Question 1

Which of the following best explains why Mycobacterium leprae primarily infects the peripheral nervous system (PNS) rather than the central nervous system (CNS)?

Accepted Answer

M. leprae thrives at cooler temperatures found in the extremities, which is characteristic of the PNS.

Question 2

A patient presents with localized sensory loss and a single skin lesion. Laboratory tests confirm an acid-fast bacillus. Which form of leprosy is most likely, and what is the prognosis?

Accepted Answer

Tuberculoid leprosy; good prognosis and easily treated.

Question 3

Which of the following is a recommended prevention strategy for infant botulism?

Accepted Answer

Avoid feeding infants under 1 year old honey.

Question 4

Botulinum toxin causes paralysis by which of the following mechanisms?

Accepted Answer

Blocking the release of acetylcholine, resulting in flaccid paralysis.

Question 5

A patient develops muscle rigidity and cannot relax their muscles after stepping on a nail. Which bacterial toxin is responsible, and what is the mechanism?

Accepted Answer

Tetanospasmin; blocks the release of inhibitory neurotransmitters in the CNS.

Question 6

Which of the following statements about fungal nervous system infections is TRUE?

Accepted Answer

Prevention of all fungal nervous system infections is nearly impossible due to ubiquitous spores.

Question 7

A patient with HIV/AIDS develops a severe CNS infection after exposure to bird droppings. Which organism is most likely responsible, and what is the recommended treatment?

Accepted Answer

Cryptococcus neoformans; treated with amphotericin B and flucytosine.

Question 8

Which of the following best describes the transmission route of African sleeping sickness?

Accepted Answer

Bite from a tsetse fly, which acts as a vector for Trypanosoma brucei.

Question 9

Which of the following is a distinguishing feature of prion diseases such as Creutzfeldt-Jakob disease?

Accepted Answer

Transformation of normal prion protein (PrPC) into infectious prion protein (PrPSC), leading to sponge-like brain tissue.

Question 10

A patient presents with confusion, headache, and fever after eating undercooked pork. Which organism is most likely responsible, and what is a key prevention strategy?

Accepted Answer

Toxoplasma gondii; avoid cleaning cat litter boxes if immunocompromised or pregnant.

Question 11

Which of the following equations correctly represents the transformation of prion proteins in transmissible spongiform encephalopathies?

Accepted Answer

$$\mathrm{PrP^C} + \mathrm{$$PrP^{SC}$$} \rightarrow 2\,\mathrm{$$PrP^{SC}$$}$$

Question 12

Which of the following best describes the difference between flaccid and spastic paralysis?

Accepted Answer

Flaccid paralysis is caused by the inability to contract muscles, while spastic paralysis is caused by the inability to relax muscles.

Question 13

Which of the following is a zoonotic transmission route for a nervous system infection?

Accepted Answer

Transmission of Toxoplasma gondii through cat feces.

Question 14

A patient develops severe neurological symptoms after using non-boiled tap water in a neti pot. Which organism is most likely responsible, and what is the typical outcome?

Accepted Answer

Naegleria fowleri; almost always fatal.

Question 15

Which of the following best explains why armadillos are natural carriers of Mycobacterium leprae?

Accepted Answer

Their cooler body temperature provides an optimal environment for M. leprae.

Question 16

Which of the following is a key reason why fungal nervous system infections are more common in immunocompromised patients?

Accepted Answer

Immunocompromised patients have reduced ability to clear fungal spores from the body.

Question 17

Which of the following best describes the mechanism of disease for tetanospasmin?

Accepted Answer

Blocks the release of inhibitory neurotransmitters, causing spastic paralysis.

Question 18

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

Accepted Answer

Routine administration of the DTaP or Tdap vaccine.

Nervous System Infections: Bacterial, Fungal, Protozoal, and Prion Diseases

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