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Some agglutination / Serological test :

  • VDRL
  • Widal
  • Weil-Felix reaction
  • Rheumatoid Arthritis (RA / RF Test)
  • Anti-Streptolysin-O(ASO)
  • C-reactive protein(CRP)
  • Blood grouping

VDRL : Venereal Disease Research Laboratory.

Indication : To diagnose Syphilis & Gonorrhoea.

Widal test :

Indication : To diagnosis of Typhoid & Paratyphoid fever.

Interpretation of Widal Test Result :

TO titreTH TitreInterpretation
1 : 801 : 40Normal
1 : 160 or more1 : 80Typhoid fever
1 : 160 or more1 : 160 or moreTyphoid fever
1 : 80 1 : 160 or moreAnamnestic reaction

Weil-Felix reaction : 

Indication : Rickettsial Fever

Rheumatoid Arthritis (RA / RF Test) : 

Indication : Rheumatoid Arthritis.

ASO titre test:

Indication : Rheumatic fever.

C-reactive protein(CRP)

Indication : Non-specific marker of inflammation such as infections, autoimmune diseases, and cancer.

Titre : It is the highest dilation of the serum giving a positive reaction.

Antigen : Any substance which binds with antibody is called antigen.It may be immunogenic or non-immunogenic.

Antibody : An antibody is a type of globulin (immunoglobulin) produced in response to an antigen with which it reacts specifically.

Antigen antibody reaction :

It is the combination of an antigen with its specific antibody. 

Importance of antigen antibody reaction :

  1. Diagnosis of disease. 
  2. To assess the progress of specific treatment. 
  3. To detect the antibody titre after immunisation.
  4. To identify organism. 
Triple Antigen Test : 
Typhoid : TO, TH
Paratyphoid A : AO, AH
Paratyphoid B : BO, BH

Weil-Felix reaction
Rickettsial Fever : OX2, OXK, OX19

Brucella Abortus : BA
Brucella Melitensis : BM

ICT : Immunochromatographic Test.

Indications of ICT :

  • ICT for Hepatitis B (HBsAg)
  • ICT for Pregnancy (Urine)
  • ICT for HCV, HIV, Dengue (NS1, IgG, IgM).
  • ICT for Syphilis
  • ICT for Malaria

CFT : Complement fixation test.

Indication of CFT :

  • CFT for Filaria
  • CFT for syphilis and Lyme disease.
  • CFT for Herpes Simplex Virus (HSV), Cytomegalovirus (CMV), and Epstein-Barr virus.

Sensitivity : 

Sensitivity is calculated as the number of true positives divided by the total number of people with the disease. For example, if a test has a sensitivity of 80%, then 80 out of 100 people with the disease will test positive.

Specificity : 

Specificity is calculated as the number of true negatives divided by the total number of people without the disease. For example, if a test has a specificity of 90%, then 90 out of 100 people without the disease will test negative.

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