Fasciolosis laboratory findings: Difference between revisions
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==Overview== | |||
==Laboratory findings== | |||
In humans, diagnosis of fasciolosis is usually achieved by parasitologically by findings the fluke eggs in stool, and immunologically by [[ELISA]] and [[Western blot]]. Coprological examinations of stool alone are generally not adequate because infected humans have important clinical presentations long before eggs are found in the stools. Moreover, in many human infections, the fluke eggs are often not found in the faeces, even after multiple faecal examinations.<ref name=Hillyer88>Hillyer, G.V., 1988. Fascioliasis and fasciolopsiasis. In: Balows, A., Hausler, W.J., Ohashi, M. and Turano, A. (eds) Laboratory Diagnosis of Infectious Diseases. Principles and Practice. I. Bacterial, Mycotic, and Parasitic Diseases, Vol. 90. Springer-Verlag, Berlin, pp. 856–862.</ref><ref name=Chen/> Furthermore, eggs of ''F. hepatica'', ''F. gigantica'' and ''Fasciolopsis buski'' are morphologically indistinguishable.<ref name=Hillyer88/> Therefore, immunonological methods such ELISA and enzyme-linked immunoelectrotransfer blot, also called Western blot, are the most important methods in diagnosis of ''F. hepatica'' infection. These immunological tests are based on detection of species-specific [[antibody|antibodies]] from [[Blood plasma|sera]]. The [[antigen]]ic preparations used have been primarily derived from extracts of excretory/secretory products from adult [[worm]]s, or with partially purified fractions.<ref name=Hillyer99>Hillyer, G.V., 1999. Immunodiagnosis of human and animal fasciolosis. In: Dalton, J.P. (Ed.), Fasciolosis. CAB International Publishing, Wallingford, pp. 435–447.</ref> Recently, purified native and [[Recombinant DNA|recombinant]] antigens have been used, e.g. recombinant ''F. hepatica'' [[cathepsin L]]-like [[protease]].<ref>O’Neill, S.M., Parkinson, M., Strauss, W., Angles, R., Dalton, J.P., 1998. Immunodiagnosis of ''Fasciola hepatica'' infection (fasciolosis) in a human population in the Bolivian Altiplano using purified cathepsin L cysteine proteinase. Am. J. Trop. Med. Hyg. 58, 417–423.</ref> Methods based on antigen detection (circulating in serum or in faeces) are less frequent. In addition, biochemical and haematological examinations of human sera support the exact diagnosis (eosinophilia, elevation of liver enzymes). [[Ultrasonography]] and [[RTG]] of the abdominal cavity, [[biopsy]] of liver, and gallbladder punctuate can also be used. False fasciolosis ([[pseudofasciolosis]]) refers to the presence of eggs in the stool resulting not from an actual infection but from recent ingestion of infected livers containing eggs. This situation (with its potential for misdiagnosis) can be avoided by having the patient follow a liver-free [[diet (nutrition)|diet]] several days before a repeat stool examination.<ref name=Hillyer99/> In animals, intravital diagnosis is based predominantly on faeces examinations and immunological methods. However, clinical signs, biochemical and haematological profile, season, climate conditions, [[epidemiology]] situation, and examinations of snails must be considered.<ref name=Torges99/><ref name=Dubinsky/> Similarly to humans, faeces examinations are not reliable. Moreover, the fluke eggs are detectable in faeces 8-12 weeks post-infection. In spite of that fact, faecal examination is still the only used diagnostic tool in some countries. While coprological diagnosis of fasciolosis is possible from 8-12 week post-infection (WPI) ''F. hepatica'' specific-antibodies are recognized using ELISA or Western blot since 2-4 week post-infection.<ref>Zimmerman, G.L., Jen, L.W., Cerro, J.E., Farnsworth, K.L., Wescott, R.B., 1982. Diagnosis of ''Fasciola hepatica'' infections in sheep by an enzyme-linked immunosorbent assay. Am. J. Vet. Res. 43, 2097–2100.</ref><ref>Duménigo, B.E., Espino, A.M., Finlay, C.M., Mezo, M., 2000. Kinetics of antibody-based antigen detection in serum and faeces of sheep experimentally infected with ''Fasciola hepatica''. Vet. Parasitol. 89, 153-161.</ref> Therefore, these methods provide early detection of the infection. | |||
==References== | ==References== | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Laboratory findings
In humans, diagnosis of fasciolosis is usually achieved by parasitologically by findings the fluke eggs in stool, and immunologically by ELISA and Western blot. Coprological examinations of stool alone are generally not adequate because infected humans have important clinical presentations long before eggs are found in the stools. Moreover, in many human infections, the fluke eggs are often not found in the faeces, even after multiple faecal examinations.[1][2] Furthermore, eggs of F. hepatica, F. gigantica and Fasciolopsis buski are morphologically indistinguishable.[1] Therefore, immunonological methods such ELISA and enzyme-linked immunoelectrotransfer blot, also called Western blot, are the most important methods in diagnosis of F. hepatica infection. These immunological tests are based on detection of species-specific antibodies from sera. The antigenic preparations used have been primarily derived from extracts of excretory/secretory products from adult worms, or with partially purified fractions.[3] Recently, purified native and recombinant antigens have been used, e.g. recombinant F. hepatica cathepsin L-like protease.[4] Methods based on antigen detection (circulating in serum or in faeces) are less frequent. In addition, biochemical and haematological examinations of human sera support the exact diagnosis (eosinophilia, elevation of liver enzymes). Ultrasonography and RTG of the abdominal cavity, biopsy of liver, and gallbladder punctuate can also be used. False fasciolosis (pseudofasciolosis) refers to the presence of eggs in the stool resulting not from an actual infection but from recent ingestion of infected livers containing eggs. This situation (with its potential for misdiagnosis) can be avoided by having the patient follow a liver-free diet several days before a repeat stool examination.[3] In animals, intravital diagnosis is based predominantly on faeces examinations and immunological methods. However, clinical signs, biochemical and haematological profile, season, climate conditions, epidemiology situation, and examinations of snails must be considered.[5][6] Similarly to humans, faeces examinations are not reliable. Moreover, the fluke eggs are detectable in faeces 8-12 weeks post-infection. In spite of that fact, faecal examination is still the only used diagnostic tool in some countries. While coprological diagnosis of fasciolosis is possible from 8-12 week post-infection (WPI) F. hepatica specific-antibodies are recognized using ELISA or Western blot since 2-4 week post-infection.[7][8] Therefore, these methods provide early detection of the infection.
References
- ↑ 1.0 1.1 Hillyer, G.V., 1988. Fascioliasis and fasciolopsiasis. In: Balows, A., Hausler, W.J., Ohashi, M. and Turano, A. (eds) Laboratory Diagnosis of Infectious Diseases. Principles and Practice. I. Bacterial, Mycotic, and Parasitic Diseases, Vol. 90. Springer-Verlag, Berlin, pp. 856–862.
- ↑
- ↑ 3.0 3.1 Hillyer, G.V., 1999. Immunodiagnosis of human and animal fasciolosis. In: Dalton, J.P. (Ed.), Fasciolosis. CAB International Publishing, Wallingford, pp. 435–447.
- ↑ O’Neill, S.M., Parkinson, M., Strauss, W., Angles, R., Dalton, J.P., 1998. Immunodiagnosis of Fasciola hepatica infection (fasciolosis) in a human population in the Bolivian Altiplano using purified cathepsin L cysteine proteinase. Am. J. Trop. Med. Hyg. 58, 417–423.
- ↑
- ↑
- ↑ Zimmerman, G.L., Jen, L.W., Cerro, J.E., Farnsworth, K.L., Wescott, R.B., 1982. Diagnosis of Fasciola hepatica infections in sheep by an enzyme-linked immunosorbent assay. Am. J. Vet. Res. 43, 2097–2100.
- ↑ Duménigo, B.E., Espino, A.M., Finlay, C.M., Mezo, M., 2000. Kinetics of antibody-based antigen detection in serum and faeces of sheep experimentally infected with Fasciola hepatica. Vet. Parasitol. 89, 153-161.