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Phylogenetic trees for a subset of 18S rDNA sequences of Hepatozoon spp. a Bayesian phylogeny. Bayesian posterior probabilities are indicated upon or arrowing each branch. b Maximum-likelihood tree. Numbers represent bootstrap supports. Sequences generated in this study are annotated in red bold letters. The clade of Hepatozoon americanum is highlighted within yellow box. GenBank accession numbers are indicated in brackets. Scale bars indicate the number of substitutions per nucleotide positions, respectively
Source publication
In South America, apicomplexan parasites of the genus Hepatozoon have been sporadically detected in mammals. Previous studies in wild canids from Brazil and Argentina demonstrated infections by species genetically related to Hepatozoon americanum. The aim of the present work was to detect the presence of Hepatozoon in road-killed foxes encountered...
Citations
... The first species is considered the primary cause of American canine hepatozoonosis (ACH) in North America [16,38,66,170]. Meanwhile, the latter is a species closely related to H. americanum, and is emerging in South American canids [13,67,171]. Although H. americanum was found infecting only two mammal species in North America, it showed higher IFs. ...
... Indeed, coyotes are commonly reported to be infected with H. americanum in North America [87,153,[181][182][183][184], while crab-eating foxes are associated with H. canis and H. americanum-like infections in South American ecosystems [67,171,185,186]. Both H. americanum and H. canis are recognized for their virulence in canids [16,66,84], as well as for their diverse modes of transmission between hosts and ticks, that are common ectoparasites of canids in the Americas [52,63,187]. ...
Background
The study of parasites provides insight into intricate ecological relationships in ecosystem dynamics, food web structures, and evolution on multiple scales. Hepatozoon (Eucoccidiorida: Hepatozoidae) is a genus of protozoan hemoparasites with heteroxenous life cycles that switch infections between vertebrates and blood-feeding invertebrates. The most comprehensive review of the genus was published 26 years ago, and currently there are no harmonized data on the epizootiology, diagnostics, genotyping methods, evolutionary relationships, and genetic diversity of Hepatozoon in the Americas.
Methods
Here, we provide a comprehensive review based on the PRISMA method regarding Hepatozoon in wild mammals within the American continent, in order to generate a framework for future research.
Results
11 out of the 35 countries of the Americas (31.4%) had data on Hepatozoon, with Carnivora and Rodentia orders having the most characterizations. Bats, ungulates, and shrews were the least affected groups. While Hepatozoon americanum, H. americanum-like, H. canis, H. didelphydis, H. felis, H. milleri, H. griseisciuri, and H. procyonis correspond to the identified species, a plethora of genospecies is pending for a formal description combining morphology and genetics. Most of the vectors of Hepatozoon in the Americas are unknown, but some flea, mite, and tick species have been confirmed. The detection of Hepatozoon has relied mostly on conventional polymerase chain reaction (PCR), and the implementation of specific real time PCR for the genus needs to be employed to improve its diagnosis in wild animals in the future. From a genetic perspective, the V4 region of the 18S rRNA gene has been widely sequenced for the identification of Hepatozoon in wild animals. However, mitochondrial and apicoplast markers should also be targeted to truly determine different species in the genus. A phylogenetic analysis of herein retrieved 18S ribosomal DNA (rDNA) sequences showed two main clades of Hepatozoon: Clade I associated with small mammals, birds, and herpetozoa, and Clade II associated with Carnivora. The topology of the tree is also reflected in the haplotype network.
Conclusions
Finally, our review emphasizes Hepatozoon as a potential disease agent in threatened wild mammals and the role of wild canids as spreaders of Hepatozoon infections in the Americas.
Graphical Abstract
... In the same study, crab-eating foxes were found infected with a lineage very similar to H. americanum [43], which was reported with high prevalence along with H. canis in another study from Brazil [261]. H. americanum DNA was recovered in Uruguay from crab-eating foxes and Lycalopex gymnocercus (grey Patagonian fox) [262]. All these findings led to the conclusion that there is a strong association between C. thous and Hepatozoon [263]. ...
... On the other hand, an Hepatozoon closely related to H. americanum, was detected in the South American gray fox (L. griseus) from Argentina, and C. thous from Uruguay and C. brachyurus from Brazil [18,43,251,261,262,265,266], Hepatozoon spp. in bush dogs (Speothos venaticus) [20], and a fox of undetermined identity from Brazil [268]. Table 2 reports the cases of molecular detection of arthropod-borne protozoa in relation to wild canid species. ...
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.
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 18S rRNA, 6.16% for hps70 and 4.91 to 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.
Humans are rapidly transforming whole ecosystems by deforestation, habitat fragmentation, pollution, and climate change, among others. Increased human populations and the transformation of original habitats to productive lands have led to increased contact between humans, domestic animals, and wildlife. Although the maintenance and circulation of pathogens at the domestic and wild carnivore interface often involves bidirectional transmission, domestic carnivores have been identified as reservoirs for infectious agents that have produced numerous epidemics in different wild carnivore species worldwide. For instance, domestic dogs have been implicated in outbreaks of canine distemper and rabies in wild carnivores, while domestic cats have been shown to transmit feline leukemia and feline immunodeficiency to wild felids. Domestic dogs and cats are particularly abundant in urban areas of some developing countries where they can act as excellent reservoirs for pathogens, since they usually inhabit large populations, are not vaccinated, and are regularly allowed to roam freely, facilitating contact between infected and susceptible hosts. In contrast, in rural areas, where domestic dogs and cat densities and population sizes are often lower, theoretically highly virulent pathogens cannot be maintained, and infections fade out without external input of infectious animals from neighboring urban areas. On the other hand, wild carnivore populations are commonly found at low densities, many are solitary, and their numbers are often not sufficient to maintain infections for highly pathogenic generalist agents. In the neotropics, approximately 28% of wild felids and 30% of wild canids of the world are found; however, very few studies have assessed the transmission of pathogens at the wildlife-domestic interface in neotropical carnivores. This chapter aims to review the current knowledge on pathogen spillover from domestic dogs and cats to wild carnivores in human-dominated landscapes in the neotropics. We discuss evidence-based predictions on how relevant diseases can spread from domestic to wild carnivores, which in many cases are endemic or threatened.
