December 1993, Volume 43, Issue 12


Diagnosis of Giardiasis

Rakhshanda Baqai  ( PMRC Research Centre, Jinnah Postgraduate Medical Centre, Karachi. )

Giardia lamblia (GL), a frequent cause of diarrhoea has often been reported to be a pathogen1-4 and giardiasis, an important unresolved, health problem in developing countries. This is perhaps due to the absence of a simple but reliable test for its diagnosis. Choice of diagnostic tests depend on their simplicity, feasibility and acceptability to the patient. When suspected on symptomatology diagnosis can be done by detection of trophozoites or cysts of GL on routine stool examination5-7. Although simple and con­venient but some cases can be missed on direct micros­copy. Its positivity varies from 36-50% mainly due to periodicity of its excretion and delay in examination of stool8-10. To increase the yield of direct microscopy three consecutive stools should be examined within one hour after defaecation11. For detection of cysts yield of concentration method is better than direct microscopy. Immunofluorescence test for the detection of giardia antigen in&ecal samples picks up 12% more true positive cases than other methods (unpublished dat4 It detects both cysts and trophozoites and immediate examination is not essential. This should be done in patients with strong clinical suspicion of giardiasis and repeated negative routine stool tests. Other diagnostic tests for the detection of giardia antigen in stools is enzyme linked immunosorbent assay (ELISA) 12. It can detect both cyst and trophozoite and remains positive at dilutions at which GL are not directly visualized13-15. ELISA is not a substitute for direct micros­copy but it can rule out infection with GL and monitor response16 to therapy. Counter immunoelectrophoresis (CIE) is also used for diagnosing giardiasis as well as monitoring chemotherapeutic effect of anti- giardia agents17. Other tests are based on the knowledge of natural habitat of GL in the duodenum and upper jejunum. String18 test direct microscopy of fresh duodenal aspirate collected during endoscopy19. duodenal jejunal mucosal imprints and detection of parasites in the intestinal mucous in small intestinal biopsies have been reported witltvarious frequencies20,21. Although there are different methods for diagnos­ing giardiasis but no single method is 100% reliable. The best approach for the detection of GL should be three consecutive stool examinations, if found negative other methods of detection of giardia antigen like immunofluorescence test, ELISA or CIE methods should be used in patients having symptoms of giardiasis.


1. Islam, A., Stoll, B.J., Ljingstons, L et al. Giardia lamblia infections in a cohort ot Bangladeshi mothers and infants followed forone year.J. Pediatr., 1983;103:996-1000.
2. Baqai, Rand Zuberi, S.J. Prevalenceofinteatinal patasites in diarrhoeal patients.J. Pak. Med. Assoc., 1986;36:7-11
3. Uthman, 5. Giardiasis. J. Med. Uban, 1970;23:173-79.
4. Addidis, D.G., Davis, J.P., Roberts, J.M. etaL Epidemiology of gisrdiasis in Wisconsin, incressingincidenceofreportedcases of unexplained seasonal trends Am.J.Trop. Med. Hyg., 1992;47:13- 19.
5. Paine, T.F. and GlucIc, F.W.A. Puzzlingcase of giardiasis. JAMA., 1976;236:2425-26.
6. Steel, LW. and McDermott, S. Disgnosisofgisrdissis. Med.J., Aust., 1977;2:876-77.
7. Yardley, J.H. and Baylees, T.M. Giardiasis. Gastroenterology, 1967;52:301-4.
8. Peterson, H. Giardissis (L.ambliasia). Scsnd. J. Gastroenterot, 1972;4:1-44.
9. Kamath, KR. and Murugash, P.. A comparative study of four methods for detecting giardia lamblia inchildrenwith diarrhoeal diseaseand malabsorption Gastroenterology, 1974;66:16-21.
10. Naik, S.R. Diagnosis ofgiardiasis. Indian J. GastroenteroL, 1984;3:125-26.
11. Ament, M.E Diagnosis and treatment of giardissis. Pediatrics, 1972;80:633-37.
12. Green, EL, Miles, MA., Warhurst, D.C Immunodiagnostic detection of giardia antigen in faeces by a rapid visual enzyme linked immunosorbent aassy. Lancet, 1985;11:691-93.
13. Nash, T.E., Hsrrington, D.A. and Levine, M.M. Usefulness of an enzyme linked immunosorbent assay for detection of giardia antigen in faeces. 3. Din. MicrobioL, 1987;25:1169-71.
14. Rossoff, 3D., Sanders, CA., Sonnad, S.S. et si Stdol diagnosis of giardiasis using a commercially available enzymeimmunosssay to detect giardia specific antigen 65 (GSA 6$). iclin.MicrobioL, 1989;27:1997-2002.
15. Addiss, D.G., Mathew, H.M., Stewart, 3M. etaL Evaluation of a commercially available enzyme linked immunosorbeot assay for giardia lamblia sntigen in stool. J. con. Microbiol., 1991;29:1137-42.
16. Ungar, B.LP., Yolkin, RH., Nash, T.E. snd Quinn, T.C Enzyme- linked immunoaor­bent assay for the detection of giardia lamblis in faecal specimens. 3. Infect Dis., 1984;149:90-97.
17. Lu, Si-qi, Wang Zheng-Yi, Wang Cheng-I snd Zhang Yue-ging. Detecting giardia lamblia antigen in faecal matter with counter immunoelectrophoresis in diagnosis of giardiasia. Chin. Med. 3., 1989;102:686-88.
18. Korman, S.H. Hais, E., and Spira, D.T. Routine invitrocultivation of giardis Iambus by using string test 3. Clin. Microbiol., 1990;28:368-69.
19. Zafar, N.M., Baqai, R, Ladi, T.Z, Ahmed, S., Ahmed, W., Qureshi, H., Zuberi, S.3., Jamal, Q., Aism, S.M. Giardia lamblia in patients undergoing upper G.I. endoscopy. iPsk.Med. Assoc., 1991;41:74-75.
20. Hoskin, LC, Winawer, S.J., Broitman, S.A. et at Clinical giardissis and intestinal malabaorption. Gastroenterology, 1967;53:265-79.
21. Desai, H.G., Kairo, RH., Zaveri, M.P. and Shreevaaan, 0. Gisrdissis an evaluation of diagnostic methods. Indian 3. Gastroenterol., 1974;3:135-37.

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