Brain Worms and deer species

[Scott_J]

Meningeal worm or brain worm has been transferred from the genus Pneumostrongylus to Parelaphostrongylus, hence is now known as Parelaphostrongylus tenuis. This species is a slender, delicate roundworm found in the cranial cavity of cervids. The white-tailed deer is the normal host of P. tenuis.

 

The adult worms are normally located between the membranes (meninges) covering both the brain and spinal cord, but are found more frequently in the meninges of the brain. The adult worms deposit eggs either on these membranes or directly into blood vessels. Those deposited on the membranes, hatch and the larvae enter small blood vessels to be carried to the lungs where they enter the alveoli. Eggs deposited into blood vessels are carried to the lungs and eventually hatch with larval penetration of the alveoli. This activity in the lung tissue produces an interstitial pneumonia. The larvae pass up the respiratory tract from the alveoli, are swallowed and then eliminated in the faeces. Larvae appear in the faeces about three months after the host becomes infected.

 

The larvae then penetrate into gastropods (snails and slugs) which act as intermediate hosts. Development of the larvae in the gastropod to a stage when they are infective to the vertebrate host takes about three weeks. Cervids become parasitized by ingesting infected gastropods with their food.

 

In the final host, development of the larva to the adult worm takes place in tissues of the central nervous system, particularly the spinal cord. Parasites leave the tissues of the spinal cord after about 20-40 days and locate between the spinal membranes where they mature. Subsequently they tend to accumulate in the cranial region. The adult worms are about 50 mm in length and may be seen fairly readily when free in the cranial cavity. From one to 20 worms have been found in the crania of infected deer. P. tenuis seldom causes damage in white-tailed deer.

 

In other cervids there is often extensive damage to tissues of the brain and spinal cord. The resulting neurologic disease is characterized by weakness, fearlessness, lack of coordination of movement, circling, deafness, impaired vision, paralysis and subsequent death. When in moose this disease is often called “moose sickness” or, “moose disease”.

 

The life cycle of P. tennis and the relationship between this parasite and "moose sickness" were first elaborated experimentally by Anderson (1963, 1964). The early experimental work stimulated extensive study of meningeal worm in the natural environment.

 

In Canada, studies by Anderson (1965, 1971, 1972), Bindemagel and Anderson (1968), Kelsall and Prescott (1971), Lankester and Anderson (1968) and Saunders (1973) have substantiated the importance of this problem in management of big game and have given us some indication of the dynamics of the hostparasite relationships among wild populations.

 

P. tenuis has a wide distribution in eastern and central North America. Within Ontario in the last 100 years, changes in the environment have resulted in the northern extension of the deer range. Both deer and meningeal worm have shared range with moose. "Moose sickness" has been restricted to areas where deer and moose ranges overlap. Declines in the moose populations of New Brunswick, Nova Scotia, Maine and Minnesota appear to be associated with this disease.

 

Failure to consider the importance of the effect of this parasite on cervids other than white-tailed deer resulted in the loss of a small herd of reindeer introduced from Norway to Ontario in 1969.

 

Damn Norweigns

[sk]

stupid question... are you ready for it??

 

are hunters or those who eat the hunted meet at any risk??

[Beck]

if you like wildlife, don't take your house dogs in the wilderness. do wildlife a favor and leave them at home. lots of that going on, the transference of disease from house dog to wildlife...

[Scott_J]

No, humans are not at risk on this particular paracite.

[Uncle_Tricky]

sisu_suomi said:

Humans are not at risk on this particular paracite.

 

Unless of course you made a habit of eating slugs as I did as a child.

 

sisu_suomi said:

The resulting neurologic disease is characterized by weakness, fearlessness, lack of coordination of movement, circling, deafness, impaired vision, paralysis...

 

This does explain a few things however.

[Dru]

Muffy_The_Wanker_Sprayer said:

stupid question... are you ready for it??

 

are hunters or those who eat the hunted meet at any risk??

 

the chronic wasting disease will kill them first

[Beck]

we are at such a state against nature with the continued lack of species diversity and propagation, i feel this explains some of the massive, contagious maladies seen being spread from animal to man like Ebola, SARS, etc.

 

with an incredible loss in diversity of species and loss of natural environment acting as buffers against disease, these fatal illnesses now crop up in a host population, then jump to man as we are the dominant species with the bigggest species footprint on the planet.

 

The death of the songbirds, the decline of fish population, the deforestation of the world, species extinction and reduction of habitat are all stressing the planet out to try to stomp us humans.

 

my 2 cents. and don't bring fido out in the mountains. do the wilderness a favor.

[EWolfe]

Beck said:

we are at such a state against nature with the continued lack of species diversity and propagation, i feel this explains some of the massive, contagious maladies seen being spread from animal to man like Ebola, SARS, etc.

 

with an incredible loss in diversity of species and loss of natural environment acting as buffers against disease, these fatal illnesses now crop up in a host population, then jump to man as we are the dominant species with the bigggest species footprint on the planet.

 

The death of the songbirds, the decline of fish population, the deforestation of the world, species extinction and reduction of habitat are all stressing the planet out to try to stomp us humans.

 

Burning Hummers will make you feel better, Beck - you should try it

[Scott_J]

Humans are heading for the endangered species list.

And that ain't no shit!

[bird]

sisu_suomi said:

Damn Norweigns

 

I fully agree.