Molecular detection and characterization of Hepatozoon canis in stray dogs from Cuba

Feasibility of implementing RPA coupled with CRISPR-Cas12a (RPA-Cas12a) for Hepatozoon canis detection in dogs

Hepatozoonosis, caused by the protozoan Hepatozoon canis, is a prevalent blood disease affecting owned and stray dogs and cats. The prevalence of these parasites among companion animals in Thailand remains poorly understood. Diagnosing the old-world form of the disease is challenging due to the wide range of nonspecific clinical signs and the reliance on finding low levels of Hepatozoon gamonts in blood smears for conventional diagnosis. PCR demonstrates high specificity and sensitivity but it requires sophisticated instrumentation. Therefore, we established recombinase polymerase amplification (RPA) coupled with Cas12a for H. canis detection based on 18S rRNA. Our findings showed that RPA-Cas12a using gRNA_H was highly specific to H. canis, without yielding positives for other pathogen species including Babesia species. Even in cases of co-infection, RPA-Cas12a only detected positives in samples containing H. canis. This approach detected minimal amounts of H. canis18S rRNA-harboring plasmid at 10 copies per reaction, whereas plasmid-spiked canine blood enabled detection at a minimal amount of 100 copies per reaction. The performance of RPA-Cas12a was validated by comparing it with quantitative PCR-high resolution melting analysis (qPCR-HRM) and sequencing based on 35 canine blood samples. RPA-Cas12a demonstrated precision and accuracy values of 94 % and 90 %, respectively comparable to qPCR-HRM. Overall, these results indicate that RPA-Cas12a serves as a promising tool for H. canis detection as indicated by comparable performance to qPCR-HRM and is suitable for implementation in small animal hospitals or clinics due to its minimal resource requirements, thereby contributing to effective diagnosis and treatment for infected dogs.

A review of Hepatozoonosis caused by Hepatozoon canis in dogs

Hepatozoon canis is a type of single-celled organism is spread by ticks and commonly affects dogs. It is responsible for causing one of the most significant parasitic diseases in dogs, called Hepatozoonosis. It is considered one of the most common causes of canine vector-borne diseases because it is closely linked to Rhipicephalus sanguineus (the brown dog tick), a species found worldwide. Hepatozoonosis caused by H. canis is prevalent in regions such as South Europe, South America, Asia, and Africa. H. canis often causes emaciation, anemia, and intermittent fever in infected dogs. The drugs used to treat H. canis infection in dogs include the combination of imidocarb dipropionate with doxycycline, toltrazoril, tetracycline hydrochloride, and the combination of trimethoprim-sulfamethoxazole.The primary solution to prevent the spread of infections caused by H. canis is to control the population of R. sanguineus ticks because H. canis is spread through ticks. This review aims to provide a brief overview of various studies conducted on the morphology, life cycle, hosts, epidemiology, clinical symptoms, laboratory diagnosis, autopsy findings, differential diagnosis, treatment, and prevention methods of H. canis.

Molecular detection of Hepatozoon canis in dogs from Ibagué, Tolima

The genus Hepatozoon consists of apicomplexan protozoans that affect mammals, birds, amphibians, and reptiles. In dogs, the Hepatozoon species include H. canis and H. americanum, which are transmitted by the Rhipicephalus sanguineus tick and cause nonspecific signs, such as fever, weight loss, diarrhea, and blood disorders. These protozoans have a worldwide distribution in Europe, Asia, Africa, and North and South America, including Colombia. The aim of this study was to determine the prevalence and risk factors associated with H. canis in the urban and rural areas of Ibagué, Colombia. Blood samples were collected from 308 dogs (180 rural areas and 128 urban areas). Collected data included dog breed, sex, age, environmental factors, and the presence of ectoparasites. A fragment of the 18S rRNA gene was amplified by PCR for detection of the pathogen and confirmed by sequencing. Among the 308 samples, 14 were positive (14/308, 4.5%) for the presence of H. canis. The partial sequence of the 18S rRNA gene showed identity values >98% with H. canis, forming a cluster with sequences from Latin America. An epidemiological survey found two protective factors: most of the time at home (P=0.055) and overnight stay at home (P=0.03). This is the first molecular study of the prevalence and phylogeny analysis of H. canis in Ibagué, Colombia. The findings may help determine risk factors and enhance our understanding of the geographic distribution of H. canis in Colombia.

Completing the Puzzle: A Cluster of Hunting Dogs with Tick-Borne Illness from a Fishing Community in Tobago, West Indies

Eight hunting dogs were visited by a state veterinarian on the island of Tobago, Trinidad and Tobago, West Indies, as owners reported anorexia and paralysis in five of their dogs. The veterinarian observed a combination of clinical signs consistent with tick-borne illness, including fever, anorexia, anaemia, lethargy and paralysis. Blood and ticks were collected from each dog and submitted to a diagnostic laboratory for analysis. Microscopic analysis revealed a mixed infection of intracytoplasmic organisms consistent with Babesia spp. (erythrocyte) and Ehrlichia spp. (monocyte), respectively, from one dog, while a complete blood count indicated a regenerative anaemia (n = 1; 12.5%), non-regenerative anaemia (n = 4; 50%), neutrophilia (n = 3; 37.5%), lymphocytosis (n = 2; 25%), thrombocytopaenia (n = 3; 37.5%) and pancytopaenia (n = 1; 12.5%). DNA isolated from the eight blood samples and 20 ticks (16 Rhipicephalus sanguineus and 4 Amblyomma ovale) were subjected to conventional PCR and next-generation sequencing of the 16S rRNA and 18S rRNA gene for Anaplasma/Ehrlichia and Babesia/Theileria/Hepatozoon, respectively. The DNA of Ehrlichia spp., closely related to Ehrlichia canis, was detected in the blood of three dogs (37.5%), Anaplasma spp., closely related to Anaplasma marginale, in two (25%), Babesia vogeli in one dog (12.5%) and seven ticks (35%) and Hepatozoon canis and Anaplasma spp., in one tick (5%), respectively. These findings highlight the need to test both the vector and host for the presence of tick-borne pathogens when undertaking diagnostic investigations. Further studies are also warranted to elucidate the susceptibility of canids to Anaplasma marginale.

Microfluidic PCR and network analysis reveals complex tick-borne pathogen interactions in the tropics

BACKGROUND

Ixodid ticks, particularly Rhipicephalus sanguineus s.l., are important vectors of various disease-causing agents in dogs and humans in Cuba. However, our understading of interactions among tick-borne pathogens (TBPs) in infected dogs or the vector R. sanguineus s.l. remains limited. This study integrates microfluidic-based high-throughput real-time PCR data, Yule's Q statistic, and network analysis to elucidate pathogen-pathogen interactions in dogs and ticks in tropical western Cuba.

METHODS

A cross-sectional study involving 46 client-owned dogs was conducted. Blood samples were collected from these dogs, and ticks infesting the same dogs were morphologically and molecularly identified. Nucleic acids were extracted from both canine blood and tick samples. Microfluidic-based high-throughput real-time PCR was employed to detect 25 bacterial species, 10 parasite species, 6 bacterial genera, and 4 parasite taxa, as well as to confirm the identity of the collected ticks. Validation was performed through end-point PCR assays and DNA sequencing analysis. Yule's Q statistic and network analysis were used to analyse the associations between different TBP species based on binary presence-absence data.

RESULTS

The study revealed a high prevalence of TBPs in both dogs and R. sanguineus s.l., the only tick species found on the dogs. Hepatozoon canis and Ehrlichia canis were among the most common pathogens detected. Co-infections were observed, notably between E. canis and H. canis. Significant correlations were found between the presence of Anaplasma platys and H. canis in both dogs and ticks. A complex co-occurrence network among haemoparasite species was identified, highlighting potential facilitative and inhibitory roles. Notably, H. canis was found as a highly interconnected node, exhibiting significant positive associations with various taxa, including A. platys, and E. canis, suggesting facilitative interactions among these pathogens. Phylogenetic analysis showed genetic diversity in the detected TBPs.

CONCLUSIONS

Overall, this research enhances our understanding of TBPs in Cuba, providing insights into their prevalence, associations, and genetic diversity, with implications for disease surveillance and management.

Overview of the Main Species of Ticks and Animal and Human Tick-Related Diseases in the Caribbean, Particularly in Haiti

The Caribbean region faces a wide diversity of ticks and tick-borne diseases (TBDs) in animals and humans. But to date, these have been the subject of few studies, resulting in a relative lack of knowledge of their epidemiology, pathogenicity, and the best prevention and control methods. Ticks are hematophagous mites, which feed on the blood of mammals, birds, and reptiles. They are subdivided into two large families: the Ixodidae or hard ticks and the Argasidae or soft ticks. Each collection of blood by ticks from infected hosts can lead to their infection, which will contaminate other previously unharmed animals and contribute to the spread of tick-borne diseases caused mainly by bacteria, viruses, and parasites. It seems important to us to draw up a state of knowledge on ticks. Some long-known tick species like Rhipicephalus, Dermacentor, and Amblyomma and diseases like Anaplasmosis and Babesiosis deserve to be better studied, and others are yet to be identified for further research. The study consists of a review of the various documents published on this theme by Haitian and foreign researchers. The data are analyzed to assess the spatiotemporal distribution of ticks and identify the pathogenic germs they harbor and the various pathologies they induce in the Caribbean and Haiti.

First molecular evidence of Mycoplasma haemocanis and 'Candidatus Mycoplasma haematoparvum' infections and its association with epidemiological factors in dogs from Cuba

Haemotrophic mycoplasmas (haemoplasmas) are unculturable, epicellular, cell wall-less gram-negative bacteria distributed worldwide, which infect several mammalian species. In dogs, Mycoplasma haemocanis and 'Candidatus Mycoplasma haematoparvum' have been reported as causative agents of infectious anaemia, especially in splenectomised or immunocompromised animals. The present cross-sectional study aims to assess the prevalence, risk factors, and molecular characterization of canine haemoplasmas in Cuba. A total of 391 dog blood samples and 247 tick samples were tested for the presence of canine haemoplasmas by species-specific quantitative TaqMan® real-time PCR assays. Overall, 17.9% (70/391; 95% CI: 14.1-21.7) blood samples were PCR-positive for at least one canine haemoplasmas species, where 15.1% (59/391; 95% CI: 11.5-18.7) for Mycoplasma haemocanis, 4.4% (17/391; 95% CI: 2.3-6.4) for 'Candidatus Mycoplasma haematoparvum', and 1.5% (6/391; 95% CI: 0.3-2.8) were co-infected. All collected ticks were identified morphologically as Rhipicephalus sanguineus sensu lato, and none of the tested tick samples was found PCR-positive for the presence of Mycoplasma haemocanis and 'Candidatus Mycoplasma haematoparvum'. Risk factors for canine haemoplasmas species infection included the presence of tick infestation, crossbreeding and living in kennels, while no association was found with the occurrence of anaemia. Phylogenetic analyses based on the 16S rRNA gene sequences of Mycoplasma haemocanis and 'Candidatus Mycoplasma haematoparvum' revealed >99% identity to other isolates distributed worldwide, indicating low genetic variability amongst these canine haemoplasmas species. To the best of the authors´ knowledge, this is the first molecular evidence of Mycoplasma haemocanis and 'Candidatus Mycoplasma haematoparvum' infections in dogs from Cuba.

Ticks and Tick-Borne Diseases in Central America and the Caribbean: A One Health Perspective

Ticks have complex life cycles which involve blood-feeding stages found on wild and domestic animals, with humans as accidental hosts. At each blood-feeding stage, ticks can transmit and/or acquire pathogens from their hosts. Therefore, the circulation of tick-borne pathogens (TBPs), especially the zoonotic ones, should be studied in a multi-layered manner, including all components of the chain of infections, following the 'One Health' tenets. The implementation of such an approach requires coordination among major stakeholders (such as veterinarians, physicians, acarologists, and researchers) for the identification of exposure and infection risks and application of effective prevention measures. In this review, we summarize our current knowledge on the epidemiology of tick-borne diseases in Central America and the Caribbean and the challenges associated with the implementation of 'One Health' surveillance and control programs in the region.

Phylogeography and population differentiation in Hepatozoon canis (Apicomplexa: Hepatozoidae) reveal expansion and gene flow in world populations

BACKGROUND

Hepatozoon canis is a protozoan transmitted to dogs and other wild carnivores by the ingestion of ticks containing mature oocysts and is considered the principal cause of canine hepatozoonosis in the world. Here, we examined ribosomal RNA 18S gene sequence variation to determine the genetic differences and phylogeographic diversity of H. canis from various geographical areas around the world.

METHODS

We used 550 publicly available sequences of H. canis from 46 countries to assess haplotype relationships, geographical structure, genetic diversity indices, and relationships among populations. We performed neutrality tests and pairwise comparisons of fixation index (FST) values between groups and pairwise comparisons of FST values between populations. To determine whether populations are structured, analyses of molecular variance (AMOVAs) and spatial analysis of molecular variance (SAMOVA) were performed.

RESULTS

The dataset of H. canis yielded 76 haplotypes. Differentiation among populations indicated that there is no phylogeographical structure (GST = 0.302 ± 0.0475). Moreover, when samples were grouped by continents a significant FST was obtained, meaning that populations were genetically differentiated. The AMOVA showed that 57.4% of the genetic variation was explained by differences within populations when all locations were treated as a single group and revealed that there is no population structure when populations are grouped into two, three, and four groups (FCT, p > 0.05), suggesting that dispersal between populations is high. SAMOVA revealed significant FCT values for groups K = 5. The Tajima's D and Fu's Fs show that populations have undergone recent expansion, and the mismatch distribution analysis showed population expansion (multimodal distribution).

CONCLUSIONS

The current molecular data confirmed that H. canis does not show phylogeographic or population structure. The haplotypes exhibit low genetic differentiation, suggesting a recent expansion due to gene flow among populations. These results provide pivotal information required for future detailed population genetic analysis or to establish control strategies of this parasite.

Abandonment of dogs in Latin America: Strategies and ideas

In this article, we gathered information from postgraduate theses and scientific articles published in several databases using inclusion criteria that had been made in Latin America, in countries with similar economic conditions, and also in the USA to present a point of comparison. The objective of this review is to broaden the readers' understanding of the causes of the increasing numbers of stray dogs and the reasons why people abandon pets in the streets, specifically in Latin America. It also discusses adoption and responsible ownership, identifies what failed in promoting positive human-dog interaction, and suggests strategies to address this problem. It concludes that adoption alone is not an effective solution but that it is necessary to offer education and awareness programs for owners, organize sterilization campaigns, and develop and apply - with the corresponding authorities - measures to ensure animal welfare that will provide benefits for society and improve animal quality of life. The role of veterinarians is fundamental in education and in disseminating the necessary information to orient people before they acquire a pet and prevent animal abandonment to resolve this problem.

Molecular epidemiology and prevalence of babesial infections in dogs in two hyperendemic foci in Brazil

Babesial parasites are some of the most ubiquitous blood pathogens and consequently have considerable worldwide veterinary impact. Dogs living in the tropics are highly exposed to babesial parasites, particularly to Babesia vogeli. Limited data on the seroprevalence and molecular prevalence of Babesia spp. in dogs are available in Latin America. We conducted a cross-sectional study combining serological and molecular tests to estimate the seroprevalence and molecular epidemiology of Babesia spp. infections in dogs in two hyperendemic foci in Brazil. A total of 630 privately owned dogs (417 from Goiana municipality, Pernambuco state, north-eastern Brazil, and 213 from São Joaquim de Bicas municipality, Minas Gerais state, south-eastern Brazil) were sampled and molecularly and serologically tested for Babesia spp. Overall, 519 dogs (82.4%) presented detectable IgG antibodies against Babesia spp., and seropositivity was significantly higher in dogs older than 1 year. Molecularly, 34 dogs (5.4%) were positive for a ~ 200 bp fragment of the 18S rRNA gene of Babesia spp. and 88 (14.0%) for a longer fragment (~ 450 bp) of the same gene of Babesia spp. and other protozoa. The 18S rRNA gene sequences generated herein corresponded to B. vogeli (n = 52) or Hepatozoon canis (n = 20). This study confirms a high level of exposure to B. vogeli in two areas of Brazil and highlights that most of the dogs living in these areas are infected during the course of their life, reflected by increased seroprevalence in older dogs. Increased awareness and prevention of tick-borne protozoa infections in dogs from Brazil and Latin America are urgently needed.