Morphological, morphometric, and molecular characterization of Hepatozoon spp. (Apicomplexa, Hepatozoidae) from naturally infected Caudisona durissa terrifica (Serpentes, Viperidae)

First molecular detection and genetic diversity of Hepatozoon sp. (Apicomplexa) and Brugia sp. (Nematoda) in a crocodile monitor in Nakhon Pathom, Thailand

The crocodile monitor (Varanus salvator) is the most common monitor lizard in Thailand. Based on habitat and food, they have the potential to transmit zoonoses, with a high possibility of infecting ectoparasites and endoparasites. Diseases that could infect crocodile monitors and be transmitted to other animals, including humans. This research aims to identify and evaluate the phylogenetic relationships of Hepatozoon sp. and sheathed microfilaria in crocodile monitors. The phylogenetic analyses of Hepatozoon, based on 18S rRNA, and sheathed microfilaria, based on the COX1 gene, revealed that the Hepatozoon sp. were grouped with H. caimani, while sheathed microfilaria were grouped together with B. timori. This study provides insights into the genetic diversity and host-parasite interactions of hemoparasites in crocodile monitors in Thailand.

Discovery of a new Hepatozoon species namely Hepatozoon viperoi sp. nov. in nose-horned vipers in Türkiye

Although Hepatozoon spp. remains the most prevalent intracellular protozoa infecting snakes, it was reported only in a few snake species of the Colubridae family in Türkiye. Moreover, studies on these hemoparasites are not available in venomous nose-horned vipers from Türkiye. In this study, we investigated Hepatozoon spp. in three individual Vipera ammodytes using morphological and molecular methods. Our results were positive for intraerythrocytic Hepatozoon spp. gamonts in all three snakes, exhibiting low parasitemia. The microscopic findings were further confirmed through molecular data. A genus-specific PCR assay targeting the 18S rRNA gene region of Hepatozoon spp., was performed using HemoF/HemoR and Hep300/Hep900 primers. The obtained sequences were concatenated and used in phylogenetic analyses in comparison with different Hepatozoon species. Although our (OP377741) isolate was separated into a different branch, it was clustered with the isolates of H. massardi (KC342526), H. cevapii (KC342525), and H. annulatum (ON262426) from Brazilian snakes. Moreover, gene similarity and pair-wise distance between our isolate and other Hepatozoon species infecting snakes were found to be 89.30-98.63% and 0.009-0.077, respectively. Hence, we reported a new species of Hepatozoon, namely Hepatozoon viperoi sp. nov. infecting V. ammodytes. Since the literature does not indicate the existence of such a Hepatozoon species in V. ammodytes in different countries, our data may contribute to the expanding knowledge of Hepatozoon species in snakes, providing new insights into the biodiversity of the haemogregarine protozoan parasite.

Morphological detection and molecular characterization of Hepatozoon spp. from venomous terrestrial snakes in Iran

Hepatozoon spp. are blood protozoans that can infect snakes. Infections with these parasites are found in more than 200 snake species and are considered to be the most frequent hemogregarines in snakes. In this study, a total of 73 dead snakes in captivity conditions, belonging to six different species, which were collected between June 2018 to October 2020 from different parts of Iran, were examined for the presence of blood parasites with microscopy and molecular methods. DNA was extracted from the removed heart, and PCR was done with two pairs of primers targeting the 18S rRNA gene. By microscopy, Hepatozoon spp. were detected in the heart blood of 29 out of the 73 (39.72%) snakes. From these 29 positive samples, eight were found to be positive using the PCR method. This study aimed to report for the first time the molecular characteristics of Hepatozoon spp. infecting venomous terrestrial snakes in Iran.

Microorganisms in the ticks Amblyomma dissimile Koch 1844 and Amblyomma rotundatum Koch 1844 collected from snakes in Brazil

Knowledge about ticks (Acari) and screening of ticks parasitizing various hosts are necessary to understand the epidemiology of tick-borne pathogens. The objective of this study was to investigate tick infestations on snakes (Reptilia: Squamata: Serpentes) arriving at the serpentarium at the Institute Vital Brazil, Rio de Janeiro. Some of the identified ticks were individually tested for the presence of bacteria of the genera Rickettsia (Rickettsiales: Rickettsiaceae), Borrelia (Spirochaetales: Spirochaetaceae), Coxiella (Legionellales: Coxiellaceae), Bartonella (Rhizobiales: Bartonellaceae), Ehrlichia (Rickettsiales: Anaplasmataceae), Anaplasma (Rickettsiales: Anaplasmataceae), and Apicomplexa protozoa of the genera Babesia (Piroplasmida: Babesiidae) and Hepatozoon (Eucoccidiorida: Hepatozoidae). A total of 115 hard ticks (Ixodida: Ixodidae) were collected from 17 host individuals obtained from four Brazilian states. Two species of tick were identified: Amblyomma dissimile Koch 1844 (four larvae, 16 nymphs, 40 adults), and Amblyomma rotundatum Koch 1844 (12 nymphs, 43 adults). Rickettsia bellii was found in A. rotundatum and A. dissimile ticks and Rickettsia sp. strain Colombianensi, Anaplasma-like and Hepatozoon sp. in A. dissimile ticks. Among the tested ticks, no DNA of Borrelia, Bartonella, Coxiella or Babesia was found. The present findings extend the geographic range of Rickettsia sp. strain Colombianensi in Brazil and provide novel tick-host associations.

Hepatozoon caimani in Caiman crocodilus yacare (Crocodylia, Alligatoridae) from North Pantanal, Brazil

Hepatozoon species are the most common intracellular hemoparasite found in reptiles. Hepatozoon caimani, whose vectors are Culex mosquitoes, has been detected in a high prevalence among caimans in Brazil by blood smears examinations. The present work aimed to detect and characterize the Hepatozoon spp. found in 33 caimans (24 free-ranging and 9 captive; 28 males and 5 females) (Caiman crocodilus yacare) sampled at Poconé, North Pantanal, state of Mato Grosso, Brazil, using blood smears examinations and molecular techniques. Hepatozoon spp.-gametocytes were found in 70.8% (17/24) and 88.8% (8/9) of blood smears from free-ranging and captive caimans, respectively. Hepatozoon spp. 18S rRNA DNA was found in 79.2% (19/24) and 88.8% (8/9) of free-ranging and captive caimans, respectively. Comparative analysis of parasitized and non-parasitized erythrocytes showed that all analyzed features were significantly different (P<0.05) for both linear and area dimensions. Phylogenetic analysis based on 18S rRNA sequences grouped the Hepatozoon spp. sequences detected in the present study together with H. caimani, recently detected in caimans in southern Pantanal.

A new species of Hepatozoon Miller, 1908 (Apicomplexa: Adelerina) from the snake Philodryas nattereri Steindachner (Squamata: Dipsadidae) in northeastern Brazil

Based on both unique morphological characteristics of the gamont, distinct changes caused to the host erythrocyte and analysis of partial 18S rRNA gene sequences, a new parasite of the genus Hepatozoon Miller, 1908 is described from the snake Philodryas nattereri Steindachner (Squamata: Dipsadidae) in northeastern Brazil. The new species, Hepatozoon musa n. sp., is characterized by large and curved mature gamonts (18.9 ± 0.9 μm in length and 3.8 ± 0.3 μm in width) that considerably engorge infected host erythrocytes and displace the nucleus laterally, which become longer and thinner. Phylogenetic estimates indicate the new species is more closely related to the recently described Hepatozoon cuestensis O'Dwyer, Moço, Paduan, Spenassatto, Silva & Ribolla, 2013, from Brazilian rattlesnakes. These recent findings highlight the need for further studies of Hepatozoon to better determine the biodiversity of this common but poorly-studied parasite group.

First report of Hepatozoon (Apicomplexa: Adeleorina) from king ratsnakes (Elaphe carinata) in Shanghai, with description of a new species

Hepatozoon species are the most common hemoparasites of snakes. In this study, Hepatozoon parasites were examined for the first time in king rat snakes (Elaphe carinata) from Shanghai, China. All 10 snakes were found to be infected with Hepatozoon gamonts. The gamonts were folded back in a hook-wise fashion for about 3 μm at one end. Parasitemia levels ranged from 4-43 infected erythrocytes per 1,000 examined. The gamonts changed the morphology of the parasitized erythrocytes. Although the gamonts showed some distinct variations in both the parasite and its nucleus, phylogenetic analysis indicated that all the E. carinata in this study formed a monophyletic group, and were distinct from all other published Hepatozoon species. A new species, Hepatozoon chinensis, was proposed based on the molecular and morphologic evidence.

Characterization of Hepatozoon spp. in Leptodactylus chaquensis and Leptodactylus podicipinus from two regions of the Pantanal, state of Mato Grosso do Sul, Brazil

Hepatozoon sp. are parasites that commonly infect frogs and arthropod vectors. This species has variability in the morphological and morphometric characteristics. Due to these variations, the naming of the species is thus impaired and only by visualizing the sporogonic cycle in vector and by molecular studies this problem can be solved. Recently, the use of molecular genetics has helped the species denomination. In this work, we collected 145 frogs (68 Leptodactylus chaquensis and 77 Leptodactylus podicipinus) in different sampling sites, where were found 18 (26.47%) L. chaquensis and 24 (31.17%) L. podicipinus parasitized; besides of gamonts, schizogonic forms were also seen in animals organs. The positivity difference between the collection sites for both frog species was not significant (p = 0.958). Comparing gamonts found in each species of anuran, we observed differences in morphology. The comparison in the molecular level for L. podicipinus was not possible due to small amount of blood obtained, just L. chaquensis had their parasites DNA sequenced. The amplified and sequenced samples, named HEP1 to HEP10, are presented in the phylogenetic tree as a different branch from other haemogregarines described on other hosts. Therefore, we have seen that, although the morphology and morphometry of the collected parasites at each site showed differences, the sequencing of these samples revealed identical species of Hepatozoon, and different compared to those from GenBank, thereby demonstrating that the species of Hepatozoon in L. chaquensis observed in this study probably represent a new species.

Patterns of genetic diversity in Hepatozoon spp. infecting snakes from North Africa and the Mediterranean Basin

Species of Hepatozoon Miller, 1908 are blood parasites most commonly found in snakes but some have been described from all tetrapod groups and a wide variety of hematophagous invertebrates. Previous studies have suggested possible associations between Hepatozoon spp. found in predators and prey. Particularly, some saurophagous snakes from North Africa and the Mediterranean region have been found to be infected with Hepatozoon spp. similar to those of various sympatric lizard hosts. In this study, we have screened tissue samples of 111 North African and Mediterranean snakes, using specific primers for the 18S rRNA gene. In the phylogenetic analysis, the newly-generated Hepatozoon spp. sequences grouped separately into five main clusters. Three of these clusters were composed by Hepatozoon spp. also found in snakes and other reptiles from the Mediterranean Basin and North Africa. In the other two clusters, the new sequences were not closely related to geographically proximate known sequences. The phylogeny of Hepatozoon spp. inferred here was not associated with intermediate host taxonomy or geographical distribution. From the other factors that could explain these evolutionary patterns, the most likely seems series of intermediate hosts providing similar ribotypes of Hepatozoon and a high prevalence of host shifts for Hepatozoon spp. This is indicated by ribotypes of high similarity found in different reptile families, as well as by divergent ribotypes found in the same host species. This potentially low host specificity has profound implications for the systematics of Hepatozoon spp.

Description of three new species of Hepatozoon (Apicomplexa, Hepatozoidae) from Rattlesnakes (Crotalus durissus terrificus) based on molecular, morphometric and morphologic characters

Hepatozoon spp. are commonly found infecting snakes. Since the latter are parasitized by diverse forms and data in the literature show divergence, we studied Hepatozoon spp. diversity on Crotalus durissus terrificus snakes using both molecular and morphological approaches. Naturally infected animals were employed. Blood was collected, blood smears were prepared and an aliquot was stored at -20°C for DNA extraction. Five specimens of C. durissus terrificus were selected, each of them infected with one gamont type. Morphological and morphometric analyses of the found gamonts led to their grouping into three populations. For molecular characterization, seven oligonucleotide pairs that amplify distinct regions of rDNA gene were tested by adopting the PCR technique. Only the oligonucleotide pairs HepF300/Hep900 and HEMO1/HEMO2 were efficient in amplifying and distinguishing different isolates of Hepatozoon spp. from snakes. The better results were obtained when both oligonucleotide pairs were used in association. Based on the molecular and morphologic differences, three new species were proposed: Hepatozoon cuestensis sp. nov.; Hepatozoon cevapii sp. nov. and Hepatozoon massardii sp. nov. This is the first description of new Hepatozoon species from snakes, based on molecular characterization and morphological data, in South America.

Developmental stages of Hepatozoon seurati (Laveran and Pettit 1911) comb. nov., a parasite of the corned viper Cerastes cerastes and the mosquito Culex pipiens from Egypt

Developmental stages of Hepatozoon seurati (Laveran and Pettit 1911) comb. nov. are described from the tissues of the corned viper Cerastes cerastes, and from the vector Culex pipiens. The parasite described in the present study is firstly recorded as Haemogregarina seurati (Laveran and Pettit 1911) in the same host. After demonstration of the sporogonous development in the mosquito vector (C. pipiens) which showed all characteristics of the genus Hepatozoon (large oocysts containing many sporocysts producing numerous sporozoites), the parasite should be transferred into the genus Hepatozoon. The infected erythrocytes measured 20 ± 0.95 × 7.3 ± 0.85 μm; while uninfected cells measured 13.3 ± 1.04 × 7.5 ± 0.16 μm. Hypertrophy and faintly stained cytoplasm are mostly occurred in infected erythrocytes. Blood stages of the parasite were found exclusively in the erythrocytes in two forms: (1) small trophozoites (10.0 ± 0.52 × 3.0 ± 0.4 μm) and (2) long (mature) sausage-shaped (16.5 ± 1.5 × 3.5 ± 0.4 μm). Merogony occurred in the endothelial cells of the blood capillaries of lung, liver, and spleen. Mature meronts was 27.6 ± 0.7 × 17.5 ± 0.5 μm in diameter and contained 20-35 merozoites (averaged in 26). These merozoites measured 16.5 ± 1.5 × 3.5 ± 0.4 μm. Syzygy and gamogony occurred in the mosquito myxocoel till the 5th day post-infection (p.i.) while sporogony took place after 15 days p.i. On the third day p.i., a large spherical macrogamete of 29.0 ± 0.8 × 20.5 ± 0.6 μm containing a distinct nucleus in association with a single microgamete were observed. The microgamete was pyriform measured 8 ± 02 μm in length. It had a prominent nucleus and a long flagellum of at least 20.4 ± 1.3 μm in length. Fertilization occurred on the 3rd to the 4th days p.i. and the formed zygote developed into an oocyst in which repeated mitotic divisions with centripetal invaginations occurred producing sporoblasts. After sporulation, each sporoblast termed as sporocyst, and contained 18 banana-shaped sporozoites measured 14.0 ± 1.6 × 3.2 ± 0.6 μm. Experimental transmission was successful by intraperitoneal inoculation of the infective stages (sporozoites) to uninfected vipers and led to the appearance of blood stages after 5-6 weeks.

Molecular survey and microscopic examination of Hepatozoon Miller, 1908 (Apicomplexa: Adeleorina) in lacertid lizards from the western Mediterranean

The genus Hepatozoon Miller, 1908 (Apicomplexa: Adeleorina) is composed of intracellular haemogregarine parasites that are widely distributed among all tetrapod groups. The present study combines microscopic and molecular data on haemogregarine parasites from lizards in the western Mediterranean. We screened tissue samples and examined blood smears for the presence of species of Hepatozoon from four lizards, namely Algyroides marchi Valverde, endemic to Southeast Spain, Podarcis bocagei Seoane from Spain and Portugal, P hispanica Steindachner from Spain, and P lilfordi Günther from Cabrera, Balearic Islands (Spain). Our results show that prevalence and intensity of Hepatozoon parasites vary between and within lizard species from different regions. Algyroides marchi and P bocagei from Spain had the lowest values, whereas P hispanica had the highest. Phylogeny based on 18S rRNA gene sequences indicates that most of the new Hepatozoon sequences are part of a clade exclusive from North African and Iberian lizards, except for a single P bocagei isolate that is found related to another clade including isolates from other reptile host species and rodents. Interestingly, isolates from Algyroides form a distinct monophyletic subgroup, which could be a signal of strict host-specificity within this host genus.

Hepatozoon infection prevalence in four snake genera: influence of diet, prey parasitemia levels, or parasite type?

Hepatozoon spp. (Apicomplexa: Haemogregarinidae) are the most commonly reported hemoparasites from snakes. Of over 300 Hepatozoon species identified, more than 120 were described from snakes. However, recent genetic assessments have found Hepatozoon lineages recovered from both prey and predators, indicating that diet may play an important role in the infection of final vertebrate hosts. Here 4 different snake genera with different diets were assessed. Hepatozoon spp. prevalence varied greatly between the genera, but only lineages already identified from potential prey, i.e., gecko and lacertid lizards, were recovered from the snakes. Interestingly, the Hepatozoon spp. lineage known from geckos was the most common in the snakes, but this does not reflect their diet. Higher parasitemia levels, reported for some geckos relative to lacertid lizards, may play a role. Alternatively, this lineage may be more effective at parasitizing snakes or may occur, despite being unrecorded, in other vertebrate groups consumed by snakes.