This slide is just made for the students who want note and don't get access to the book which cost more. So, hope you all will get information about the immunological diagnosis of parasitic infection.

1. PARASITE IMMUNODIAGNOSIS
Prepared by: Raghwendra sah
Bsc.MLT
Note: I have taken all the information from the book, only language is mine.

2. • Immunodiagnosis means diagnosis of diseases or organisms based on antigen-antibody
reactions in the body of diseased person , while antigen may be organism or extract of
organism.
• There is the requirements of various reagents for the immunodiagnosis of any disease:
Antigen
Antibody
Label/Particles to visualize antigen-antibody reaction
• Obviously, for the diagnosis of Parasite: we require, parasite antigen, antibody against
parasite antigen as major requirements.
• Definitive diagnosis of parasitic infections is made by identification of parasites in properly
collected specimens or affected tissues.
• Microscopy for observation and identification of parasites: choice for laboratory diagnosis of
some important parasitic infections, namely, malaria, babesiosis, and enteric parasitic
infections.
• However in infections such as; angiostrongyliasis, schistosomiasis, paragonimiasis, and
strongyloidiasis, parasites may be detected in the stool or other specimens but with
limitations of intermittent shedding or sampling, direct observation of parasites are not
sensitive or reliable.
Introduction

3. • Such parasite diseases other parasite diseases caused by parasites that are localized and
sequestered in tissues, such as baylisascariasis, cysticercosis, echinococcosis, toxocariasis,
toxoplasmosis, or trichinellosis, are detected on the basis of specific antibodies; almost always
required to confirm clinical suspicion.
• Most parasitic infections induce a vigorous humoral immune response, so the presence of
parasite-specific antibodies can be a valuable indicator of infection, especially if the patient has
no prior history of exposure.
• But, it doesn’t indicate current infection in the patient who reside in endemic area.
• Parasite-specific antibodies may persist for as little as 6 months after infection or treatment or
for many years, depending on the infecting parasite.
• The humoral immune response usually precedes clinical manifestations for most parasitic
infections.
• Various antibodies against parasite and its antigenic component produced after infection to host
bodies.
• Detection of IgA and IgE alone is not informative, requires IgG detection that are specific to
parasite or its antigen component.
• Except in Toxoplasma-specific IgM and IgA as indicators of acute neonatal toxoplasmosis.

4.  Specimen for antigen detection
• Fresh or preserved stool samples for most of enteric protozoa.
• Venous blood with EDTA and capillary blood
(Note:- Polyvinyl alcohol fixed stool may be acceptable but not formaldehyde/formalin-fixed
specimen)
Specimen Requirements
 Specimens for antibody detection
• Serum or plasma for most of the parasitic infections.
• Aqueous and vitreous eye fluids as well serum for toxocariasis and toxoplasmosis.
• CSF for cysticercosis and toxoplasmosis.

5. African trypanosomiasis
• Caused by Trypanosoma brucei gambiense.
• Diagnosed by 3-step laboratory algorithm: Screening, Conformation and Staging.
• Detection of specific antibodies is the best method for screening, while diagnostic
confirmation and staging require examination of csf.
• Card agglutination test for trypanosoma (CATT) is the most reliable test available for
screening.
• CATT utilizes whole ,fixed, Coomassie blue-stained trypanosomes that react with
serum IgG or IgM Abs to form visible precipitate/agglutination.

6. Amebiasis caused by Entamoeba histolytica
• Entamoeba histolytica is associated with both intestinal and extraintestinal infections.
• Antibody detection is the most useful in patients with extraintestinal disease, i.e. amebic
liver abscess, when organisms are not generally found upon stool examination.
• Antigen used is crude soluble extracts of axenically cultured organisms.
• Enzyme immunoassay and indirect hemagglutination assay are mostly used.
• Immunodetection of E. histolytica antigens in fecal specimens may be used to
distinguish the morphologically identical pathogenic E. histolytica and non-pathogenic
E. dispar.
• The assay detect the galactose inhibitable adherence proteins, which is necessary for
pathogenesis.

7. Chagas’ disease
• Caused by Tryanosoma cruzi
• Immunodiagnosis is mehod of choice in chronic stage of infection , diagnosis.
• Diagnosis usually requires positive results from at least two different serological
methods.
• Serological methods include IHA, IFA assay, complement fixation, EIA ,
immunoblotting, and radioimmunoprecipitation.
• Detect antibody that react with parasite antigens found in crude trypanosome extracts or
in the excretory-secretory (ES) products of cultured parasites or recombinant proteins.

8. Cryptosporidiosis
• Caused by cryptosporidium spp.
• Microscopic identification of cryptosporidium parasites and detection of antigen in stool
specimens are the current diagnostic test of choice.
• DFA test, identifies oocysts in concentrated or unconcentrated fecal samples by using a
fluorescein isothiocyanate labeled monoclonal antibody.
• EIAs detects cryptosporidial antigen in the fresh or frozen stool samples.

9. Cysticercosis (larva Tinea solium)
• Caused by Tinea solium.
• Enzyme linked immunoelectrotransfer blot (EITB) are the antibody detection test formats
most frequently used for the diagnosis of NCC (Neurocysticercosis).
• EITB utilizes partially purified T. solium antigens.
• Detects antibodies to one or more of seven lentil lectin-bound glycoprotein (LLGP)
present in an extract of T. solium cysts.

10. Echinococcosis
• Caused by Echinococcus granulosis.
• Fissuration or rupture of the cyst is followed by an abrupt stimulation of antibody
production.
• Patients with senescent, calcified, or dead cyst is generally found to be seronegative.
• EIA and immunoblotting detect antibody in sera of patient with hydatid disease.
• Crude hydatid cyst fluid is generally employed as the antigen.

11. Lymphatic filariasis
• A definitive diagnosis of lymphatic filariasis can be made only by detection of Wuchereria
bancrofti and Brugia spp. and hence can be difficult.
• Assays for circulating antigens for W. bancrofti permit the diagnosis of microfilaremic and
cryptic (amicrofilaremic) infection.
• ELISA and rapid-format immunochromatographic card test.
• No test for circyulating antigens in Brugian filariasis.

12. Giardiasis
• Caused mainly by Giardia lamblia.
• DFA assay that employ fluorescein isothiocyanate-labelled monoclonal antibody for the
detection of Giardia cyst.
• EIA are available in the microplate format for the detection of Giardia antigen in stool.

13. Leishmaniasis
• Caused by Leishmania donovanii.
• Immunodiagnosis technique detect antibody against cultured epimastigotes of various
Leishmania spp., or crude solubilized epimastigotes.
• Rapid immunochromatographic card test use recombinant proteins k39 or rK28.

14. Malaria
• Caused by Plasmodium spp.
• Rapid diagnostic technique uses histidine rich protein-2 of Plasmodium falciparium and
lactate dehydrogenase, a pan malarial parasite antigens.
• Antibody against these antigen is detected in serum sample.

15. Paragonimiasis
• Caused by Paragonimus spp.
• EIA and immunoblot test are used for diagnosis of paragonimiasis.
• Crude antigen extract of Paragonimus westermani is used for antibody detection.
• Now a days, 8-kDa antigen are used.

16. Toxoplasmasis
• Caused by Toxoplasma gondii.
• Sabin-Feldman dye test, Acetone (AC)- fixed versus formalin (HS)- fixed tachyzoites
(AC/HS) agglutination test, and an IgG avidity test, as well as test for Toxoplasma-
specific IgA and IgE are used as immunological techniques.

17. Trichinellosis
• Caused by Trichinella spiralis.
• EIA detects antibodies specific to Trichinella spiralis ES produced by cultured larvae.
• Currently TSL-1 group of larva secretory antigens is used, which is conserved in all
species/isolates of Trichinella.