Re: What causes the increased sex drive in rabid animals?

Interesting question. After reading a several textbooks on human neurology 
I think I found an explanation for this phenomenon. But before I start off 
I might as well provide some more info on rabies (quite possibly you 
already have heard some of this).

The disease is caused by the Lyssa virus which is a member of the 
rhabdovirus family. It's an RNA virus having a lipid envelope 
(therefore, the virus can be inactivated by applying detergents or 
disinfectants to ones skin after being bitten).
The Lyssa virus is predominantly (in Europe and North America) spread by 
wild animals such as foxes, bats, raccoons, skunks, and rodents. In a lot 
of cases the virus is then passed on to humans by pet dogs or cats (scratch 
wounds, etc.!).
Numbers of infected persons vary widely. In Germany the number runs around 
50 cases from 1950 until 1990 whereas in India appr. 15000 persons 
a year contract the virus. This enormous difference is attributable to 
widespread measures in Europe to break the chain of transmission. Most 
notably, foxes are fed 'vaccine' baits that make them build up an immunity 
to the virus and eliminates them as 'vectors', i.e. carriers of the virus.

What happens in rabies?
From the wound virus particles usually make their way into the peripheral 
nervous system (uptake through muscle spindles or muscle end plates!) and 
are subsequently transported towards the spinal cord or within the facial 
nerves (depending on where the injury was). 
After multiplying within the spinal ganglia the virus starts spreading 
throughout the CNS and causes havoc there.One might well describe it as a 
severe form of encephalitis which affects neurons and glia cells 
(the virus replicates within these cells in later stages of the disease). 
Nerve cells in various areas of the CNS start to degenerate and/or die. One 
cardinal diagnostic criterion is, by the way, the presence of so called 
Negri inclusion bodies found predominantly in glial cells of the 
hippocampus and cerebellum. 
Important areas which are destroyed are: brain stem, spinal cord, 
basal ganglia and cerebellum (this explains the motor symptoms such 
as spasms, and later on paralysis), thalamus, hippocampus, cortex, 
hypothalamus, and the limbic system.
Here is where I come to answer your question: since the limbic 
system and the hypothalamus both are involved in control of and  
emotional aspects of behavior, destruction of these areas should explain 
symptoms such as depression and states of anxiety on the one side, 
aggressiveness, excitedness, and rage on the other side. 
In humans, the destruction of cortical areas might play a role, too, since 
the frontal lobes seem to play a role in controlling sexual behavior as 
has been shown in lesion experiments done on monkeys (described in  the 
Kolb and Whishaw textbook on Human Neuropsychology). 

Is rabies curable?
Once the severest symptoms show - no (so far, only 3 persons have survived 
the disease). Rabies ultimately leads to death by cardiac arrest and 
paralysis of the breathing musculature. Patients' lives can be extended by 
life support measures but that's merely delaying the inevitable.
On the other side, if treatment is immediately started after being bitten 
by an animal you suspect of having rabies chances for survival are 
excellent since rabies has a long incubation period (from 2 weeks up to 8 
months). This is in most cases sufficient time for your body to build up an 
immune response after vaccination. The alternative is to treat the person 
with an immune serum like the ones used to treat snake bites (both do 
not lead per se to an active immune response but help the body fight off 
the virus/venom).

I will provide you with the references I used but I doubt if they are of 
any help since these textbooks were written in German. But any English
textbook on neurology or neuropathology should work fine. Apart from that I 
found some articles which might provide more insight (I haven't read them 
myself because they're not easily accessible in libraries around here).

Any other questions?
Send me an email. 

References

   
Scheid W: Lehrbuch der Neurologie [textbook of neurology], 5th 
edition, 1983.
   
Poeck and Hacke: Neurologie [neurology], 10th edition, 1998.
   
Hopf/Deuschl/Diener/Reichmann: Neurologie in Praxis und Klinik 
[Neurology for the practitioner and clinician], Vol. 1, 3rd edition, 1999.
   
Minor R. 1994): Rabies and behaviour. The veterinary record, 135: 
47-48.
   
Lindtjorn A (1982): Clinical features of rabies in man. Trop 
Doct, 12: 9-12.
  
Macrae AD (1973): Rabies. British Medical Journal, 1: 604-6.