Question 1

Which of the following best describes the function of the blood-brain barrier (BBB) in the central nervous system?

Accepted Answer

It is a highly selective semipermeable barrier composed of endothelial cells that protects the brain from pathogens and toxins.

Question 2

A patient presents with fever, headache, stiff neck, and later develops convulsions and coma. Which condition is most likely based on these symptoms?

Accepted Answer

Bacterial meningitis

Question 3

Which bacterial pathogen is most commonly associated with meningitis in children aged 6 months to 4 years and is preventable by the Hib vaccine?

Accepted Answer

Haemophilus influenzae type B

Question 4

Which of the following statements about Clostridium tetani is TRUE?

Accepted Answer

It produces a neurotoxin that blocks inhibitory neurotransmitter release, leading to rigid paralysis.

Question 5

A child develops muscle weakness and floppy movements after consuming honey. Which organism is most likely responsible?

Accepted Answer

Clostridium botulinum

Question 6

Which of the following is the correct equation for calculating the mortality rate (%) of a disease given the number of deaths ($$D) $$and the number of cases ($$N$$)?

Accepted Answer

$$\frac{D}{N} 	imes 100$$

Question 7

Which of the following best explains why vaccines for Neisseria meningitidis target multiple serotypes?

Accepted Answer

There are several serotypes associated with disease, so targeting multiple increases vaccine effectiveness.

Question 8

A patient with a history of eating unpasteurized cheese develops sepsis and meningitis. Which organism is most likely responsible, and what is the primary route of transmission?

Accepted Answer

Listeria monocytogenes; foodborne infection

Question 9

Which of the following is a distinguishing feature of lepromatous (progressive) leprosy compared to tuberculoid (neural) leprosy?

Accepted Answer

Disfiguring nodules over the body and involvement of mucous membranes

Question 10

Which of the following best describes the mechanism of action of botulinum toxin?

Accepted Answer

It blocks the release of acetylcholine at neuromuscular junctions, causing flaccid paralysis.

Question 11

Which of the following is the most effective prevention strategy for tetanus?

Accepted Answer

Vaccination with tetanus toxoid (DTaP) and regular boosters

Question 12

A patient presents with fever, headache, and a stiff neck. A lumbar puncture is performed to obtain cerebrospinal fluid. Which space is targeted during this procedure?

Accepted Answer

Subarachnoid space

Question 13

Which of the following is a common source of infection for Cryptococcus neoformans, especially in immunocompromised patients?

Accepted Answer

Pigeon and chicken droppings

Question 14

Which of the following best explains why African trypanosomiasis is difficult to control with vaccines?

Accepted Answer

The parasite undergoes antigenic variation, evading antibody responses.

Question 15

Amebic meningoencephalitis caused by Naegleria fowleri is most likely acquired through which activity?

Accepted Answer

Swimming in contaminated freshwater

Question 16

Which of the following is a key difference between the Salk and Sabin polio vaccines?

Accepted Answer

Salk is injectable and inactivated; Sabin is oral and live attenuated.

Question 17

Which of the following best describes the transmission route of rabies virus in the United States?

Accepted Answer

Bite or saliva exposure from infected animals, especially bats

Question 18

Which of the following is a recommended strategy by the WHO to reduce the incidence of neglected tropical diseases?

Accepted Answer

Preventative chemotherapy, vector control, and improved sanitation

Question 19

A patient develops polio-like paralysis after being bitten by a mosquito in the United States. Which virus is most likely responsible?

Accepted Answer

West Nile virus

Question 20

Which of the following best describes the pathogenesis of Listeria monocytogenes in causing meningitis?

Accepted Answer

It reproduces inside phagocytes and spreads from cell to cell, crossing the blood-brain barrier.

Microbial Diseases of the Nervous System: Structure, Pathogenesis, and Clinical Features

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