Phylogenetic analysis of Sarcocystis nesbitti (Coccidia: Sarcocystidae) suggests a snake as its probable definitive host

Tian, Mingyi; Yuan-xiao, Chen; Wu, Lanou; Rosenthal, Benjamin M.; Liu, Xu; He, Yongshu; Dunams, Detiger; Cui, Liwang; Zhou, Yang

doi:10.1016/j.vetpar.2011.07.034

Cited by 30 publications

(38 citation statements)

References 24 publications

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“…Another report also identified a patient with sarcocysts in the temporalis muscle and another with sarcocysts in a leg muscle, for which DNA sequences matched 100% of those for S. nesbitti in the clade with S. atheridis (25). Still another study (27) reported the same 18S rDNA findings as those reported by AbuBakar et al (25) and Tian et al (34). The 18S rDNA sequence from the muscle biopsy specimen of a patient who had visited Tioman Island in Malaysia also showed 100% homology with the S. nesbitti gene sequence reported under GenBank accession number HF544323 (28).…”

Section: Species Infecting Humansmentioning

confidence: 61%

“…This suggested that a final host for S. nesbitti might be a snake. PCR evidence of Sarcocystis was found in feces from a cobra (26); the 18S rDNA sequence clustered with Sarcocystis sequences from other snakes and with the two S. nesbitti sequences obtained from M. fascicularis by Tian et al (34). Three reports from the Pangkor Island outbreak in Malaysia reported similar findings.…”

Section: Species Infecting Humansmentioning

confidence: 63%

“…Sarcocysts in muscles from M. fascicularis identified as S. nesbitti by Yang et al (33) were later examined by molecular methods (34), and 18S rDNA sequence data from two sarcocysts placed this species in a cluster with S. atheridis and S. singaporensis, species with rodent intermediate hosts and snake definitive hosts. This suggested that a final host for S. nesbitti might be a snake.…”

Section: Species Infecting Humansmentioning

confidence: 99%

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Human Infections with Sarcocystis Species

2015

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SUMMARY Recurrent outbreaks of muscular sarcocystosis among tourists visiting islands in Malaysia have focused international attention on sarcocystosis, a disease once considered rare in humans. Sarcocystis species require two hosts, definitive and intermediate, to complete their life cycle. Humans can serve as definitive hosts, with intestinal sarcocystosis for two species acquired from eating undercooked meat: Sarcocystis hominis , from beef, and Sarcocystis suihominis , from pork. Symptoms such as nausea, stomachache, and diarrhea vary widely depending on the number of cysts ingested but appear more severe with pork than with beef. Humans serve as intermediate hosts for Sarcocystis nesbitti , a species with a reptilian definitive host, and possibly other unidentified species, acquired by ingesting sporocysts from feces-contaminated food or water and the environment; infections have an early phase of development in vascular endothelium, with illness that is difficult to diagnose; clinical signs include fever, headache, and myalgia. Subsequent development of intramuscular cysts is characterized by myositis. Presumptive diagnosis based on travel history to tropical regions, elevated serum enzyme levels, and eosinophilia is confirmed by finding sarcocysts in muscle biopsy specimens. There is no vaccine or confirmed effective antiparasitic drug for muscular sarcocystosis, but anti-inflammatory drugs may reduce symptoms. Prevention strategies are also discussed.

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Section: Species Infecting Humansmentioning

confidence: 61%

Section: Species Infecting Humansmentioning

confidence: 63%

Section: Species Infecting Humansmentioning

confidence: 99%

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Human Infections with Sarcocystis Species

2015

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“…A phylogenetic tree based on 18S rDNA sequences distinctly shows that S. nesbitti MAL-1 and MAL-3 form a cluster with Sarcocystis sp. MAL-2, S. nesbitti isolates 1 and 2 found in monkey, 7 and other Sarcocystis species such as S. atheridis and Sarcocystis sp. U97524 for which snakes are definitive hosts (Figure 2).…”

mentioning

confidence: 99%

“…5 A BLAST result indicated that these sequences share 99% homology with S. nesbitti found in the muscle of M. fascicularis from Yunnan Province, China. 7 To investigate the possibility that snakes may be a definitive host for S. nesbitti, 7 snake feces were collected from several locations in Malaysia, including Pangkor Island. Exhaustive efforts were made to look for oocysts and/or sporocysts in these feces, including using the fecal concentration method, but none were found.…”

mentioning

confidence: 99%

Sarcocystis nesbitti Infection in Human Skeletal Muscle: Possible Transmission from Snakes

Lau¹,

Chang²,

Tan³

et al. 2014

The American Society of Tropical Medicine and Hygiene

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Abstract. Sarcocystis nesbitti is an intracellular protozoan parasite found as sarcocysts within muscle fibers of intermediate hosts (monkey and baboon). The definitive host is suspected to be the snake. We report two cases from a larger cohort of 89 patients who had fever, headache, and generalized myalgia after a trip to Pangkor Island, Malaysia. Sarcocysts were detected in skeletal muscle biopsy specimens by light and electron microscopy from these two patients. DNA sequencing based on the 18S ribosomal DNA region identified the Sarcocystis species as S. nesbitti. We also identified S. nesbitti sequences in the stools of a snake (Naja naja). Phylogenetic analysis showed that these sequences form a cluster with most of the other known Sarcocystis species for which the snake is a definitive host. We believe these two patients were likely to have symptomatic acute muscular sarcocystosis after S. nesbitti infection that may have originated from snakes.Sarcocystis species are an intracellular protozoan with a life cycle based on a prey-predator relationship in which various animal species serve as either intermediate or definitive hosts, respectively. Asexual development occurs in the intermediate host after ingestion of sporocysts produced by the definitive host and excreted in the feces. Ingestion of sarcocysts found in the muscles of the intermediate host by the predator definitive host completes the life cycle.1 Humans serve as the definitive hosts for Sarcocystis hominis and S. suihominis after eating improperly cooked, sarcocyst-infected meat from intermediate hosts (cattle and pigs, respectively). Furthermore, humans can also serve as accidental intermediate hosts for some Sarcocystis species of hitherto unknown origin. In these cases, it is assumed that humans became infected through food or drinks contaminated by sporocysts, resulting in skeletal muscle sarcocystosis. Human sarcocystosis is reported to be widely distributed. 361

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