MICROPARA | CHAPTER 9

Inflammation of the meninges

Meningitis

Initial symptoms of meningitis are a triad of fever, headache, and a stiff neck.

• Nausea and vomiting often follow. Eventually, meningitis may progress to __________

convulsions and coma.

Causative agents of meningitis are varied, but they enter the ____ through the __________

CSF; bloodstream

One of the causative agents of meningitis where the bacterium is normally in the throat

• Hib-caused meningitis is mostly in children under age 4; can be prevented by vaccine

Haemophilus influenzae

One of the causative agents of meningitis that is normally present in the nose and throat of carriers

Neisseria meningitidis

Transmission by droplet aerosol or direct contact

Symptoms caused by an endotoxin that is produced very rapidly and is capable of causing death within just a few hours

The most distinguishing feature is a rash that does not fade when pressed.

6 serotypes cause the disease, but serotype B has no vaccine

Neisseria meningitidis

One of the causative agents of meningitis that is inhabitant of the nasopharyngeal region

• Has vaccines, but the many serotypes make it difficult to develop vaccines against all of them

Streptococcus pneumoniae

caused by Listeria monocytogenes

Listeriosis

• Widely distributed in soil and water

• The bacterium reproduces in phagocytes

• Acquired by ingestion of contaminated food

• May be asymptomatic in healthy adults, but can cause meningitis in newborns, immunosuppressed, pregnant women, and cancer patients.

• Can cross placenta and cause spontaneous abortion and stillbirth

Listeriosis

Caused by Clostridium tetani, a spore-forming, obligate anaerobe found in soil

Tetanus

The wound by which C. tetani enters the body must provide anaerobic growth conditions

Tetanus

many cases of tetanus arise from trivial injuries, such as sitting on a tack, that are considered too minor to bring to the attention of a physician.

true

In tetanus, the bacteria do not spread from site of infection but their potent neurotoxin, _____________, is released upon death and lysis

tetanospasmin

Tetanospasmin blocks ________________ in muscles, leading to ___________ and ________; back muscles can spasm

relaxation pathway; muscle spasms; lockjaw

In tetanus, death results from spasms of the ______________________

respiratory muscles

Back muscle spasms, known as ___________, cause the head and heels to bowl backwards, as in this image. This can actually result in a fractured spine.

opisthotonos

Facial tetanus involving contraction of the __________

masseter

Tetanus can be prevented by vaccines

• Prevention by vaccination with inactivated toxin, what are those?

the tetanus toxoid (DTaP), and booster (dT)

a form of food poisoning caused by Clostridium botulinum

Botulism

In botulism, if the endospores are swallowed, usually harmless – unless the environment is __________

anaerobic

C. botulinum produces an exotoxin, the botulinum toxin, in anaerobic conditions that blocks __________________

acetylcholine release

Symptoms of Botulism: progressive _____________ for 1 to 10 days and may result in _______________ failure

flaccid paralysis; respiratory and cardiac

• Nausea, but no fever, may precede the ___________ symptoms.

• Initial neurological symptoms vary but nearly all sufferers have __________________.

• Other symptoms include difficulty _____________ and general weakness

neurological; double or blurred vision; swallowing

Type of botulism, from toxin-contaminated food. Common sources: improperly canned, preserved, or fermented homemade food. Though uncommon, store-bought foods also can be contaminated, e.g. canned goods

Foodborne

Type of botulism, spores get into a wound and make toxin. Mostly from drug injection, but can occur after traumatic injury

Wound

Type of botulism, – spores of the bacteria get into an infant’s intestines, spores grow and produce toxin

Infant

Type of botulism, very rare kind of botulism; spores get into an adult’s intestines, grow, and produce the toxin

Adult intestinal toxemia

Type of botulism, too much botulinum toxin is injected for cosmetic reasons

Iatrogenic

Botulinum toxin types:

Type ___ toxin – most virulent; can cause death when food is only tasted but not swallowed

Type ____ – responsible for most European outbreaks

Type ___ – can be destroyed by boiling, but can be produced at refrigerator temp

A

B

E

Botulinum toxin is also known for its medical use, such as ____________

Botox

Caused by Mycobacterium leprae, an acid-fast rod

Leprosy (Hansen’s disease)

Leprosy grows best in ________ body regions, e.g. peripheral nerves and skin cells

cooler

Transmission requires ___________ with an infected person

Mostly via ____________ of lepromatous leprosy patients

prolonged contact

nasal secretions

Type of Leprosy, skin regions with loss of sensation and surrounded by border of nodules; occurs in effective immune responses

Tuberculoid

Type of Leprosy, progressive form; skin cells infected, disfiguring lesions all over body; occurs if cell-mediated immune response is least effective

Lepromatous

Lion-faced appearance and deformation of hand; necrosis can occur

Lepromatous

Caused by poliovirus

Poliomyelitis

Transmission by ingestion of water contaminated with feces that have the virus

Poliomyelitis

• From throat to small intestine, the virus travels to the lymph nodes, then to bloodstream, causing viremia

• If viremia is persistent, the virus enters the CNS and has affinity for motor nerve cells in the upper spinal cord.

• Death results from respiratory failure

Poliomyelitis

• A disease that almost always results in fatal encephalitis

• Caused by the rabies virus

Rabies

Proliferates in the ____ and moves, fatally, to the _____

PNS; CNS

Rabies is unique in that the _______ period is usually long enough to allow immunity to develop from postexposure vaccination.

incubation

Symptoms in humans

Preliminary: varied and mild

When virus reaches _____: alternating periods of agitation and intervals of calm; spasms of the muscles of the mouth and pharynx and ________

Final stages: extensive damage to nerve cells of brain and spinal cord

CNS; hydrophobia

Symptoms in animals

__________ – highly excitable, will bite at anything; nervous control progressively lost; death

___________ – minimal excitability (common in cats)

Furious (classical); Paralytic (dumb or numb)

are arthropod-borne viruses that belong to several families.

Arboviruses

Cryptococcus neoformans meningitis

Cryptococcosis

Soil fungus associated with pigeon and chicken (aerosolization of dried up contaminated droppings)

Cryptococcosis

Transmitted through respiratory route; spreads through blood to the CNS

Cryptococcosis

sleeping sickness caused by Trypanosoma brucei gambiense and T. brucei rhodesiense

These parasites are capable of antigenic variation to escape the immune system

African trypanosomiasis

• Transmitted by tsetse fly

• Occurs throughout western and central Africa

African trypanosomiasis

also causes daytime sleepiness and night sleep disturbance

T. brucei gambiense

Naegleria fowleri and can be found in recreational freshwater

Amoebic meningoencephalitis

Causes primary amebic meningoencephalitis (PAM);

Initially infects the nasal mucosa and later penetrates to the brain and proliferates, feeding on brain tissue. The fatality rate is nearly 100%, death occurring within a few days after symptoms appear.

Can be found in recreational freshwater

Causes granulomatous amebic encephalitis (GAE)

• chronic, slowly progressive, and fatal in a matter of weeks or months

• has an unknown incubation period, and months may elapse before symptoms appear.

Acanthamoeba

are caused by prions. These are neurodegenerative, rapidly progressive, always fatal diseases

Transmissible spongiform encephalopathies (TSE)

• Most people develop the disease spontaneously (sporadic CJD); inherit the mutation (familial CJD); or, rarely, be acquired from medical procedures, such as a cornea or skin transplant, and brain surgery (iatrogenic CJD)

• Median age of death: 68 yrs

• Dementia and early neurologic signs distinguish it from another form, variant CJD

Classic Creutzfeldt-Jakob disease (CJD)

• The prion disease obtained from eating beef with mad cow disease (bovine spongiform encephalopathy or BSE)

• Psychiatric symptoms and delayed neurological signs observed in patients

• Median age of death: 28 yrs 

Variant Creutzfeldt-Jakob disease (vCJD)

Observed in the Fore people in Papua New Guinea, who used to practice ritual cannibalism

Disease is disappearing as the practice is dying out

Kuru