In vitro cultivation of a newly recognized Babesia sp. in dogs in North Carolina

Prevalence of Babesia and Ehrlichia in owned dogs with suspected tick-borne infection in Hong Kong, and risk factors associated with Babesia gibsoni

Babesiosis and ehrlichiosis are the most clinically significant tick-borne infections in dogs. Although epidemiological investigations of these diseases have been performed in some Asian regions, little data is available in Hong Kong, where competent vector tick species are endemic. The objectives of this study were to determine the molecular prevalence of Ehrlichia canis and Babesia species (B. canis, B. gibsoni, B. vogeli) in owned dogs suspected of tick-borne infection in Hong Kong and to identify risk factors associated with B. gibsoni infection. Electronic records from the Veterinary Diagnostic Laboratory of City University of Hong Kong were searched to identify canine blood samples submitted for molecular testing of these pathogens by real time PCR between March 2018 and May 2021. Electronic patient records from the affiliated veterinary hospital were searched to identify a subset of tested dogs to investigate the potential risk factors for B. gibsoni infection using logistic regression models. Among 1508 tested dogs for all four pathogens of interest, Babesia spp. were detected in 435 (28.8%) and E. canis in 112 (7.4%). Babesia gibsoni was detected in 408 dogs while B. vogeli was detected in 27 dogs. Babesia canis was not detected in any dog. Co-infections of different combinations of B. gibsoni, B. vogeli and E. canis were present in 25 dogs. In multivariable logistic regression, mixed breed dogs were more likely to be infected with B. gibsoni than purebreds (P = 0.005), while dogs > 10 years of age were less likely to be infected than younger dogs (P = 0.019). Hematological abnormalities significantly associated with B. gibsoni infection included thrombocytopenia, neutropenia, or pancytopenia. Babesiosis caused by B. gibsoni is a common infection in owned dogs suspected of tick-borne infection in Hong Kong. The risk factors reported should be considered in diagnosing dogs suspected of infection with this agent. Furthermore, consideration for testing for B. gibsoni infection should be given if the results of a complete blood count show thrombocytopenia even in the absence of anemia, neutropenia or pancytopenia.

Effect of Urbanization on Presence, Abundance, and Coinfection of Bacteria and Protozoa in Ticks in the US Great Plains

Urbanization alters components of natural ecosystems which can affect tick abundance and tick-borne disease prevalence. Likely due to these changes, tick-borne pathogen prevalence has increased in many U.S. urban areas. Despite the growing public health importance of tick-borne diseases, little is known about how they are influenced by urbanization in North America, especially in the central U.S. where several pathogens occur at or near their highest levels of incidence nationally. To determine whether urban development influences tick infection with bacteria and protozoa, we collected ticks at 16 parks across a gradient of urbanization intensity in Oklahoma City, Oklahoma, USA and tested them using a variety of PCR assays. Adult ticks tested positive for Rickettsia parkeri, R. amblyommatis, R. rhiphicephali, 'Candidatus R. andeanae', Ehrlichia chaffeensis, E. ewingii, Panola Mountain Ehrlichia, 'Borrelia lonestari', Theileria cervi, Babesia spp. Coco, and Cytauxzoon felis. These results indicate the presence of a high diversity of tick-borne bacteria and protozoa across an expanding urban area in the U.S. Great Plains. Although there appeared to be some risk of encountering tick-borne microorganisms across the entire urbanization gradient, E. chaffeensis, E. ewingii, and T. cervi-infected ticks and microbe diversity decreased with increasing urbanization intensity. We identified a low rate of coinfection between different microorganisms, with coinfected ticks mainly collected from sites in the least-urbanized areas. This study suggests the need for awareness of tick-borne disease risk throughout urban areas in the central U.S., and highlights a need for studies of tick host habitat use and movement in cities.

Immune Response of Mice Against Babesia canis Antigens is Enhanced When Antigen is Coupled to Gold Nanoparticles

PURPOSE

The aim of this study was to isolate Babesia canis soluble antigens and to investigate the effect of their conjugates with gold nanoparticles on the immunogenicity in laboratory animals.

METHODS

A procedure was developed for isolating and purifying B. canis antigens. The isolated culture antigen of B. canis 495 was coupled to gold nanoparticles, and the conjugate was used to immunize laboratory mice.

RESULTS

Western blotting showed that the resultant antiserum specifically recognized the proteins of the B. canis strains isolated from naturally infected dogs. The antibody titer, the respiratory activity of peritoneal macrophages, the proliferative activity of splenocytes, and the production of cytokines were maximal when the animals were immunized with the antigen-nanoparticle conjugate emulsified in complete Freund's adjuvant. Without adjuvant, the babesial antigen was weakly immunogenic.

CONCLUSION

Therefore, the use of gold nanoparticles as an antigen carrier induced a broad immune response involving both cellular and humoral responses. The antibodies raised by the proposed procedure are potentially effective at immunodetection of Babesia canis infections in dogs.

Molecular detection and genetic characteristics of Babesia gibsoni in dogs in Shaanxi Province, China

Background

Several members of genus Babesia are important pathogens causing babesiosis in dogs. In China, at least five Babesia species have been described in dogs or ticks. This study sought to determine the prevalence and molecular characteristics of various Babesia spp. in dogs in cities in Shaanxi Province in China, including Xi’an and Hanzhong.

Methods

A total of 371 blood samples were collected from pet dogs presenting to veterinary clinics in the cities of Xi’an and Hanzhong in Shaanxi, China. Babesia spp. DNA was detected via amplification of partial 18S rRNA genes by semi-nested PCR. Almost full-length 18S rRNA, ITS, partial TRAP and complete cytb genes were recovered for analysis of the genetic characteristics and relationships with known isolates.

Results

A single species, Babesia gibsoni, was identified in dogs in Xi’an and Hanzhong. Consistently, B. gibsoni was also detected in 14 ticks collected from positive dogs. Sequence similarities and phylogenetic analysis suggested that the isolates identified herein showed a closer genetic relationship with isolates from East Asian countries rather than India, Bangladesh, or the USA. Sequence analysis based on tandem repeat analysis of the TRAP gene further revealed that specific haplotypes were circulating in both Xi’an and Hanzhong, with no specific regionality. In addition, 10.9% of all isolates with atovaquone (ATV)-resistance were identified because of M121I mutation in the deduced cytb protein.

Conclusions

This study revealed a high prevalence rate of Babesia infection. Babesia gibsoni was the only Babesia species identified in cases of canine babesiosis in the cities of Xi’an and Hanzhong cities in Shaanxi, China. In addition, the TRAP gene presented high genetic diversity across isolates. Such information is useful for elucidating the epidemiological characteristics of canine babesiosis, as well as the overall genetic diversity of Babesia spp. circulating in dog populations in Shaanxi Province.

Prevalence of protozoan parasites in small and medium mammals in Texas, USA

Wildlife interaction with humans increases the risk of potentially infected ticks seeking an opportunistic blood meal and consequently leading to zoonotic transmission. In the United States, human babesiosis is a tick-borne zoonosis most commonly caused by the intraerythrocytic protozoan parasite, Babesia microti. The presence of Babesia microti and other species of Babesia within Texas has not been well characterized, and the molecular prevalence of these pathogens within wildlife species is largely unknown. Small (e.g. rodents) and medium sized mammalian species (e.g. racoons) represent potential reservoirs for specific species of Babesia, though this relationship has not been thoroughly evaluated within Texas. This study aimed to characterize the molecular prevalence of Babesia species within small and medium sized mammals at two sites in East Texas with an emphasis on detection of pathogen presence in these two contrasting wild mammal groups at these sites. To that end, a total of 480 wild mammals representing eight genera were trapped, sampled, and screened for Babesia species using the TickPath layerplex qPCR assay. Two sites were selected for animal collection, including The Big Thicket National Preserve and Gus Engeling Wildlife Management Area. Molecular analysis revealed the prevalence of various Babesia and Hepathozoon species at 0.09% each, and Sarcocystis at 0.06% . Continued molecular prevalence surveys of tick-borne pathogens in Texas wild mammals will be needed to provide novel information as to which species of Babesia are most prevalent and identify specific wildlife species as pathogen reservoirs.

Establishment of a stable transfection system for genetic manipulation of Babesia gibsoni

Background

Genetic manipulation techniques, such as transfection, have been previously reported in many protozoan parasites. In Babesia, stable transfection systems have only been established for bovine Babesia parasites. We recently reported a transient transfection system and the selection of promoter candidates for Babesia gibsoni. The establishment of a stable transfection system for B. gibsoni is considered to be urgent to improve our understanding of the basic biology of canine Babesia parasites for a better control of babesiosis.

Results

GFP-expressing parasites were observed by fluorescence microscopy as early as two weeks after drug selection, and consistently expressed GFP for more than 3 months without drug pressure. Genome integration was confirmed by PCR, sequencing and Southern blot analysis.

Conclusions

We present the first successful establishment of a stable transfection system for B. gibsoni. This finding will facilitate functional analysis of Babesia genomes using genetic manipulation and will serve as a foundation for the development of tick-Babesia and host-Babesia infection models.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2853-1) contains supplementary material, which is available to authorized users.

Microscopic and molecular analysis of Babesia canis in archived and diagnostic specimens reveal the impact of anti-parasitic treatment and postmortem changes on pathogen detection

BACKGROUND

Classification of Babesia parasites has traditionally relied on morphological differentiation based on piroplasm size and shape. Molecular typing has subsequently revealed a more complex taxonomy for these piroplasms than previously thought. To evaluate the factors that influence the morphology of Babesia species upon microscopic examination and hence, their taxonomic classification, we performed detailed characterizations of piroplasms from archival and prospective collections of cytological samples of dogs with piroplasmosis before and after death. Merozoite morphology and time of parasite disappearance following imidocarb dipropionate was also investigated.

METHODS

The study was divided into a (i) review of archived cytological slides from confirmed cases of canine piroplasmosis, and (ii) a prospective study of smears and tissue imprints from 15 recently necropsied dogs. The latter group could be further sub-divided into a non-treated group and an imidocarb dipropionate-treated group. Exact times of treatment before death were reviewed. Additional blood smears prepared from the live dogs and taken before therapy were also evaluated in the latter group. Parasite burden per each slide was determined in both studies. The shape and size of merozoites were described from blood smears taken while the dogs were alive and from different organs during necropsy. The results of all measurements were statistically analyzed.

RESULTS

The morphology and size of merozoites from live dogs corresponded to that of previously described 'large' Babesia. The morphology and size of merozoites were significantly different (P < 0.001) in postmortem samples, however, and more consistent in shape and size with piroplasm cells previously referred to as 'small' Babesia. PCR and sequencing confirmed B. canis as the causative agent of disease in all investigated dogs, including in postmortem negative tissue imprints from dogs treated at least 24 h before death.

CONCLUSIONS

Changes in the morphology of 'large' B. canis to 'small'-like Babesia observed by light microscopy appear to represent a common postmortem change. Classification of Babesia parasites into 'large' and 'small' Babesia using only microscopy of postmortem slides should be treated with caution. PCR-based methodologies for detection and molecular typing of Babesia spp. may prove valuable for investigating suspected cases of babesiosis following necropsy.

Transient transfection of intraerythrocytic Babesia gibsoni using elongation factor-1 alpha promoter

The development of gene manipulation techniques has been reported in many protozoan parasites over the past few years. However, these techniques have not yet been established for Babesia gibsoni. Here, we report for the first time, the successful transient transfection of B. gibsoni. The plasmid containing the firefly luciferase reporter gene (pBS-ELA) was transfected into B. gibsoni by an AMAXA 4D Nucleofector™ device. Transfection using program FA113 and Lonza buffer SF showed the highest luciferase expression. Twenty micrograms of plasmid produced the highest relative transfection efficiency. The fluorescent protein-expressing parasites were determined by GFP-containing plasmid (pBS-EGA) at 48 and 72h post transfection. This finding is the first step towards a stable transfection method for B. gibsoni, which may contribute to a better understanding of the biology of the parasite.

Zoonotic intestinal parasites and vector-borne pathogens in Italian shelter and kennel dogs

This study investigated the presence of zoonotic parasites and vector-borne pathogens in dogs housed in kennels and shelters from four sites of Italy. A total of 150 adoptable dogs was examined with different microscopic, serological and molecular methods. Overall 129 dogs (86%) were positive for one or more parasites and/or pathogens transmitted by ectoparasites. Forty-eight (32%) were positive for one infection, while 81 (54%) for more than one pathogen. The most common zoonotic helminths recorded were hookworms, roundworms and Capillaria aerophila, followed by mosquito-borne Dirofilaria spp. and Dipylidium caninum. One hundred and thirteen (77.9%), 6 (4.1%) and 2 (1.4%) dogs were positive for Rickettsia spp., Leishmania infantum and Anaplasma spp., respectively. The results show that dogs living in rescue facilities from the studied areas may be infected by many zoonotic internal parasites and vector-borne pathogens, and that control measures should be implemented.

Molecular identification of Babesia spp. in naturally infected dogs of Kerala, South India

Canine babesiosis is a tick borne haemoprotozoan disease caused by large and small intraerythrocytic apicomplexan piroplasms of the genus Babesia spp. The clinical manifestations of the disease vary from inapparent subclinical form to hyperacute shock related haemolytic crisis. Microscopic examination of blood smears from suspected dogs revealed Babesia canis and B. gibsoni in 3.45 and 25.86 % of samples respectively. A seminested PCR based on previously published species specific primers targeting the 18S rRNA gene was utilized to identify the Babesia species infecting dogs of Kerala at the sub species level. The study revealed 57.5 % prevalence of Babesia spp. among dogs. This report also presents the first molecular evidence of Babesia canis vogeli and B. gibsoni among naturally infected dogs in Kerala, South India. Molecular survey revealed a high prevalence of B. gibsoni infections when compared with B. canis vogeli infections among canines of the state. Preliminary survey of the tick population revealed the presence of Rhipicephalus sanguineus, R. haemaphysaloides and Haemaphysalis bispinosa in infected animals. Further studies need be directed towards utilizing the PCR protocol for confirming the vectors of these species in the region.

Ehrlichiosis, babesiosis, anaplasmosis and hepatozoonosis in dogs from St. Kitts, West Indies

Background

Although tick-borne diseases are important causes of morbidity and mortality in dogs in tropical areas, there is little information on the agents causing these infections in the Caribbean.

Methodology

We used PCRs to test blood from a cross-section of dogs on St Kitts for Ehrlichia (E.) canis, Babesia (B.) spp., Anaplasma (A.) spp. and Hepatozoon (H.) spp. Antibodies against E. canis and A. phagocytophilum/platys were detected using commercial immunochromatography tests. Records of the dogs were examined retrospectively to obtain clinical and laboratory data.

Principal findings

There was serological and/or PCR evidence of infections of dogs with E. canis (27%; 46/170), Babesia spp. (24%; 90/372) including B. canis vogeli (12%; 43/372) and B. gibsoni (10%; 36/372), A. platys (11%; 17/157) and H. canis (6%; 15/266). We could not identify the Babesia sp. detected in nine dogs. There was evidence of multiple infections with dual infections with E. canis and B. canis vogeli (8%; 14/179) or B. gibsoni (7%; 11/170) being the most common. There was agreement between immunochromatography and PCR test results for E. canis for 87% of dogs. Only 13% of exposed dogs had signs of a tick-borne disease and 38% had laboratory abnormalities. All 10 dogs presenting for a recheck after treatment of E. canis with doxycycline were apparently healthy although all remained seropositive and six still had laboratory abnormalities despite an average of two treatments with the most recent being around 12 months previously. Infections with Babesia spp. were also mainly subclinical with only 6% (4/67) showing clinical signs and 13% (9/67) having laboratory abnormalities. Similarly, animals with evidence of infections with A. platys and H. canis were largely apparently healthy with only occasional laboratory abnormalities.

Conclusions

Dogs are commonly infected with tick-borne pathogens in the Caribbean with most having no clinical signs or laboratory abnormalities.

Detection and molecular characterization of piroplasms species from naturally infected dogs in southeast Brazil

Rangelia vitalii is a protozoon described from dogs in the south and southeast regions of Brazil. It is phylogenetically related to Babesia spp. that infects dogs, but data on this enigmatic parasite is still limited. The aim of this work was to detect piroplasm species in dogs in the state of Rio de Janeiro, Brazil, by 18S rRNA gene-based PCR assay, restriction fragment length polymorphism (RFLP) and sequence analyses. Of 103 dogs examined, seven (6.8%) were positive for Babesia spp. by PCR. The amplified products were digested by restriction enzymes to differentiate the Babesia species, and one sample was identified as Babesia vogeli. The pattern observed for the other six amplification products did not match with pattern described for large Babesia infecting dogs. Sequencing analysis confirmed these six samples as R. vitalii, with high homologies (99-100%) with a sequence from south Brazil. This study confirms the presence of Babesia vogeli and Rangelia vitalii circulate in domestic dogs in Teresópolis, Rio de Janeiro, Brazil.

Major prospects for exploring canine vector borne diseases and novel intervention methods using 'omic technologies

Canine vector-borne diseases (CVBDs) are of major socioeconomic importance worldwide. Although many studies have provided insights into CVBDs, there has been limited exploration of fundamental molecular aspects of most pathogens, their vectors, pathogen-host relationships and disease and drug resistance using advanced, 'omic technologies. The aim of the present article is to take a prospective view of the impact that next-generation, 'omics technologies could have, with an emphasis on describing the principles of transcriptomic/genomic sequencing as well as bioinformatic technologies and their implications in both fundamental and applied areas of CVBD research. Tackling key biological questions employing these technologies will provide a 'systems biology' context and could lead to radically new intervention and management strategies against CVBDs.

Diversity of Babesia and Theileria species in symptomatic and asymptomatic dogs in Croatia

Babesiosis, the disease caused by tick-borne hematozoan parasites of the genus Babesia, is particularly common in dogs, and is caused by several "large" species of Babesia, as well as by an increasing number of "small" species of Babesia, some of which appear to be more closely related to members of the genus Theileria. In this work, blood samples were collected from 848 randomly selected, asymptomatic dogs and from 81 symptomatic dogs, microscopically positive for Babesia, and characterised by PCR and sequence analysis of a fragment of the ssrRNA gene. A prevalence of 3.42% (29 of 848) was found in asymptomatic dogs and sequence analysis revealed the presence of Babesia canis canis in 20 dogs (69%), Babesia gibsoni in six dogs (21%), Babesia canis vogeli in two dogs (7%) and Theileria annae in one dog (3%). In the group of symptomatic dogs, which were all positive by PCR, B. canis canis was the predominant species (78 dogs, or 96%), followed by single infections with B. canis vogeli, Babesia caballi and Theileria equi. Our study has confirmed that dogs are infected with a wide range of both large and small piroplasm species and subspecies, including B. caballi and T. equi, two parasites usually found in horses. The detection of the pathogenic species B. canis canis and B. gibsoni in asymptomatic dogs indicates that the relationship between parasite species/subspecies and clinical signs of infection in dogs deserves further investigation. Finally, the identities of the tick vectors transmitting T. annae and B. caballi remain to be elucidated.

Detection of a large unnamed Babesia piroplasm originally identified in dogs in North Carolina in a dog with no history of travel to that state

CASE DESCRIPTION

A 12-year-old 46-kg (101.2-lb) sexually intact male Labrador Retriever was evaluated because of lymphadenomegaly. The dog resided in Texas, and its travel history included many southeastern and eastern shore states but not North Carolina.

CLINICAL FINDINGS

Following evaluation of the dog, a diagnosis of stage IVa intermediate- to large-cell lymphoma was made. A cyclophosphamide-hydroxydaunorubicin (doxorubicin)-vincristine-prednisone chemotherapy protocol was initiated. One week after the first chemotherapeutic treatment, a routine blood smear evaluation revealed single and paired intraerythrocytic large piroplasms that resembled Babesia canis. Via molecular testing, the organism was identified as a Babesia sp that had been detected previously in dogs in North Carolina.

TREATMENT AND OUTCOME

The dog was administered imidocarb diproprionate (7 mg/kg [3.2 mg/lb], IM) on 2 occasions (3-week interval). At 1, 4, 15, and 50 weeks after the second treatment, blood samples were analyzed specifically for the North Carolina Babesia sp via PCR assay; the result of each assay was positive.

CLINICAL RELEVANCE

Because of the morphologic similarity of the large piroplasm detected in dogs in North Carolina to B canis, molecular testing of large piroplasms detected in dogs is needed to definitively identify the infective Babesia sp. In the dog of this report, the infection was not eliminated following treatment with imidocarb diproprionate, which may have been a result of the immunocompromised state of the dog or the drug's ineffectiveness against this parasite. If imidocarb diproprionate is ineffective against the North Carolina Babesia sp, treated dogs may act as reservoirs of infection.

Detection of Babesia gibsoni and the canine small Babesia 'Spanish isolate' in blood samples obtained from dogs confiscated from dogfighting operations

OBJECTIVE

To determine the prevalence of Babesia gibsoni infection in dogs that were confiscated from dogfighting operations.

DESIGN

Cross-sectional study.

ANIMALS

157 pit bull-type dogs that were confiscated as part of dogfighting prosecution cases in Iowa, Michigan, Mississippi, Ohio, Pennsylvania, Virginia, and Washington and 218 randomly selected animal shelter dogs with no known history of dogfighting.

PROCEDURES

Blood samples collected from confiscated dogs were tested for infection with B gibsoni by use of a nested PCR assay. Samples that yielded positive results underwent DNA sequencing to confirm infection with B gibsoni. Control blood samples collected from 218 randomly selected dogs in animal shelters (ie, dogs that had no known involvement in dogfighting events) were also analyzed.

RESULTS

Results of nested PCR assays indicated that 53 of 157 (33.8%) confiscated dogs were infected with B gibsoni; 1 (0.6%) dog was infected with the canine small Babesia 'Spanish isolate' (also known as Theileria annae). To the authors' knowledge, this is the first report of infection with this small Babesia 'Spanish isolate' in a North American dog. Dogs with scars (indicative of fighting) on the face, head, and forelimbs were 5.5 times as likely to be infected with B gibsoni as were dogs without scars. Of the control dogs, 1 (0.5%) pit bull-type dog was infected with B gibsoni.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that B gibsoni is a common parasite of dogs confiscated from dogfighting operations and suggested that dogs with a history of fighting should be evaluated for infection with B gibsoni.

Canine babesiosis: from molecular taxonomy to control

Canine babesiosis is a clinically significant emerging vector-borne disease caused by protozoan haemoparasites. This review article considers recent literature pertaining to the taxonomic classification of Babesia and Theileria species affecting dogs and the geographical distribution of these parasites. The diagnosis of canine babesiosis by traditional, molecular and serological methods is reviewed, together with recent advances in our understanding of the pathophysiology of piroplasmosis, and of the treatment and prevention of this disease.