Schistosoma malayensis

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Schistosoma malayensis
Schistosoma malayensis in liver granuloma.jpg
Scientific classification
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Trematoda
Subclass: Digenea
Order: Stringeiformes
Genus: Schistosoma
Species: S. malayensis
Binomial name
Schistosoma malayensis
Greer, Ow-Yang & Yong, 1988

Schistosoma malayensis is a schistome parasite. It was first described in 1988 in Peninsular Malaysia and appears to be a zooenotic infection.[1] The species is named after the country of Malaysia. The natural vertebrate host is van Müller's rat (Rattus muelleri). The intermediate hosts are aquatic snails, Robertsiella kaporenisis. Among Robertsiella kaporenisis are two other Roberstiella species.[2]

Among humans exposed to this parasite the lifetime incidence appears to be 5-10%.[3] The symptoms are unclear, because the symptoms have never been reported. The disease has been little studied and it is currently considered to be a relatively minor public health problem.

Taxonomy[edit]

Schistosoma malayensis is a member within the genus japonicum. It is also seen as closely related to Shistosoma mekongi.[2]

Morphology of adult[edit]

Size is the only morphological difference compared to it's natural host possibly due to host-induced variation. The adult S. malayensis is typically smaller than S. mekongi and S. japonicum.[4]

Epidemiology[edit]

Serologic surveys for schistosomiasis due to S. malayensis indicate of 3.9% prevalence in rural populations. [5] It was unsuccessful at adapting to human host. Rodents infected are often found near snail habitats. [6] Person is most likely to become effected while fishing, canoeing on small streams. Although infections in humans are unlikely and are considered rare.

Genome[edit]

The eggs are often found embedded in dense fibrous tissue. The eggs of S. malayensis are thin-walled, yellowish shell. Eggs contain miracidial cells. Size of an egg is approximately 50 μm long × 28 μm wide. The ova is not operculated and had no bipolar plugs and the thin covering was not striated. [7]


Intermediate Host[edit]

Freshwater snail (Robertsiella sp.) acts as an intermediate host that infects humans and other mammals in Malaysia. This species is known to be located in limestone areas in the foothills of the mountain chains of Kedah and Perak States, West Malaysia. It also appears to serve as a likely intermediate host for the parasitic blood fluke Schistosoma malayensis. The species are caenogastropod snails of the family Pomatiopsidae. [8]

Definitive Host[edit]

The final or definitive mammalian hosts include Rattus muelleri and R. tiomanicus. Usually the definitive hosts are often found in river banks. There is a possibility that infected rodent feces could contaminate the water with schistosome eggs. [9]

References[edit]

  1. ^ Greer G.J., Ow-Yang C.K., Yong H.S.(1988) Schistosoma malayensis n. sp.: a Schistosoma japonicum-complex schistosome from Peninsular Malaysia. J. Parasitol. 74(3):471-48
  2. ^ a b "Schistosoma malayensis". Farlex Partner Medical Dictionary. Farlex, Inc. Retrieved 21 April 2015. 
  3. ^ Sagin D.D., Ismail G., Fui J.N., Jok J.J.(2001) Schistosomiasis malayensis-like infection among the Penan and other interior tribes (Orang Ulu) in upper Rejang River Basin Sarawak Malaysia. Southeast Asian J. Trop. Med. Public Health 32(1):27-32
  4. ^ Greer, George (1988). "Schistosoma malayensis n. sp.: a Schistosoma japonicum-complex schistosome from Peninsular Malaysia.". J. Parasitol 74 (3): 471–480. 
  5. ^ Latif, B; Heo, CC; Razuin, R; Shamalaa, DV; Tappe, D (August 2013). "Autochthonous Human Schistosomiasis, Malaysia". Emerging Infectious Disease Journal 19 (8). doi:10.3201/eid1908.121710. Retrieved 22 April 2015. 
  6. ^ Latif, B; Heo, CC; Razuin, R; Shamalaa, DV; Tappe, D (August 2013). "Autochthonous Human Schistosomiasis, Malaysia". Emerging Infectious Disease Journal 19 (8). doi:10.3201/eid1908.121710. Retrieved 22 April 2015. 
  7. ^ Latif, B; Heo, CC; Razuin, R; Shamalaa, DV; Tappe, D (August 2013). "Autochthonous Human Schistosomiasis, Malaysia". Emerging Infectious Disease Journal 19 (8). doi:10.3201/eid1908.121710. Retrieved 22 April 2015. 
  8. ^ Attwood, S. W.; Lokman, H. S.; Ong, K. Y. (November 2005). "Robertsiella Silvicola, A New Species Of Triculine Snail (Caenogastropoda: Pomatiopsidae) From Peninsular Malaysia, Intermediate Host Of Schistosoma Malayensis (Trematoda: Digenea)" (PDF). Journal of Molluscan Studies 71 (4): 379–391. doi:10.1093/mollus/eyi040. Retrieved 22 April 2015. 
  9. ^ Latif, B; Heo, CC; Razuin, R; Shamalaa, DV; Tappe, D (August 2013). "Autochthonous Human Schistosomiasis, Malaysia". Emerging Infectious Disease Journal 19 (8). doi:10.3201/eid1908.121710. Retrieved 22 April 2015.