A shared pathogen: Babesia rossi in domestic dogs, black-backed jackals (Canis mesomelas) and African wild dogs (Lycaon pictus) in South Africa

Description and molecular characterisation of Babesia ailuropodae n. sp., a new piroplasmid species infecting giant pandas

BACKGROUND

Babesia spp. are protozoan parasites that infect the red blood cells of domesticated animals, wildlife and humans. A few cases of giant pandas (a flagship species in terms of wildlife conservation) infected with a putative novel Babesia sp. have been reported. However, comprehensive research on the morphological and molecular taxonomic classification of this novel Babesia sp. is still lacking. This study was designed to close this gap and formally describe this new Babesia sp. infecting giant pandas.

METHODS

Detailed morphological, molecular and phylogenetic analyses were conducted to characterise this Babesia sp. and to assess its systematic relationships with other Babesia spp. Blood samples from giant pandas infected with Babesia were subjected to microscopic examination. The 18S ribosomal RNA (18S rRNA), cytochrome b (cytb) and mitochondrial genome (mitogenome) of the new Babesia sp. were amplified, sequenced and assembled using DNA purified from blood samples taken from infected giant pandas. Based on the newly generated 18S rRNA, cytb and mitogenome sequences, phylogenetic trees were constructed.

RESULTS

Morphologically, the Babesia sp. from giant pandas exhibited various forms, including round to oval ring-shaped morphologies, resembling those found in other small canine Babesia spp. and displaying typical tetrads. Phylogenetic analyses with the 18S rRNA, cytb and mitogenome sequences revealed that the new Babesia sp. forms a monophyletic group, with a close phylogenetic relationship with the Babesia spp. that infect bears (Ursidae), raccoons (Procyonidae) and canids (Canidae). Notably, the mitogenome structure consisted of six ribosomal large subunit-coding genes (LSU1-6) and three protein-coding genes (cytb, cox3 and cox1) arranged linearly.

CONCLUSIONS

Based on coupled morphological and genetic analyses, we describe a novel species of the genus Babesia, namely, Babesia ailuropodae n. sp., which infects giant pandas.

Description of Babesia galileei sp. nov. A Piroplasmid species causing severe disease in domestic cats

BACKGROUND

Babesiosis is a tick-borne infection caused by piroplasmid protozoa and associated with anemia and severe disease in humans, domestic animals and wildlife. Domestic cats are infected by at least six Babesia spp. that cause clinical disease.

METHODS

Infection with a piroplasmid species was detected by microscopy of stained blood smears in three sick cats from Israel. Genetic characterization of the piroplasmid was performed by PCR amplification of the 18S rRNA, cytochorme B (CytB) and heat shock protein 70 (HSP70) genes and the internal transcribed spacer (ITS) locus, DNA sequencing and phylogenetic analysis. In addition, Haemaphysalis adleri ticks collected from two cats were analyzed by PCR for piroplasmids.

RESULTS

The infected cats presented with anemia and thrombocytopenia (3/3), fever (2/3) and icterus (1/3). Comparison of gene and loci sequences found 99-100% identity between sequences amplified from different cats and ticks. Constructed phylogenetic trees and DNA sequence comparisons demonstrated a previously undescribed Babesia sp. belonging to the Babesia sensu stricto (clade X). The piroplasm forms detected included pear-shaped merozoite and round-to-oval trophozoite stages with average sizes larger than those of Babesia felis, B. leo and B. lengau and smaller than canine Babesia s.s. spp. Four of 11 H. adleri adult ticks analyzed from cat # 3 were PCR positive for Babesia sp. with a DNA sequence identical to that found in the cats. Of these, two ticks were PCR positive in their salivary glands, suggesting that the parasite reached these glands and could possibly be transmitted by H. adleri.

CONCLUSIONS

This study describes genetic and morphological findings of a new Babesia sp. which we propose to name Babesia galileei sp. nov. after the Galilee region in northern Israel where two of the infected cats originated from. The salivary gland PCR suggests that this Babesia sp. may be transmitted by H. adleri. However, incriminating this tick sp. as the vector of B. galilee sp. nov. would require further studies.

Phylogenetic inferences based on distinct molecular markers reveals a novel Babesia (Babesia pantanalensis nov. sp.) and a Hepatozoon americanum-related genotype in crab-eating foxes (Cerdocyon thous)

Piroplasmids and Hepatozoon spp. Are apicomplexan protozoa that may cause disease in several canid species. The present study aimed to expand the knowledge on the diversity of piroplasmids and Hepatozoon in crab-eating foxes (Cerdocyon thous; n = 12) sampled in the Pantanal of Mato Grosso do Sul State, central-western Brazil. PCR assays based on the 18S rRNA were used as screening. Three (25%) and 11 (91.7%) were positive for piroplasmids and Hepatozoon spp., respectively. Co-infection was found in three C. thous. Phylogenetic analyses based on the near-complete 18S rRNA, cox-1 and hsp70 genes evidenced the occurrence of a novel of Babesia spp. (namely Babesia pantanalensis nov. sp.) closely related to Rangelia vitalii and Babesia sp. 'Coco'. This finding was supported by the genetic divergence analysis which showed (i) high divergence, ranging from 4.17 to 5.62% for 18 S rRNA, 6.16% for hps70 and 4.91-9.25% for cox-1 and (ii) the genotype network (which displayed sequences separated from the previously described Piroplasmida species by median vectors and several mutational events). Also, phylogenetic analysis based on the 18S rRNA gene of Hepatozoon spp. positioned the sequences obtained herein in a clade phylogenetically related to Hepatozoon sp. 'Curupira 2', Hepatozoon sp. detected in domestic and wild canids from Uruguay and Hepatozoon americanum. The present study described Babesia pantanalensis nov sp. and Hepatozoon closely related to H. americanum in crab-eating foxes from Brazil. Moreover, the coinfection by piroplasmids and Hepatozoon sp. for the first time in crab-eating foxes strongly suggesting that this wild canid species potentially acts as a bio-accumulate of hemoprotozoan in wild environment.

Canine Babesiosis Caused by Large Babesia Species: Global Prevalence and Risk Factors-A Review

Canine babesiosis is a disease caused by protozoan pathogens belonging to the genus Babesia. Four species of large Babesia cause canine babesiosis (B. canis, B. rossi, B. vogeli, and the informally named B. coco). Although canine babesiosis has a worldwide distribution, different species occur in specific regions: B. rossi in sub-Saharan Africa, B. canis in Europe and Asia, and B. coco in the Eastern Atlantic United States, while B. vogeli occurs in Africa, southern parts of Europe and Asia, northern Australia, southern regions of North America, and in South America. B. vogeli is the most prevalent large Babesia species globally. This results from its wide range of monotropic vector species, the mild or subclinical nature of infections, and likely the longest evolutionary association with dogs. The most important risk factors for infection by large Babesia spp. include living in rural areas, kennels or animal shelters, or regions endemic for the infection, the season of the year (which is associated with increased tick activity), infestation with ticks, and lack of treatment with acaricides.

Arthropod-Borne Pathogens in Wild Canids

Wild canids, as well as other wild animal species, are largely exposed to bites by ticks and other hematophagous vectors where the features favoring their presence and spread are found in wooded and semi-wooded areas. Much of the information about arthropod-borne infections concerns domestic and companion animals, whereas data about these infections in wild canids are not exhaustive. The present study is a narrative review of the literature concerning vector-borne infections in wild canids, highlighting their role in the epidemiology of arthropod-borne bacteria and protozoa.