Novel Focus of Sin Nombre Virus in Peromyscus eremicus Mice, Death Valley National Park, California, USA.

The deer mouse (Peromyscus maniculatus) is the primary reservoir for Sin Nombre virus (SNV) in the western United States. Rodent surveillance for hantavirus in Death Valley National Park, California, USA, revealed cactus mice (P. eremicus) as a possible focal reservoir for SNV in this location. We identified SNV antibodies in 40% of cactus mice sampled.

Detection and characterization of a novel spotted fever group Rickettsia genotype in Haemaphysalis leporispalustris from California, USA.

The rabbit tick, Haemaphysalis leporispalustris Packard, is known for its association with Rickettsia rickettsii as it harbors both virulent and avirulent strains of this pathogen. In this manuscript we report findings and preliminary characterization of a novel spotted fever group rickettsia (SFGR) in rabbit ticks from California, USA. Rickettsia sp. CA6269 (proposed "Candidatus Rickettsia lanei") is most related to known R. rickettsii isolates but belongs to its own well-supported branch different from those of all R. rickettsii including strain Hlp2 and from Rickettsia sp. 364D (also known as R. philipii) and R. peacockii. This SFGR probably exhibits both transovarial and transstadial survival since it was found in both questing larvae and nymphs. Although this rabbit tick does not frequently bite humans, its role in maintenance of other rickettsial agents and this novel SFGR warrant further investigation.

Fatal Flea-Borne Typhus in Texas: A Retrospective Case Series, 1985-2015.

AbstractFlea-borne (murine) typhus is a global rickettsiosis caused by Rickettsia typhi. Although flea-borne typhus is no longer nationally notifiable, cases are reported for surveillance purposes in a few U.S. states. The infection is typically self-limiting, but may be severe or life-threatening in some patients. We performed a retrospective review of confirmed or probable cases of fatal flea-borne typhus reported to the Texas Department of State Health Services during 1985-2015. When available, medical charts were also examined. Eleven cases of fatal flea-borne typhus were identified. The median patient age was 62 years (range, 36-84 years) and 8 (73%) were male. Patients presented most commonly with fever (100%), nausea and vomiting (55%), and rash (55%). Respiratory (55%) and neurologic (45%) manifestations were also identified frequently. Laboratory abnormalities included thrombocytopenia (82%) and elevated hepatic transaminases (63%). Flea or animal contact before illness onset was frequently reported (55%). The median time from hospitalization to administration of a tetracycline-class drug was 4 days (range, 0-5 days). The median time from symptom onset to death was 14 days (range, 1-34 days). Flea-borne typhus can be a life-threatening disease if not treated in a timely manner with appropriate tetracycline-class antibiotics. Flea-borne typhus should be considered in febrile patients with animal or flea exposure and respiratory or neurologic symptoms of unknown etiology.

Top-down-assisted bottom-up method for homologous protein sequencing: hemoglobin from 33 bird species.

Ticks are vectors for disease transmission because they are indiscriminant in their feeding on multiple vertebrate hosts, transmitting pathogens between their hosts. Identifying the hosts on which ticks have fed is important for disease prevention and intervention. We have previously shown that hemoglobin (Hb) remnants from a host on which a tick fed can be used to reveal the host's identity. For the present research, blood was collected from 33 bird species that are common in the U.S. as hosts for ticks but that have unknown Hb sequences. A top-down-assisted bottom-up mass spectrometry approach with a customized searching database, based on variability in known bird hemoglobin sequences, has been devised to facilitate fast and complete sequencing of hemoglobin from birds with unknown sequences. These hemoglobin sequences will be added to a hemoglobin database and used for tick host identification. The general approach has the potential to sequence any set of homologous proteins completely in a rapid manner. Graphical Abstract ᅟ.

Large scale spatial risk and comparative prevalence of Borrelia miyamotoi and Borrelia burgdorferi sensu lato in Ixodes pacificus.

Borrelia miyamotoi is a newly described emerging pathogen transmitted to people by Ixodes species ticks and found in temperate regions of North America, Europe, and Asia. There is limited understanding of large scale entomological risk patterns of B. miyamotoi and of Borreila burgdorferi sensu stricto (ss), the agent of Lyme disease, in western North America. In this study, B. miyamotoi, a relapsing fever spirochete, was detected in adult (n=70) and nymphal (n=36) Ixodes pacificus ticks collected from 24 of 48 California counties that were surveyed over a 13 year period. Statewide prevalence of B. burgdorferi sensu lato (sl), which includes B. burgdorferi ss, and B. miyamotoi were similar in adult I. pacificus (0.6% and 0.8%, respectively). In contrast, the prevalence of B. burgdorferi sl was almost 2.5 times higher than B. miyamotoi in nymphal I. pacificus (3.2% versus 1.4%). These results suggest similar risk of exposure to B. burgdorferi sl and B. miyamotoi from adult I. pacificus tick bites in California, but a higher risk of contracting B. burgdorferi sl than B. miyamotoi from nymphal tick bites. While regional risk of exposure to these two spirochetes varies, the highest risk for both species is found in north and central coastal California and the Sierra Nevada foothill region, and the lowest risk is in southern California; nevertheless, tick-bite avoidance measures should be implemented in all regions of California. This is the first study to comprehensively evaluate entomologic risk for B. miyamotoi and B. burgdorferi for both adult and nymphal I. pacificus, an important human biting tick in western North America.

Survival of host blood proteins in Ixodes scapularis (Acari: Ixodidae) ticks: a time course study.

Ixodes scapularis Say, 1821 larvae were fed on mice and allowed to molt under laboratory conditions. A liquid chromatography-tandem mass spectrometry-based proteomic study was conducted to identify the type of mammalian proteins present in the derived nymphal ticks at different time intervals after molting. Albumin was present for 85 d; transferrin was present for 29 d; and, more importantly, hemoglobin remained detectable for up to 309 d postmolting. Peptides of actin, keratin, and tubulin are highly similar between mouse and tick, and therefore, unambiguous assignment of these proteins to different species was not possible. Establishing a time line for the persistence of hemoglobin, one of the most abundant blood proteins, at detectable levels in ticks after the bloodmeal and molting advances our efforts to use this protein to identify the host species.

Development of a host blood meal database: de novo sequencing of hemoglobin from nine small mammals using mass spectrometry.

We report the successful de novo sequencing of hemoglobin using a mass spectrometry-based approach combined with automatic data processing and manual validation for nine North American species with currently unsequenced genomes. The complete α and ß chain of all nine mammalian hemoglobin samples used in this study were successfully sequenced. These sequences will be appended to the existing database containing all known hemoglobins to be used for identification of the mammalian host species that provided the last blood meal for the tick vector of Lyme disease, Ixodes scapularis.

Absence of the symbiont Candidatus Midichloria mitochondrii in the mitochondria of the tick Ixodes holocyclus.

Candidatus Midichloria mitochondrii (M. mitochondrii) belongs to a novel clade of bacteria within the order Rickettsiales. Recent PCR-based screening studies indicate that it is present in a number of blood-sucking arthropods, as well as the blood of some vertebrates. Its medical and veterinary significance remains to be determined. Electron microscopic examinations of M. mitochondrii have thus far been conducted on two infected tick species. Remarkably, the bacterium was found in abundance within the mitochondria of the ovarian cells of each tick species. This makes it the only characterized bacterium able to invade the mitochondria of any multicellular organism. To examine whether mitochondrial invasion is a consistent characteristic of M. mitochondrii, we examined two tick species found in Eastern Australia. One of these species, Ixodes holocyclus, was infected with two M. mitochondrii strains; however, no bacteria were seen in the mitochondria. Comparative studies involving these strains may shed light on the unique phenomenon of mitochondrial invasion.

Evidence for the presence of Francisella and spotted fever group rickettsia DNA in the tick Amblyomma fimbriatum (Acari: Ixodidae), Northern Territory, Australia.

Ticks (n = 252) were collected from five wild-caught reptile species during routine trapping in the Djukbinj National Park and Fogg Dam Reserve, Northern Territory, Australia. Pooling of ticks (one to four ticks per pool), according to sex or host animal, resulted in 187 samples used for screening for the presence of Rickettsia species via molecular methods. Rickettsia DNA was detected via the amplification of the gltA, ompA, and ompB genes in 57 (34%) of the 187 tick samples, all of which contained only the tick Amblyomma fimbriatum Koch (Acari: Ixodidae). Further amplification and sequencing of nine of the positive samples (4.8%) for the gltA, ompA, ompB, 17-kDa, and 16S rRNA genes identified a Rickettsia species sharing closest identity to Rickettsia tamurae. In addition, amplification and sequencing of the 16S rRNA gene detected in the same tick samples the presence of a Francisella species closely related to other tick-borne Francisellae identified in ticks from the Northern Hemisphere.

Bartonella-like DNA detected in Ixodes tasmani ticks (Acari: Ixodida) infesting Koalas (Phascolarctos cinereus) in Victoria, Australia.

A total of 42 ticks comprising Ixodes tasmani (n = 41) and Ixodes trichosuri (n = 1) were collected from wild koalas (Phascolarctos cinereus) at the Koala Convention Centre, Philip Island, Victoria, Australia and screened for the presence of Bartonella using the target gene gltA. Bartonella-like DNA was detected in 4 of the 19 pooled tick samples (21%). All positive ticks were male. Analysis of partial sequences for the gltA gene indicated the presence of a Bartonella-related species similar to that reported in another Ixodid species. This is the first report of Bartonella-like organisms in a native Australian marsupial.

Detection of a Hepatozoon and spotted fever group Rickettsia species in the common marsupial tick (Ixodes tasmani) collected from wild Tasmanian devils (Sarcophilus harrisii), Tasmania.

Tasmanian devils are the largest extant marsupial carnivores, confined to the Australian island state of Tasmania. The iconic marsupial has dramatically declined in number since the discovery of devil facial tumor disease in 1996 and efforts are being made to uncover vital information to assist in the long-term survival of the species. Ticks are the main vectors of arthropod-borne disease in animals, raising the question of whether Tasmanian devils may be host to arthropods capable of harboring infectious agents. Partially engorged ticks were collected from 35 wild Tasmanian devils and tested for the presence of a range of tick-borne genera. A spotted fever group Rickettsia was detected in 45.5% of samples of the tick Ixodes tasmani (n=44), from all trapping locations, sharing close sequence identity to members of the Rickettsia massiliae group. A Hepatozoon species was also identified in 34.1% of the same sample set, sharing sequence similarities to Hepatozoon felis, a known pathogen of felids. Dual detection was identified in 13.6% of tick samples, where prevalence of the two genera overlapped. The existence of two previously undetected species of genera known for containing pathogens identifies additional potential risks to the health of the devil population.

Molecular detection of Rickettsia, Coxiella and Rickettsiella DNA in three native Australian tick species.

Three Australian native animal species yielded 60 samples composed of three indigenous ticks. Hosts included twelve koalas, two echidnas and one wombat from Victoria, and ticks were of the species Ixodes tasmani (n = 42), Bothriocroton concolor (n = 8) and B. auruginans (n = 10), respectively. PCR screening and sequencing detected a species of Coxiella, sharing closest sequence identity to C. burnetii (>98%), in all B. auruginans, as well as a species of Rickettsia, matching closest to R. massiliae, in 70% of the same samples. A genotype sharing closest similarity to Rickettsia bellii (>99%) was identified in three female B. concolor collected from one of the echidnas. Three samples of I. tasmani, taken from three koalas, yielded different genotypes of Rickettsiella. These results represent the first detection of the three genera in each tick species and identify a high level of previously undetected bacterial diversity in Australian ticks.

Molecular and morphological description of a Hepatozoon species in reptiles and their ticks in the Northern Territory, Australia.

Ticks, representing 3 species of Amblyomma, were collected from the water python (Liasis fuscus) and 3 additional reptile species in the Northern Territory, Australia, and tested for the presence of Hepatozoon sp., the most common blood parasites of snakes. In addition, blood smears were collected from 5 reptiles, including the water python, and examined for the presence of the parasite. Hepatozoon sp. DNA was detected in all tick and reptile species, with 57.7% of tick samples (n = 187) and 35.6% of blood smears (n=35) showing evidence of infection. Phylogenetic analysis of the 18S rRNA gene demonstrated that half of the sequences obtained from positive tick samples matched closest with a Hepatozoon species previously identified in the water python population. The remaining sequences were found to be more closely related to mammalian and amphibian Hepatozoon species. This study confirms that species of Amblyomma harbor DNA of the same Hepatozoon species detected in the water pythons. The detection of an additional genotype suggests the ticks may be exposed to 2 Hepatozoon species, providing further opportunity to study multiple host-vector-parasite relationships.

Detection of a spotted fever group Rickettsia in the tick Ixodes tasmani collected from koalas in Port Macquarie, Australia.

Four species of Rickettsia are recognized as endemic to Australia. This study reports the detection of a new spotted fever group Rickettsia in the common marsupial tick Ixodes tasmani Neumann collected from koalas (Phascolarctos cinereus) in Port Macquarie, NSW, Australia. Based on the results of polymerase chain reaction (PCR) amplification of extracted tick DNA with primers targeting the citrate synthase gene (gltA) and the outer membrane proteins A and B (ompA. ompB), Rickettsiae were detected in 22 of 78 I. tasmani tick samples (28.2%). Sequence data obtained for the three genes displayed the closest degree of similarity to Rickettsia heilongjiangiensiss for gltA (99.4%; 331/333 bp), Rickettsia amblyommii for the ompA gene (94.8%; 417/440 bp), and both Rickettsia massiliae and Rickettsia rhipicephali for the ompB gene (97%; 770/803 bp). BLAST and phylogenetic analysis of partial sequences obtained for the three genes were found to have sufficient nucleotide variation from the current recognized Australian species to be considered a distinct spotted fever group Rickettsia.