Changes

*Eastern Equine Encephalitis (EEE)

*Eastern Equine Encephalitis (EEE)

*Western Equine Encephalitis (WEE)

*Western Equine Encephalitis (WEE)

*Venezuelan Equine Encephalitis (VEE) - '''reportable''' in the USA<ref>Pasquini, C, Pasquini S, Woods, P (2005)'''Volume 1: Guide to Equine Clinics''', third edition, p266, SUDZ publishing.</ref>

*Venezuelan Equine Encephalitis (VEE) - '''reportable''' in the USA<ref name="same">Pasquini, C, Pasquini S, Woods, P (2005)'''Volume 1: Guide to Equine Clinics''', third edition, p266, SUDZ publishing.</ref>

==Aetiology==

==Aetiology==

===EEE and WEE===

===EEE and WEE===

Following an incubation period of up to 21days, an initial pyrexia and mild depression are short-lived and often missed.  The acute phase of the disease presents with mild to severe pyrexia, anorexia and stiffness, lasting up to 5 days.  During this time, the horse is viraemic and capable of amplifying the disease.  The fever may then fluctuate with neurological derangements appearing a few days post-infection.  These changes indicate disease progression, which occurs more frequently with EEE (the most virulent of the three serotypes).  Any of the following may be observed:

Following an incubation period of up to 21days<ref name="multiple">Bertone, J.J (2010) Viral Encephalitis in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), ''Saunders'', Chapter 12</ref>, an initial pyrexia and mild depression are short-lived and often missed.  The acute phase of the disease presents with mild to severe pyrexia, anorexia and stiffness, lasting up to 5 days.  During this time, the horse is viraemic and capable of amplifying the disease.  The fever may then fluctuate with neurological derangements appearing a few days post-infection.<ref name="same">Pasquini, C, Pasquini S, Woods, P (2005)'''Volume 1: Guide to Equine Clinics''', third edition, p266, SUDZ publishing.</ref> These changes indicate disease progression, which occurs more frequently with EEE (the most virulent of the three serotypes).  Any of the following may be observed<ref name="multiple">Bertone, J.J (2010) Viral Encephalitis in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), ''Saunders'', Chapter 12</ref>:

*conscious proprioceptive deficits

*conscious proprioceptive deficits

*propulsive walking

*propulsive walking

*restlessness

*restlessness

*hypersensitivity to sound and touch

*hypersensitivity to sound and touch

Worsening neurological deficits may result in:

Worsening neurological deficits may result in<ref name="multiple">Bertone, J.J (2010) Viral Encephalitis in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), ''Saunders'', Chapter 12</ref>:

*head pressing

*head pressing

*head tilt

*head tilt

*apparent blindness

*apparent blindness

*facial and appendicular muscle fasciculations

*facial and appendicular muscle fasciculations

*pharynx, larynx and tongue paralysis

*pharynx, larynx and tongue paralysis

*recumbency for 1-7 days followed by death

*recumbency for 1-7 days followed by death<ref name="same">Pasquini, C, Pasquini S, Woods, P (2005)'''Volume 1: Guide to Equine Clinics''', third edition, p266, SUDZ publishing.</ref>

===VEE===

===VEE===

==Diagnosis==

==Diagnosis==

Presumptive based on epidemiology and clinical signs.  Definitive diagnosis requires virus identification, serological tests and/or post-mortem examination.   

Presumptive based on history, epidemiology and clinical signs.<ref name="same">Pasquini, C, Pasquini S, Woods, P (2005)'''Volume 1: Guide to Equine Clinics''', third edition, p266, SUDZ publishing.</ref> Definitive diagnosis requires virus identification, serological tests and/or post-mortem examination.   

===Laboratory Tests===

===Laboratory Tests===

==Treatment<ref name="multiple">Bertone, J.J (2010) Viral Encephalitis in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), ''Saunders'', Chapter 12</ref>==

==Treatment<ref name="multiple">Bertone, J.J (2010) Viral Encephalitis in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), ''Saunders'', Chapter 12</ref>==

No effective, specific treatment is available.  Supportive management includes:

No effective, specific treatment is available.<ref name="same">Pasquini, C, Pasquini S, Woods, P (2005)'''Volume 1: Guide to Equine Clinics''', third edition, p266, SUDZ publishing.</ref> Supportive management includes:

*NSAIDs (phenylbutazone, flunixin meglumine) to control pyrexia, inflammation and discomfort

*NSAIDs (phenylbutazone, flunixin meglumine) to control pyrexia, inflammation and discomfort

*DMSO IV in a 20% solution to control inflamation, provide some analgesia and mild sedation

*DMSO IV in a 20% solution to control inflamation, provide some analgesia and mild sedation

===Vector control===

===Vector control===

Responsible use of insecticides and repellents, elimination of standing water, and stable screening will all help to reduce viral transmission.  Environmental application of insecticides may be useful in endemic areas or during an outbreak.  Horses infected with Venezuelan EEV should be isolated for 3 weeks after complete recovery.

Responsible use of insecticides and repellents<ref name="same">Pasquini, C, Pasquini S, Woods, P (2005)'''Volume 1: Guide to Equine Clinics''', third edition, p266, SUDZ publishing.</ref>, elimination of standing water, and stable screening will all help to reduce viral transmission.  Environmental application of insecticides may be useful in endemic areas or during an outbreak.  Horses infected with Venezuelan EEV should be isolated for 3 weeks after complete recovery.<ref name="same">Pasquini, C, Pasquini S, Woods, P (2005)'''Volume 1: Guide to Equine Clinics''', third edition, p266, SUDZ publishing.</ref>

==References==

==References==