, is transmitted by Ixodes ticks and can cause aseptic meningitis and meningoencephalitis. Recently, this virus was observed in certain provinces of European part of Russia, Ural, and Western and Eastern Siberia. However, the occurrence and genetic diversity of KEMV in Western Siberia remain poorly studied. Therefore, the aim of this work was to investigate the prevalence and genetic variability of KEMV in Ixodes ticks from Western Siberia. A total of 1958 Ixodes persulcatus, I. pavlovskyi ticks and their hybrids from Novosibirsk and Omsk provinces, Altai Republic (Russia) and East Kazakhstan province (Kazakhstan) were analyzed for the presence of KEMV and tick-borne encephalitis virus (TBEV) RNA. It was observed that the KEMV distribution area in Western Siberia was wider than originally thought and included Northern and Northeastern Altai in addition to the Omsk and Novosibirsk provinces. For the first time, this virus was found in Kazakhstan. The occurrence of KEMV was statistically lower than TBEV in most locations in Western Siberia. KEMV was found both in I. persulcatus and I. pavlovskyi ticks and in their hybrids. Notably, KEMV variants observed in the 2010s were genetically different from those isolated in the 1960s, which indicated the ongoing process of evolution of the Kemerovo virus group. Moreover, the possibility of reassortment for KEMV was demonstrated for the first time.     

Isolation and molecular characterization of a tick-borne encephalitis virus strain from a new tick-borne encephalitis focus with severe cases in Bavaria,Germany

Tick-borne encephalitis (TBE) is the most important viral infection transmitted by ticks in Central Europe. In Germany, where TBE was classified as a notifiable disease in 2001, a highly variable number of clinically apparent human cases was reported in the last few years, ranging from the lowest number of 238 in 2007 to a maximum of 546 in 2006. The dynamics of the virus and its vector tick remain poorly understood. We investigated a highly active TBE focus in south-eastern Germany where from 2003 to 2008 a total of 9 clinical human cases was diagnosed. Three out of these 9 cases were fatal indicating an unusually high mortality rate possibly due to a highly virulent TBEV strain. From 2005 till 2008, 2150 Ixodes ricinus ticks were collected and tested for the presence of TBE virus. Five TBEV-positive ticks were detected by real-time RT-PCR. A viable virus strain was isolated from one of the positive ticks sampled in 2005. This is the first TBE virus isolate from a tick in Germany for 30 years. Sequencing of the full-length genome of this virus strain (AS33) revealed 2 unique amino acid substitutions in the envelope protein known to play a role in the pathogenicity of TBE virus. Amplification of the envelope gene using 2 TBEV-PCR-positive ticks from 2006 also showed these particular mutations indicating that this TBE virus strain was present in at least 2 consecutive years. The entire sampling area was divided into smaller sectors for the exact location of TBEV-positive ticks. Virus-positive ticks were found to be randomly distributed throughout the investigated focus, which is used as recreational area by the local people.     

Deer ticks (Ixodes scapularis) and the agents of Lyme disease and human granulocytic ehrlichiosis in a New York City park.

Rodent trapping and drag sampling in Van Cortlandt Park, New York City, yielded all stages of Ixodes scapularis, the deer tick vector of Lyme disease and human granulocytic ehrlichiosis (HGE). Polymerase chain reaction analyses of the ticks showed Borrelia burgdorferi and the Ehrlichia sp. that causes HGE.     

A focus of deer tick virus transmission in the northcentral United States.

We screened salivary glands from adult deer ticks collected near Spooner and Hayward, Wisconsin, to determine whether deer tick virus, a recently described flavivirus, occurs with other tickborne agents in the upper Midwest. Intraacinar inclusions suggestive of replicating virus were detected in 4 (4.6%) of 87 ticks. The virus was isolated by suckling-mouse inoculation.     

New genetic lineage within the Siberian subtype of tick-borne encephalitis virus found in Western Siberia,Russia

Tick-borne encephalitis virus (TBEV), a member of the Flaviviridae family, is a causative agent of a severe neurological disease. There are three main TBEV subtypes: the European (TBEV-Eu), Far Eastern (TBEV-FE), and Siberian (TBEV-Sib). Currently, three lineages within TBEV-Sib have been recorded. In this study, the genetic and biological characteristics of a new original strain, TBEV-2871, isolated in the Novosibirsk province of Western Siberia, Russia were investigated. The strain has low neuroinvasiveness in mice. Phylogenetic analysis demonstrated that TBEV-2871 belongs to TBEV-Sib, but does not cluster with any of the TBEV-Sib lineages. The TBEV-2871 strain has 88–89% nucleotide sequence identity with the other TBEV-Sib strains, 84–86% nucleotide sequence identity with the TBEV-FE and TBEV-Eu subtypes and is genetically close to the subtype division border. The TBEV-2871 polyprotein sequence includes 43 unique amino acid substitutions, 30 of which are recorded at positions that are conserved among all TBEV subtypes. Strain TBEV-2871 and two similar but not identical isolates found in Kemerovo province, Western Siberia are separated into a new lineage tentatively named Obskaya after the name of Ob riber, in the vicinity of which the TBEV-2871 was first found. A molecular evolution investigation demonstrated that within TBEV-Sib, the Obskaya lineage likely separated 1535 years ago, which is even earlier than the Baltic lineage.     

A new species of tick,Ixodes (Ixodes) mojavensis (Acari: Ixodidae), from the Amargosa Valley of California

Ixodes (Ixodes) mojavensis, n. sp. (Acari: Ixodidae), is described from all parasitic stages collected from the endangered vole Microtus californicus scirpensis Bailey, 1900 (Rodentia: Cricetidae), Mus musculus L. 1758 (Rodentia: Muridae), and Reithrodontomys megalotis (Baird; 1857) (Rodentia: Cricetidae) in the Amargosa Valley of California. When first collected in 2014, this tick was tentatively identified as Ixodes minor Neumann, 1902 because the nucleotide similarity between its 16S rDNA sequence and a homologous GenBank sequence from an I. minor from the eastern U.S. was 99.51%. Nevertheless, adults of I. mojavensis differ morphologically from I. minor by hypostomal dentition, absence of a spur on palpal segment I, and punctation patterns; nymphs by the shapes of basis capituli, auriculae, cervical grooves and external files of hypostomal denticles; and larvae by the length of idiosomal setae and hypostomal dentition. DNA sequencing of fragments of 4 different genes, 12S rDNA, 16S rDNA, cytochrome c oxidase subunit I (COI), and intergenic transcribed spacer 2 (ITS2) of I. mojavensis and of closely related species of Ixodes shows that the mitochondrial gene sequences of the new tick species are almost identical to the I. minor homologous genes. Phylogenetically, the two species do not cluster in mutually exclusive monophyletic clades. However, ITS2 sequences of I. mojavensis and I. minor diverge deeply (≥ 5.74% maximum likelihood divergence) and are as different as homologous genes from other recognized species. The discrepancy between the two sets of genes is suggestive of past mitochondrial introgression or incomplete mitochondrial lineage sorting.     

Differences in prevalence of Borrelia burgdorferi and Anaplasma spp. infection among host-seeking Dermacentor occidentalis,Ixodes pacificus,and Ornithodoros coriaceus ticks in northwestern California

Previous studies revealed that the Pacific Coast tick (Dermacentor occidentalis) is infected occasionally with the agents of Lyme disease (Borrelia burgdorferi) or human granulocytic anaplasmosis (Anaplasma phagocytophilum) and that it is an inefficient experimental vector of B. burgdorferi. The relationship of the pajahuello tick (Ornithodoros coriaceus) to each of these bacterial zoonotic agents has not been reported. The primary bridging vector of both bacterial zoonotic agents to humans is the western black-legged tick (Ixodes pacificus). Because of the spatial and temporal overlap of D. occidentalis and O. coriaceus populations with those of I. pacificus in natural foci of B. burgdorferi and A. phagocytophilum in northwestern California, we conducted field and laboratory studies to determine if the Pacific Coast tick or the pajahuello tick potentially may serve as secondary vectors of either bacterium. Our findings reconfirmed that wild-caught D. occidentalis ticks are infected infrequently with B. burgdorferi or A. phagocytophilum, but some adult ticks from dense woodlands or chaparral were found to contain two important veterinary pathogens for the first time (Anaplasma bovis, A. ovis). The high prevalence of A. bovis infection (4.3%, n = 185 ticks) within chaparral-derived ticks suggests that D. occidentalis could be an efficient vector of this rickettsia. Experimental attempts to transmit borreliae or Anaplasma spp. that may have been present in >100 wild-caught D. occidentalis adults to naïve rabbits were unsuccessful. Anaplasma spp. were not detected in O. coriaceus, but one (4.3%) of 23 nymphs was infected with B. bissettii. This finding and an antecedent report of a B. burgdorferi-like spirochete from the same tick species demonstrate that O. coriaceus sometimes acquires and transstadially passes Lyme disease group spirochetes. I. pacificus nymphs inhabiting a woodland nidus of B. burgdorferi and A. phagocytophilum had a 5-fold higher prevalence of borreliae than adult ticks from the same generational cohort. In contrast to the results of preceding studies carried out at the same site, none of the nymphal or adult ticks was PCR-positive for A. phagocytophilum. This suggests that the distribution of this rickettsia is highly focal or variable from year-to-year within this particular woodland.     

A new, surface-antigen-adsorbed influenza virus vaccine. I. Studies on immunogenicity in hamsters.

The ability of a new, surface-antigen-adsorbed influenza virus vaccine to induce serum antibody in hamsters, and to protect these hamsters against subsequent homologous virus challenge, is reported. In addition, similar studies in hamsters have also been carried out using the surface antigen material prior to adsorption to the aluminium hydroxide carrier. The new, adsorbed vaccine is at least as effective as inactivated saline influenza virus vaccine in inducing serum antibody and protection in hamsters; the unadsorbed surface antigen material, however, did not confer protection to hamsters challenged subsequently with homologous virus.     

An epidemiological study on parainfluenza, DA and mumps virus infections in domestic animals in New England

Recent studies have shown high levels of antibody to the parainfluenza virus group in human sera collected in New England and in other populations in various parts of the world. In view of the importance of animals as reservoirs of viruses affecting man, studies were carried out to assess the level of immunity to the parainfluenza, DA and mumps viruses in domestic animals (cows, swine, dogs, cats, lambs, and sheep) in New England.