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Central Nervous System Infectious Inflammation (view source)
Revision as of 12:52, 8 March 2011
, 12:52, 8 March 2011Created page with "==Routes of Entry== * CNS inflammation is usually the result of infection. ** This may be caused by: *** Bacteria *** Fungi *** Protozoa *** Viruses * Organisms must first enter..."
==Routes of Entry==
* CNS inflammation is usually the result of infection.
** This may be caused by:
*** Bacteria
*** Fungi
*** Protozoa
*** Viruses
* Organisms must first enter the CNS in order to establish infection.
** There are several routes of entry that allow this:
**# '''Haematogenous entry'''
**#* This is the most common route.
**# '''Entry via the peripheral nerves'''
**#* Organisms track within the axoplasm of axons.
**#* For example, ''Listeria monocytogenes''.
**# '''Penetrating trauma'''
**#* For example, dehorning wounds, skull fracture or tail docking.
**# '''Direct spread of infection'''
**#* From the nasal cavity, middle ear or paranasal sinuses.
==Localisation of Infectious Organisms==
* After entry, organisms may establish in one or more of four main areas:
*# '''Epidural space'''
*#* Infection tends to manifest as abscess formation.
*# '''Subdural space'''
*#* Manifests as abscess formation.
*#* Fairly uncommon.
*# '''Leptomeninges'''
*#* Causes leptomeningitis, which may be:
*#*# Suppurative
*#*#* The most common form.
*#*#* Neutrophils are the predominant cell type.
*#*#* Caused by bacteria
*#*#** E.g. ''E. coli'' and ''Streptococcus''
*#*#* There are often no gross lesions, but the brain may appear swollen and the meninges opaque.
*#*#* Usually results in death.
*#*# Eosinophilic meningoencephalitis
*#*#* The classic example of this is porcine salt poisoning, when water has been restricted and the suddenly replenished.
*#*#* Perivascular eosinophilic cuffing is seen in the cerebrum and meninges.
*#*# Lymphocytic
*#*#* Usually of viral origin.
*#*# Granulomatous
*#*#* Caused by fungal diseases and Mycobacteriosis.
*# '''CNS parenchyma'''
==Bacterial Infections==
[[Image:pneumococcalmeningitis.jpg|thumb|right|150px|Pneumococcal meningitis. Image courtesy of BioMed Archive]]
* Bacterial infections typically result in abscesses.
** These may be single or multiple depending on the route of entry, and vary in size.
** They contain a central, liquefied cavity.
* There are differences between cerebral abscesses and those occuring elsewhere.
** Encapsulation is slow.
*** This is due to a lack of fibroblasts.
*** There is therefore less collagen in the capsule.
** Astrocytic glial fibers are not as strong as collagen
* Other organisms may cause similar infections:
** Rickettsial organisms
*** E.g. ''Ehrlichia''
** Spirochates
*** E.g. Leptospirosis
==Viral Infections==
* Viral infections tend to reach the CNS by haematogenous spread and via peripheral nerves.
* There are three hallmark lesions of CNS viral infections:
*# Neuronal necrosis
*# Gliosis
*# Vascular changes
* Several types of virus may cause inflammation in the CNS. [[Image:negribodies.jpg|thumb|right|150px|Negri bodies, as seen in rabies. Image courtesy of BioMed Archive]]
** '''Neurotropic''', e.g.
*** Rabies (rhabdovirus)
*** Aujesky’s disease (herpesvirus)
*** Visna (ovine lentivirus)
** '''Endotheliotropic''', e.g.
*** Infectious canine hepatitis (canine adenovirus)
*** Classical swine fever (pestivirus)
*** Equine herpesvirus type 1 (herpes)
** '''Pantropic'''
*** Infectious canine distemper (morbillivirus)
*** Infectious bovine rhinotracheitis (bovine herpesvirus type 1)
* Other examples of viruses affecting the CNS:
** Distemper
** Parvovirus
** Parainfluenza
** Herpes
** FIP
** FIV
** FeLV
** Pseudorabies
** Rabies
==[[Prion Disease]]==
[[Category:Central Nervous System - Inflammatory Pathology]]
* CNS inflammation is usually the result of infection.
** This may be caused by:
*** Bacteria
*** Fungi
*** Protozoa
*** Viruses
* Organisms must first enter the CNS in order to establish infection.
** There are several routes of entry that allow this:
**# '''Haematogenous entry'''
**#* This is the most common route.
**# '''Entry via the peripheral nerves'''
**#* Organisms track within the axoplasm of axons.
**#* For example, ''Listeria monocytogenes''.
**# '''Penetrating trauma'''
**#* For example, dehorning wounds, skull fracture or tail docking.
**# '''Direct spread of infection'''
**#* From the nasal cavity, middle ear or paranasal sinuses.
==Localisation of Infectious Organisms==
* After entry, organisms may establish in one or more of four main areas:
*# '''Epidural space'''
*#* Infection tends to manifest as abscess formation.
*# '''Subdural space'''
*#* Manifests as abscess formation.
*#* Fairly uncommon.
*# '''Leptomeninges'''
*#* Causes leptomeningitis, which may be:
*#*# Suppurative
*#*#* The most common form.
*#*#* Neutrophils are the predominant cell type.
*#*#* Caused by bacteria
*#*#** E.g. ''E. coli'' and ''Streptococcus''
*#*#* There are often no gross lesions, but the brain may appear swollen and the meninges opaque.
*#*#* Usually results in death.
*#*# Eosinophilic meningoencephalitis
*#*#* The classic example of this is porcine salt poisoning, when water has been restricted and the suddenly replenished.
*#*#* Perivascular eosinophilic cuffing is seen in the cerebrum and meninges.
*#*# Lymphocytic
*#*#* Usually of viral origin.
*#*# Granulomatous
*#*#* Caused by fungal diseases and Mycobacteriosis.
*# '''CNS parenchyma'''
==Bacterial Infections==
[[Image:pneumococcalmeningitis.jpg|thumb|right|150px|Pneumococcal meningitis. Image courtesy of BioMed Archive]]
* Bacterial infections typically result in abscesses.
** These may be single or multiple depending on the route of entry, and vary in size.
** They contain a central, liquefied cavity.
* There are differences between cerebral abscesses and those occuring elsewhere.
** Encapsulation is slow.
*** This is due to a lack of fibroblasts.
*** There is therefore less collagen in the capsule.
** Astrocytic glial fibers are not as strong as collagen
* Other organisms may cause similar infections:
** Rickettsial organisms
*** E.g. ''Ehrlichia''
** Spirochates
*** E.g. Leptospirosis
==Viral Infections==
* Viral infections tend to reach the CNS by haematogenous spread and via peripheral nerves.
* There are three hallmark lesions of CNS viral infections:
*# Neuronal necrosis
*# Gliosis
*# Vascular changes
* Several types of virus may cause inflammation in the CNS. [[Image:negribodies.jpg|thumb|right|150px|Negri bodies, as seen in rabies. Image courtesy of BioMed Archive]]
** '''Neurotropic''', e.g.
*** Rabies (rhabdovirus)
*** Aujesky’s disease (herpesvirus)
*** Visna (ovine lentivirus)
** '''Endotheliotropic''', e.g.
*** Infectious canine hepatitis (canine adenovirus)
*** Classical swine fever (pestivirus)
*** Equine herpesvirus type 1 (herpes)
** '''Pantropic'''
*** Infectious canine distemper (morbillivirus)
*** Infectious bovine rhinotracheitis (bovine herpesvirus type 1)
* Other examples of viruses affecting the CNS:
** Distemper
** Parvovirus
** Parainfluenza
** Herpes
** FIP
** FIV
** FeLV
** Pseudorabies
** Rabies
==[[Prion Disease]]==
[[Category:Central Nervous System - Inflammatory Pathology]]