Molecular investigations of cat fleas (Ctenocephalides felis) provide the first evidence of Rickettsia felis in Malta and Candidatus Rickettsia senegalensis in Israel

Current Data on Rickettsia felis Occurrence in Vectors, Human and Animal Hosts in Europe: A Scoping Review

Rickettsia felis is an emerging pathogen with increasing reports of human cases and detection in arthropod and animal host species worldwide. In this scoping review we record the newest data reported for R. felis in Europe: the vector and host species found to be infected, and the geographical distribution and prevalence of R. felis infection in vectors and hosts. A total of 15 European countries reported the occurrence of R. felis in hosts and vectors during 2017−2022. The vectors found to be infected by R. felis were flea, tick and mite species; Ctenocephalides felis and Ixodes ricinus were the dominant ones. The hosts found to be infected and/or exposed to R. felis were humans, cats and small mammals. Physicians should be aware of the epidemiology and include illness caused by R. felis in the differential diagnosis of febrile disease. Veterinarians should keep training pet owners on the need for effective year-round arthropod control on their pets, especially for fleas.

Survey of bacterial and protozoan agents in ticks and fleas found on wild animals in the state of Rio de Janeiro, Brazil

This study evaluates the presence of bacterial and protozoan agents in ticks and fleas found on wild animals in the state of Rio de Janeiro, Brazil. These ectoparasites were collected on mammal species Hydrochoerus hydrochaeris, Tapirus terrestris, Dicotyles tajacu, Didelphis aurita, Cuniculus paca, Cerdocyon thous, and Coendou prehensilis, and on the terrestrial bird Dromaius novaehollandiae. Ticks and fleas were identified morphologically using specific taxonomic keys. A total of 396 ticks and 54 fleas were tested via polymerase chain reaction (PCR) for the presence of Rickettsia spp., Borrelia spp., microorganisms of the order Piroplasmida and Anaplasmataceae family. This total is distributed among nine tick species of the genus Amblyomma and one flea species. Rickettsia bellii was detected in Amblyomma dubitatum and Amblyomma pacae; Rickettsia sp. strain AL was found in Amblyomma longirostre; Rickettsia parkeri strain Atlantic rainforest was found in Amblyomma ovale; and "Candidatus Rickettsia senegalensis" and Rickettsia felis were detected in Ctenocephalides felis felis. Wolbachia sp. was detected in C. f. felis, and Borrelia sp. was detected in Amblyomma calcaratum (here named Borrelia sp. strain Acalc110). All tested samples were negative for Ehrlichia spp. and microorganisms of the Piroplasmida order. This study detected a new bacterial strain, Borrelia sp. strain Acalc 110 (which is genetically close to B. miyamotoi and B. venezuelensis) and the Rickettsia sp. strain 19P, which is 100% similar to "Ca. R. senegalensis", a bacterium recently discovered and now being reported for the first time in Brazil.

Ticks and Tick-Borne Pathogens in Domestic Animals, Wild Pigs, and Off-Host Environmental Sampling in Guam, USA

Background: Guam, a United States of America (USA) island territory in the Pacific Ocean, is known to have large populations of ticks; however, it is unclear what the risk is to wildlife and humans living on the island. Dog (Canis familiaris), cat (Felis catus), and wild pig (Sus scrofa) sentinels were examined for ticks, and environmental sampling was conducted to determine the ticks present in Guam and the prevalence of tick-borne pathogens in hosts.

Methods and Results: From March 2019-November 2020, ticks were collected from environmental sampling, dogs, cats, and wild pigs. Blood samples were also taken from a subset of animals. A total of 99 ticks were collected from 27 environmental samples and all were Rhipicephalus sanguineus, the brown dog tick. Most ticks were collected during the dry season with an overall sampling success rate of 63% (95% CI: 42.4–80.6). 6,614 dogs were examined, and 12.6% (95% CI: 11.8–13.4) were infested with at least one tick. One thousand one hundred twelve cats were examined, and six (0.54%; 95% CI: 0.20–1.1) were found with ticks. Sixty-four wild pigs were examined and 17.2% (95% CI: 9.5–27.8) had ticks. In total, 1,956 ticks were collected and 97.4% of ticks were R. sanguineus. A subset of R. sanguineus were determined to be the tropical lineage. The other tick species found were Rhipicephalus microplus (0.77%), Amblyomma breviscutatum (0.77 %), and a Haemaphysalis sp. (0.51%). Blood samples from 136 dogs, four cats, and 64 wild pigs were tested using polymerase chain reaction (PCR) and DNA sequencing methods. Five different tick-borne pathogens with the following prevalences were found in dogs: Anaplasma phagocytophilum 5.9% (95% CI: 2.6–11.3); Anaplasma platys 19.1% (95% CI: 12.9–26.7); Babesia canis vogeli 8.8% (95% CI: 4.6–14.9); Ehrlichia canis 12.5% (95% CI: 7.5–19.3); Hepatozoon canis 14.7% (95% CI: 9.2–28.8). E. canis was detected in one cat, and no tick-borne pathogens were detected in wild pigs. Overall, 43.4% (95% CI: 34.9–52.1) of dogs had at least one tick-borne pathogen. Serological testing for antibodies against Ehrlichia spp. and Anaplasma spp. showed prevalences of 14.7% (95% CI: 9.2–28.8) and 31.6% (95% CI: 23.9–40), respectively.

Conclusion: Four different tick species were found in Guam to include a Haemaphysalis sp., which is a previously unreported genus for Guam. Dogs with ticks have a high prevalence of tick-borne pathogens which makes them useful sentinels.

Rickettsiaceae in two reptile-associated tick species, Amblyomma exornatum and Africaniella transversale: First evidence of Occidentia massiliensis in hard ticks (Acari: Ixodidae)

All species of hard ticks associated with reptiles as hosts throughout their life cycle, are currently assigned to genera including Amblyomma and Africaniella. Among these species, based on literature data, Africaniella transversale has never been investigated for the presence of tick-borne pathogens. In this study, seven DNA extracts (two from A. transversale and five from Amblyomma exornatum) were screened for the presence of important tick-borne protozoa (piroplasms) and bacteria (Anaplasmataceae and Rickettsiaceae) with conventional PCRs and sequencing. A new heat shock protein chaperonin (groEL) gene-specific PCR was also developed to identify Occidentia spp. in these samples. In A. transversale, Occidentia massiliensis (previously detected in rodent-associated soft ticks) and Rickettsia hoogstraalii were present. While the latter was molecularly identical with formerly reported sequences of this rickettsia, the genotype of O. massiliensis was new based on sequence and phylogenetic analyses of its groEL gene. In A. exornatum, a Rickettsia genotype closely related to R. tamurae and R. monacensis, was detected. The ompA sequence of this genotype was identical to that of Rickettsia sp. Ae-8 reported from A. exornatum in a reptile breeding facility in the USA. These results show that A. transversale might carry O. massiliensis which (unless having a symbiotic nature in ticks) may originate either from the reptile host of this hard tick species or the rodent prey of reptiles. This is also the first detection of the reptile tick-associated Rickettsia sp. Ae-8 (phylogenetically aligning with R. tamurae, R. monacensis) in Africa, i.e. within the original geographical range of A. exornatum.

Molecular detection of Rickettsia spp. in ticks and fleas collected from rescued hedgehogs (Erinaceus europaeus) in Portugal

Hedgehogs (e.g., Erinaceus europaeus, E. roumanicus) are wild mammals that frequently are observed near residential areas. The aim of this study was to investigate ticks and fleas collected from European hedgehogs in Portugal and to evaluate the prevalence of Rickettsia in those ectoparasites. Ticks and fleas were identified by morphological and molecular methods, and molecular detection by PCR and genotypic characterization of Rickettsia spp. was performed targeting ompB, ompA and gltA gene fragments. In total, 1892 ticks and 213 fleas were collected from 33 rescued European hedgehogs captured in seven districts of the north and centre of Portugal. Two tick species were identified - Rhipicephalus sanguineus accounted for 91 % (n = 1719) of the total ticks collected and 9 % (n = 173) were Ixodes hexagonus. All fleas were identified as Archaeopsylla erinacei. Regarding pathogen detection, Rickettsia massiliae DNA was found in 22 of the 212 tested Rh. sanguineus. None of the 48 I. hexagonus tested showed to be positive for rickettsiae. Rickettsia asembonensis DNA was identified in 55 A. erinacei fleas tested (n = 117). These results show that European hedgehogs are exposed to R. massiliae transmitted by ticks and to R. asembonensis via fleas suggesting that these mammals might be involved in the natural transmission cycle of these Rickettsia species. This study is the first report of R. asembonensis in fleas in Portugal.

Manifestations and Management of Flea-Borne Rickettsioses

Murine typhus and flea-borne spotted fever are undifferentiated febrile illnesses caused by Rickettsia typhi and Rickettsia felis, respectively. These organisms are small obligately intracellular bacteria and are transmitted to humans by fleas. Murine typhus is endemic to coastal areas of the tropics and subtropics (especially port cities), where rats are the primary mammalian host and rat fleas (Xenopsylla cheopis) are the vector. In the United States, a cycle of transmission involving opossums and cat fleas (Ctenocephalides felis) are the presumed reservoir and vector, respectively. The incidence and distribution of murine typhus appear to be increasing in endemic areas of the US. Rickettsia felis has also been reported throughout the world and is found within the ubiquitous cat flea. Flea-borne rickettsioses manifest as an undifferentiated febrile illness. Headache, malaise, and myalgia are frequent symptoms that accompany fever. The incidence of rash is variable, so its absence should not dissuade the clinician to consider a rickettsial illness as part of the differential diagnosis. When present, the rash is usually macular or papular. Although not a feature of murine typhus, eschar has been found in 12% of those with flea-borne spotted fever. Confirmatory laboratory diagnosis is usually obtained by serology; the indirect immunofluorescence assay is the serologic test of choice. Antibodies are seldom present during the first few days of illness. Thus, the diagnosis requires acute- and convalescent-phase specimens to document seroconversion or a four-fold increase in antibody titer. Since laboratory diagnosis is usually retrospective, when a flea-borne rickettsiosis is considered, empiric treatment should be initiated. The treatment of choice for both children and adults is doxycycline, which results in a swift and effective response. The following review is aimed to summarize the key clinical, epidemiological, ecological, diagnostic, and treatment aspects of flea-borne rickettsioses.

Molecular detection and identification of Rickettsia felis in Polygenis (Siphonaptera, Rhopalopsyllidae, Rhopalopsyllinae) associated with cricetid rodents in a rural area from central Argentina

The aim of this study was to detect and identify the presence of Rickettsia in fleas associated with cricetid rodents from northeastern Buenos Aires Province, Argentina. Sixteen fleas belonging to three species of Polygenis were collected from 56 cricetid rodents and analyzed for the presence of Rickettsia performing the conventional polymerase chain reaction (PCR) technique. Only one specimen of Polygenis (Polygenis) axius axius collected from Oxymycterus rufus was positive for Rickettsia felis using the gltA gene, and to ompA gene. This is the first report of R. felis in a Rhopalopsyllidae flea from Argentina, and the first detection of this bacterium in P. (P.) a. axius. Since both, O. rufus and P. (P.) a. axius, are common in areas close to humans, and enzootic cycle of R. felis is not fully understood, the results herein obtained might be of epidemiological importance. Further studies are needed in order to analyze the capacity of the species of Polygenis to transmit R. felis.

Detection of Flea-Borne Pathogens from Cats and Fleas in a Maltese Shelter

In a sanctuary located on the island of Malta, 23 clinically healthy cats randomly selected were sampled for blood and fleas. Only fleas were collected from 35 cats. All fleas were identified as Ctenocephalides felis, except for one specimen of Ctenocephalides canis. To the best of the authors' knowledge, this may be the first time to establish the occurrence of Bartonella koehlerae and B. clarridgeiae, as well as of Candidatus Mycoplasma haemominutum in the blood samples of 11 cats (47.82% [95% CI: 29.33-67.04]) with conventional PCR assays. One or more pathogens were found in 54 (96.42% [95% CI: 86.74-99.70]) out of 56 pooled flea samples, the most prevalent was Rickettsia felis. The DNA of Bartonella henselae, the commonest etiological agent of cat scratch disease, was detected first time in a pooled flea sample of a cat.

First broad-range molecular screening of tick-borne pathogens in Ixodes (Pholeoixodes) kaiseri, with special emphasis on piroplasms

Recently, the occurrence of Ixodes (Pholeoixodes) kaiseri has been reported for the first time in several European countries, but data on the molecular analysis of this hard tick species are still lacking. Therefore, in this study DNA extracts of 28 I. kaiseri (collected from dogs and red foxes in Germany, Hungary and Romania) were screened with reverse line blot hybridisation (RLB), PCR and sequencing for the presence of 43 tick-borne pathogens or other members of their families from the categories of Anaplasmataceae, piroplasms, rickettsiae and borreliae. Rickettsia helvetica DNA was detected in one I. kaiseri female (from a red fox, Romania), for the first time in this tick species. Six ticks (from red foxes, Romania) contained the DNA of Babesia vulpes, also for the first time in the case of I. kaiseri. Molecular evidence of R. helvetica and B. vulpes in engorged I. kaiseri does not prove that this tick species is a vector of the above two pathogens, because they might have been taken up by the ticks from the blood of foxes. In addition, one I. kaiseri female (from a dog, Hungary) harboured Babesia sp. badger type-B, identified for the first time in Hungary and Central Europe (i.e. it has been reported previously from Western Europe and China). The latter finding can be explained by either the susceptibility of dogs to Babesia sp. badger type-B, or by transstadial survival of this piroplasm in I. kaiseri.

Candidatus Rickettsia senegalensis in Cat Fleas (Siphonaptera: Pulicidae) Collected from Dogs and Cats in Cauca, Colombia

Rickettsia typhi and Rickettsia felis (Rickettsiales: Rickettsiaceae) are flea-transmitted pathogens. They are important causes of acute febrile illness throughout the world. We, therefore, sought to identify the rickettsial species present in the fleas of dogs and cats in the department of Cauca, Colombia. In this study, we collected 1,242 fleas from 132 dogs and 43 fleas from 11 cats. All fleas were morphologically identified as Ctenocephalides felis (Bouché) adults and organized in pools for DNA extraction (234 pools from dogs and 11 from cats). The gltA gene from rickettsiae was targeted for screening amplification using conventional PCR. In total, 144 of the 245 pools (58.7%) were positive. The positive samples were then processed for the amplification of the 17kDa antigen gene (144/144; 100% positive) and sca5 gene (140/144; 97.2% positive). In addition, restriction enzyme length polymorphism analysis using NlaIV on the amplified product of the sca5 gene demonstrated several organisms: 21/140 (15%) were R. felis, 118/140 (84.3%) were Rickettsia asemboensis, and 1/140 (0.7%) were Candidatus Rickettsia senegalensis. Subsequent sequencing confirmed Candidatus Rickettsia senegalensis in C. felis collected from dogs the first reported from Colombia.

Rickettsia species in ticks collected from wild pigs (Sus scrofa) and Philippine deer (Rusa marianna) on Guam, Marianna Islands, USA

The prevalence and diversity of ticks on wildlife species on Guam is understudied, as to date no work has been conducted on the infection of these ticks with Rickettsia (obligate intracellular pathogens that use a variety of ectoparasites as vectors and can cause disease in humans, domestic animals, and wildlife species). The goal of our study was to investigate the presence of Rickettsia species on the island of Guam by testing ticks found on Philippine deer (Rusa marianna) and wild pigs (Sus scrofa). Increasing numbers of these species have led to increased interactions with humans, including hunting, highlighting the importance of studies on vector prevalence and associated zoonotic pathogens. In this study, ticks were removed from Philippine deer and wild pigs in March and April of 2015 and tested for Rickettsia spp. using nested PCR. Overall, a low prevalence of Rickettsia spp. was detected (5.4% (6/112 ticks)). Ticks removed from wild pigs were identified as Amblyomma breviscutatum, one of which was positive for Rickettsia ambylommatis. Ticks recovered from Philippine deer were identified as Rhipicephalus microplus, and five were positive for Rickettsia; two with R. amblyommatis and one with 'Candidatus Rickettsia senegalensis', a recently proposed species in the R. felis cluster. The remaining two sequences were short and species classification was not possible. Rickettsia felis is a known zoonotic pathogen in the spotted fever group of Rickettsia and there is evidence that 'C. R. senegalensis' can also cause illness in people. This study confirms the occurrence of Rickettsia in ticks on Guam and highlights the presence of potential human pathogenic species in the R. felis cluster.

A Case of Letting the Cat out of The Bag-Why Trap-Neuter-Return Is Not an Ethical Solution for Stray Cat (Felis catus) Management

Trap-Neuter-Return (TNR) programs, in which stray cats are captured, neutered and returned to the environment are advocated as a humane, ethical alternative to euthanasia. We review the TNR literature in light of current debate over whether or not there should be further TNR trials in Australia. We revisit the problems arising from stray cats living in association with human habitation and estimate how many stray cats would have to be processed through a scientifically-guided TNR program to avoid high euthanasia rates. We also identify 10 ethical and welfare challenges that have to be addressed: we consider the quality of life for stray cats, where they would live, whether the TNR process itself is stressful, whether TNR cats are vulnerable to injury, parasites and disease, can be medically treated, stray cats' body condition and diet, and their impacts on people, pet cats, and urban wildlife, especially endemic fauna. We conclude that TNR is unsuitable for Australia in almost all situations because it is unlikely to resolve problems caused by stray cats or meet ethical and welfare challenges. Targeted adoption, early-age desexing, community education initiatives and responsible pet ownership have greater promise to minimize euthanasia, reduce numbers rapidly, and address the identified issues.