Letters

More laboratories should test for Dientamoeba fragilis infection

EDITORDientamoeba fragilis was first described by Jepps and Dobell in 1918¹ and has subsequently been shown to be an important enteric pathogen. It is therefore surprising that only a few laboratories look for this pathogen. D fragilis infections are effectively treated with di-iodohydroxyquinoline or tetracyline.² In contrast, no treatment is available for Cryptosporidium spp, which most laboratories screen for routinely.

Successful diagnosis of D fragilis is closely associated with the use of stained faecal smears. After using a suitable faecal stain as part of our routine methodology we found D fragilis to be the most common enteropathogen (occurring in 5.1% of faecal samples) in the Sultanate of Oman.³ A similar incidence (5.0%) has been reported recently among American soldiers stationed in Egypt.⁴ In the United Kingdom, however, few laboratories stain faecal smears. The laboratory reports of the Communicable Disease Surveillance Centre show that in 1992, 68 cases of D fragilis infection were reported from seven laboratories and that by 1996 this figure had increased to 231 cases reported from 20 laboratories (unpublished data). These results reflect an increase in the number of laboratories performing faecal stains. It can be assumed, however, that the true incidence of D fragilis infection is many times higher: there are an estimated 450 diagnostic laboratories in the United Kingdom, most of which do not look for this pathogen.

Clinicians should add dientamoebiasis to their differential diagnosis in patients presenting with abdominal pain, diarrhoea, unexplained flatulence, nausea, and vomiting. Indeed, requests from clinicians to their laboratories to look for this organism will result in this neglected pathogen taking its rightful place alongside the more established enteropathogens. Ultimately, patients will be the true beneficiaries.

J J Windsor, Senior biomedical scientist. 
Department of Microbiology and Immunology, College of Medicine, Sultan Qaboos University, PO Box 35, Muscat 123, Sultanate of Oman jeffjoewindsor{at}hotmail.com

E H Johnson, Associate professor. 
Department of Animal and Veterinary Sciences, College of Agriculture, Sultan Qaboos University, PO Box 34, Muscat 123

1. Jepps MW, Dobell C. Dientamoeba fragilis, ng, nsp, a new intestinal amoeba from man. Parasitology 1918; 10: 352-367.
2. Murray P. ASM pocket guide to clinical microbiology. Washington: American Society for Microbiology Press , 1996.
3. Windsor JJ, Rafay AM, Shenoy AK, Johnson EH. Incidence of Dientamoeba fragilis in faecal samples submitted for routine microbiological analysis. Br J Biomed Sci 1998; 55: 172-175[Medline].
4. Oyofo BA, Persuski LF, Ismail TF, El-Etr SH, Churilla AM, Wasfy MO, et al. Enteropathogens associated with diarrhoea among military personnel during operation bright star 96, in Alexandria, Egypt. Mil Med 1997; 162: 396-400[Medline].