Q.Name the causative agent of typhoid fever?
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Typhoid is an acute intestinal infection caused by the Gram-negative bacterium Salmonella typhi, whose pathogenicity involves its lipopolysaccharide O-antigen and flagellar H-antigen. Symptoms include prolonged fever (up to 104 degF), nausea, fatigue, headache, abdominal pain, a rose-coloured rash, a white-coated tongue, cough and anorexia, with breathlessness/haemorrhage if untreated. It is food- and water-borne, spread further by houseflies/cockroaches and poor sanitation. Diagnosed by the **Widal test …
Typhoid fever is caused by the Gram-negative bacterium Salmonella ty …
Typhoid fever is caused by the Gram-negative bacterium Salmonella typhi.
Step 1. The typhoid section names Salmonella typhi, a Gram-negative bacterium found in the intestinal lumen of an infected person, as the causative agent. …
- Confusing Salmonella typhi (typhoid) with other bacterial pathogens named elsewhere in the chapter, …
Showing the 12 most recent of 16 on this concept.
- CBSE 2026Set ANNUAL1 markQ.Which pathogenic bacterium causes typhoid fever in human?
›Reveal solutionSolution
Typhoid fever in humans is caused by the bacterium Salmonella typhi, transmitted through contaminated food and water.
Salmonella typhi is a rod-shaped, Gram-negative pathogenic bacterium that causes typhoid fever. It typically enters the body through food or water contaminated with the bacteria and causes symptoms like sustained high f …
- CBSE 2026Set ANNUAL1 markQ.Write the name of Typhoid disease-causing micro-organism.
›Reveal solutionSolution
Typhoid fever is caused by the bacterium Salmonella typhi.
Salmonella typhi is a Gram-negative bacterium that causes typhoid fever, a common bacterial disease transmitted through contaminated food and water. The bacteria enter the small intestine, penetrate the intestinal wall, and reach various organs through the blood. Symptoms include sustained high fever (typically 39–40°C), weakness, stomach pain, constipation, headache, and …
- CBSE 2025Set X11 markMCQQ.Which is the test that can be suggested among the given for a patient with symptoms such as - sustained high fever (39°C – 40°C), weakness, stomach pain, constipation, headache and loss of appetite?(a) Widal test(b) ELISA(c) CT(d) MRI
›Reveal solutionSolution
The symptoms described are typical of typhoid, which is diagnosed by the Widal test.
Sustained high fever (39–40°C), weakness, stomach pain, constipation, headache and loss of appetite are the classic symptoms of typhoid fever, caused by Salmonella typhi. Typhoid is confirmed by the Widal test, which detects antibodies against the bacterium. ELISA is …
- CBSE 2025Set ANNUAL1 markMCQQ.Widal test is done to detect which of the following disease?(a) Malaria(b) Typhoid(c) AIDS(d) Cancer
›Reveal solutionSolution
The Widal test is a serological test used to diagnose typhoid fever.
The Widal test detects antibodies (agglutinins) produced against the O and H antigens of Salmonella typhi, the bacterium responsible for typhoid fever, in a patient's serum. A significant rise in antibody titre confirms typhoid infection. It is not used for malaria (diagnosed by microscopic blood smear examination o …
- CBSE 2025Set ANNUAL1 markMCQQ.Typhoid fever could be confirmed by which test -(a) Widal(b) ALISA(c) Biopsy(d) Sonography
›Reveal solutionSolution
The Widal test detects antibodies against Salmonella typhi antigens in a patient's serum, confirming typhoid.
Typhoid fever is caused by the bacterium Salmonella typhi. The Widal test is an agglutination test that detects specific antibodies (against O and H antigens of S. typhi) in the patient's blood serum, and is the classical diagnostic test used to confirm typhoid. ELISA (option b, spelled ALISA in the question) is used for various antigen/antibody detec …
- CBSE 2025Set ANNUAL1 markMCQQ.The clinical test that is used for diagnosis of typhoid is(a) ELISA(b) ESR(c) PCR(d) Widal test
›Reveal solutionSolution
The Widal test detects antibodies against Salmonella typhi in a patient's blood serum, making it the standard diagnostic test for typhoid.
The Widal test is a serological (agglutination-based) test that detects the presence of antibodies against the O and H antigens of Salmonella typhi (the bacterium causing typhoid fever) in a patient's blood serum, and is the classical clinical test used for diagnosing typhoid. ELISA (a) is a general immunological technique used to detect various antigens/antibodies (e.g., in HIV diagnosis), ESR (b, Erythrocyte Sedimentation Rate) is …
- CBSE 2024Set 57/3/11 markMCQQ.Which disease is the patient suffering from who is showing symptoms such as sustained high fever (39°C to 40°C), stomach pain, constipation, headache, loss of appetite and weakness ? (A) Pneumonia (B) Malaria (C) Typhoid (D) Amoebiasis
›Reveal solutionSolution
Sustained high fever (39–40°C), stomach pain, constipation, headache, loss of appetite and weakness are the hallmark symptoms of typhoid fever, caused by the bacterium Salmonella typhi.
The question describes a clinical picture that points unmistakably toward a specific bacterial infection of the intestinal tract. Let's work through the symptom cluster and see why each option fits or fails.
Typhoid fever presents with a very characteristic pattern. The causative agent, Salmonella typhi, enters the body through contaminated food or water and invades the small intestine, eventually spreading into the bloodstream. This systemic infection produces a sustained high fever — typically in the range of 39°C to 40°C — that persists for weeks if untreated. Unlike the cyclical fever spikes of malaria, typhoid fever remains continuously elevated.
The gastrointestinal symptoms are equally telling. Patients experience stomach pain and, notably, constipation in the early stages (though diarrhoea may appear later). Headache, profound weakness, and loss of appetite round out the picture. The NCERT textbook explicitly lists these symptoms when describing typhoid.
Now consider the other options. Pneumonia is primarily a respiratory disease; its hallmark is cough, chest pain, and difficulty breathing — none of which appear in this symptom list. Malaria does cause high fever, but it follows a periodic pattern (fever spikes every 48 or 72 hours depending on the Plasmodium species), and the key symptoms are chills, sweating, and often an enlarged spleen — again, not matching what we see here. Amoebiasis, caused by Entamoeba histolytica, mainly produces abdominal pain and bloody diarrhoea (dysentery), not sustained high fever and constipation. …
- CBSE 2024Set E1 markMCQQ.Which fever is confirmed by Widal test?(a) Malaria(b) Typhoid(c) AIDS(d) Pneumonia
›Reveal solutionSolution
The Widal test confirms typhoid fever.
Typhoid is caused by the bacterium Salmonella typhi, which infects the intestine and can spread through the blood to other organs:
- The WIDAL test is a serological (agglutination) test that detects antibodies produced against Salmonella typhi in the patient's blood. …
- CBSE 2024Set ANNUAL1 markQ.By which test, typhoid fever is examined?
›Reveal solutionSolution
The Widal test detects antibodies against Salmonella typhi antigens in a patient's blood serum.
Typhoid fever is caused by the bacterium Salmonella typhi, transmitted through contaminated food and water. It is diagnosed by the Widal test, a serological (agglutination) test in which the patient's serum is mixed with known O and H antigens of S. typhi. If the patient has b …
- CBSE 2024Set ANNUAL1 markMCQQ.Confirmatory test for Typhoid is :(a) ELISA(b) Western Blot(c) Widal Test(d) All the above.
›Reveal solutionSolution
Typhoid fever, caused by the bacterium Salmonella typhi, is confirmed using the Widal test, which detects antibodies against Salmonella antigens in the patient's serum.
Typhoid is a bacterial disease transmitted through contaminated food and water, causing sustained high fever, weakness, stomach pain, headache and loss of appetite. The Widal test is the classical serological test used to confirm typhoid — it detects agglutinating antibodies (against the O and H antigens of Salmonella typhi) that develop in the patient's blood in response to …
- CBSE 2023Set CG1 markMCQQ.Widal test is used for the diagnosis of which disease?(a) Pneumonia(b) Typhoid(c) Malaria(d) Cholera
›Reveal solutionSolution
The Widal test diagnoses typhoid — option (b).
Concept: Typhoid fever is caused by the bacterium Salmonella typhi. The Widal test is an agglutination test that detects the presence of antibodies (agglutinins) against the O and H antigens of Salmonella typhi in the patient's serum — a rise in titre confirms typhoid.
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- CBSE 2023Set A1 markQ.What is the conformities test of Typhoid?
›Reveal solutionSolution
The Widal test detects antibodies against Salmonella typhi antigens in a patient's blood serum and confirms typhoid infection.
Typhoid fever is caused by the bacterium Salmonella typhi, transmitted through contaminated food and water. The Widal test is the standard confirmatory (serological) test — it detects the presence of agglutinating antibodies against the …
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