In their Global Health editorial BJGP (October) on exotic infections, Behrens and Coltart did not mention the more mundane high prevalence of protozoal infections in warmer climates.1 We caught the anaerobic protozoa Blastocystis spp and Dientamoeba fragilis in Burma, however they are already common in UK, but little known to practitioners.
Blastocystis was the most common enteric parasite (6.9%) found in routine stool samples in a study in Wales2 and D. fragilis was found in up to 16.9% of samples submitted to alternative practitioners.3 However, the detection of both parasites is difficult and requires specialist laboratories; even then they may not be found. Faeco-oral seems their likely mode of transmission.
The pathogenic nature of D. fragilis is now more accepted,4 but two forms are known;5 while nine different subtypes of Blastocystis have been reported, observed disorders appear to be subtype dependent.6 Both protozoa have been linked to IBS.7,8
Treatment of Blastocystis is varied and metronidazole has shown resistance.9 For D. fragilis, only secnidazole10 and paromomycin11 gave very low treatment failure rates. Although both medicines are old, and both are registered and used within the EU, neither is registered for any use in UK.
My wife and I presented common severely debilitating symptoms of chronic fatigue and inability to concentrate for extended periods. I initially had severe diarrhoea, followed by soreness in the lower bowel, while my wife showed almost no intestinal disturbance or discomfort, however when we both had the same diet, the symptoms were the same. Later, headaches became more prevalent. The addition of milk (2% fat) plus cereals, particularly wheat based, increased the bowel disturbance. We had many blood and stool tests, with essentially no adverse findings. After many months and over 10 stool samples from each, I was diagnosed with D. fragilis and my wife with Blastocystis. Both had been found by microscopic examination of preserved stained specimens.
The parasites were treated: D. fragilis with paromomycin (750 mg tid) for 10 days (28 mg/kg) and Blastocystis with nitazoxanide (500 mg bid) for 3 days. Bowel disturbance continued for several weeks in both patients.
Our experiences, although limited, do offer direct comparisons between the parasites and support the conclusion that both can be pathogenic and the effects of both organisms can be similar, giving the ME (myalgic encephalopathy) symptoms of chronic physical and mental fatigue, with bowel disturbances related to cereal/milk diet. However, for patients and practitioners, the biggest problem is lack of efficacious approved drugs in UK.
I wish to thank the laboratory staff in the Department of Medical Parasitology at the London School of Hygiene and Tropical Medicine for making the diagnoses.
REFERENCES
- 1.Coltart CE, Behrens RH. The new health threats of exotic and global travel. Br J Gen Pract. 2012;62(603):512–513. doi: 10.3399/bjgp12X654821. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Windsor JJ, Macfarlane L, Hughes-Thapa G, et al. Incidence of Blastocytis hominis in faecal samples submitted for routine microbiological analysis. Br J Biomed Sci. 2002;59(3):154–157. doi: 10.1080/09674845.2002.11783653. [DOI] [PubMed] [Google Scholar]
- 3.Schuster H, Jackson RS. Prevalence of Dientamoeba fragilis among patients consulting complementary medicine practitioners in the British Isles. J Clin Pathol. 2009;62(2):182–184. doi: 10.1136/jcp.2008.059659. [DOI] [PubMed] [Google Scholar]
- 4.Barratt JL, Harkness J, Marriott D, et al. A review of Dientamoeba fragilis carriage in humans: several reasons why this organism should be considered in the diagnosis of gastrointestinal illness. Gut Microbes. 2011;2(1):3–12. doi: 10.4161/gmic.2.1.14755. [DOI] [PubMed] [Google Scholar]
- 5.Johnson JA, Clark CG. Cryptic genetic diversity in Dientamoeba fragilis. J Clin Microbiol. 2000;38(12):4653–4654. doi: 10.1128/jcm.38.12.4653-4654.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Tan KSW, Mirza H, Teo JDW, et al. Current views on the clinical relevance of Blastocystis spp. Curr Infect Dis Rep. 2010;12(1):28–35. doi: 10.1007/s11908-009-0073-8. [DOI] [PubMed] [Google Scholar]
- 7.Borody T, Warren E, Wettstein A, et al. Eradication of Dientamoeba fragilis can resolve IBS-like symptoms. J Gastroenterol Hepatol. 2002;17(Suppl):A103. [Google Scholar]
- 8.Jimenez-Gonzalez DE, Martinez-Flores WA, Reyes-Gordillo J, et al. Blastocystis infection is associated with irritable bowel syndrome in a Mexican patient population. Parasitol Res. 2012;110(3):1269–1275. doi: 10.1007/s00436-011-2626-7. [DOI] [PubMed] [Google Scholar]
- 9.Haresh K, Suresh K, Khairul Anus A, Saminathan S. Isolate resistance of Blastocystis hominis to metronidazole. Trop Med Int Health. 1999;4(4):274–277. doi: 10.1046/j.1365-3156.1999.00398.x. [DOI] [PubMed] [Google Scholar]
- 10.Girginkarde şler N, Coşkun S, Cüneyt Balcioşlu I, et al. Dientamoeba fragilis, a neglected cause of diarrhea, successfully treated with secnidazole. Clin Microbiol Infect. 2003;9(2):110–113. doi: 10.1046/j.1469-0691.2003.00504.x. [DOI] [PubMed] [Google Scholar]
- 11.van Hellemond JJ. Superior efficacy of paromomycin for eradication of Dientamoeba fragilis in adults. Abstract 335. 22nd European Congress of Clinical Microbiology and Infectious Diseases, 31 March – 3 April 2012, London.