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26.E: Nervous System Infections (Exercises)

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    26.1: Anatomy of the Nervous System

    The human nervous system can be divided into two interacting subsystems: the peripheral nervous system (PNS) and the central nervous system (CNS). The CNS consists of the brain and spinal cord. The peripheral nervous system is an extensive network of nerves connecting the CNS to the muscles and sensory structures.

    Multiple Choice

    What is the outermost membrane surrounding the brain called?

    1. pia mater
    2. arachnoid mater
    3. dura mater
    4. alma mater
    Answer

    C

    What term refers to an inflammation of brain tissues?

    1. encephalitis
    2. meningitis
    3. sinusitis
    4. meningoencephalitis
    Answer

    A

    Nerve cells form long projections called ________.

    1. soma
    2. axons
    3. dendrites
    4. synapses
    Answer

    B

    Chemicals called ________ are stored in neurons and released when the cell is stimulated by a signal.

    1. toxins
    2. cytokines
    3. chemokines
    4. neurotransmitters
    Answer

    D

    The central nervous system is made up of

    1. sensory organs and muscles.
    2. the brain and muscles.
    3. the sensory organs and spinal cord.
    4. the brain and spinal column.
    Answer

    D

    Matching

    Match each strategy for microbial invasion of the CNS with its description.

    ___intercellular entry A. pathogen gains entry by infecting peripheral white blood cells
    ___transcellular entry B. pathogen bypasses the blood-brain barrier by travel along the olfactory or trigeminal cranial nerves
    ___leukocyte-facilitated entry C. pathogen passes through the cells of the blood-brain barrier
    ___nonhematogenous entry D. pathogen passes between the cells of the blood-brain barrier
    Answer

    D, C, A, B

    Fill in the Blank

    The cell body of a neuron is called the ________.

    Answer

    soma

    A signal is transmitted down the ________ of a nerve cell.

    Answer

    axon

    The ________ is filled with cerebrospinal fluid.

    Answer

    subarachnoid space

    The ________ ________ prevents access of microbes in the blood from gaining access to the central nervous system.

    Answer

    blood-brain barrier

    The ________ are a set of membranes that cover and protect the brain.

    Answer

    meninges

    Short Answer

    Briefly describe the defenses of the brain against trauma and infection.

    Describe how the blood-brain barrier is formed.

    Identify the type of cell shown, as well as the following structures: axon, dendrite, myelin sheath, soma, and synapse.

    Drawing of a neuron. The large round regions with a darker purple circle is A. Short projections from A are G. A long projection from A is B. This is wrapped in structure E and has gaps labeled F. E is made from C. The end of the long projection is D.

    Critical Thinking

    What important function does the blood-brain barrier serve? How might this barrier be problematic at times?

    26.2: Bacterial Diseases of the Nervous System

    Bacterial infections that affect the nervous system are serious and can be life-threatening. Fortunately, there are only a few bacterial species commonly associated with neurological infections.

    Multiple Choice

    Which of the following organisms causes epidemic meningitis cases at college campuses?

    1. Haemophilus influenzae type b
    2. Neisseria meningitidis
    3. Streptococcus pneumoniae
    4. Listeria monocytogenes
    Answer

    B

    Which of the following is the most common cause of neonatal meningitis?

    1. Haemophilus influenzae b
    2. Streptococcus agalactiae
    3. Neisseria meningitidis
    4. Streptococcus pneumoniae
    Answer

    B

    What sign/symptom would NOT be associated with infant botulism?

    1. difficulty suckling
    2. limp body
    3. stiff neck
    4. weak cry
    Answer

    C

    Which of the following can NOT be prevented with a vaccine?

    1. tetanus
    2. pneumococcal meningitis
    3. meningococcal meningitis
    4. listeriosis
    Answer

    D

    How is leprosy primarily transmitted from person to person?

    1. contaminated toilet seats
    2. shaking hands
    3. blowing nose
    4. sexual intercourse
    Answer

    C

    Fill in the Blank

    The form of meningitis that can cause epidemics is caused by the pathogen ________.

    Answer

    Neisseria meningitidis

    The symptoms of tetanus are caused by the neurotoxin ________.

    Answer

    tetanospasmin

    ________ is another name for leprosy.

    Answer

    Hansen’s disease

    Botulism prevents the release of the neurotransmitter ________.

    Answer

    acetylcholine

    ________ is a neurological disease that can be prevented with the DTaP vaccine.

    Answer

    Tetanus

    Tetanus patients exhibit ________ when muscle spasms causes them to arch their backs.

    Answer

    opisthotonos

    Short Answer

    A physician suspects the lesion and pustule pictured here are indicative of tuberculoid leprosy. If the diagnosis is correct, what microorganism would be found in a skin biopsy?

    Discolored tissue.

    (credit: Centers for Disease Control and Prevention)

    Critical Thinking

    Explain how tetanospasmin functions to cause disease.

    The most common causes of bacterial meningitis can be the result of infection by three very different bacteria. Which bacteria are they and how are these microbes similar to each other?

    Explain how infant botulism is different than foodborne botulism.

    26.3: Acellular Pathogenic Diseases of the Nervous System

    A number of different viruses and subviral particles can cause diseases that affect the nervous system. Viral diseases tend to be more common than bacterial infections of the nervous system today. Fortunately, viral infections are generally milder than their bacterial counterparts and often spontaneously resolve. Some of the more important acellular pathogens of the nervous system are described in this section.

    Multiple Choice

    Which of these diseases can be prevented with a vaccine for humans?

    1. eastern equine encephalitis
    2. western equine encephalitis
    3. West Nile encephalitis
    4. Japanese encephalitis
    Answer

    D

    Which of these diseases does NOT require the introduction of foreign nucleic acid?

    1. kuru
    2. polio
    3. rabies
    4. St. Louis encephalitis
    Answer

    A

    Which of these is true of the Sabin but NOT the Salk polio vaccine?

    1. requires four injections
    2. currently administered in the United States
    3. mimics the normal route of infection
    4. is an inactivated vaccine
    Answer

    C

    Which of the following animals is NOT a typical reservoir for the spread of rabies?

    1. dog
    2. bat
    3. skunk
    4. chicken
    Answer

    D

    Fill in the Blank

    The rogue form of the prion protein is called ________.

    Answer

    PrPSc

    ________ are the most common reservoir for the rabies virus worldwide.

    Answer

    Dogs

    ________ was the scientist who developed the inactivated polio vaccine.

    Answer

    Jonas Salk

    ________ is a prion disease of deer and elk.

    Answer

    Chronic wasting disease

    The rogue form of prion protein exists primarily in the ________ conformation.

    Answer

    beta sheet

    Short Answer

    Explain how a person could contract variant Creutzfeldt-Jakob disease by consuming products from a cow with bovine spongiform encephalopathy (mad cow disease).

    Critical Thinking

    If the Sabin vaccine is being used to eliminate polio worldwide, explain why a country with a near zero infection rate would opt to use the Salk vaccine but not the Sabin vaccine?

    26.4: Neuromycoses and Parasitic Diseases of the Nervous System

    Fungal infections of the nervous system, called neuromycoses, are rare in healthy individuals. However, neuromycoses can be devastating in immunocompromised or elderly patients. Several eukaryotic parasites are also capable of infecting the nervous system of human hosts. Although relatively uncommon, these infections can also be life-threatening in immunocompromised individuals. In this section, we first discuss neuromycoses, followed by parasitic infections of the nervous system.

    Multiple Choice

    Which of these diseases results in meningitis caused by an encapsulated yeast?

    1. cryptococcosis
    2. histoplasmosis
    3. candidiasis
    4. coccidiomycosis
    Answer

    A

    What kind of stain is most commonly used to visualize the capsule of cryptococcus?

    1. Gram stain
    2. simple stain
    3. negative stain
    4. fluorescent stain
    Answer

    C

    Which of the following is the causative agent of East African trypanosomiasis?

    1. Trypanosoma cruzi
    2. Trypanosoma vivax
    3. Trypanosoma brucei rhodanese
    4. Trypanosoma brucei gambiense
    Answer

    C

    Which of the following is the causative agent of primary amoebic meningoencephalitis?

    1. Naegleria fowleri
    2. Entameba histolyticum
    3. Amoeba proteus
    4. Acanthamoeba polyphaga
    Answer

    A

    What is the biological vector for African sleeping sickness?

    1. mosquito
    2. tsetse fly
    3. deer tick
    4. sand fly
    Answer

    B

    How do humans usually contract neurocysticercosis?

    1. the bite of an infected arthropod
    2. exposure to contaminated cat feces
    3. swimming in contaminated water
    4. ingestion of undercooked pork
    Answer

    D

    Which of these is the most important cause of adult onset epilepsy?

    1. neurocysticercosis
    2. neurotoxoplasmosis
    3. primary amoebic meningoencephalitis
    4. African trypanosomiasis
    Answer

    A

    Fill in the Blank

    The ________ is the main virulence factor of Cryptococcus neoformans.

    Answer

    capsule

    The drug of choice for fungal infections of the nervous system is ________.

    Answer

    Amphotericin B

    The larval forms of a tapeworm are known as ________.

    Answer

    cysticerci

    ________ sign appears as swollen lymph nodes at the back of the neck in early African trypanosomiasis.

    Answer

    Winterbottom’s

    ________ African trypanosomiasis causes a chronic form of sleeping sickness.

    Answer

    West

    The definitive host for Toxoplasma gondii is ________.

    Answer

    cats

    Trypanosomes can evade the immune response through ________ variation.

    Answer

    antigenic

    Short Answer

    Why do nervous system infections by fungi require such long treatment times?

    Briefly describe how humans are infected by Naegleria fowleri.

    Briefly describe how humans can develop neurocysticercosis.

    Critical Thinking

    The graph shown tracks the body temperature of a patient infected with Trypanosoma brucei. How would you describe this pattern, and why does it occur?

    Graph with Days on the X axis and Temperature on the Y axis. There is a peak to 40 degrees C early on then a drop back to normal temperatures (37 degree C) for 7 days. Then another peak, then another drop to normal for 9 days, then another peak and then another drop to normal for 9 days.

    (credit: modification of work by Wellcome Images)

    Fungal meningoencephalitis is often the ultimate cause of death for AIDS patients. What factors make these infections more problematic than those of bacterial origin?

    Compare East African trypanosomiasis with West African trypanosomiasis.

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