Genetic diversity and pathogenicity of Blastocystis
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Department of Genetics, Faculty of Biology, University of Szczecin, Poland
Blastocystis is a unicellular, anaerobic protist which lives in the intestinal tract of diverse animals, including humans. It was found that the host specificity and the pathogenic potential of different isolates are correlated with sequence variations in the SSU-rRNA gene. Identification of the organism to the species level is still an unresolved challenge. Genetic diversity revisions have led to the identification of 17 subtypes (STs) within the Blastocystis genus, and 9 (ST1 to ST9) have been reported in humans with varying prevalence. Since the members of the genus revealed a large genetic diversity, several molecular modalities of subtyping methods have been developed. Numerous studies on conveying the pathogenic potential to the molecular subtypes are available, but they could not be compared or analysed with the different molecular techniques employed. The use of different approaches may give false positives during diagnosis and the possibility of missed infections. A review of recent scientific literature indicates that the development of PCR assays is needed for molecular epidemiology and for mixed infections in health and disease cohorts, and also to help identify sources of Blastocystis transmission to humans, as well as to identify potential animal and environmental reservoirs. This review summarizes some of the recent progress and improvements in Blastocystis research on genetic diversity, taxonomy, molecular epidemiology, pathogenicity and subtyping methods.
Bogumiła Skotarczak   
Department of Genetics, Faculty of Biology, University of Szczecin, Poland, Felczaka 3c, 71-412 Szczecin, Poland
1. Menounos PG, Spanakos G, Tegos N, Vassalos CM, Papadopoulou C, Vakalis NC. Direct detection of Blastocystis sp. in human faecal samples and subtype assignment using single strand conformational polymorphism and sequencing. Mol Cell Probes. 2008; 22(1): 24–29.
2. Alfellani MA, Stensvold CR, Vidal-Lapiedra A, Onuoha ES, Fagbenro-Beyioku AF, Clark CG. Variable geographic distribution of Blastocystis subtypes and its potential implications. Acta Trop. 2013a; 126: 11–18. doi:10.1016/j.actatropica.2012.12.011.
3. Alfellani MA, Taner-Mulla D, Jacob AS, Imeede CA, Yoshikawa H, Stensvold CR, Clark CG. Genetic diversity of Blastocystis in livestock and zoo animals. Protist. 2013b; 164: 497–509. doi:10.1016/j.protis.2013.05.003.
4. Leelayoova S, Siripattanapipong S, Thathaisong U, Naaglor T, Taamasri P, Piyaraj P, Mungthin M. Drinking water: a possible source of Blastocystis spp. subtype 1 infection in schoolchildren of a rural community in central Thailand. Am J Trop Med Hyg. 2008; 79(3): 401–406.
5. El Safadi D, Gaayeb L, Meloni D, Cian A, Poirier P, Wawrzyniak I, Delbac F, Dabboussi F, Delhaes L, Seck M, Hamze M, Riveau G, Viscogliosi E. Children of Senegal River Basin show the highest prevalence of Blastocystis sp. ever observed worldwide. BMC Infect Dis. 2014; 14: 164. doi: 10.1186/1471–2334–14–164.
6. Scanlan PD, Stensvold CR, Cotter PD. Development and application of a Blastocystis subtype-specific PCR assay reveals that mixed-subtype infections are common in a healthy human population. Appl Environ Microbiol. 2015; 81(12): 4071–4076. doi: 10.1128/AEM.00520–15.
7. Scanlan PD, Stensvold CR, Rajilić-Stojanović M, Heilig HG, De Vos WM, O’Toole PW, Cotter PD. The microbial eukaryote Blastocystis is a prevalent and diverse member of the healthy human gut microbiota. FEMS Microbiol Ecol. 2014; 90: 326–330. doi: 10.1111/1574-6941.12396.
8. Krogsgaard LR, Engsbro AL, Stensvold CR, Nielsen HV, Bytzer P. The prevalence of intestinal parasites is not greater among individuals with irritable bowel syndrome: a population-based case-control study. Clin Gastroenterol Hepatol. 2015; 13(3): 507–513. doi: 10.1016/j.cgh.2014.07.065.
9. Clark CG, van der Giezen M, Alfellani MA, Stensvold CR. Recent developments in Blastocystis research. Adv Parasitol. 2013; 82: 1–32. doi: 10.1016/B978–0–12–407706–5.00001–0.
10. Stensvold CR, Suresh GK, Tan KS, Thompson RC, Traub RJ, Viscogliosi E, Yoshikawa H, Clark CG.. Terminology for Blastocystis subtypes – a consensus. Trends Parasitol. 2007; 23: 93–96. doi: 10.1016/
11. Noel C, Dufernez F, Gerbod D, Edgcomb VP, Delgado-Viscogliosi P, Ho LC, Singh M, Wintjens R, Sogin ML, Capron M, Pierce R, Zenner L, Viscogliosi E. Molecular phylogenies of Blastocystis isolates from different hosts: implications for genetic diversity, identification of species, and zoonosis. J Clin Microbiol. 2005; 43: 348–355. doi: 10.1128/JCM.43.1.348-355.2005.
12. Stensvold CR. Blastocystis: genetic diversity and molecular methods for diagnosis and epidemiology. Trop Parasitol. 2013a; 3: 26–34. doi: 10.4103/2229-5070.113896.
13. Stensvold CR, Clark CG. Current status of Blastocystis: a personal view. Parasitol Int. 2016a; 65(6 Pt B): 763–771. doi: 10.1016/j.parint.2016.05.015.
14. Ramirez JD, Sánchez LV, Bautista DC, Corredor AF, Flórez AC, Stensvold CR. Blastocystis subtypes detected in humans and animals from Colombia. Infect Genet Evol. 2014; 22: 223–228. doi: 10.1016/j.meegid.2013.07.020.
15. Yoshikawa H, Wu Z, Kimata I, Iseki M, Ali IK, Hossain MB, Zaman V, Haque R, Takahashi Y. Polymerase chain reaction-based genotype classification among human Blastocystis hominis populations isolated from different countries. Parasitol Res. 2004; 92: 22–29. doi:10.1007/s00436-003-0995-2.
16. Yoshikawa H, Wu Z, Pandey K, Pandey BD, Sherchand JB, Yanagi T, Kanbara H. Molecular characterization of Blastocystis isolates from children and rhesus monkeys in Kathmandu, Nepal. Vet Parasitol. 2009; 160: 295–300. doi:10.1016/j.vetpar.2008.11.029.
17. Rivera WL. Phylogenetic analysis of Blastocystis isolates from animal and human hosts in the Philippines. Vet Parasitol 2008; 156: 178–182. doi:10.1016/j.vetpar.2008.06.001.
18. Stensvold CR, Alfellani MA, Nørskov–Lauritsen S, Prip K, Victory EL, Maddox C, Nielsen HV, Clark CG. Subtype distribution of Blastocystis isolates from synanthropic and zoo animals and identification of a new subtype. Int J Parasitol. 2009; 39: 473–479. doi: 10.1016/j.ijpara.2008.07.006.
19. Alfellani MA, Jacob AS, Perea NO, Krecek RC, Taner-Mulla D, Verweij JJ, Levecke B, Tannich E., Clark CG, Stensvold CR. Diversity and distribution of Blastocystis sp. subtypes in non-human primates. Parasitol. 2013c; 140: 966–971. doi: 10.1017/S0031182013000255.
20. Parkar U, Traub RJ, Vitali S, Elliot A, Levecke B, Robertson I, Geurden T, Steele J, Drake B, Thompson RC. Molecular characterization of Blastocystis isolates from zoo animals and their animal-keepers. Vet Parasitol. 2010; 169: 8–17. doi:10.1016/j.vetpar.2009.12.032.
21. Scicluna SM, Tawari B, Clark CG. DNA barcoding of Blastocystis. Protist. 2006; 157(1): 77–85. doi:10.1016/j.protis.2005.12.001.
22. Petrasova J, Uzlíková M, Kostka M, Petrželková KJ, Huffman MA, Modrý D. Diversity and host specificity of Blastocystis in syntopic primates on Rubondo Island, Tanzania. Int J Parasitol. 2011; 41(11): 1113–1120. doi: 10.1016/j.ijpara.2011.06.010.
23. Santin M, Gomez-Munoz MT, Solano-Aguilar G, Fayer R. Development of a new PCR protocol to detect and subtype Blastocystis spp. from humans and animals. Parasitol Res. 2011; 109: 205–212. doi: 10.1007/s00436–010–2244–9.
24. Yoshikawa H, Koyama Y, Tsuchiya E, Takami K. Blastocystis phylogeny among various isolates from humans to insects. Parasitol Int. 2016; 65(6 Pt B): 750–759. doi: 10.1016/j.parint.2016.04.004.
25. Nagel R, Cuttell L, Stensvold CR, Mills PC, Bielefeldt-Ohmann H, Traub RJ. Blastocystis subtypes in symptomatic and asymptomatic family members and pets and response to therapy. Intern Med J. 2012; 42: 1187–1195. doi: 10.1111/j.1445–5994.2011.02626.x.
26. Wang W, Owen H, Traub RJ, Cuttell L, Inpankaew T, Bielefeldt-Ohmann H. Molecular epidemiology of Blastocystis in pigs and their in-contact humans in Southeast Queensland, Australia, and Cambodia. Vet Parasitol. 2014; 203: 264–269. doi: 10.1016/j.vetpar.2014.04.006.
27. Iguchi A, Ebisu A, Nagata S, Saitou Y, Yoshikawa H, Iwatani S, et al. Infectivity of different genotypes of human Blastocystis hominis isolates in chickens and rats. Parasitol Int. 2007; 56: 107–112.
28. Ajjampur SSR, Png CW, Chia WN, Zhang Y, Tan KSW. Ex vivo and in vivo mice models to study Blastocystis spp. adhesion, colonization and pathology: closer to proving Koch’s postulates. PLoS One 2016; 11: e0160458. doi: 10.1371/journal.pone.0160458.
29. Cian A, El Safadi D, Osman M, Moriniere R, Gantois N, Benamrouz-Vanneste S, Delgado-Viscogliosi P, Guyot K, Li L-L, Monchy S, Noël C, Poirier P, Nourrisson C, Wawrzyniak I, Delbac F, Bosc S, Chabé M, Petit T, Certad G, Viscogliosi E. Molecular epidemiology of Blastocystis sp. in various animal groups from two French zoos and evaluation of potential zoonotic risk. PLoS One 2017; 12(1): e0169659. doi: 10.1371/journal.pone.0169659.
30. Yan Y, Su S, Lai R, Liao H, Ye J, Li X, Luo X, Chen G. Genetic variability of Blastocystis hominis isolates in China. Parasitol Res. 2006; 99: 597–601. doi:10.1007/s00436-006-0186-z.
31. Ozyurt M, Kurt O, Mølbak K, Nielsen HV, Haznedaroglu T, Stensvold CR. Molecular epidemiology of Blastocystis infections in Turkey. Parasitol Int. 2008; 57(3): 300–306. doi: 10.1016/j.parint.2008.01.004.
32. Vogelberg C, Stensvold CR, Monecke S, Ditzen A, Stopsack K, Heinrich-Gräfe U, Pöhlmann C. Blastocystis sp. subtype 2 detection during recurrence of gastrointestinal and urticarial symptoms. Parasitol Int. 2010; 59: 469–471. doi:10.1016/j.parint.2010.03.009.
33. Tan KS. New insights on classification, identification, and clinical relevance of Blastocystis spp. Clin Microbiol Rev. 2008; 21: 639–665. doi:10.1128/CMR.00022-08.
34. Khademvatan S, Masjedizadeh R, Rahim F, Mahbodfar H, Salehi R, Yousefi-Razin E, Foroutan M. Blastocystis and irritable bowel syndrome: frequency and subtypes from Iranian patients Parasitol Int. 2017; 66: 142–145. doi: 10.1016/j.parint.2017.01.005.
35. Udkow MP, Markell EK. Blastocystis hominis: prevalence in asymptomatic versus symptomatic hosts J Infect Dis. 1993; 168: 242–244.
36. Ajjampur SSR, Tan KSW. Pathogenic mechanisms in Blastocystis spp.–Interpreting results from in vitro and in vivo studies. Parasitol Int. 2016; 65(6 Pt B): 772–779. doi: 10.1016/j.parint.2016.05.007.
37. Andersen LO, Stensvold CR. Blastocystis in health and disease: are we moving from a clinical to a public health perspective? J Clin Microbiol. 2016; 54: 524–528. doi: 10.1128/JCM.02520-15.
38. Denoeud F, Roussel M, Noel B, Wawrzyniak I, Da Silva C, Diogon M, Viscogliosi E, Brochier-Armanet C, Couloux A, Poulain J, Segurens B, Anthouard V, Texier C, Blot N, Poirier P, Ng GC, Tan KS, Artiguenave F, Jaillon O, Aury JM, Delbac F, Wincker P, Vivarès CP, El Alaoui H. Genome sequence of the stramenopile Blastocystis, a human anaerobic parasite. Genome Biol. 2011; 12(3): R29. doi: 10.1186/gb-2011-12-3-r29.
39. Wu Z, Mirza H, Tan KSW. Intra-subtype variation in enteroadhesion accounts for differences in epithelial barrier disruption and is associated with metronidazole resistance in Blastocystis subtype-7. PLoS Negl Trop Dis. 2014; 8: e2885 doi: 10.1371/journal.pntd.0002885.
40. Poirier P, Wawrzyniak I, Vivarès CP, Delbac F, El Alaoui H. New insights into Blastocystis spp.: a potential link with irritable bowel syndrome. PLoS Pathog. 2012; 8: e1002545. doi:10.1371/journal.ppat.1002545.
41. Lepczynska M, Chen WC, Dzika E. Mysterious chronic urticarial caused by Blastocystis spp.? Int J Dermatol. 2016; 55: 259–266. doi: 10.1111/ijd.13064.
42. El Safadi D, Meloni D, Poirier P, Osman M, Cian A, Gaayeb L, Wawrzyniak I, Delbac F, El Alaoui H, Delhaes L, Dei-Cas E, Mallat H, Dabboussi F, Hamze M, Viscogliosi E. Molecular epidemiology of Blastocystis in Lebanon and correlation between subtype 1 and gastrointestinal symptoms. Am J Trop Med Hyg. 2013; 88: 1203–1206. doi: 10.4269/ajtmh.12-0777.
43. Clark CG. Extensive genetic diversity in Blastocystis hominis. Mol Biochem Parasitol. 1997; 87: 79–83. doi: 10.1016/S0166-6851(97)00046-7.
44. Kaneda Y, Horiki N, Cheng X, Tachibana H, Tsutsumi Y. Serologic response to Blastocystis hominis infection in asymptomatic individuals. Tokai J Exp Clin Med. 2000; 25: 51–56.
45. Wawrzyniak I, Poirier P, Viscogliosi E, Dionigia M, Texier C, Delbac F, Alaoui HE. Blastocystis, an unrecognized parasite: an overview of pathogenesis and diagnosis. Ther Adv Infect Dis 2013; 1: 167–178. doi:10.1177/2049936113504754.
46. Berrilli F, Di Cave D, Cavallero S, D’Amelio S. Interactions between parasites and microbial communities in the human gut. Front Cell Infect Microbiol. 2012; 2: 141. doi:10.3389/fcimb.2012.00141.
47. Ramirez JD, Sánchez A, Hernández C, Flórez C, Bernal MC, Giraldo JC, Reyes P, López MC, García L, Cooper PJ, Vicuña Y, Mongi F, Casero RD. Geographic distribution of human Blastocystis subtypes in South America. Infect Genet Evol. 2016; 41: 32–35. doi:10.1016/j.meegid.2016.03.017.
48. Ramirez JD, Flórez C, Olivera M, Bernal MC, Giraldo JC. Blastocystis subtyping and its association with intestinal parasites in children from different geographical regions of Colombia. PLoS One 2017; 12(2): e0172586. doi: 10.1371/journal.pone.0172586.
49. Forsell J, Granlund M, Stensvold CR, Clark CG, Evengård B. Subtype analysis of Blastocystis isolates in Swedish patients. Eur J Clin Microbiol Infect Dis. 2012; 31: 1689–1696. doi:10.1007/s10096-011-1416-6.
50. Meloni D, Sanciu G, Poirier P, El Alaoui H, Chabé M, Delhaes L, Dei-Cas E, Delbac F, Fiori PL, Di Cave D, Viscogliosi E. Molecular subtyping of Blastocystis sp. isolates from symptomatic patients in Italy. Parasitol Res. 2011; 109: 613–619. doi: 10.1007/s00436-011-2294-7.
51. Dogruman-Al F, Kustimur S, Yoshikawa H, Tuncer C, Simsek Z, Tanyuksel M, Araz E, Boorom K. Blastocystis subtypes in irritable bowel syndrome and inflammatory bowel disease in Ankara, Turkey.Mem Inst Oswaldo Cruz 2009; 104: 724–727. doi:10.1590/S0074-02762009000500011.
52. Jantermtor S, Pinlaor P, Sawadpanich K, Pinlaor S, Sangka A, Wilailuckana C, Wongsena W, Yoshikawa H. Subtype identification of Blastocystis spp. isolated from patients in a major hospital in northeastern Thailand. Parasitol Res. 2013; 112(4): 1781–1786. doi: 10.1007/s00436-012-3218-x.
53. Dogan N, Aydin M, Tuzemen NU, Dinleyici EC, Oguz I, Dogruman-Al F. Subtype distribution of Blastocystis spp. isolated from children in Eskisehir, Turkey. Parasitol Int. 2017; 66(1): 948–951. doi: 10.1016/j.parint.2016.10.008.
54. Scanlan PD. Blastocystis past pitfalls and future perspectives. Trends Parasitol. 2012; 28: 327–334. doi: 10.1016/
55. McHardy IH, Wu M, Shimizu-Cohen R, Couturier MR, Humphries RM. Detection of intestinal protozoa in the clinical laboratory. J Clin Microbiol. 2014; 52:712–720. doi: 10.1128/JCM.02877-13.
56. Verweij JJ. Application of PCR-based methods for diagnosis of intestinal parasitic infections in the clinical laboratory. Parasitol. 2014; 141: 1863–72. doi: 10.1017/S0031182014000419.
57. Skotarczak B. Methods for parasitic protozoan detection in the environmental samples. Parasite 2009; 16(3): 183–190.
58. Stensvold CR, Clark CG. Molecular identification and subtype analysis of Blastocystis. Curr Protoc Microbiol. 2016b; 43: 20A.2.1–20A.2.10. doi: 10.1002/cpmc.17.
59. Hebert PD, Cywinska A, Ball SL, de Waard J.R. Biological identifications through DNA barcodes. Proc R Soc London B. 2003; 270: 313–321.
60. Stensvold CR, Christiansen DB, Olsen KE, Nielsen HV. Blastocystis sp. subtype 4 is common in Danish Blastocystis-positive patients presenting with acute diarrhea. Am J Trop Med Hyg. 2011; 84: 883–885. doi:10.4269/ajtmh.2011.11-0005.
61. Roberts T., Stark D, Harkness J, Ellis J. Subtype distribution of Blastocystis isolates from a variety of animals from New South Wales, Australia. Veterinary Parasitol. 2013; 196: 85–89. doi: 10.1016/j.vetpar.2013.01.011.
62. Stensvold CR. Comparison of sequencing (barcode region) and sequence-tagged-site PCR for Blastocystis subtyping. J Clin Microbiol. 2013b; 51: 190–194. doi:10.1128/JCM.02541-12.
63. Dagci H, Kurt Ö, Demirel M, Mandiracioglu A, Aydemir S, Saz U, Bart A, VAN Gool T. Epidemiological and diagnostic features of Blastocystis infection in symptomatic patients in Izmir province, Turkey. Iran J Parasitol. 2014; 9(4): 519–529.
64. Lee LL, Chye TT, Karmacharya BM, Govind SK. Blastocystis sp.: waterborne zoonotic organisms, a possibility? Parasit Vec. 2012; 5: 130 doi: 10.1186/1756-3305-5-130.
65. Moosavi A, Haghighi A, Mojarad EN, Zayeri F, Alebouyeh M, Khazan H, Kazemi B, Zali MR. Genetic variability of Blastocystis sp. isolated from symptomatic and asymptomatic individuals in Iran. Parasitol Res. 2012; 111: 2311–2315. doi:10.1007/s00436-012-3085-5.
66. Yoshikawa H, Iwamasa A. Human Blastocystis subtyping with subtype-specific primers developed from unique sequences of the SSU rRNA gene. Parasitol Int. 2016; 65(6 Pt B): 785–791. doi: 10.1016/j.parint.2016.03.002.