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. 2014 Dec 20;40(3):971–975. doi: 10.1007/s12639-014-0617-1

First record of protozoan parasites, Tetrahymena rostrata and Callimastix equi from the edible oyster in Sundarbans region of West Bengal, India

Tanima Biswas 1, Probir Kumar Bandyopadhyay 1,✉
PMCID: PMC4996230  PMID: 27605821

Abstract

Several protozoan parasites have been found infecting the edible oysters, hence deteriorating the meat quality. Protozoan parasites such as, Tetrahymena rostrata and Callimastix equi infested the edible oyster in Sundarbans region, West Bengal, India, are first record from this region. Due to filter feeding habit of the organisms, oysters provides excellent ecological services in regard to efficient cleaning of infectious agents from surrounding water as a potential measure to improve water quality. However, these environmental benefits are associated with public heath risks from contaminated oysters intended for human consumption.

Keywords: Tetrahymena rostrata, Callimastix equi, Protozoan parasite, Edible oyster, West Bengal

Introduction

Sundarbans region of West Bengal coast is highly diverse and ecologically important as it supports large number of protozoans, annelids, molluscs, crabs and shrimps, fin fishes, reptiles and mammals. These habitats play an important role in the socio-economical interest of the coastal people as they can provide jobs in rural areas in agriculture, forestry, fisheries and the tourism industry. The edible oysters are capable of tolerating a wide range of salinity and heavy metal pollution (Biswas et al. 2013). They contribute a great tonnage of animal protein in the food market (Korringa 1976). Its tender flesh forms a cheaper, nutritious and easily digestible food source. The oysters are known to show large variations in their meat quality depending on their physiological conditions and associated environmental factors (Durve 1964). Several protozoan parasites have been found infecting the edible oyster, hence deteriorating the meat quality. Parasites have evolved numerous ways to adapt to the dramatic changes in environment experienced through out their life cycle. According to Kinne (1983), the main biologic agents causing diseases in marine bivalve molluscs involve viruses, bacteria, fungi, protists, digenean trematodes, polychaetes and copepods. But the present study concentrated on the identification of protozoan parasites infecting edible oyster such as Crassostrea gryphoides and Saccostrea cucullata in Sundarbans region, West Bengal, India.

Materials and methods

A systematic monitoring practice was undertaken for a period of 3 years during 2009–2012. Samples of oyster were collected randomly during low tide from the two selected study sites namely, Frasergunj and Kaikhali of Sundarbans region during the study period. Stainless steel hammer and rod were used to separate oysters from their surrounding cliffs. Both C. gryphoides and S. cucullata were collected from Frasergunj, C. gryphoides only were collected from Kaikhali.

In the laboratory, the shell of the oyster were opened with a fine knife. One of the first stages of examination was to observe the size and colour of the organs such as the adductor muscle, digestive gland, gill, mantle, labial palps, contents of stomach and intestines minutely. The smear materials were scrapped out from adductor muscle, digestive gland, gill, mantle, labial palps and other visceral tissues from oysters and placed on glass slides in 0.6 % saline and observed under the microscope for examination of parasites. Thin and uniform smears were drawn on slide without allowing them to dry. Semidried smears containing the protozoans were stained with Giemsa.

Measurements of the parasites were taken with the aid of a calibrated ocular micrometer. All measurements are presented in μm. Drawings were made on stained material with the aid of a mirror type camera lucida. Photographs were taken with Olympus phase contrast microscope fitted with Olympus digital camera.

Results and discussion

Molluscan shellfish such as oysters, mussels, cockles and clams can concentrate pathogenic microorganisms as a result of filtering large volumes of water (Trollope 1984). Incidences of various infectious protozoan parasites have been observed and indentified by their characteristic features from edible oyster during the course of study. Six types of protozoan parasites such as Cristigera crassostrae, C. susmai, Tetrahymena rostrata, Cryptosporidium sp., Peneroplis sp. and Callimastix equi infection (Biswas and Bandyopadhyay 2013a, b; Biswas et al. 2011) were discovered from which two types of protozoan parasites T. rostrata and C. equi have been recorded for the first time from C. gryphoides and S. cucullata from Kaikhali and Frasergunj of South 24 Parganas of West Bengal, India.

Tetrahymena rostrata

Site of infection

Tetrahymena rostrata are isolated from the mantle, gill and labial palp of C.gryphoides and S. cucullata.

Symptoms

Infections of T. rostrata are accompanied by yellow discolouration and extensive lesions in the gills and mantle. Gills of infested oysters are covered with cysts of different sizes and colours. A brown scar often occurs on the shell, adjacent to abscess on the mantle surface. Heavy lesions appear as a swollen mantle edge or nodules on the mantle though these lesions are not unique to T.rostrata infection.

Systematic position

Kingdm Animalia
Phylum Ciliophora
Class Ciliatea
Subclass Rhabdophorina
Order Hymenostomatida
Suborder Tetrahymenina
Family Tetrahymenidae
Genus Tetrahymena
Species rostrata
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Morphology

Relatively slender body, narrowing anteriorly with slightly curved pointed end. Body contains food vacuoles, terminal contractile vacuole, spherical macronucleus placed more or less centrally and ovoid micronucleus (Fig. 1a, b). Measurements are given in Table 1.

Fig. 1.

Fig. 1

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a Phase contrast microscopic photograph of Tetrahymena rostrata b Camera lucida drawing of Tetrahymena rostrata c Phase contrast microscopic photograph of Callimastix equi d Camera lucida drawing of Callimastix equi

Table 1.

Morphometric parameters of Tetrahymena rostrata found from edible oyster

Parameters Normal range (μm) Mean ± SD (μm) CV % SE
Length of the body 39.78–26.52 33.677 ± 4.223 12.541 1.336
Width of the body 19.89–8.16 12.376 ± 5.237 42.317 1.656
Length of the macronucleus 6.63–4.42 5.372 ± 1.021 18.999 0.323
Width of the macronucleus 6.63–2.21 5.049 ± 1.372 27.171 0.434
Diameter of the micronucleus 4.80–2.21 3.429 ± 1.292 37.691 0.409
Distance of the macronucleus from the anterior end 13.26–7.14 10.540 ± 2.742 26.018 0.867
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Callimastix equi

Site of infection

Callimastix equi are isolated from the mantle and labial palp of the oysters C. gryphoides and S. cucullata.

Symptoms

The gross signs of include the visceral tissues losing their pigmentation and become pale yellow. In some cases the mantle becomes translucent and shell growth may cease. The mantle and labial palps become brownish to blackish in colour that can lead to ulcerations in such areas.

Systematic position

Kingdom Animalia
Phylum Plasmodroma/protozoa
Class Mastigophora
Subclass Zoomastigina
Order Polymastigina
Suborder Monomonadina
Family Callimastigidae
Genus Callimastix
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Species equi

Morphology

Callimastix equi is morphologically distinct from the other flagellate protozoa, with characteristic movements. It is ovoid with compact nucleus placed at central or anterior of the body. A tuft of long flagella are present near anterior end and vibrate in unison (Fig. 1c, d). Body measurements are given in Table 2.

Table 2.

Morphometric parameters of Callimastix equi found from edible oyster

Parameters Normal range (μm) Mean ± SD (μm) CV % SE
Length of the body 10.20–8.16 8.874 ± 0.840 9.463 0.266
Width of the body 6.12–4.08 4.794 ± 0.840 17.516 0.266
Diameter of the nucleus 2.04–1.02 1.224 ± 0.430 35.136 0.136
Length of flagella 8.16–6.12 6.732 ± 0.713 10.594 0.226
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In Protozoa, comparatively highly complicated organisms are represented by numerous ciliates which are a diverse and successful group of protozoan parasites. Ciliates, T. rostrata have been isolated and identified during present study. The parasite was first described as Paraglaucoma rostrata by Kahl (1926). Corliss (1952) transferred this species to the genus Tetrahymena as T. rostrata on the basis of its capacity to form both reproductive and resting cysts, to exhibit edaphic and parasitic forms and to possess histophagous or parasitic habits, Corliss (1952) established it as the ‘type’ of the rostrata complex. Hauschka and Doll (1944) observed Paraglaucoma present in the gastro-vascular cavities of Hydra americana and its complete immunity to Hydra digestive enzymes strongly suggested its facultative parasitism. In culture, the form of T. rostrata from Deroceras reticulatum appears to be morphologically identical with a strain (NZ-4) recovered from soil of New Zealand (Kozloff 1957). Brooks (1968) demonstrated that T. rostrata enters into the slug host through dorsal integumentary pouch.

Tetrahymena (Paraglaucoma) rostrata (Kahl 1926; Corliss 1952) occurs commonly in litter and occasionally in soil. It has previously been recorded from moss. In nature it feeds on cytolyzed or moribund tissue but in presence of peptone it feeds on bacteria and flagellates. The ciliate is an obligate histophage and a facultative parasite of enchytraeid worms which it infects through degenerate setal follicles (Stout 1954). Ciliate infections in certain other invertebrates are also characterized by rapid pathogenicity (Stout 1954). It may also infect accidentally injured worms. From the point of view of food, it depends on the turnover of microbial life and the frequent incidence of dead worms, rotifers, nematodes, tardigrades or even dead ciliates, as much as the incidence of living enchytraeids which in nature are probably only occasionally parasitized (Stout 1958). The ciliates are attracted by histolysis and by peptone. Resistant cysts are formed regularly in absence of food and encystment appears to be accelerated by crowding. Excystment is readily obtained with hypotonic salt solution. Theront, trophont, tomont and tomite stages are recognizable in the life cycle (Stout 1954).

Callimastix cyclopis, was originally described as a protozoan a polyflagellate parasite of Cyclops (Weissenberg 1912). This organism had also been associated with Blastocladiales (Weissenberg 1950; Vavra and Joyon 1966). Whisler et al. (1972) demonstrated that Callimastix-like organisms were an alternate stage of the mosquito parasite Coelomomzyces psorophorae Couch, a member of the Blastocladiales. Subsequently, Vavra and Joyon (1966) concluded that C. cyclopsis was likely a fungus related to the chytrids (Phylum Chytridiomycota). Earle et al. (1950) found rumen protozoa, Callimastix frontalis in Florida dairy cattle.

C. equi was reported from the large intestine of the horse (Hsiung 1929). The length of this flagellate ranged from 12 to 18 μ, (mean14.4 μ), width from 7 to 10 μ, (mean 8.16 μ), length of the flagella from 25 to 30 μ. Its nucleus was centrally located and had a large karyosome.

During the present study, heterogenecity in T. rostrata and C. equi has been observed as they are present in the edible oyster, C. gryphoides and S. cucullata collected from Kaikhali and Frasergunj of South 24 Parganas. Marine organisms serve as hosts for a diversity of parasites and pathogens. Dogiel (1964) suggested that ‘more or less a definitive number of species is characteristic of different animal host groups differing perhaps from one part of their distribution range to another’ in explaining patterns and processes influencing the number of parasite species a host can support. It is especially undesirable that any species should suffer from the regions of diseases. Parasites that alter the phenotype of their host can have several indirect effects on the whole community. When a host species constitutes an important component of habitat structure, manipulative parasites altering the characteristics of host populations could have a variety of indirect effects on other species. However, ecological consequences of phenotypic alterations induced by parasites remain largely unexplored. Humans can be intermediate, paratenic or accidental hosts. While the transmissive stages of some of these zoonoses can be transmitted directly or through contaminated water and foods, parasitic diseases can pose major threats to animal populations and have serious economic impacts on host health, therefore, research into host parasitology eology is essential and critical (Cleaveland et al. 2002; Galvani 2003). Diseases of bivalve molluscs are noteworthy not only for their impact on population dynamics, especially of key commercial species, but also for characteristics that separate them from typical diseases affecting mammals and fish. Most described bivalve diseases are of protozoan origin (Bower et al. 1994) and transmission is commonly via the water column since most adult hosts are immobile. Transmission occurs over large distances and can be rapid under favorable climatic conditions, resulting in rapid parasite proliferation and elevated adult mortalities (Andrews and Wood 1967; Lafferty and Kuris 1993; Burreson and Ragone-Calvo 1996; Ford and Tripp 1996). Throughout the region in which the disease organism can exist, most hosts are exposed to the disease organism and probably become infected, even though infections may be undetected (Bushek et al. 1994; Stokes et al. 1995; Culloty et al. 2003). The spread and intensification of infections can result in epizootics, which are disease epidemics in nonhuman animal populations. Parasite-induced alterations in host phenotype have been frequently reported in a wide range of protozoan and metazoan parasites with complex life cycles (Combes 1991; Poulin 1998). Unfortunately, the aetiology of diseases is poorly understood and warrants a deeper study.

Although most of the organisms living in intertidal habitats are hosts for parasites (Thomas et al. 1997), ecologists in general paid little attention to the possible influence of parasites in structuring intertidal communities. The study of parasites and diseases affecting molluscs with economic interest is important both for the management of natural stock and for aquaculture. It could even be helpful for the sanitary evaluation for human consumption. However the knowledge on how host and parasites interact in natural systems remains limited and consequently, international bodies like the World Health Organization have advocated an increased study of host-parasite ecology in wild host populations (Real 1996; Schall and Pearson 2000).

Acknowledgments

One of the authors (TB) is thankful to the University of Kalyani for financial support in the form of a research scholarship to carry out this work. Sincere thanks are also due to Dr. Nelendu Jyoti Moitra and Avay Haldar of Ramkrishna Ashram Krishi Vigyan Kendra, Nimpith,South 24 Parganas, W.B. for their active cooperation.

References

  1. Andrews JD, Wood JL. Oyster mortality studies in Virginia. VI. History and distribution of Minchinianelsoni, a pathogen of oysters, in Virginia. Chesap Sci. 1967;8:1–13. doi: 10.2307/1350351. [DOI] [Google Scholar]
  2. Biswas T, Bandyopadhyay PK (2013a) First record of the genus Cryptosporidium sp. (Apicomplexa: Eucoccidiorida: Cryptosporidiidae) from the edible oyster in Sundarbans region, West Bengal, India. Proc Nat Conf Chal Bio Res Manag 189–193
  3. Biswas T, Bandyopadhyay PK (2013b) Prevalence of a protozoan parasite Cristigera sp. (Ciliophora:Ciliatea) from edible oysters (Mollusca:Bivalvia) of Sundarbans, West Bengal, India. J Parasit Dis. doi 10.1007/s12639-012-0230-0 [DOI] [PMC free article] [PubMed]
  4. Biswas T, Molla SH, Bandyopadhyay PK (2011) On the occurrence of a protozoan parasite from edible oysters of Sunderbans region of West Bengal. Proc 22nd Nat Cong Parasitol 315–318
  5. Biswas T, Bandyopadhyay PK, Chatterjee SN. Accumulation of cadmium, copper, lead, zinc and iron in the edible oyster, Saccostrea cucullata in coastal areas of West Bengal. Afr J Biotechnol. 2013;12(24):3872–3877. [Google Scholar]
  6. Bower SM, McGladdery SE, Price IM. Synopsis of infectious diseases and parasites of commercially exploited shellfish. Annu Rev Fish Dis. 1994;4:1–200. doi: 10.1016/0959-8030(94)90028-0. [DOI] [Google Scholar]
  7. Brooks WM. Tetrahymenid ciliates as parasites of the gray garden slug. Hilgardia. 1968;39:205–276. doi: 10.3733/hilg.v39n08p205. [DOI] [Google Scholar]
  8. Burreson EM, Ragone-Calvo LM. Epizootiology of Perkinsus marinus disease of oysters in Chesapeake Bay, with emphasis on data since 1985. J Shellfish Res. 1996;15:17–34. [Google Scholar]
  9. Bushek D, Ford SE, Allen SK. Evaluation of methods using Ray’s fluid thioglycollate medium for the diagnosis of Perkinsus marinus infection in the eastern oyster, Crassostrea virginica. Annu Rev Fish Dis. 1994;4:210–217. doi: 10.1016/0959-8030(94)90029-9. [DOI] [Google Scholar]
  10. Cleaveland S, Hess GR, Dobson AP, Laurenson KM, McCallum HI, Roberts MG, Woodroffe R, et al. The role of pathogens in biological conservation. In: Hudson PJ, Rizzoli A, Grenfell BT, Heesterbeek H, Dobson AP, et al., editors. The ecology of wildlife diseases. Oxford: Oxford University Press; 2002. pp. 139–150. [Google Scholar]
  11. Combes C. Ethological aspects of parasite transmission. Am Nat. 1991;138:866–880. doi: 10.1086/285257. [DOI] [Google Scholar]
  12. Corliss JO. Le cycle autogamique de Tetrahymena rostrata. C R Acad Sci. 1952;235:399–402. [PubMed] [Google Scholar]
  13. Culloty SC, Cronin MA, Mulcahy MF. Possible limitations of diagnostic methods recommended for the detection of the protistan, Bonamia ostrae in the European flat oyster, Ostrea edulis. Bull Eur Assoc Fish Pathol. 2003;23:67–71. [Google Scholar]
  14. Dogiel VA. General parasitology. Edinburgh: Oliver and Boyd; 1964. [Google Scholar]
  15. Durve VS. On the percentage edibility and the index of condition of the oyster Crassostrea gryphoides (Schlotheim) J Mar Biol Assoc India. 1964;6(1):128–135. [Google Scholar]
  16. Earle M, Uzzell E, Ruffin JJ, Becker RB. Rumen protozoa in florida dairy cattle. Am Midl Nat. 1950;43(2):480–483. doi: 10.2307/2421915. [DOI] [Google Scholar]
  17. Ford SE, Tripp ME. Diseases and defense mechanisms. In: Kennedy VS, Newell RIE, Eble AF, editors. The Eastern Oyster Crassostrea virginica. College Park, Maryland: Maryland Sea Grant; 1996. pp. 581–660. [Google Scholar]
  18. Galvani AP. Epidemiology meets evolutionary ecology. Trends Ecol Evol. 2003;18:132–139. doi: 10.1016/S0169-5347(02)00050-2. [DOI] [Google Scholar]
  19. Hauschka TS, Doll RB. Paraglaucoma sp., a facultative parasite of coelenterates. J Parasitol. 1944;30(3):198–199. doi: 10.2307/3272801. [DOI] [Google Scholar]
  20. Hsiung TS. A survey of the protozoan fauna of the large intestine of the horse. Soc Proc J Parasitol. 1929;16(2):96–108. [Google Scholar]
  21. Kahl A. Neue und wenig bekannte formen der holotrichen und heterotrichen ciliaten. Arch Protistenkd. 1926;55:197–438. [Google Scholar]
  22. Kinne O. Diseases of marine animals. Hamburg: Biologische Anstalt Helgoland; 1983. [Google Scholar]
  23. Korringa P. Farming of the Cupped oyster of the genus Crassostrea. New York: Elsevier Sc Pub Co; 1976. pp. 1–123. [Google Scholar]
  24. Kozloff EN. A species of Tetrahymena parasitic in the renal organ of the slug Deroceras reticulatum. J Eukaryo Microbiol. 1957;4:75–79. [Google Scholar]
  25. Lafferty KD, Kuris AM. Mass mortality of abalone Haliotis cracherodii on the California channel Islands: tests of epidemiological hypothesis. Mar Ecol Prog Ser. 1993;96:239–248. doi: 10.3354/meps096239. [DOI] [Google Scholar]
  26. Poulin R. Evolutionary ecology of parasites. London: Chapman and Hall; 1998. [Google Scholar]
  27. Real LA. Sustainability and the ecology of infectious disease. Bioscience. 1996;46:88–97. doi: 10.2307/1312811. [DOI] [Google Scholar]
  28. Schall JJ, Pearson AR. Body condition of a Puerto Rican anole, Anolis gundlachi: effect of a malaria parasite and weather variation. J Herpetol. 2000;34:489–491. doi: 10.2307/1565380. [DOI] [Google Scholar]
  29. Stokes NA, Siddall ME, Burreson EM. Detection of Haplosporidium nelsoni (Haplospodidia: Haplosporidiidae) in oysters by PCR amplification. Dis Aquat Org. 1995;23:145–152. doi: 10.3354/dao023145. [DOI] [Google Scholar]
  30. Stout JD. The ecology, life history and parasitism of Tetrahymena (Paraglaucoma) rostrata (Kahl) Corliss. J Protozool. 1954;1:211–215. doi: 10.1111/j.1550-7408.1954.tb00819.x. [DOI] [Google Scholar]
  31. Stout JD. Biological studies of some tussock grassland soils. N Z J Agricul Res. 1958;1:974–984. doi: 10.1080/00288233.1958.10422400. [DOI] [Google Scholar]
  32. Thomas F, Mete K, Helluy S, Santalla F, Verneau O, de Meefs T, Cezilly F, Renaud F. Hitch-hiker parasites or how to benefit from the strategy of another parasite. Evolution. 1997;51:1316–1318. doi: 10.1111/j.1558-5646.1997.tb03978.x. [DOI] [PubMed] [Google Scholar]
  33. Trollope DR. Use of molluscs to monitor bacteria in water. In: Grainger JM, Lynch JM, editors. Microbiological methods for environmental biotechnology. Society for applied bacteriology technical series number 19. London: Acad Press; 1984. pp. 393–409. [Google Scholar]
  34. Vavra J, Joyon L. Egtude sur la morphologie le cycle evolutif et la position systematique de Callimastixcyclopis Weissenberg 1912. Protistologica. 1966;2:5–13. [Google Scholar]
  35. Weissenberg R. Callimastix cyclopis, n. g., n. sp., ein geisseltragendes Protozoon aus dem Serum von Cyclops. Sitzungsber Ges Naturfr Freunde. 1912;5:299–305. [Google Scholar]
  36. Weissenberg R. The development and affinities of Callimastix cyclopis Weissenberg, a parasitic microorganism from the serum of Cyclops. Proc Amer Soc Protozool. 1950;1:4–5. [Google Scholar]
  37. Whisler HC, Shemanchuk JA, Travland LB. Germination of the resistant sporangia of Coelomomyces psorophorae. J Invertebr Pathol. 1972;19:139–147. doi: 10.1016/0022-2011(72)90200-5. [DOI] [Google Scholar]

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