Question

Widal test is used for the diagnosis of
A) Typhoid
B) Plague
C) Pneumonia
D) Diphtheria

Answer 1

Widal test is a serological test that is accomplished for the analysis of typhoid fever. This test identifies the ''0 ''and '' H'' antigen of Salmonella typhi.

Complete answer:
In 1896 and named after its creator, Georges-Fernand Widal, is a backhanded agglutination test for enteric fever or undulant fever whereby microbes causing typhoid fever are blended in with a serum containing explicit antibodies acquired from a contaminated person.
Typhoid fever, likewise referred to just as typhoid, is a bacterial disease because of a particular kind of Salmonella that causes manifestations. In instances of Salmonella contamination, it is a show of the presence of O-soma bogus positive outcome.
The conventional Widal test estimates antibodies against flagellar (H) and physical (O) antigens of the causative living being. In intense disease, O neutralizer shows up first, rising logically, later falling and frequently vanishing inside a couple of months. H immune response seems somewhat later however perseveres for more. Ascending or high O immunizer titre for the most part demonstrates intense contamination, though raised H neutralizer assists with recognizing the sort of enteric fever.
The primary rule of Widal test is that if homologous immune response is available in patients serum, it will respond with individual antigen in the reagent and gives noticeable bunching on the test card and agglutination in the cylinder. The antigens utilized in the test are "H" and "O" antigens of Salmonella Typhi and "H" antigen of S.
In this test, the serum is blended in with a dead bacterial suspension of salmonella having explicit antigens on it. On the off chance that the patient's serum is conveying antibodies against those antigens, at that point they get connected to them framing clustering which shows the energy of the test. In the event that agglutination doesn't happen, at that point the test is negative.

Hence the correct answer is option ‘A’.

Note: Widal test is a type of agglutination reaction and works on the principle of Antigen-Antibody interaction. The primary rule of Widal test is that if homologous immune response is available in patients serum, it will respond with individual antigen in the reagent and gives noticeable bunching on the test card and agglutination in the cylinder.