Transstadial Transmission of Hepatozoon canis by Rhipicephalus sanguineus (Acari: Ixodidae) in Field Conditions

Molecular Survey of Tick-Borne Haemoparasites of Dogs by Multiplex Polymerase Chain Reaction from Punjab, India

PURPOSE

Tick-transmitted parasites as Babesia gibsoni, Babesia vogeli, Ehrlichia canis, and Hepatozoon canis are major health concern for dogs. Owing to prevalence and infection severity, there is need of sensitive, specific, and affordable test for their simultaneous detection.

METHODS

Prevalence of B. gibsoni, B. vogeli, E. canis, and H. canis infections was assessed on 719 blood samples by microscopy and multiplex PCR assay targeting 18S rRNA (B. gibsoni & H. canis), ITS1 & 5.8S rRNA (B. vogeli) and VirB9 gene (E. canis). An internal control (canine-actin) was also included to increase the accuracy of assay and effect of associated risk factors with disease prevalence was also studied.

RESULTS

Microscopic prevalence of B. gibsoni, B. vogeli, E. canis and H. canis was 5.0%, 0.1%, 1.4% and 1.0%, respectively, whereas with multiplex PCR assay, the corresponding values were 8.9%, 1.1%, 2.6% and 5.1% besides concurrent infections of B. gibsoni & H. canis (0.4%), B. gibsoni & E. canis (0.4%), E. canis & H. canis (0.3%) and B. gibsoni & B. vogeli (0.1%). Analytical sensitivity of developed assay was 0.1pg (B. gibsoni & H. canis), 0.01pg (B. vogeli), and 1.0pg (E. canis). A ″fair″ (B. vogeli & H. canis) to ″substantial″ (B. gibsoni & E. canis) agreement between two tests was observed with data as statistically significant. Breed, sex and location were significantly associated with B. gibsoni infection.

CONCLUSION

The developed multiplex PCR assay offers a potential solution to detect these pathogens simultaneously, aiding in timely diagnosis and effective disease management in suspected dogs.

Diversity of Rickettsia spp. in ticks from wild mammals of Morocco and Mauritania

Ticks are known as vectors and reservoirs of rickettsiae and, wildlife vertebrate hosts as suitable dispersers of ticks contributing to the life cycle of rickettsial agents in nature. In the herein study, the presence of rickettsiae was investigated in ticks from wild mammals (Gerbillus and Jaculus, Vulpes rueppellii, Canis anthus, Felis lybica and Felis margarita) in Mauritania and Morocco. Morphological and molecular analysis of ticks allowed their identification as Rhipicephalus sanguineus sensu lato and Hyalomma impeltatum. A total of 126 partially engorged adult ticks, collected from 40 animals, were screened for the presence of rickettsial DNA by conventional PCR targeting the ompB gene, followed by ompA and gltA targets and bidirectional sequencing. As a result of the sequence analyses, that at least three different species of pathogenic spotted fever group rickettsiae were detected. Rickettsia parkeri-like was detected in a R. sanguineus s.l. (n=1) collected from an African wildcat from Morocco. Rickettsia aeschlimannii was detected in a H. impeltatum (n=1) collected from a gerbil rodent. Rickettsia massiliae was detected in R. sanguineus s.l. ticks (n=5) collected from two Ruppells' foxes. The herein study demonstrates that pathogenic Rickettsia species are circulating in Morocco and Mauritania wildlife.

First report on detection of Hepatozoon ayorgbor in Rhipicephalus haemaphysaloides and Hepatozoon colubri in Haemaphysalis sulcata and Hyalomma anatolicum: risks of spillover of Hepatozoon spp. from wildlife to domestic animals

This study aimed to detect Hepatozoon spp. in ticks infesting asymptomatic domestic animals and to provide insight into their potential spillover from wild to domestic animals. In total, 537 tick specimens were collected in Khyber Pakhtunkhwa, Pakistan, and morphologically identified. The most prevalent tick species was Haemaphysalis cornupunctata (69; 12.8%), followed by Haemaphysalis kashmirensis (62; 11.5%), Rhipicephalus microplus (58; 10.8%), Haemaphysalis montgomeryi (51; 9.5%), Rhipicephalus sanguineus (49; 9.1%), each Haemaphysalis bispinosa and Haemaphysalis sulcata (43; 8.0%), each Hyalomma anatolicum and Rhipicephalus turanicus (37; 6.9%), Rhipicephalus haemaphysaloides (33; 6.1%) Hyalomma scupense (30; 5.6%), and Hyalomma isaaci (25; 4.7%). The extracted DNA from a subset of each tick species was subjected to PCR to amplify 18S rRNA fragments of Hepatozoon spp. By BLAST analysis, the Hepatozoon sp. detected in Hy. anatolicum infesting cows and in Ha. sulcata infesting sheep showed 99.7% maximum identity with Hepatozoon colubri. Similarly, the Hepatozoon sp. detected in R. haemaphysaloides infesting goats shared 99.49% maximum identity with Hepatozoon ayorgbor, and the Hepatozoon sp. detected in R. sanguineus infesting dogs exhibited 99.7% identity with Hepatozoon canis. Having an overall infection rate (9.3%; 16/172), the highest infection rate was recorded for each H. canis, and H. colubri (3.5%; 6/172), followed by H. ayorgbor (2.3%; 4/172). In the phylogenetic tree, H. colubri clustered with corresponding species from Iran, H. ayorgbor clustered with the same species from Croatia, Ghana, and Portugal, and H. canis clustered with the conspecifics from Iran, Israel, Romania, and Zambia. Regarding the potential spillover of Hepatozoon spp. from wildlife through ticks, free ranging animals was at higher risk compared to confined animals (RR = 3.05), animals consuming food from wildlife habitats were at higher risk compared to those consuming domestic food (RR = 3.06), and animals residing in farm buildings located in wildlife habitats were at higher risk compared to those residing in farm buildings located in villages (RR = 3.28). In addition to the first report on H. canis in R. sanguineus in Pakistan, this is the earliest data showing H. ayorgbor in R. haemaphysaloides and H. colubri in Ha. sulcata and Hy. anatolicum. These preliminary findings suggest a potential spillover of Hepatozoon spp. from wild to domestic animals via ticks under certain risk factors.

Red fox (Vulpes vulpes) play an important role in the propagation of tick-borne pathogens

The red fox (Vulpes vulpes) is the most widespread free-living carnivore in the world. Over the years, foxes have been recognized as hosts for a number of tick-borne pathogens. However, their role as reservoirs for zoonotic tick-borne diseases is poorly understood. The aim of our study was to investigate tick-borne pathogens in the red fox population in the Czech Republic. Out of 117 red foxes, 110 (94.02%) individuals tested positive for the presence of at least one pathogen by the combined PCR and sequencing approach. Hepatozoon canis was the most frequently detected pathogen (n = 95; 81.2%), followed by Babesia vulpes (n = 75; 64.1%). Babesia canis was not detected in our study. Four (3.42%) red foxes were positive for Candidatus Neoehrlichia sp., 3 (2.56%) for Anaplasma phagocytophilum, and one red fox (0.85%) tested positive for the presence of Ehrlichia sp. DNA. Overall, DNA of spirochetes from the Borrelia burgdorferi s.l. complex was detected in 8.6% of the foxes and B. miyamotoi in 5.12% of the samples. As a carnivore found in all ecosystems of Central Europe, foxes obviously contribute to transmission of tick-borne pathogens such as A. phagocytophilum, B. burgdorferi s.l., and B. myiamotoi. In addition, foxes apparently harbour a community of pathogens, associated with this host in local ecological context, dominated by H. canis and B. vulpes (possibly also Candidatus Neoehrlichia sp.). These species have the potential to spread to the domestic dog population and should be included in the differential diagnosis of febrile diseases with hematologic abnormalities in dogs.

Potential Role of Hepatozoon canis in a Fatal Systemic Disease in a Puppy

Canine hepatozoonosis caused by Hepatozoon canis is an emerging disease in Europe. Clinical pictures vary from subclinical to life-threatening and non-specific clinical signs are predominantly reported. A 2-month-old female puppy originating from Southern Italy was adopted and moved to Northern Italy. Then, the dog was brought to a local veterinary practice for gastrointestinal signs, migrating lameness and pruritic dermatitis, and then tested positive for Hepatozoon spp. gamonts at the blood smear. After treatment with imidocarb dipropionate and doxycycline, the dog showed an initial clinical improvement. However, gastrointestinal signs recurred, and diffuse superficial pyoderma appeared on the thoracolumbar region, along with fever, lethargy, and weight loss. Eight months from the first onset of clinical signs, the dog was referred to a veterinary clinic and subjected to complete blood count, urine and fecal analysis, along with abdominal ultrasonography, whole-body CT and gastroduodenal endoscopy. Skin biopsies and blood samples were subjected to a PCR-coupled sequencing protocol, which scored both positive for H. canis. Alterations were consistent with a pre-existing cholangiohepatitis and multiple acquired extrahepatic shunts secondary to portal hypertension. The dog was euthanatized due to a clinical worsening two months later. The potential role of H. canis in the systemic disease observed, clinic-pathological findings and epizootiological implications are discussed.

Development and application of multiplex PCR assay for the simultaneous detection of Babesia vogeli, Ehrlichia canis and Hepatozoon canis in dogs

A multiplex PCR assay was standardized and evaluated to simultaneously detect the DNA of Babesia vogeli, Ehrlichia canis and Hepatozoon canis in dogs of selected districts of Punjab state, India. Amplicons of 602 bp, 380 bp and 306 bp corresponding to B. vogeli (18S rRNA gene), E. canis (VirB9 gene), and H. canis (18S rRNA gene) were obtained, without any non-specific amplification. The results of multiplex PCR assay were further compared with the corresponding singleplex PCR assay. The diagnostic sensitivity and specificity of multiplex PCR assay with respect to singleplex PCR assay in the detection of B. vogeli, E. canis and H. canis varied from 50% to 100% and 92.08% to 98.79%, respectively revealing "moderate" to "very good" agreement by kappa value statistics. Blood samples from 322 dogs collected from selected districts of Punjab state, India, when screened by microscopy revealed the prevalence of B. vogeli, E. canis and H. canis as 0.31%, 0.93% and 1.86%, respectively whereas with multiplex PCR assay the values were 0.93%, 10.24% and 4.65%, respectively, with concurrent infection of E. canis & H. canis (1.86%) and B. vogeli & E. canis (0.31%). The diagnostic sensitivity and specificity of multiplex PCR assay with respect to microscopy in the detection of B. vogeli, E. canis and H. canis varied from 69.15% to 100% and 85.11% to 92.33%, respectively revealing "fair" agreement by kappa value statistics and the data was statistically significant. The analytical sensitivity of multiplex PCR assay in the detection of B. vogeli, E. canis and H. canis was 100 pg, 10 pg and 0.1 pg, respectively, whereas the values for the singleplex counterpart were 0.1 pg, 0.01 pg and 0.01 pg. Furthermore, various risk factors viz. age, breed, sex, season and districts were non-significantly associated with the prevalence of these haemoparasites except for E. canis that revealed a significant association with districts by multiplex PCR assay. Therefore the multiplex PCR assay developed may be useful in identification of the aetiological agents of these diseases during their early phase, which may in turn be useful in development of better health care and appropriate treatment of suspected dogs, particularly in endemic regions.

Upscaling the Surveillance of Tick-borne Pathogens in the French Caribbean Islands

Despite the high burden of vector-borne disease in (sub)tropical areas, few information are available regarding the diversity of tick and tick-borne pathogens circulating in the Caribbean. Management and control of vector-borne disease require actual epidemiological data to better assess and anticipate the risk of (re)emergence of tick-borne diseases in the region. To simplify and reduce the costs of such large-scale surveys, we implemented a high-throughput microfluidic real-time PCR system suitable for the screening of the main bacterial and parasitic genera involved in tick-borne disease and potentially circulating in the area. We used the new screening tool to perform an exploratory epidemiological study on 132 adult specimens of Amblyomma variegatum and 446 of Rhipicephalus microplus collected in Guadeloupe and Martinique. Not only the system was able to detect the main pathogens of the area-Ehrlichia ruminantium, Rickettsia africae, Anaplasma marginale, Babesia bigemina and Babesia bovis-but the system also provided evidence of unsuspected microorganisms in Caribbean ticks, belonging to the Anaplasma, Ehrlichia, Borrelia and Leishmania genera. Our study demonstrated how high-throughput microfluidic real-time PCR technology can assist large-scale epidemiological studies, providing a rapid overview of tick-borne pathogen and microorganism diversity, and opening up new research perspectives for the epidemiology of tick-borne pathogens.

First detection and genetic identification of Hepatozoon canis in Rhipicephalus sanguineus sensu lato ticks collected from dogs of Taiwan

We determined the prevalence of infection and genetic identity of Hepatozoon spp. harbored by Rhipicephalus sanguineus sensu lato ticks in Taiwan. A total of 1082 ticks were collected from dogs and DNA extraction was performed from individual tick specimens. Hepatozoon infection was detected by performing a nested-PCR assay based on the 18S small subunit ribosomal RNA (ssrRNA) gene. The genetic identity of detected Hepatozoon was identified by gene sequencing and phylogenetic analysis. Hepatozoon infection was detected in nymphs, males and females of R. sanguineus s. l. ticks with an infection rate of 20.8%, 22.8% and 29.4%, respectively. Sequence and phylogenetic analysis revealed that these Hepatozoon spp. of Taiwan were genetically affiliated to the same clade within the genospecies of H. canis and can be discriminated from other genospecies of H. americanum and H. felis. Intraspecies analysis based on the genetic distance (GD) values indicates a lower level (GD < 0.005) genetic divergence within the same genospecies of H. canis detected in Taiwan, Brazil and Spain. Interspecies analysis also reveals a higher heterogeneity of Taiwan strains distinguished from other genospecies of H. felis (GD > 0.040) and H. americanum (GD > 0.056). This study provides the first molecular evidence of H. canis detected and identified in various stages of R. sanguineus s. l. ticks in Taiwan. Detection of H. canis in unfed male ticks may imply the possible mechanism of transstadial survival in R. sanguineus s. l. ticks. Further investigations on Hepatozoon spp. harbored by various vector ticks in Taiwan may illustrate the epidemiological significance of this parasite.

Babesia Life Cycle - When Phylogeny Meets Biology

Although Babesia represents an important worldwide veterinary threat and an emerging risk to humans, this parasite has been poorly studied as compared to Plasmodium, its malaria-causing relative. In fact, Babesia employs highly specific survival strategies during its intraerythrocytic development and its intricate journey through the tick vector. This review introduces a substantially extended molecular phylogeny of the order Piroplasmida, challenging previous taxonomic classifications. The intriguing developmental proficiencies of Babesia are highlighted and compared with those of other haemoparasitic Apicomplexa. Molecular mechanisms associated with distinctive events in the Babesia life cycle are emphasized as potential targets for the development of Babesia-specific treatments.

Molecular Evidence for a Novel Species of Babesia in Unfed Rhipicephalus sanguineus sensu lato (Acari: Ixodidae)

This study reports a novel species of Babesia in unfed Rhipicephalus sanguineus sensu lato and its phylogenetic relationship to other species. One-hundred and forty DNA samples extracted from tick pools comprising 5,403 unfed R. sanguineus s.l. ticks were screened for Babesia. Overall Babesia infection was detected in female, male, and nymph pools with an infection rate maximum likelihood estimate (MLE) of 1.98 (CI 0.65-4.74), 0.50 (CI 0.03-2.40), and 0.07 (CI 0.01-0.21), respectively. Three adult female tick pools (MLE 1.44, CI 0.38-3.88) and one adult male pool (MLE 0.50, CI 0.03-2.40) hybridized to the catchall and Babesia genus probes but did not hybridize to any species-specific probe tested, suggesting the presence of an unidentified Babesia species. Phylogenetic analysis and sequencing revealed the newly detected Babesia isolate to form a clade distinct from fully identified canine, bovine, equine, and ovine Babesia species, with a range of 88.6-92.9% nucleotide identity.

Detection of Hepatozoon canis in the Brown Dog Tick and Domestic Dogs in Peninsular Malaysia

Hepatozoon canis has been widely reported in dogs. Its prevalence in ticks, however, has not been well-established. Here we determine the occurrence of Hepatozoon DNA in the brown dog tick Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) sensu lato (s.l.) and domestic dogs from Peninsular Malaysia using a polymerase chain reaction (PCR) assay based on amplification of the 18S ribosomal RNA coding sequence. Our results revealed a relatively low prevalence of H. canis DNA in both R. sanguineus s.l. (0.7%) and dogs (3.33%). This study represents the first report of H. canis DNA in R. sanguineus s.l. in Malaysia, highlighting the risk of this infection in dogs.

An Australian dog diagnosed with an exotic tick-borne infection: should Australia still be considered free from Hepatozoon canis?

Recent molecular and sero-surveillance studies of the tick-borne pathogen Hepatozoon canis have identified new hosts, potential vector species, and have revealed that H. canis is more widespread than previously thought. We report the first diagnosed case of canine hepatozoonosis in Australia from a Maremma Sheepdog in Sarina, Queensland. Hepatozoon canis was detected with blood smear examination and 18S rRNA sequencing. It is unknown when or how the organism was introduced into Australia, which raises questions about border biosecurity policies and the H. canis infection status of its potential vectors and hosts in Australia. Surveillance for this pathogen is required to determine whether H. canis has established in Australia.

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.

Molecular confirmation of Hepatozoon canis in Mauritius

In this study, Hepatozoon species was molecularly identified and characterized for the first time on the Indian Ocean island of Mauritius. Partial sequences of the 18S rRNA gene of the Hepatozoon isolates were analysed from three naturally infected dogs. The sequences of H. canis were similar to the 18S rRNA partial sequences (JX112783, AB365071 99%) from dog blood samples from West Indies and Nigeria. Our sequences were deposited in the GenBank database.