Best Practices for Preventing Vector-Borne Diseases in Dogs and Humans

Assessment of a metabarcoding approach for the characterisation of vector-borne bacteria in canines from Bangkok, Thailand

BACKGROUND

Globally, bacterial vector-borne disease (VBD) exerts a large toll on dogs in terms of morbidity and mortality but nowhere is this more pronounced than in the tropics. Tropical environments permit a burgeoning diversity and abundance of ectoparasites some of which can transmit an extensive range of infectious agents, including bacteria, amongst others. Although some of these vector-borne bacteria are responsible for both animal and human diseases in the tropics, there is a scarcity of epidemiological investigation into these pathogens' prevalence. The situation is further exacerbated by frequent canine co-infection, complicating symptomatology that regular diagnostic techniques may miss or be unable to fully characterise. Such limitations draw attention to the need to develop screening tools capable of detecting a wide range of pathogens from a host simultaneously.

RESULTS

Here, we detail the employment of a next-generation sequencing (NGS) metabarcoding methodology to screen for the spectrum of bacterial VBD that are infecting semi-domesticated dogs across temple communities in Bangkok, Thailand. Our NGS detection protocol was able to find high levels of Ehrlichia canis, Mycoplasma haemocanis and Anaplasma platys infection rates as well as less common pathogens, such as "Candidatus Mycoplasma haematoparvum", Mycoplasma turicensis and Bartonella spp. We also compared our high-throughput approach to conventional endpoint PCR methods, demonstrating an improved detection ability for some bacterial infections, such as A. platys but a reduced ability to detect Rickettsia.

CONCLUSIONS

Our methodology demonstrated great strength at detecting coinfections of vector-borne bacteria and rare pathogens that are seldom screened for in canines in the tropics, highlighting its advantages over traditional diagnostics to better characterise bacterial pathogens in environments where there is a dearth of research.

Ticks (Ixodida: Argasidae, Ixodidae) of Brazil: Updated species checklist and taxonomic keys

Ticks are ectoparasites of great medical and veterinary significance in the neotropical region. In Brazil, they are responsible for enormous economic losses to the livestock industry and also for considerable morbidity and mortality in companion animals and humans. Therefore, recognizing the identity of a given species is important, not only from a biodiversity perspective, but also from the medical and veterinary standpoints. The Brazilian tick fauna is one of the most diverse and well-studied in the neotropical region. In the past few years, several new species were discovered and/or recorded for the first time in this country. The main objectives of this study were to provide an updated list of tick species occurring in Brazil and taxonomic keys for their identification. The updated list of Brazilian ticks includes 70 species, 47 in the family Ixodidae and 23 in the family Argasidae. The genera Amblyomma (32 spp.) and Ornithodoros (18 spp.) are the most representative. Updated taxonomic keys for the identification of ticks of Brazil are provided. Finally, the medico-veterinary significance of ticks occurring in this country is briefly discussed.

Assessment of Vaccine-Induced Immunity Against Canine Visceral Leishmaniasis

Canine visceral leishmaniasis is an increasingly important public health problem. Dogs infected by Leishmania infantum are the main domestic reservoir of the parasite and play a key role in its transmission to humans. Recent findings have helped in the development of novel diagnostic methods, and of control measures such as vaccines, some of which are already commercially available. However, quantitative procedures should be followed to confirm whether these vaccines elicit a cell-mediated immune response. The present work describes the need for this evaluation, and the techniques available for confirming this type of immune response.

Prevalence of Endoparasites in Urban Stray Dogs from Brazil Diagnosed with Leishmania, with Potential for Human Zoonoses

BACKGROUND

In tropical environments, abandoned animals can be an important source for human zoonotic infections, such as human visceral leishmaniasis and other vector-borne diseases. Here, we report the frequency of protozoan and helminth intestinal parasites in stray dogs, which might have an implication for human health in urban Brazilian settings.

MATERIAL AND METHODS

We performed necropsies on 93 animals, euthanized due to canine visceral leishmaniasis control program, and examined their intestines looking for the presence of helminths; we determined the parasite load, and the elimination of eggs and cysts of protozoan parasites in fecal samples. Further, we performed serology tests for the detection of specific antibodies against Toxoplasma gondii.

RESULTS

Overall, a high prevalence of intestinal parasites with potential for human zoonoses resulted and only 8.6% of examined intestines remained negative. The most prevalent helminths were Ancylostoma caninum and Dipylidium caninum. For nematodes, high worm burdens were detected for A. caninum and Trichuris vulpis. Additionally, we analyzed worm burdens and quantitative stool examinations, but found no significant association between positive serology for Leishmania infection and intestinal parasite burden. Interestingly, serology for T. gondii infection revealed a prevalence of 33.3% and a positive result was significantly associated with a higher A. caninum adult worm recovery (p = 0.0087).

CONCLUSION

Our results showed stray dogs living in urban areas are heavily parasitized, which presents a potential risk for humans. Beyond the control of canine visceral leishmaniasis, we propose an improvement of the control program to reduce the risk for other parasitic diseases in dogs and humans.

Efficacy of Two Monoterpenoids, Carvacrol and Thymol, and Their Combinations against Eggs and Larvae of the West Nile Vector Culex pipiens

Background: Insect vector control is facing the challenges of resistance development and environmental hazards caused by synthetic pesticides. This has led to a considerable market opportunity for botanical insecticides. In this scenario, our study investigated the potential of selected bioactive monoterpenoids, carvacrol and thymol, as safe and effective tools to control the West Nile vector Culex pipiens. Furthermore, the combined effect of thymol-carvacrol mixtures and their possible interactions were assessed. Methods: For determining larvicidal and ovicidal 50% lethal concentration (LC₅₀), each monoterpenoid was tested at different concentrations (5–500 mg/L). Then, the fixed ratio method was used for evaluating their combinational efficacy. Results: Carvacrol was more toxic against larvae of Cx. pipiens, with a LC₅₀ value of 14 mg/L, whereas thymol exhibited a LC₅₀ value of 49 mg/L. Comparable trends of efficacy were observed when toxicity on Cx. pipiens eggs was investigated, with LC₅₀ values of 7 and 13 mg/L for carvacrol and thymol, respectively. In combinational toxicity assays, the mixture thymol-carvacrol at 1:4 ratio achieved a synergistic effect against larvae of Cx. pipiens, whereas an additive effect was observed on eggs. Other ratios showed antagonistic effects. Conclusions: Overall, our findings pointed out that the 1:4 ratio of thymol-carvacrol blend can enhance the insecticidal efficacy on Cx. pipiens young instars and can be considered further as active ingredient for developing botanical insecticides to be used in mosquito control operations.

Plant extracts for developing mosquito larvicides: From laboratory to the field, with insights on the modes of action

In the last decades, major research efforts have been done to investigate the insecticidal activity of plant-based products against mosquitoes. This is a modern and timely challenge in parasitology, aimed to reduce the frequent overuse of synthetic pesticides boosting resistance development in mosquitoes and causing serious threats to human health and environment. This review covers the huge amount of literature available on plant extracts tested as mosquito larvicides, particularly aqueous and alcoholic ones, due to their easy formulation in water without using surfactants. We analysed results obtained on more than 400 plant species, outlining that 29 of them have outstanding larvicidal activity (i.e., LC₅₀ values below 10 ppm) against major vectors belonging to the genera Anopheles, Aedes and Culex, among others. Furthermore, synergistic and antagonistic effects between plant extracts and conventional pesticides, as well as among selected plant extracts are discussed. The efficacy of pure compounds isolated from the most effective plant extracts and - when available - their mechanism of action, as well as the impact on non-target species, is also covered. These belong to the following class of secondary metabolites: alkaloids, alkamides, sesquiterpenes, triterpenes, sterols, flavonoids, coumarins, anthraquinones, xanthones, acetogenonins and aliphatics. Their mode of action on mosquito larvae ranges from neurotoxic effects to inhibition of detoxificant enzymes and larval development and/or midugut damages. In the final section, current drawbacks as well as key challenges for future research, including technologies to synergize efficacy and improve stability - thus field performances - of the selected plant extracts, are outlined. Unfortunately, despite the huge amount of laboratory evidences about their efficacy, only a limited number of studies was aimed to validate their efficacy in the field, nor the epidemiological impact potentially arising from these vector control operations has been assessed. This strongly limits the development of commercial mosquito larvicides of botanical origin, at variance with plant-borne products developed in the latest decades to kill or repel other key arthropod species of medical and veterinary importance (e.g., ticks and lice), as well as mosquito adults. Further research on these issues is urgently needed.

Potential role of dogs as sentinels and reservoirs for piroplasms infecting equine and cattle in Riyadh City, Saudi Arabia

Canine tick-borne diseases have been considered emerging and re-emerging threats, given their increasing global prevalence. In this molecular survey, we aimed to detect and identify common tick-borne pathogens in dogs from Riyadh city in Saudi Arabia. Initially, the study included 36 dogs visiting private veterinary clinics. PCRs targeting the 18S ribosomal RNA gene (rDNA) of haemoparasites (Babesia, Theileria and Hepatozoon) and the 16S rDNA of Anaplasmataceae were performed. The results showed that 26 (72.2%) dogs were infected by some of the haemoparasites under investigation. The sequencing analysis of the amplicons confirmed the infections due to two parasite species Theileria equi and Theileria velifera. Further examination of guard dogs kept in the horse stables of the Riyadh Municipality revealed that the majority of the tested dogs (65.2%: 30 out of 46) were infected with either of the parasites. In addition, the genotypes of all the parasites in these dogs were identical to those of the parasites in the dogs from the veterinary clinics. Thus, it can be concluded that dogs are infected with these haemoparasites and serve as a reservoir for both T. equi and T. velifera in the study area; however, the clinical implication of this finding is to be studied.

Polyparasitism and zoonotic parasites in dogs from a rural area of the Argentine Chaco

Dogs play an important role as reservoirs and hosts of multiple pathogens shared with humans and wildlife, which contribute significantly to the global burden of disease. Here, we assessed the occurrence of a broad range of zoonotic and non-zoonotic parasites in dogs from a rural area in the humid Chaco; determined the occurrence of polyparasitism; and explored its association with selected risk factors. In total, 212 dogs were examined serologically to determine Trypanosoma cruzi infection and 152 of them also were examined for Ehrlichia canis, Borrelia bugderfori, Anaplasma phagocitophylum, Dirofilaria immitis and Toxoplasma gondii. Fecal samples from 85 dogs were examined for intestinal parasites. Seventeen parasite species were seen, 77% of which are zoonotic. The most prevalent parasites were Ancylostoma caninum (68.2%), T. gondii (55.3%, first report for dogs in Argentina), Giardia sp. (25.9%), Cryptosporidium sp. (20.0%), T. cruzi (16.5%), trematodes (15.3%) and Toxocara canis (14.1%). Polyparasitism was found in 96% of the dogs, with up to six parasite species in a single dog, and was significantly associated with age of dog but not with host body condition or sex. The most frequent pair of parasites found together were T. gondii-A. caninum (46%), A. caninum-T. cruzi (34%) and T. gondii-T. cruzi (27%). The prevalence of anemia and leukocytosis was significantly higher in dogs showing the worst body condition. Our findings likely reflect structural poverty, poor sanitation and lack of a safe water supply. Importantly, many of the prevalent parasites seen are threats to human health. 243 words.

Molecular detection of spotted fever group rickettsiae in ticks parasitizing pet dogs in Shihezi City, northwestern China

A total of 178 adult ticks were collected from 32 pet dogs from five veterinary clinics in Shihezi City, Xinjiang Uygur Autonomous Region (XUAR), northwestern China. All the ticks were identified by comprehensive morphological and genetic analyses, and rickettsiae were detected by seven Rickettsia-specific genetic markers in the ticks. The ticks collected were identified as Rhipicephalus sanguineus sensu lato. Twenty-one of the 178 samples (11.8%) were positive for rickettsiae. Among these, in 13 (61.9%) samples Candidatus R. barbariae were identified, in five (23.8%) samples R. massiliae, and in three (14.3%) samples R. conorii. This study indicates that more attention should be paid to rickettsial infection in pet dogs and their ticks, because the latter may pose an epidemiological risk for tick-borne transmission of rickettsiae to human beings.

Molecular detection of vector borne pathogens in anemic and thrombocytopenic dogs in southern Brazil

Abstract Arthropod-borne pathogens are medically important because of their ability to cause diseases in their hosts. The purpose of this study was to detect the occurrence of Ehrlichia spp., piroplasmids and Hepatozoon spp. in dogs with anemia and thrombocytopenia in southern Brazil. EDTA-whole blood was collected from 75 domestic dogs presenting anemia or/and thrombocytopenia from Guarapuava, state of Paraná, Brazil. DNA samples were subjected to conventional PCR assays for Ehrlichia spp. (dsb), piroplasmids (18S rRNA) and Hepatozoon spp. (18S rRNA), followed by sequencing and phylogenetic analyses. Among the 75 dogs, one (1.33%) was positive for Hepatozoon sp. and six (8%) were positive for piroplasmids in 18S rRNA cPCR assays. None of the dogs showed positive results in Ehrlichia spp.-cPCR targeting dsb gene. The phylogenetic analyses revealed that three piroplasm sequences were clustered with Rangellia vitalii, while one sequence was grouped with B. vogeli. The only sequence obtained from Hepatozoon spp.-PCR protocol was pooled with H. canis. Therefore, there is urgent need for differential molecular diagnosis of the two piroplasm species cited as etiological agents in clinical cases of canine hemoparasitic diseases, given the higher pathogenic potential of R. vitalii than of B. vogeli.

A national survey of Ixodidae ticks on privately owned dogs in Italy

BACKGROUND

The geographical distribution of ticks on companion animals needs to be monitored to develop and plan effective control measures, as suggested by the European Scientific Counsel on Companion Animal Parasites. The aim of this study was to conduct the first Italian national survey of tick distribution on privately owned dogs.

METHODS

The study was performed over 20 months (February 2016 - September 2017) and involved 153 veterinary practices in 64 different provinces covering 17/20 (85%) Italian regions. Participating practitioners were asked to examine five different dogs per month at random and complete a questionnaire for each dog. Differences in tick infestation associated with: sex, age and hair length (long and short); the dog's habitat (indoor or outdoor/kennel); and the dog's environment (urban or rural/sylvatic) were evaluated. The attachment site of ticks on the dog was also recorded. Acaricide efficacy was evaluated for the subset of dogs for which complete information on product used, date of sampling and date of last ectoparasiticide treatment was available.

RESULTS

Of the 3026 dogs examined, 1383 (45.7%) were carrying at least one tick. Overall, 2439 tick samples were collected and a total of 14 tick species identified. Rhipicephalus sanguineus group were the most predominant ticks (63.6%), followed by Ixodes ricinus (30.6%) and I. hexagonus (5.6%). Twenty-four dogs had mixed tick infestations. Long-haired dogs had a higher tick infestation risk as did dogs with outdoor and rural/sylvatic lifestyles. Ticks were located on the head (37.4%), the neck (28.8%), the muzzle (15.5%) and the back (15.3%). A higher prevalence of Rhipicephalus was found in the interdigital spaces (10.8%) compared to Ixodes (0.2%). Finally, ectoparasiticide treatments were found significantly protective against tick infestation, especially orally administered formulations.

CONCLUSIONS

Privately owned dogs in Italy have a high prevalence (45.7%) of infestation with ixodid ticks and this risk varies by dog phenotype and lifestyle.

Managing mosquitoes and ticks in a rapidly changing world - Facts and trends

Vector-borne diseases transmitted by mosquitoes and ticks are on the rise. The effective and sustainable control of these arthropod vectors is a puzzling challenge for public health worldwide. In the present review, I attempted to provide a concise and updated overview of the current mosquito and tick research scenario. The wide array of control tools recently developed has been considered, with special reference to those approved by the World Health Organization Vector Control Advisory Group (WHO VCAG), as well as novel ones with an extremely promising potential to be exploited in vector control programs. Concerning mosquitoes, a major focus has been given on genetically modified vectors, eave tubes, attractive toxic sugar baits (ATSB) and biocontrol agents. Regarding ticks, the recent development of highly effective repellents and acaricides (including nanoformulated ones) as well as behavior-based control tools, has been highlighted. In the second part of the review, key research questions about biology and control of mosquitoes and ticks have been critically formulated. A timely research agenda outlining hot issues to be addressed in mosquito and tick research is provided. Overall, it is expected that the present review will contribute to boost research and applications on successful mosquito and tick control strategies, along with an improved knowledge of their biology and ecology.

Cross-sectional survey of health management and prevalence of vector-borne diseases, endoparasites and ectoparasites in Samoan dogs

OBJECTIVE

To determine the prevalence of selected canine vector-borne diseases (Leishmania infantum, Anaplasma spp., Ehrlichia canis, Borrelia burgdorferi and Dirofilaria immitis) and endo- and ectoparasites in Samoan dogs presenting for surgical sterilisation and to report on the general health management of the dogs.

METHODS

This study was a prospective serological cross-sectional survey. Management data were obtained for 242 dogs by interview with their owners. Blood samples were collected from 237 dogs and screened for the canine vector-borne diseases using point-of-care qualitative ELISA assays. Anaplasma spp. positive samples were screened by PCR and sequenced for species identification. Rectal faecal samples were collected from 204 dogs for faecal flotation and immunofluorescent antibody tests were performed for Giardia and Cryptosporidium spp. on a subset of 93 faecal samples. The skin and coat of 221 dogs were examined for presence of ectoparasites.

RESULTS

The D. immitis antigen was detected in 46.8% (111/237) of dogs. Seroprevalence of Anaplasma spp. was 8.4% (20/237); A. platys was confirmed by PCR. Prevalence of hookworm was 92.6% (185/205) and Giardia was 29.0% (27/93). Ectoparasites were detected on 210/221 (95.0%) of dogs examined and 228/242 dogs (94.2%) had previously never received any preventative medication.

CONCLUSIONS

There was a very high prevalence of D. immitis, hookworm and external parasites in Samoan dogs, and prophylactic medication is rarely administered. This is the first report confirming A. platys in Samoa and the South Pacific islands. The public health implications of poor management of the dogs should be considered and investigated further.

Molecular evidence for trans-stadial transmission of Anaplasma platys by Rhipicephalus sanguineus sensu lato under field conditions

This study investigated the transmission of Anaplasma platys by Rhipicephalus sanguineus sensu lato (Ixodida: Ixodidae). Engorged nymphs (n = 404) removed from A. platys-infected dogs were incubated at 28 °C until moulting. Unfed adults were obtained and divided into 48 pools. Unfed ticks collected from the grounds of the dog shelter, comprising 1800 larvae (n = 18 pools), 3100 nymphs (n = 62 pools) and 85 adults (n = 10 pools, including three male and seven female pools) were sorted into 90 pools. All pools were screened by polymerase chain reaction for the 16S rRNA gene of A. platys. Of 48 pools of unfed adults obtained from engorged nymphs, 12 were positive for A. platys; the infection rate maximum likelihood estimate (MLE) was 3.36 [95% confidence interval (CI) 1.84-5.68]. Anaplasma platys was detected in five of 23 male pools (MLE 2.82, 95% CI 1.06-6.20) and seven of 25 female pools (MLE 3.83, 95% CI 1.72-7.57). Of seven pools of unfed adult females collected from the shelter grounds, one was positive for A. platys (MLE 1.74, 95% CI 0.11-8.22). Among 62 unfed nymph pools, eight were infected with A. platys (MLE 0.27, 95% CI 0.13-0.52). No A. platys DNA was detected in the larva pools. The present results reveal molecular evidence for the trans-stadial transmission of A. platys by R. sanguineus s.l.

Repellence of essential oils and selected compounds against ticks-A systematic review

Ticks act as vectors of a wide range of infectious agents, far encompassing any other group of bloodsucking arthropods worldwide. The prevention of tick-borne diseases is strictly linked to the successful management of tick vector populations. The employ of repellents can represent a worth solution to avoid tick bites. It is widely adopted to protect travellers and pets exposed to ticks during limited periods of the year. The use of natural products as active ingredients in eco-friendly repellent formulations is currently a prominent research area, due to the wide diversity and high effectiveness of a number of plant-borne compounds, with special reference to essential oils (EOs) extracted from medicinal and aromatic species. Here, we reviewed current knowledge available on EOs tested as repellents against tick species of veterinary importance. Furthermore, we analysed the effectiveness of pure compounds isolated from EOs as tick repellents and their potential implications for practical use in the öreal world". A quantitative analysis of literature available is this research field was provided, along with its impact (i.e., in terms of citations over time) on the scientific community of researchers in tick control science and natural product chemistry. In the final sections, future outlooks are highlighted. We discussed major challenges to stabilize the most effective EOs and pure molecules, explore the synergistic and antagonistic effects in blends of EOs and/or pure constituents, standardize currently adopted testing methods, and evaluate non-target risks of herbal repellents.

Molecular Evidence for Transstadial Transmission of Ehrlichia canis by Rhipicephalus sanguineus sensu lato Under Field Conditions

This study investigated possible transstadial transmission of Ehrlichia canis by Rhipicephalus sanguineus sensu lato collected from shelter dogs and the shelter grounds in Diyarbakır Province of south-eastern Turkey. Totally 225 engorged nymphs were collected from eight infected dogs with E. canis and incubated at 28°C for moulting. Unfed ticks from the shelter grounds comprising 1,800 larvae, 3,100 nymphs, and 85 adults were sorted according to sampling origin, life stage, and sex into 116 pools and screened by 16S rRNA PCR. Nine out of 26 pools of unfed adult ticks were positive for E. canis, with overall infection rate maximum likelihood estimation (MLE) of 4.83 (CI 2.39-8.87). E. canis was detected in three of 12 male pools (MLE 3.22, CI 0.86-8.83) and six of 14 female pools (MLE 6.16, CI 2.59-12.90). No adult pools collected from the shelter grounds were positive. Among 62 unfed nymph pools collected from the shelter, six were infected with E. canis (MLE 0.20, CI 0.08-0.42). No E. canis DNA was detected in any of the larva pools. Our results revealed molecular evidence for transstadial transmission of E. canis by R. sanguineus s.l. both from larva to nymph and from nymph to adult. We found no evidence of transovarial transmission.

A Molecular Survey of Rickettsias in Shelter Dogs and Distribution of Rhipicephalus sanguineus (Acari: Ixodidae) sensu lato in Southeast Turkey

Canine tick-borne pathogens are the source of emerging diseases and have important zoonotic relevance. Dogs play a major role in the transmission of several zoonotic tick-borne pathogens, as reservoirs and/or sentinels. To simultaneously detect Anaplasma and Ehrlichia species, a reverse line blot assay was conducted on 219 blood samples collected from autochthonous asymptomatic shelter dogs. One hundred and three (47.0%, CI 40.3-53.9) dogs were positive for one or both rickettsial pathogens. Seventy-one (32.4%, CI 26.3-39.0) dogs were infected with Anaplasma platys and 23 (10.5%, CI 6.8-15.3) with Ehrlichia canis. Concurrent infection with A. platys and E. canis was detected in nine (4.1%, CI 1.9-7.6) dogs. Partial sequences of the 16S ribosomal RNA gene shared 100% identity with the corresponding published sequences for A. platys and E. canis. Infection with Anaplasma phagocytophilum was not detected in the examined dogs. In total, 1018 (range 1-70, mean intensity 13.1, mean abundance 4.6) Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) sensu lato ticks (45.7% nymphs, 54.3% adults) were collected from the dogs. There was no significant association between Anaplasma/Ehrlichia infection and dog sex or age, but a significant correlation was found between rickettsia infection and presence of R. sanguineus. Improved tick control strategies to reduce the risk of these pathogens spreading among dogs and humans are needed in the region.

Behavioral asymmetries in ticks - Lateralized questing of Ixodes ricinus to a mechatronic apparatus delivering host-borne cues

Ticks are considered among the most dangerous arthropod vectors of disease agents to both humans and animals worldwide. Lateralization contributes to biological fitness in many animals, conferring important functional advantages, therefore studying its role in tick perception would critically improve our knowledge about their host-seeking behavior. In this research, we evaluated if Ixodes ricinus (L.) (Ixodiidae) ticks have a preference in using the right or the left foreleg to climb on a host. We developed a mechatronic device moving a tuft of fox skin with fur as host-mimicking combination of cues. This engineered approach allows to display a realistic combination of both visual and olfactory host-borne stimuli, which is prolonged over the time and standardized for each replicate. In the first experiment, the mechatronic apparatus delivered host-borne cues frontally, to evaluate the leg preference during questing as response to a symmetrical stimulus. In the second experiment, host-borne cues were provided laterally, in an equal proportion to the left and to the right of the tick, to investigate if the host direction affected the questing behavior. In both experiments, the large majority of the tested ticks showed individual-level left-biased questing acts, if compared to the ticks showing right-biased ones. Furthermore, population-level left-biased questing responses were observed post-exposure to host-mimicking cues provided frontally or laterally to the tick. Overall, this is the first report on behavioral asymmetries in ticks of medical and veterinary importance. Moreover, the mechatronic apparatus developed in this research can be exploited to evaluate the impact of repellents on tick questing in highly reproducible standardized conditions.

Arthropod-borne pathogens of dogs and cats: From pathways and times of transmission to disease control

Vector-borne pathogens have developed a close relationship with blood feeding arthropod ectoparasites (e.g., mosquitoes, ticks, phlebotomine sand flies, black flies, fleas, kissing bugs, lice) and exploited a huge variety of vector transmission routes. Therefore, the life cycles of these pathogens result in a long evolved balance with the respective arthropod biology, ecology and blood feeding habits, instrumentally to the infection of several animal species, including humans. Amongst the many parasite transmission modes, such as ingestion of the arthropod, with its faeces or secretions, blood feeding represents the main focus for this article, as it is a central event to the life of almost all arthropod vectors. The time frame in which pathogens are transmitted to any animal host is governed by a large number of biological variables related to the vector, the pathogen, the host and environmental factors. Scientific data available on transmission times for each pathogen are discussed relative to their impact for the success of vector-borne disease control strategies. Blocking pathogen transmission, and thus preventing the infection of dogs and cats, may be achievable by the use of chemical compounds if they are characterised by a fast onset of killing activity or repellence against arthropods. The fast speed of kill exerted by systemic isoxazoline, as well as the repellent effect of pyrethroids have renewed the interest of the scientific community and pharmaceutical companies towards reducing the burden of vector-borne diseases under field conditions. However, endosymbionts and vaccines targeting arthropods or pathogen antigens should be further investigated as alternative strategies towards the goal of achieving an effective integrated control of vector-borne diseases.

Epidemiologic profile and clinical course of four confirmed rickettsiosis cases in Southern Mexico during 2016

Domestic animals can carry ticks or fleas, which constitute common vectors of rickettsial infections. The contact with them should be considered as suggestive of rickettsial infections in symptomatic patients. Misdiagnosis might occur in regions where other vector-borne diseases are endemic. Anamnesis is essential for an accurate clinical diagnosis.

Epidemiological survey of ticks and tick-borne pathogens in pet dogs in south-eastern China

To understand the epidemiology of tick infestation and tick-borne diseases in pet dogs in south-eastern China and to develop a reference for their prevention and treatment, we collected 1550 ticks parasitizing 562 dogs in 122 veterinary clinics from 20 cities of south-eastern China. Dogs were tested for common tick-borne pathogens; collected ticks were identified and processed for the detection of tick-borne pathogens. The use of an in vitro ELISA diagnostic kit for antibody detection (SNAP®4Dx® Plus) on dog sera found the infection rates with Borreliaburgdorferi sensu lato, Ehrlichia canis, and Anaplasma spp. to be 0.4%, 1.3% and 2.7%, respectively. By using a specific ELISA method, the infection rate with Babesia gibsoni was 3.9%. Rhipicephalus sanguineus sensu lato, Haemaphysalis longicornis and Rhipicephalus haemaphysaloides were the major tick species identified on pet dogs. PCR tests were conducted to detect five tick-borne pathogens in 617 ticks. The infection rate was 10.2% for E. canis, 3.4% for Anaplasma platys, 2.3% for B. gibsoni, 0.3% for B. burgdorferi s.l. and 0% for Babesia canis. Some ticks were co-infected with two (1.46%) or three pathogens (0.16%). These results indicate the infestation of pet dogs by ticks infected with tick-borne pathogens in south-eastern China, and the need for effective treatment and routine prevention of tick infestations in dogs.

A PCR survey of vector-borne pathogens in different dog populations from Turkey

In the present study, a total of 192 blood samples were collected from pet dogs, kennel dogs and shepherd dogs in Konya district, Turkey, and tested by specific PCR for the presence of vector-borne pathogens. Several pathogens were identified, most of which can cause substantial morbidity in dogs. PCR results revealed that 54 (28.1%) dogs were infected with one or more pathogens. Positive results were obtained for Babesia spp. in 4 dogs (2.1%), Hepatozoon spp. in 8 dogs (4.2%) and Mycoplasma spp. in 46 dogs (24%). Three dogs (1.6%) were infected with two or three pathogens. The sequence analysis of the positive DNA samples revealed the presence of Babesia canis vogeli, Hepatozoon canis, Hepatozoon sp. MF, Mycoplasma haemocanis and Candidatus Mycoplasma haematoparvum. Ehrlichia canis and Anaplasma platys were not detected. Regardless of ownership status, vector-borne diseases were common in these dog populations. There was significant difference of pathogen prevalence among the different dog populations. Mycoplasma spp. was more frequent in the kennel dogs (31.9%) than in the pet (21.4%) and shepherd dogs (13.8%). Additionally, the frequency of Babesia spp. and Hepatozoon spp. was higher in the shepherd dogs which account for three quarters and half of the total number of Babesia spp. and Hepatozoon spp., respectively. To our knowledge, this is the first report of Mycoplasma infection in dogs in Turkey. The results of the present study provide a foundation for understanding the epidemiology of canine vector-borne diseases (CVBDs), and for strategies to control these diseases in Turkey.

A survey of canine haemoprotozoan parasites from Turkey, including molecular evidence of an unnamed Babesia

Canine tick-borne apicomplexan parasites have emerged in recent years, showing a wider geographic distribution and increased global prevalence. A reverse line blot assay was performed on 219 blood samples collected from domestic dogs for simultaneous detection of all named canine piroplasm species as well as Hepatozoon canis. Ten samples hybridized to the Theileria/Babesia and Babesia catch all probes but did not hybridize to any species-specific probe tested, suggesting the presence of an unrecognized Babesia species or genotype. Sequencing results showed 91.5%, 91.9%, 92.4%, 92.4%, and 89.2% similarity to B. canis, B. vogeli, B. rossi, B. gibsoni, and B. conradae, respectively. The highest homology (98.1-98.5%) observed was with unnamed Babesia sp. isolates (Ludhiana and Malbazar) described in dogs, Babesia sp. of buffalo origin, Babesia sp. Kashi 2, and Babesia orientalis, along with Babesia occultans of cattle origin. The partial cox1 sequence indicated that this isolate was most similar to Babesia sp. 1 HG-2012, with an identity of 86.5%. The survey revealed high prevalence of haemoprotozoans in domestic dogs (57.5%, CI 50.7-64.2), with Hepatozoon canis the most prevalent (54.3%, CI 47.5-61.117%), followed by Babesia sp. (4.6%, CI 2.2-8.2), B. vogeli (1.4%; CI 0.3-3.9), and B. canis (0.4%, CI 0-2.5). Combined infection of Hepatozoon canis and Babesia sp. was detected in five (2.3%, CI 0.7-5.2) samples and of H. canis and B. vogeli in two (0.9%, CI 0.1-3.2) dogs. The study contributes insight into the distribution and phylogenetic diversity of canine piroplasms in Turkey.

Epidemiological role of dogs since the human leishmaniosis outbreak in Madrid

Background

Canine leishmaniosis (CanL) has been in the spotlight since the 2009 outbreak of human leishmaniosis in Madrid. In the framework of the Leishmaniosis Surveillance Programme set up in Madrid, this study examines Leishmania-specific seroprevalences in stray dogs for the outbreak area and rest of the Madrid region over the period spanning from the outbreak to the present (2009–2016). These data are of interest because stray dogs could be sentinels for disease surveillance in endemic areas. Since 2011, we have also been monitoring owned dogs in the outbreak area.

Methods

Over the study period, Leishmania infantum seroprevalence was determined in 2,123 stray dogs from the outbreak and non-outbreak areas. A serological study was also performed for owned dogs in the outbreak area: high-risk dogs such as hunting or farm dogs (n = 1,722) and pets (n = 1372). All dogs were examined and blood was collected. The variables recorded for each animal were: breed, age, sex, and clinical history indicating if the animal was healthy or clinically suspected of having any disease, and if they showed a clinical picture compatible with CanL.

Results

Seroprevalences of L. infantum in stray dogs were similar in the two areas examined: 4.7% (20 out of 346) in the outbreak area and 5.4% (96 out of 1,777) in the remaining Madrid region (χ² = 0.080, P = 0.777). A significant association was found between seroprevalence and age (z = -6.319; P < 0.001). Seroprevalence in owned dogs in the outbreak area was 2.1% in high-risk dogs (37 out of 1,722) and 1.2% in pets (17 out of 1,372) (χ² = 3.561, P = 0.0591).

Conclusions

Both stray and owned dogs do not seem to play an important role in maintaining the transmission cycle of L. infantum in the Madrid outbreak area. The stable seroprevalence of infection observed in sentinel dogs suggests the good clinical management and prevention of CanL by local practitioners in owned dogs.

Five-month serological monitoring to assess the effectiveness of permethrin/fipronil (Frontline Tri-Act®) spot-on in reducing the transmission of Leishmania infantum in dogs

Canine vector-borne diseases are highly endemic in European countries of the Mediterranean basin. The use of repellent insecticides aids to reduce the risk of pathogen transmission. The primary objective of this 5-month serological field study conducted in a highly endemic area of canine leishmaniosis in Greece was to comparatively assess the effectiveness of a topical formulation of fipronil/permethrin (Frontline Tri-Act®/Frontect®) and of a deltamethrin collar (Scalibor®) for the prevention of Leishmania infantum transmission. Initially, 72 clinically healthy owned dogs were sampled for inclusion. Ten out of the 72 (13.8%) were seropositive according to the Snap Leish® ELISA test and removed. Ultimately, a total of 56 dogs were followed from May to October 2015 with monthly blood samples and serological tests based on Snap Leish® and Snap 4Dx® ELISA tests. Twenty-five dogs were treated with deltamethrin collar (Scalibor®) (Group 1) and 31 were treated monthly with the topical fipronil/permethrin formulation (Group 2). In group 1, three dogs out of 25 (12%) seroconverted for Leishmania whereas none of the dogs (0/31) seroconverted in group 2. In addition, this trial provided means to serological assess the transmission of other vector-borne pathogens. Regarding Anaplasma spp., one dog in each group was seropositive at the beginning of the study and no dogs became positive during the study. For Ehrlichia canis, 9/25 (36%) dogs in group 1 and 5/31 (16.1%) in group 2 were seropositive at inclusion time. Two out of 16 (11.8%) and 3/26 (11.5%) dogs became positive for E. canis after 3months in groups 1 and 2, respectively. No Borrelia burgdorferi sensu lato seropositive dog was found during the study. In regard to Dirofilaria immitis, 7/25 (28%) dogs and 12/31 (38.7%) were antigen-positive in groups 1 and 2, respectively, at inclusion. There was no significant difference between groups 1 and 2 in regard to new seroconversions during the trial. This study, conducted in a highly endemic area for vector-borne pathogen transmission, confirmed that the use of deltamethrin and permethrin is a suitable approach to reduce the risk of L. infantum infection by sandflies.

Detection of Rickettsia hoogstraalii, Rickettsia helvetica, Rickettsia massiliae, Rickettsia slovaca and Rickettsia aeschlimannii in ticks from Sardinia, Italy

Tick-borne diseases represent a large proportion of infectious diseases that have become a world health concern. The presence of Rickettsia spp. was evaluated by standard PCR and sequencing in 123 ticks collected from several mammals and vegetation in Sardinia, Italy. This study provides the first evidence of the presence of Rickettsia hoogstralii in Haemaphysalis punctata and Haemaphysalis sulcata ticks from mouflon and Rickettsia helvetica in Ixodes festai ticks from hedgehog. In addition, Rickettsia massiliae, Rickettsia slovaca and Rickettsia aeschlimannii were detected in Rhipicephalus sanguineus, Dermacentor marginatus and Hyalomma marginatum marginatum ticks from foxes, swine, wild boars, and mouflon. The data presented here increase our knowledge of tick-borne diseases in Sardinia and provide a useful contribution toward understanding their epidemiology.

Evaluation of Leishmania (Leishmania) infantum excreted-secreted antigens for detection of canine leishmaniasis

The efficacy of tests with L. (L.) infantum excreted-secreted antigens (ESA) to detect canine leishmaniasis (CanL) was evaluated using immunoblotting (ESA-blot), ELISA (ESA-ELISA) and ELISA with alkaline extract from promastigotes (PAE). Of one hundred fifty-five domestic dogs tested, 100 were suspected of CanL, 23 had other diseases and 32 were healthy. Sera from the dogs suspected of CanL were tested by immunohistochemistry (IHC), and 54% were confirmed to be infected by L. (L.) infantum (38 symptomatic and 16 asymptomatic). Of these, 100% were positive by ESA-blot, ESA-ELISA and PAE-ELISA. In the ESA-blot their sera recognized polypeptides in the 26.5-31.5kDa region. Of the 46% of dogs with negative IHC, 44-53% tested positive in all three tests irrespective of clinical status. The twenty-three dogs with other diseases were negative by ESA-blot, but sera from 9% and 26% of them reacted with ESA-ELISA and PAE-ELISA, respectively. The 32 healthy dogs were negative in all the tests. ESA-blot showed good correlation with IHC in the detection of CanL and a high specificity index.

Molecular detection of Leishmania infantum, filariae and Wolbachia spp. in dogs from southern Portugal

Background

Leishmaniosis caused by the protozoan Leishmania infantum and dirofilariosis caused by the nematodes Dirofilaria immitis or Dirofilaria repens are vector-borne zoonoses widely present in the Mediterranean basin. In addition, some studies reported that the endosymbiont Wolbachia spp. play a role in the biology and pathogenesis of filarial parasites. The aim of this work was to evaluate the frequency of mono- and co-infections by L. infantum, filariae and Wolbachia spp. and their association with clinical signs in dogs from the south of Portugal. Leishmanial, filarial and Wolbachia spp. DNA were evaluated by specific real-time polymerase chain reaction (qPCR) assays in blood samples from 230 dogs.

Findings

One hundred and thirty-nine (60.4 %) dogs were qPCR-positive for L. infantum and 26 (11.3 %) for filariae (24 for D. immitis only, one D. immitis and for Acanthocheilonema dracunculoides and another one for Acanthocheilonema reconditum only). Wolbachia spp. DNA was amplified from 16 (64.0 %) out of the 25 D. immitis-positive dogs. Nineteen (8.3 %) dogs were co-infected with L. infantum and D. immitis, including the one (0.4 %) A. drancunculoides-positive animal. In dogs without clinical signs consistent with leishmaniosis and/or dirofilariosis, L. infantum prevalence was 69 %, whereas in those dogs with at least one clinical manifestation compatible with any of the two parasitoses prevalence was 42.7 %. Leishmania prevalence was significantly higher in apparently healthy mongrels (77.2 %) and pets (76.9 %) than in defined-breed dogs (including crosses; 58.8 %) and in dogs with an aptitude other than pet (i.e. farm, guard, hunting, shepherd or stray), respectively, whereas in those dogs with at least one clinical sign, the detection of L. infantum DNA was higher in males (53.3 %) and in those dogs not receiving insect repellents (52.8 %).

Conclusions

The molecular detection of canine vector-borne disease (CVBD) agents, some of which are zoonotic, reinforces the need to implement efficient prophylactic measures, such as insect repellents and macrocyclic lactones (including compliance to administration), in the geographical areas where these agents are distributed, with the view to prevent infection and disease among mammalian hosts including humans.

Control of Ixodes ricinus and Dermacentor reticulatus tick infestations in rabbits vaccinated with the Q38 Subolesin/Akirin chimera

Diseases transmitted by ticks greatly impact human and animal health and their control is important for the eradication of tick-borne diseases. Vaccination is an environmentally friendly alternative for tick control. Recent results have suggested that Subolesin/Akirin (SUB/AKR) are good candidate antigens for the control of arthropod vector infestations. Here, we describe the effect of vaccination with the Q38 chimera containing SUB/AKR conserved protective epitopes on Ixodes ricinus and Dermacentor reticulatus tick larval mortality, feeding and molting. We demonstrated that Q38 vaccination had an efficacy of 99.9% and 46.4% on the control of I. ricinus and D. reticulatus larvae by considering the cumulative effect on reducing tick survival and molting. The effect of the Q38 vaccine on larval feeding and molting is essential to reduce tick infestations and supports that Q38 might be a candidate universal antigen for the control of multiple tick species that can infest the same host.

Strategic evaluation of vaccine candidate antigens for the prevention of Visceral Leishmaniasis

Infection with Leishmania parasites results in a range of clinical manifestations and outcomes, the most severe of which is visceral leishmaniasis (VL). Vaccination will likely provide the most effective long-term control strategy, as the large number of vectors and potential infectious reservoirs renders sustained interruption of Leishmania parasite transmission extremely difficult. Selection of the best vaccine is complicated because, although several vaccine antigen candidates have been proposed, they have emerged following production in different platforms. To consolidate the information that has been generated into a single vaccine platform, we expressed seven candidates as recombinant proteins in E. coli. After verifying that each recombinant protein could be recognized by VL patients, we evaluated their protective efficacy against experimental L. donovani infection of mice. Administration in formulation with the Th1-potentiating adjuvant GLA-SE indicated that each antigen could elicit antigen-specific Th1 responses that were protective. Considering the ability to reduce parasite burden along with additional factors such as sequence identity across Leishmania species, we then generated a chimeric fusion protein comprising a combination of the 8E, p21 and SMT proteins. This E. coli –expressed fusion protein was also demonstrated to protect against L. donovani infection. These data indicate a novel recombinant vaccine antigen with the potential for use in VL control programs.

Evaluation of the in vitro expression of ATP binding-cassette (ABC) proteins in an Ixodes ricinus cell line exposed to ivermectin

Background

Ticks are among the most important vectors of pathogens causing human and animal disease. Acaricides are used to control tick infestation, although there are increasing reports of resistance. Recently, over-expression of ATP-binding cassette (ABC) transporter proteins (P-glycoproteins, PgP) has been implicated in resistance to the acaricide ivermectin in the ticks Rhipicephalus (Boophilus) microplus and Rhipicephalus sanguineus sensu lato. Ixodid tick cell lines have been used to investigate drug resistance mechanisms. The aim of the present study was to evaluate expression of several PgPs in the Ixodes ricinus-derived cell line IRE/CTVM19 and to determine modulation of expression following treatment with ivermectin.

Findings

IRE/CTVM19 cells were treated with different concentrations of ivermectin (0, 11, 22 or 33 μM) and incubated for 10 days. Evaluation of viability and relative expression of ABCB1, ABCB6, ABCB8 and ABCB10 genes were carried out at day 10 post treatment. Cell viability ranged between 84 % and 92 % with no significant differences between untreated and treated cells. qRT-PCR showed that ABC pump expression was not significantly modulated by ivermectin treatment. Expression of the ABCB8 PgP subfamily revealed a biphasic trend, based on the ivermectin concentration. ABCB6 and ABCB10 gene expression was not modulated by ivermectin treatment and ABCB1 expression was not detected.

Conclusions

This is the first report of PgP expression in an I. ricinus-derived tick cell line. Development of an in vitro model for the study of acaricide resistance mechanisms would greatly facilitate screening for drug resistance in ticks.

The southernmost foci of Dermacentor reticulatus in Italy and associated Babesia canis infection in dogs

BACKGROUND

Two clustered clinical cases of canine babesiosis were diagnosed by veterinary practitioners in two areas of northeastern Italy close to natural parks. This study aimed to determine the seroprevalence of babesial infection in dogs, the etiological agents that cause canine babesiosis and the potential tick vector for the involved Babesia spp.

METHODS

The study area was represented by two parks in northeastern Italy: Groane Regional Park (Site A) and the Ticino Valley Lombard Park (Site B). From March to May 2015 ticks were collected from the vegetation in three transects in each site. In the same period, blood samples were collected from 80 dogs randomly chosen from veterinary clinics and kennel located in the two areas. Morphological identification of the ticks was performed and six specimens were molecularly characterised by the amplification and sequencing of partial mitochondrial 12S rRNA, 16S rRNA and cox1 genes. For phylogenetic analyses, sequences herein obtained for all genes and those available from GenBank for other Dermacentor spp. were included. Dog serum samples were analysed with a commercial indirect fluorescent antibody test to detect the presence of IgG antibodies against Babesia canis. Ticks and blood samples were tested by PCR amplification using primers targeting 18S rRNA gene of Babesia spp.

RESULTS

Ticks collected (n = 34) were morphologically identified as adults of D. reticulatus. Twenty-eight ticks were found in all transects from Site A and the remaining six were collected in Site B. Blast analysis of mitochondrial sequences confirmed the morphological identification of processed tick specimens by revealing a highest nucleotide similarity (99-100%) with those of D. reticulatus available in the GenBank database. The phylogenetic trees were concordant in clustering D. reticulatus in a monophyletic clade. Seven dogs (8.8%) had antibodies against B. canis, most of which (n = 6) came from Site A. Analysis of nucleotide sequences obtained from one tick and from one dog identified B. canis displayed a 100% similarity to those available in GenBank.

CONCLUSIONS

This study morphologically and molecularly confirms the presence of D. reticulatus in Italy and links it, for the first time, with the occurrence of B. canis infection in dogs in this country.

Identification of Immunoreactive Leishmania infantum Protein Antigens to Asymptomatic Dog Sera through Combined Immunoproteomics and Bioinformatics Analysis

Leishmania infantum is the etiologic agent of zoonotic visceral leishmaniasis (VL) in countries in the Mediterranean basin, where dogs are the domestic reservoirs and represent important elements in the transmission of the disease. Since the major focal areas of human VL exhibit a high prevalence of seropositive dogs, the control of canine VL could reduce the infection rate in humans. Efforts toward this have focused on the improvement of diagnostic tools, as well as on vaccine development. The identification of parasite antigens including suitable major histocompatibility complex (MHC) class I- and/or II-restricted epitopes is very important since disease protection is characterized by strong and long-lasting CD8⁺ T and CD4⁺ Th1 cell-dominated immunity. In the present study, total protein extract from late-log phase L. infantum promastigotes was analyzed by two-dimensional western blots and probed with sera from asymptomatic and symptomatic dogs. A total of 42 protein spots were found to differentially react with IgG from asymptomatic dogs, while 17 of these identified by Coommasie stain were extracted and analyzed. Of these, 21 proteins were identified by mass spectrometry; they were mainly involved in metabolism and stress responses. An in silico analysis predicted that the chaperonin HSP60, dihydrolipoamide dehydrogenase, enolase, cyclophilin 2, cyclophilin 40, and one hypothetical protein contain promiscuous MHCI and/or MHCII epitopes. Our results suggest that the combination of immunoproteomics and bioinformatics analyses is a promising method for the identification of novel candidate antigens for vaccine development or with potential use in the development of sensitive diagnostic tests.

Assessment of the prophylactic speed of kill of Frontline Tri-Act(®) against ticks (Ixodes ricinus and Rhipicephalus sanguineus) on dogs

The objective of the study was to assess the speed of kill of a single topical treatment with a combination of fipronil and permethrin (Frontline Tri-Act^®/Frontect^®) against experimental infestations of Ixodes ricinus and Rhipicephalus sanguineus ticks on dogs. In this parallel group designed, randomised, single centre, controlled efficacy study, 16 healthy adult dogs were allocated to two groups: 8 dogs were treated with the topical combination on Day 0 and the other 8 dogs served as untreated controls. Each dog was exposed in a crate to 100 I. ricinus (50 females, 50 males) and 50 R. sanguineus (25 males, 25 females) on Days 2, 7, 14, 21 and 28. Ticks were counted in situ at 6 and 12 h after exposure and removed at 24 h after exposure. Frontline Tri-Act^® was effective (≥90%) against both R. sanguineus and I. ricinus tick infestations at 6, 12 and 24 h after exposure, from 2 to 28 days after treatment. This is the first time that a topical ectoparasiticide has demonstrated a preventive killing effect against these two tick species in 6 h for a full month.