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Varna Medical Forum

Blastocystosis and prevalence of Blastocystis Hominis invasion in children and adults from the Varna region

Kalina Stoyanova, Tatyana Cvetkova


Blastocystis hominis is the most commonly diagnosed protozoan organism in routine stool specimens testing worldwide. In the majority of cases the invasion is asymptomatic, but more studies confirm the pathogenicity of the parasite in immunocompromised and immunocompetent persons. The aim of this study was to reveal the occurrence of B. hominis in different age groups of the population of the Varna region and to determine the prevalence of clinically confirmed cases. Materials and Methods: For a 5-year period a total number of 20 646 children and 17 088 adults, were tested for intestinal parasites, including B. hominis, with fecal wet mount preparation stained with Lugol`s iodine solution.

Results and Discussion: In the investigated patients from the Varna region, B. hominis was diagnosed in nearly 3.28% of the tested samples and is proven to be the most common intestinal protozoa, followed by G. intestinalis (0.59%), Entamoeba coli and other intestinal amoebas (0.25%). The systematic analysis revealed a progressive increase in prevalence with the increasing of age, with the smallest percentage of invasion in children from 0 to 4 years (0.70%) and the highest in the age groups 50-54 years (8.45%), followed by those aged 55-59 (7.72%). Based on diagnostic, clinical and epidemiological criteria blastocystosis was confirmed in 52 cases, therefore, the prevalence of the disease in a 5-year interval was 0.14% ± 0.09%. Regardless of the relatively high frequency of invasion in patients from the Varna region blastocystosis remains a lesser-known disease. Testing for B. hominis and oth er intestinal protozoan pathogens should be included systematically in the differential diagnosis of patients with nonspecific gastrointestinal signs, diarrhea and allergic symptoms, in children and adults alike.


B. hominis, blastocystosis, prevalence, intestinal parasitoses

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Ангелов И. Бластоцистоза – етиологични, епидемиологични, клинични, диагностични и терапевтични аспекти. Инфекто- логия. 2000; 2 (ХХХVІІ): 32–36.

Ангелов И. PCR базирана идентификация на бластоцистни изолати от хора. Инфектология. 2010; 2 (47): 44–47.

Ангелов И. Бластоцистоза. В: Петров П, Курдова Р. ред. Клинична паразитология и тропическа медицина, София: Из- ток-Запад, 2016: 229–232

Ангелов И, Курдова Р. Бластоцистоза в детската възраст. Педиатрия. 2008. 1: 21–23.

Боева-Бангьозова В, Панайотова М. Бластоцистоза. Лекарска практика. 2008. 4: 21–26.

Курдова Р, Йорданова Д. Опортюнистич- ни паразитози и HIV инфекция в България. Инфектология. 2000. 4 (37): 16–19.

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 Tropica. 2013. 1(126):11–18.

Angelov I. Clinical, immunological and parasitological parallels in patients with Blastocystosis Journal of IMAB - Annual Proceeding. 2008. (1): 55–58.

Boeva-Bangyozova V, Panayotova M, Chakarova B. Blastocystosis: pathogenesis, clinical course, diagnostics and treatement. Trakia Journal of Sciences. 2008. 1 (6): 90–93.

Boeva-Bangyozova V, Panayotova M, Chakarova B. Blastocystosis - ethiology, biology and prevalence. Trakia Journal of Sciences. 2008. № Suppl.1 (6): 90–93.

Kanda Y. Investigation of the freely available easy-to-use software ‘EZR’ for medical statistics Bone Marrow Transplantation. 2013. 3 (48): 452–458.

Kurdova R, Marinova T, Jordanova D, Ivanova M, Tzvetkova N, Rainova I. Opportunistic parasitic diseases associated with HIV infection in Bulgaria. Proceedings of the IX European Multicolloquium of Parasitology. 2004. (1009): 435–440.

Kurdova R, Atanasova I, Cvetanov J. Blastocystosis in Bulgarian travellers. Problems of Infectious and Parasitic Diseases. 1995. suppl. (22): 18–20.

Logar J, Andlovic A, Poljsak-Prijatelj M Incidence of Blastocystis hominis in patients with diarrhoea. The Journal of Infection. 1994. 2 (28): 151–154.

Miné JC, Rosa JA. Frequency of Blastocystis hominis and other intestinal parasites in stool samples examined at the Parasitology Laboratory of the School of Pharmaceutical Sciences at the São Paulo State University, Araraquara Revista da Sociedade Brasileira de Medicina Tropical. 2008. № 6 (41): 565–569.

Noël C, Dufernez F, Gerbod D, Edgcomb VP, Delgado-Viscogliosi P, Ho LC, at al. Molecular phylogenies of Blastocystis isolates from different hosts: implications for genetic diversity, identification of species, and zoonosis. Journal of Clinical Microbiology. 2005. № 1 (43): 348–355.

R Core Team R: A Language and Environment for Statistical Computing / R Core Team, Vienna, Austria: R Foundation for Statistical Computing, 2014.

Stensvold CR, Nielsen HV, Mølbak K, Smith HV. Pursuing the clinical significance of Blastocystis-diagnostic limitations. Trends in Parasitology. 2009. 1 (25): 23–29.

Stenzel DJ, Boreham PF. Blastocystis hominis revisited. Clinical Microbiology Reviews. 1996. 4 (9): 563–584.

Stenzel DJ, Boreham RE. Blastocystis. In: Gillespie P, Pearson RD editors. Principle and Practice of Clinical Parasitology. Chichester; New York: Wiley, 2001:355–366

Tan KSW. New insights on classification, identification, and clinical relevance of Blastocystis spp.. Clinical Microbiology Reviews. 2008. 4 (21): 639–665.

Tengku AS, Ghani MKA, Azreen SN, Salleh FM, Moktar N. Blastocystis infection in Malaysia: Evidence of waterborne and human-to-human transmissions among the Proto-Malay, Negrito and Senoi tribes of Orang Asli. Parasites and vectors. 2013. (6): 40.

Vassalos CM, Papadopoulou C, Vakalis NC. Blastocystosis: an emerging or re-emerging potential zoonosis? Veterinaria Italiana. 2008. 4 (44): 679–684.

Windsor JJ, Macfarlane L, Hughes-Thapa G, Jones SK, Whiteside TM. Incidence of Blastocystis hominis in faecal samples submitted for routine microbiological analysis. British Journal of Biomedical Science. 2002. 3 (59): 154–157.

Zierdt CH. Blastocystis hominis, a protozoan parasite and intestinal pathogen of human beings Clinical Microbiology Newsletter. 1983. 9 (5) : 57–59.



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