Typhoid Fever Practice Questions
20 free Typhoid Fever practice questions for the Microbiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
What is the causative agent of typhoid fever?
- A Salmonella typhi
- B Escherichia coli
- C Vibrio cholerae
- D Shigella flexneri
Correct answer: Salmonella typhi
Typhoid fever is caused by Salmonella typhi, a gram-negative bacterium. It primarily infects humans and spreads through contaminated food and water.
Which route is the most common mode of transmission for typhoid fever?
- A Airborne spread
- B Vector-borne spread
- C Direct skin contact
- D Fecal-oral route
Correct answer: Fecal-oral route
Typhoid fever spreads through ingestion of food or water contaminated with feces containing Salmonella typhi. Poor sanitation increases transmission risk.
Which symptom is characteristic of typhoid fever?
- A High-grade sustained fever
- B Severe cough with hemoptysis
- C Skin rash with vesicles
- D Joint swelling and stiffness
Correct answer: High-grade sustained fever
Typhoid fever typically presents with a sustained high fever. Other symptoms include abdominal pain, weakness, and sometimes a rash.
What are 'rose spots' in typhoid fever?
- A Painful deep-seated ulcers
- B Fluid-filled blisters on hands
- C Purulent subcutaneous nodules
- D Small red macules on abdomen
Correct answer: Small red macules on abdomen
Rose spots are faint, salmon-colored macules usually found on the abdomen. They are a classic but not always present sign of typhoid fever.
Which organ is primarily affected in typhoid fever?
- A Heart and lungs
- B Kidneys and bladder
- C Liver and spleen
- D Brain and spine
Correct answer: Liver and spleen
Salmonella typhi infects the reticuloendothelial system, including the liver and spleen. This leads to enlargement of these organs.
Which laboratory test is considered the gold standard for diagnosing typhoid fever?
- A Urine culture
- B Stool microscopy
- C Blood culture
- D Widal test
Correct answer: Blood culture
Blood culture is the gold standard, especially in early stages of the disease. It detects the presence of Salmonella typhi in the bloodstream.
Which antigen is detected in the Widal test?
- A Capsular antigen
- B Exotoxin antigen
- C O and H antigens
- D Lipopolysaccharide only
Correct answer: O and H antigens
The Widal test detects antibodies against O (somatic) and H (flagellar) antigens of Salmonella typhi. It is used as a supportive diagnostic tool.
Which of the following is a major complication of untreated typhoid fever?
- A Intestinal perforation
- B Massive pulmonary embolism
- C Acute renal failure
- D Complete heart block
Correct answer: Intestinal perforation
Intestinal perforation is a serious complication caused by necrosis of Peyer's patches in the intestine. It can lead to peritonitis and death if untreated.
Which type of bacteria is Salmonella typhi?
- A Gram-negative bacilli
- B Gram-positive cocci
- C Acid-fast bacilli
- D Endospore-forming rods
Correct answer: Gram-negative bacilli
Salmonella typhi is a gram-negative, rod-shaped bacterium. It is non-spore-forming and facultatively anaerobic.
Which structure helps Salmonella typhi evade host immunity?
- A Vi capsule
- B Polar flagella
- C Type IV pili
- D Endospore
Correct answer: Vi capsule
The Vi antigen capsule helps Salmonella typhi evade phagocytosis and immune detection. It is an important virulence factor.
Which of the following antibiotics is commonly used to treat typhoid fever?
- A Ceftriaxone
- B Amoxicillin
- C Vancomycin
- D Penicillin G
Correct answer: Ceftriaxone
Ceftriaxone is commonly used to treat typhoid fever, especially in resistant cases. Other options include azithromycin and fluoroquinolones.
Which part of the intestine is most affected in typhoid fever?
- A Duodenum
- B Jejunum
- C Ileum
- D Colon
Correct answer: Ileum
The ileum is most affected due to the presence of Peyer's patches. These lymphoid tissues become inflamed and may ulcerate.
What is the incubation period of typhoid fever?
- A 1–2 days
- B 3–7 days
- C 7–14 days
- D 1–2 months
Correct answer: 7–14 days
The incubation period for typhoid fever is typically 7–14 days. It can vary depending on the infecting dose and host factors.
Which cell type does Salmonella typhi primarily invade?
- A Red blood cells
- B Macrophages
- C Neurons
- D Epithelial skin cells
Correct answer: Macrophages
Salmonella typhi invades macrophages and survives within them. This allows systemic dissemination through the reticuloendothelial system.
Which vaccine is available for typhoid fever prevention?
- A BCG vaccine
- B Ty21a vaccine
- C MMR vaccine
- D Hepatitis A vaccine
Correct answer: Ty21a vaccine
Ty21a is an oral live attenuated vaccine used for typhoid prevention. Injectable Vi polysaccharide vaccines are also available.
Which feature distinguishes typhoid fever from other salmonellosis?
- A Localized infection
- B Systemic infection
- C Skin infection
- D Respiratory infection
Correct answer: Systemic infection
Typhoid fever is a systemic illness, unlike other Salmonella infections that usually cause localized gastroenteritis. It involves bacteremia and organ involvement.
What is the role of carriers in typhoid fever transmission?
- A They pass it by coughing
- B They transmit it via skin contact
- C They shed bacteria in feces
- D They spread it via insect bites
Correct answer: They shed bacteria in feces
Chronic carriers can shed Salmonella typhi in feces for long periods. They play a significant role in spreading the disease.
Which organ is commonly associated with chronic carrier state of typhoid?
- A Bone marrow
- B Gallbladder
- C Appendix
- D Spleen
Correct answer: Gallbladder
The gallbladder can harbor Salmonella typhi, leading to chronic carriage. This is especially common in individuals with gallstones.
Which preventive measure is most effective against typhoid fever?
- A Wearing gloves
- B Boiling drinking water
- C Using antibiotics regularly
- D Avoiding sunlight
Correct answer: Boiling drinking water
Boiling water kills Salmonella typhi and prevents infection. Safe food and water practices are key preventive measures.
Which toxin is associated with Salmonella typhi pathogenesis?
- A Cholera toxin
- B Endotoxin (LPS)
- C Botulinum toxin
- D Tetanus toxin
Correct answer: Endotoxin (LPS)
Salmonella typhi produces endotoxin (lipopolysaccharide) that contributes to fever and inflammation. It plays a role in systemic symptoms.