Unit 15. Infectious Diseases Affecting the Nervous System

Central nervous system (CNS):

brain and spinal cord

Peripheral nervous system (PNS)

nerves that emanate from the brain and spinal cord to sense organs and the periphery of the body

CNS:

Dense organs made of neurons Surrounded by membranes: the meninges

Cerebrospinal fluid (CSF)

provides nutrients and protection

Defenses and normal biota of the nervous system

Link between the gut microbiome and the nervous system:

the gut-brain axis

Viruses (like herpes simplex) in a dormant state are not considered…

normal biota

Meningitis

-general term

-inflammation of the meninges

-Most often infectious, severe forms caused by bacteria

Meningococcal meningitis cause & treatment

-meningococcemia; bacterial endotoxin stimulates cytokine production by WBCs. Damage to blood vessels provokes petechiae

C:Neisseria meningitidis

T: Ceftriaxone & penicillin

pneumococcal meningitis:

-caused by Streptococcus pneumoniae

•Most common cause & type of bacterial meningitis

-Produces hemolysin & H2O2 to
damage tissue. induces
apoptosis

-T:Vancomycin, ceftriaxone or cefotaxime

Haemophilus influenzae causes…

•Severe meningitis.

-T: ceftriaxone

listeriosis

-caused by Listeria monocytogenes

•mild or subclinical type of meningitis, Affects brain and meninges.

-T:ampicillin + gentamicin

Fungal meningitis caused by Cryptococcus neoformans

-Unicellular fungus (yeast) with great capsule. that may turn systemic & affect other organs

-T: Amphotericin B & flucytosine followed by fluconazole

Fungal meningitis caused by Coccidioides

-Coccidioides immitis, Systemic, highly virulent infection

T: Fluconazole or ampthotericin B

Viral meningitis

• Caused by enteroviruses or herpesviruses

• Milder than bacterial or fungal meningitis

-T: none unless specific virus is identified & antiviral exists

Neonatal and Infant meningitis

• Bacterial meningitis, transmitted vertically during birth. Also in baby formula

Neonatal and Infant meningitis: caused by Streptococcus agalactiae

T: penicillin G + aminoglycosides

Neonatal and Infant meningitis: caused by E.coli

T: ceftazidime or cefepime +/- gentamicin

Neonatal and Infant meningitis: caused by listeria monocytogenes

T:ampicillin, trimethoprim-sulfamethoxazole

Neonatal and Infant meningitis: caused by cronobacter sakazakii

T: begin w broad spectrum drugs until specifics determined

Meningoencephalitis

Infections affecting the meninges and brain.

two types:

Naegleria fowleri

Acanthamoeba

Meningoencephalitis: Primary amoebic meningoencephalitis (PAM)

•infection affecting the meninges & brain caused by Naegleria fowleri

-rapid destruction of brain and spinal tissue -> hemorrhage and coma -> death within a week.

-T: pentamidine, sulfadizine

Meningoencephalitis: granulomatous amoebic meningoencephalitis (GAM) 

• infection affecting the meninges & brain caused by Acanthamoeba

•slower course of death

-T: surgical excision of granulomas; pentamidine

Acute encephalitis

- various conditions involving an inflammatory process in the brain

• A viral diseases caused by a variety of viruses

• Some may be treated with antivirals (acyclovir, zydovudine, etc.)

Subacute encephalitis: toxoplasmosis

• Most common form of subacute encephalitis

• Caused by protozoan parasite Toxoplasma gondii

-T: pyrimethamine and/or leucovorin and or sulfadiazine

Other forms of subacute encephalitis:Subacute sclerosing panencephalitis (SSPE)

C-reactivated measels virus

T- None

Other forms of subacute encephalitis: Creutzfeldt-Jakob disease (CJD)

• Caused by prions, human form of transmissible spongiform encephalopaties

-Death usually occurs within 1 year of diagnosis

-T: none

Zyka Virus Disease

•Caused by the Zika Virus

-T: supportive(i.e. not cure for disease so treatment is focused on symptoms)

Rabies

•Zoonosis characterized by fatal encephalitis

•Caused by the rabies virus (Rhabdoviridae)

-T: postexposure passive & active immunization, induced coma + ventilators if symptoms are present

Poliomyelitis (polio)

•Acute enteroviral infection of the spinal cord causing neuromuscular paralysis

•Caused by poliovirus

-T:none, palliative ,support

Polio Nonparalytic disease:

invasion but not the destruction of nervous tissue. Muscle pain and spasm, meningeal inflammation, hypersensitivity.

Polio Paralytic disease:

invasion of motor neurons causes flaccid paralysis, leading to muscle atrophy. Sensation is not impaired and crippled limbs may be painful

Tetanus

-Neuromuscular disease leading to spastic paralysis

-C: clostridium tetani

-T: Passive antitoxin & tetanus toxoid active immunization, metronidazole, muscle relaxants; sedation

Botulism

Neuromuscular disease leading to flaccid paralysis

-C: clostridium botulinum

-T:antioxin, penicillin G for wound botulism(when it enters through wound), supportive care

African sleeping sickness

-Neurological disease, endemic in Africa

-caused by parasitic protozoan Trypanosoma brucei

-T suramin or pentamidine(early), eflornithine or melarsoprol(late)