Molecular identification of Sarcocystis spp. helped to define the origin of green pythons (Morelia viridis) confiscated in Germany

Sarcocystis sp. shed by the common boa snake (Boa constrictor) in Brazil

The genus Sarcocystis contains around 200 species and 25 of these infect snakes. Two Sarcocystis spp. shed by snakes have called special attention of the scientific community. S. nesbitti, which is shed by scrub pythons (Simalia amethistina), causes myopathy in humans that consume water or food contaminated with the parasite. Sporocysts of S. singaporensis, excreted by reticulated pythons (Malayopython reticulatus), is letal for rats and was successfully tested in the biological control of these rodents. A high biodiversity of snakes is found in Brazil, however, scarce information is available about Sarcocystis spp. in Brazilian snakes. Herein, we investigated Sarcocystis sp. in feces of the common boa (Boa constrictor) from Salvador, as it is widely distributed in Brazil and it is also bred in other countries. Feces of 65 boas were examined, and Sarcocystis sp. was found in 1/65 (1.53%) snakes. All snakes were alive, and for this reason, intestinal scrapping, which is the most sensitive method to detect the parasite, was not performed. Morphometric evaluation of sporocysts showed significant differences in their sizes. PCR and multilocus sequencing of four genetic markers (cox1, 18S, ITS1, and 28S) revealed that sporocysts corresponded to a new Sarcocystis species. Sequences of cox1 and 18S had identities of 100% and higher than 98%, respectively, with sequences obtained from the rodent Lagostomus maximus in Argentina. ITS1 and 28S sequences did not match with any known Sarcocystis sp. No ITS1 and 28S sequences were available for the Sarcocystis sp. found in the Argentinian L.maximus. Bioassay using the boa sporocysts was conducted in three mouse lineages and in Rattus norvegicus, but no parasitic stages were detected in these rodents. We concluded that the common boa is probably the definitive host of a new species of Sarcocystis sp. that has L. maximus or related rodents as intermediate hosts.

Sarcocystis moreliae sp. nov. in the imported green tree python Morelia cf. viridis (Reptilia, Pythonidae)

Species of Sarcocystis use various vertebrates as intermediate or definitive hosts in their life cycles. One of these is snakes, whose role as intermediate hosts for these protozoans is scarce; in fact, there are six records, but only three with molecular characterization. An imported green tree python was involved in the morphological and molecular characterization (four loci) of a new species of Sarcocystis localized in skeletal muscles. Sarcocystis moreliae sp. nov. has a type 1 sarcocyst with a smooth wall and is genetically similar (at the 18S rRNA gene) to two unnamed species of Sarcocystis found in Lytorhynchus diadema from Oman and Varanus salvator macromaculatus from Malaysia, but their detailed comparison is impossible. The new species showed lower similarity to its congeners in other loci (28S rRNA, ITS1, and cox1). This is the first morphological and genetic characterization of a Sarcocystis species in snakes of the genus Morelia, particularly M. viridis, using four loci, but more data are needed to fill the knowledge gap about snakes as intermediate hosts of Sarcocystis.

Sarcocystis sp. infection (Apicomplexa: Sarcocystidae) in invasive California kingsnake Lampropeltis californiae (Serpentes: Colubridae) in Gran Canaria

Invasive species pose a threat not only to biodiversity because they displace or compete with native fauna, but also because of the pathogens they can host. The Canary Islands are an Atlantic biodiversity hotspot threatened by increasing numbers of invasive species, including the California kingsnake Lampropeltis californiae, which was recently introduced to Gran Canaria. Seventy-seven snakes were examined for gastrointestinal parasites in 2019–2020. Sporocysts of Sarcocystis sp. were detected in 10 of them; detection of gamogonia stages in histological sections of 3 snakes confirmed the snake as a definitive host. Partial ssrDNA was amplified using SarcoFext/SarcoRext primers; an additional sequence of Sarcocystis was obtained from the tail muscle of the endemic Gran Canaria giant lizard Gallotia stehlini for a comparison. Identical ssrDNA sequences of unknown Sarcocystis sp. were obtained from 5 different snakes. Phylogenetic analysis showed that Sarcocystis sp. isolated from invasive California kingsnakes is unrelated to Sarcocystis provisionally considered S. stehlini from the endemic lizard. The dixenous coccidia are rarely reported to invade new predator–prey systems. However, the present data suggest that previously unknown Sarcocystis sp. is circulating among invasive snakes and as yet unknown vertebrate intermediate hosts, with undetermined consequences for the Gran Canaria ecosystem.

Examination of Sarcocystis spp. of giant snakes from Australia and Southeast Asia confirms presence of a known pathogen - Sarcocystis nesbitti

We examined Sarcocystis spp. in giant snakes from the Indo-Australian Archipelago and Australia using a combination of morphological (size of sporocyst) and molecular analyses. We amplified by PCR nuclear 18S rDNA from single sporocysts in order to detect mixed infections and unequivocally assign the retrieved sequences to the corresponding parasite stage. Sarcocystis infection was generally high across the study area, with 78 (68%) of 115 examined pythons being infected by one or more Sarcocystis spp. Among 18 randomly chosen, sporocyst-positive samples (11 from Southeast Asia, 7 from Northern Australia) the only Sarcocystis species detected in Southeast Asian snakes was S. singaporensis (in reticulated pythons), which was absent from all Australian samples. We distinguished three different Sarcocystis spp. in the Australian sample set; two were excreted by scrub pythons and one by the spotted python. The sequence of the latter is an undescribed species phylogenetically related to S. lacertae. Of the two Sarcocystis species found in scrub pythons, one showed an 18S rRNA gene sequence similar to S. zamani, which is described from Australia for the first time. The second sequence was identical/similar to that of S. nesbitti, a known human pathogen that was held responsible for outbreaks of disease among tourists in Malaysia. The potential presence of S. nesbitti in Australia challenges the current hypothesis of a snake-primate life cycle, and would have implications for human health in the region. Further molecular and biological characterizations are required to confirm species identity and determine whether or not the Australian isolate has the same zoonotic potential as its Malaysian counterpart. Finally, the absence of S. nesbitti in samples from reticulated pythons (which were reported to be definitive hosts), coupled with our phylogenetic analyses, suggest that alternative snake hosts may be responsible for transmitting this parasite in Malaysia.

Nidovirus-Associated Proliferative Pneumonia in the Green Tree Python (Morelia viridis)

In 2014 we observed a noticeable increase in the number of sudden deaths among green tree pythons (Morelia viridis). Pathological examination revealed the accumulation of mucoid material within the airways and lungs in association with enlargement of the entire lung. We performed a full necropsy and histological examination on 12 affected green tree pythons from 7 different breeders to characterize the pathogenesis of this mucinous pneumonia. By histology we could show a marked hyperplasia of the airway epithelium and of faveolar type II pneumocytes. Since routine microbiological tests failed to identify a causative agent, we studied lung tissue samples from a few diseased snakes by next-generation sequencing (NGS). From the NGS data we could assemble a piece of RNA genome whose sequence was <85% identical to that of nidoviruses previously identified in ball pythons and Indian pythons. We then employed reverse transcription-PCR to demonstrate the presence of the novel nidovirus in all diseased snakes. To attempt virus isolation, we established primary cultures of Morelia viridis liver and brain cells, which we inoculated with homogenates of lung tissue from infected individuals. Ultrastructural examination of concentrated cell culture supernatants showed the presence of nidovirus particles, and subsequent NGS analysis yielded the full genome of the novel virus Morelia viridis nidovirus (MVNV). We then generated an antibody against MVNV nucleoprotein, which we used alongside RNA in situ hybridization to demonstrate viral antigen and RNA in the affected lungs. This suggests that in natural infection MVNV damages the respiratory tract epithelium, which then results in epithelial hyperplasia, most likely as an exaggerated regenerative attempt in association with increased epithelial turnover.IMPORTANCE Novel nidoviruses associated with severe respiratory disease were fairly recently identified in ball pythons and Indian pythons. Herein we report on the isolation and identification of a further nidovirus from green tree pythons (Morelia viridis) with fatal pneumonia. We thoroughly characterized the pathological changes in the infected individuals and show that nidovirus infection is associated with marked epithelial proliferation in the respiratory tract. We speculate that this and the associated excess mucus production can lead to the animals' death by inhibiting normal gas exchange in the lungs. The virus was predominantly detected in the respiratory tract, which renders transmission via the respiratory route likely. Nidoviruses cause sudden outbreaks with high rates of mortality in breeding collections, and most affected snakes die without prior clinical signs. These findings, together with those of other groups, indicate that nidoviruses are a likely cause of severe pneumonia in pythons.

Molecular characterization of Sarcocystis spp. in intestine mucosal scrapings and fecal samples of Pampas fox (Lycalopex gymnocercus)

Sarcocystis spp. are obligatory intracellular protozoan parasites which can infect humans and animals. Most of Sarcocystis species were identified based on the detection of muscle cysts in different intermediate hosts (IH). Regarding to natural infection in definitive host, there are few reports which have reached to determining species of Sarcocystis. The present work was aimed to studying the occurrence of Sarcocystis spp. (oocysts and sporocysts) in mucosal scrapings of small intestine and fecal samples of one the most abundant wild canids from South America, Lycalopex gymnocercus (Pampas fox), and to identify the Sarcocystis spp. using molecular tools. A total of 131 free-living L. gymnocercus were sampled in rural areas located in several departments from Buenos Aires province, Argentina. Fecal samples from all the animals and 33 small intestines were analyzed. Fecal and mucosal scrapings samples were analyzed by sugar flotation method and once oocysts or sporocysts were detected, sedimentation was performed and DNA extracted with a commercial kit. A PCR was conducted using primers targeting a fragment of the 18S rRNA gene and the amplicons were purified and sequenced. Of the total Pampas foxes analyzed, 23 (17.6%) had Sarcocystis spp. oocysts/sporocysts in fecal and/or mucosal samples. Sarcocystis spp. sporocysts were detected in 13.0% (17/131) of fecal samples and in 39.4% (13/33) of mucosal samples by the initial sugar flotation. Twenty one L. gymnocercus samples were processed by DNA extraction and PCR. Molecular identification of Sarcocystis spp. infection was successfully achieved in 14 foxes and was distributed as follows: 4.6% S. cruzi (6/131), 3.8% Sarcocystis spp. using birds as IH (S. albifronsi and S. anasi among others, 5/131), 0.8% S. tenella (1/131) and 1.5% (2/131) with low homology (97%) with S. miescheriana. In one fecal sample with spherical oocysts, the sequencing results showed a 100% sequence identity with Hammondia heydorni. The results show that the mucosal scrapings are the eligible sample to identify prevalence and to proceed with species identification. Lycalopex gymnocercus is suggested as definitive host for S. cruzi, S. tenella and probably various Sarcocystis spp. using birds as intermediate hosts as well as for H. heydorni.

Sarcocystis masoni, n. sp. (Apicomplexa: Sarcocystidae), and redescription of Sarcocystis aucheniae from llama (Lama glama), guanaco (Lama guanicoe) and alpaca (Vicugna pacos)

There is considerable confusion concerning the species of Sarcocystis in South American camelids (SAC). Several species names have been used; however, proper descriptions are lacking. In the present paper, we redescribe the macroscopic sarcocyst forming Sarcocystis aucheniae and describe and propose a new name, Sarcocystis masoni for the microscopic sarcocyst forming species. Muscles samples were obtained from llamas (Lama glama) and guanacos (Lama guanicoe) from Argentina and from alpacas (Vicugna pacos) and llamas from Peru. Individual sarcocysts were processed by optical and electron microscopy, and molecular studies. Microscopic sarcocysts of S. masoni were up to 800 µm long and 35–95 µm wide, the sarcocyst wall was 2·5–3·5 µm thick, and had conical to cylindrical villar protrusions (vp) with several microtubules. Each vp had 11 or more rows of knob-like projections. Seven 18S rRNA gene sequences obtained from sarcocysts revealed 95–96% identity with other Sarcocystis spp. sequences reported in the GenBank. Sarcocysts of S. aucheniae were macroscopic, up to 1·2 cm long and surrounded by a dense and laminar 50 µm thick secondary cyst wall. The sarcocyst wall was up to 10 µm thick, and had branched vp, appearing like cauliflower. Comparison of the 11 sequences obtained from individual macroscopic cysts evidenced a 98–99% of sequence homology with other S. aucheniae sequences. In conclusion, 2 morphologically and molecularly different Sarcocystis species, S. masoni (microscopic cysts) and S. aucheniae (macroscopic cysts), were identified affecting different SAC from Argentina and Peru.

Molecular identification of Sarcocystis spp. in foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) from Germany

More than 200 Sarcocystis spp. have been named and most of them appear to be involved in a particular predator-prey cycle. Among canids, the European fox (Vulpes vulpes) and the raccoon dog (Nyctereutes procyonoides) are widely distributed in Europe and probably play an important role as definitive hosts in the epidemiology of Sarcocystis spp. infections. A total of 50 small intestines from foxes and 38 from raccoon dogs were sampled in the Federal State of Brandenburg, Germany. Mucosal scrapings were collected and analyzed by sugar flotation and when oocysts or sporocysts were detected, an overnight sedimentation was performed and DNA extracted with a commercial kit. A PCR was conducted using primers targeting a fragment of the 18S rRNA gene (with a size of approximately 850 bp) and the amplicons were purified and sequenced. Samples with an inconclusive sequencing were cloned into plasmids and ≥ 3 plasmids from each amplicon were sequenced. Sarcocystis spp. oocysts/sporocysts were detected in 38% (19/50) of fox and 52.6% (20/38) of raccoon dog samples. Sequencing analysis of amplicons from oocyst DNA revealed mixed infections in 9 fox and 5 raccoon dog samples. In the fox samples, the most often identified Sarcocystis spp. were S. tenella or S. capracanis (10.0%); S. miescheriana (8.0%) and S. gracilis (8.0%) followed by Sarcocystis spp., which use birds as intermediate hosts (6.0%), and S. capreolicanis (4.0%). In the raccoon dog samples, sequences with a ≥99% identity with the following species were detected: S. miescheriana (18.4%), S. gracilis (13.1%), Sarcocystis spp. using birds as IH (10.5%), S. tenella or S.capracanis (2.6%) and S. capreolicanis (2.6%). The estimated prevalence of Sarcocystis spp. infections determined using mucosal scrapings was higher than in related studies performed by analyzing faecal samples. The methodology of 18S rRNA gene amplification, cloning and sequencing is suitable to identify mixed infections with Sarcocystis spp. and to gather information on potential definitive hosts of these parasite species.

Diagnosis of gastrointestinal parasites in reptiles: comparison of two coprological methods

Background

Exotic reptiles have become increasingly common domestic pets worldwide and are well known to be carriers of different parasites including some with zoonotic potential. The need of accurate diagnosis of gastrointestinal endoparasite infections in domestic reptiles is therefore essential, not only for the well-being of captive reptiles but also for the owners. Here, two different approaches for the detection of parasite stages in reptile faeces were compared: a combination of native and iodine stained direct smears together with a flotation technique (CNF) versus the standard SAF-method.

Results

A total of 59 different reptile faeces (20 lizards, 22 snakes, 17 tortoises) were coprologically analyzed by the two methods for the presence of endoparasites. Analyzed reptile faecal samples contained a broad spectrum of parasites (total occurence 93.2%, n = 55) including different species of nematodes (55.9%, n = 33), trematodes (15.3%, n = 9), pentastomids (3.4%, n = 2) and protozoans (47.5%, n = 28). Associations between the performances of both methods to detect selected single parasite stages or groups of such were evaluated by Fisher's exact test and marginal homogeneity was tested by the McNemar test. In 88.1% of all examined samples (n = 52, 95% confidence interval [CI] = 77.1 - 95.1%) the two diagnostic methods rendered differing results, and the McNemar test for paired observations showed highly significant differences of the detection frequency (P < 0.0001).

Conclusion

The combination of direct smears/flotation proved superior in the detection of flagellates trophozoites, coccidian oocysts and nematode eggs, especially those of oxyurids. SAF-technique was superior in detecting larval stages and trematode eggs, but this advantage failed to be statistically significant (P = 0.13). Therefore, CNF is the recommended method for routine faecal examination of captive reptiles while the SAF-technique is advisable as additional measure particularly for wild caught animals and individuals which are to be introduced into captive collections.