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TITLE: Laboratory diagnosis of human ciliate protozoan parasites: Balantidium coli and
beyond
[REFERENCE CASE REPORT: Urinary infection due to Balantioides coli: a rare accidental
zoonotic disease in an addicted and diabetic young female in Iran]
Author Name: Alireza Abdolrasouli
Address:
Department of Medical Microbiology
Charing Cross Hospital
Imperial College Healthcare National Health Service Trust
Fulham Palace Road
London, W6 8RF
United Kingdom
Email: [email protected]
The full names, institutional addresses and email addresses for all authors must be included on the title page.
In order to assist us in choosing the correct editor to handle your paper, please choose one box in each of the
following categories:
Field: ☒Human
☐Dental
Subject: ☐Bacteriology
☐Veterinary/Fisheries
☐Virology
☐ Mycology
☒ Parasitology
Keywords: Please provide at least one keyword for each of the following categories:
Disease/Indication: Balantidiosis
Pathology/Symptoms: extra-intestinal infections
Treatment: NA
CORRESPONDENCE Up to 350 words
To the Editor - I read with interest, an article recently published in the Journal of Medical
Microbiology Case Reports describing a rare case of urinary tract infection due to Balantidium coli in
a female patient from Iran (Soleimanpour et al. 2015). I agree with authors that balantidiasis is
considered a neglected disease and extra-intestinal infections in particular, are uncommon in
humans despite the high prevalence of B. coli in tropical and sub-tropical areas (Schuster and
Ramirez-Avila, 2008). Recently, more extra-intestinal cases of “balantidiasis”, mainly in the urinary
tract were reported in the medical literature (Bandyopadhyay et al. 2013; Karuna and Khadanga,
2014; Khanduri et al. 2014) perhaps reflecting on the role of ciliate protozoan parasites in
immunocompromised host. One very important missing feature in almost all published cases is
indeed molecular confirmation of B. coli. Identifications were solely based on the morphological
characteristics of ciliate trophozoites seen in direct microscopic examination of urine samples
(Bandyopadhyay et al. 2013; Karuna and Khadanga. 2014; Khanduri et al. 2014).
Microscopic image provided in the published report demonstrates a high similarity to Balantidium
species. However, careful examination of presented first photograph also provides another vital
piece of information on the structure of observed trophozoites: length of cilia. Although lack of scale
bar makes the precise measurement impossible, elongated and profound cilia with uneven
distribution captured in Figure one (Soleimanpour et al. 2015) is in sharp contrast with the classic
‘short’ and ‘fine’ cilia ‘covering the entire body’ of Balantidium spp. (Garcia, 2007) and those clearly
depicted in The 5th Edition of Atlas of Human Parasitology (Ash and Orihel, 2007). Notably, due to
delegate nature of cilia in B. coli, they can even be missed on light microscopic examination and
techniques like phase-contrast may be required to enhance their visualisation. Moreover, from
taxonomy point of view, as nomenclature of ‘Balantioides coli’ was not either formally approved or
commonly applied by parasitologists and hence, should be avoided to prevent further confusion.
More importantly, a different ciliate soil protozoan with wide distribution in nature, namely Colpoda
species has previously been observed in human urinary samples (Costache et al, 2011). In the
absence of DNA-based confirmatory methods, morphological similarities between Balantidium and
Colpoda in addition to their characteristic motility, make their accurate identification troublesome.
Recently, an extensive evaluation of genetic diversity in B. coli based on the polymorphism of SSU
rDNA sequences, confirmed the diversity of cyst-forming ciliates among non-human primates.
Presence of novel Buxtonella-like ciliates in primates opens the question about the possible
occurrence of these pathogens in human and highlights the need for application of broad molecularbased diagnostics for ciliate infections in man (Pomajbíková et al, 2013).
Currently very few Balantidium sequences are available in GenBank, and most represent the SSU
rDNA or Internal Transcribed Spacer regions of B. coli (Verweij and Stensvold, 2014). Application of
general, broad-specificity primers targeting nonhuman eukaryotic SSU rDNA may be of significant
utility in efforts to correctly identify ciliate protozoa detected in human and animal clinical samples.
This in turn, provides a better understanding of epidemiology, pathophysiology and genetic diversity
of these microorganisms.
References:
1. Soleimanpour, S., Babaei, A., Movahhedi Roudi, A., Raeisalsadati, S. S. (2015). Urinary infection
due to Balantioides coli: a rare accidental zoonotic disease in an addicted and diabetic young female
in Iran. J Med Micobiol Case Reports. doi: 10.1099/jmmcr.0.000102
2. Schuster, F. L., and Ramirez-Avila, L. (2008). Current world status of Balantidium coli. Clin
Microbiol Rev 21, 626-638.
3. Bandyoppadhyay, A., Majumder, K., Goswami, B. K. (2013). Balantidium coli in urine sediment:
report of a rare case presenting with hematuria. J Parasit Dis 37, 283-285.
4. Karuna, T., and Khadanga S. (2014). A rare case of urinary balantidiasis in an elderly renal failure
patient. Trop Parasitol 4, 47-49.
5. Kanduri, A., Chauhan, S., Chandola, Mahawal, B. S., Kataria, V. K. (2014). Balantidiosis: a rare
accidental finding in the urine of a patient with acute renal failure. J Clin Diagnostic Res 8, 3-4.
6. Garcia, L. S. (2007). Diagnostic Medical Parasitology, 5th ed. American Society for Microbiology
Press, Washington DC, USA.
7. Ash, L. R., Rrihel, T. C. Atlas of human parasitology, 5th ed. American Society for Clinical Pathology
Press, Chicago, Illinois, USA.
8. Costache, C., Bursaşiu, S., Filipaş, C., Colosi, I. (2011). A case of ciliate protozoa Colpoda spp.
(Ciliata: Colpodidae) detected in human urine. Iranian J Parasitol 6, 99-104.
9. Pomajbı´kova´ K, Obornı´k M, Hora´k A, Petrzˇelkova´ KJ, Grim JN, et al. (2013) Novel insights
into the genetic diversity of Balantidium and Balantidium-like cyst-forming ciliates. PLoS Negl Trop
Dis 7(3): e2140. doi:10.1371/journal.pntd.0002140
10. Verweij, J. J., Stensvold, C. R. (2014). Molecular testing for clinical diagnosis and epidemiological
investigations of intestinal parasitic infections. Clin Microbiol Rev 27, 371– 418.
Acknowledgements/Declaration of Interest
Author declares he had no conflict of interest.
Signature: Mr. A. Abdolrasouli
Date: 06/02/2016
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