Vaccination

[Guest guest]

Clementien Pauws <clementien asked:

>Is vaccination against Rabies for all people and animals not an

>option???? If not, what are the milliards of vaccinations doing in

>the freezers for birdflue???

 

This requires some explanation about how vaccination works.

 

Yes, vaccination can & should be done to control rabies in

China, but there is apparently a big problem in southern China with

the sale of ineffective fake vaccines, not only for rabies but also

for avian flu H5N1, and even if prophylactic vaccine of dogs is

properly done to prevent further rabies outbreaks, this will be a

project somewhat different from what is done to stop the spread of

epidemics in animals who are raised for food.

 

By way of preface, let me mention that there is a precedent

for vaccinating dogs on the scale that would be necessary to stop

rabies in China. Dr. Oscar Larghi, of Argentina, organized the

mass vaccination drives that virtually eliminated canine rabies from

much of Argentina, Brazil, and several other Latin American

nations, approximately 20 years ago. Unfortunately, for fiscal

reasons, Larghi's initiative was not properly followed up, and

rabies is again a problem in parts of Argentina, apparently

spreading to dogs from bats. Nonetheless, what Larghi did can be

done again, and would probably be easier to do in a much more

organized society, such as China.

 

The first essential element of understanding epidemic control

through vaccination is to understand the principle of ring

vaccination, which also applies to sterilizing street dogs and feral

cats in the manner that most rapidly reduces the population and keeps

the animals out of the sensitive locations where they are not welcome.

 

Keep in mind that surgical sterilization is really just using

a surgical method to " vaccinate " animals against pregnancy. Whether

the subject is viruses, microbes, street dogs, feral cats, or

human beings, it is necessary to prevent more than 70% of the

population from reproducing in order to keep the subject from

expanding beyond the original host, i.e. breeding at more than

replacement level.

 

The first step is to isolate the target area. The target

area in disease control is the location of the disease outbreak. The

target area in dog and cat population control is the area from which

it is necessary to entirely remove street dogs and/or feral cats,

i.e. a hospital, marketplace, wildlife preserve, or home of a

prominent politician who hates animals.

 

You have to isolate the target area by vaccinating the

surroundings. You have to vaccinate the potential hosts, not remove

them, because you have to keep the habitat occupied, at least

temporarily, instead of creating a void that will attract in more

potential carriers of the disease, or more unsterilized dogs and

cats.

 

The second step is to eliminate the threat within the target area.

 

In disease control, this is usually done by means of the

procedure that the World Health Organization calls " stamping out, "

which includes killing all of the potentially infected hosts, i.e.

unvaccinated animals who may have been exposed to diseased animals.

 

In dog and cat population control, eliminating the threat

within the target area may involve simply capturing the animals for

relocation or rehoming, as appropriate.

 

The third step, in most agricultural applications of ring

vaccination, is to kill all of the vaccinated animals after the

disease outbreak is stamped out.

 

Why? Because ordinary blood tests usually cannot distinguish

an animal who has been vaccinated from an animal who is carrying a

disease in the latent & therefore most contagious phase.

 

This is why vaccinated animals are often considered unfit for

human consumption, and is why dogs raised for meat in China are not

vaccinated.

 

The third step in dog and cat population control is simply

maintaining at least 70% sterilization of all dogs and cats within

the ring surrounding the target area. The " ring " typically needs to

be at least two kilometres wide, unless there are natural barriers

to street dog and feral cat population movement, such as a river.

 

Effective ring vaccination always requires eliminating the

possibility of the threat migrating back in from the surrounding

areas.

 

A classic demonstration of how ring vaccination works, and

the catastrophe that results when the principle is ignored, involved

the hoof-and-mouth disease epidemic that hit Britain and western

continental Europe in early 2001.

 

The Netherlands, Germany, France, and other continental

nations knew that hoof-and-mouth disease could spread like wildfire,

so immediately practiced very effective ring vaccination to isolate

their outbreaks before trying to eradicate the hosts. They stopped

the epidemic cold in very little time.

 

Britain made the mistake of thinking that because it is an

island, it was effectively protected already. Instead of practicing

ring vaccination, Britain tried to eradicate the hosts right from

the start. The British colossally underestimated the potential for

local spreading and re-infection of " cleaned " areas. Britain ended

up fighting the outbreak for most of a year, and ultimately achieved

eradication only by doing ring vaccination, many months after the

whole epidemic was over with on the mainland.

 

Stopping the spread of street dogs or feral cats works the

same way. Wildlife populations breed up to the carrying capacity of

the habitat, if they can, just as diseases spread until they are

either stopped by antibodies or kill the host. The main thing that

stops either animal population growth or the spread of a disease, in

nature, is lack of food, i.e. a host

 

If you want to get street dogs or feral cats out of a

particular location that still has an adequate food supply to sustain

a population, the only way you can succeed is to ensure that all of

the cats in the surrounding territory lack the reproductive capacity

to fill the void.

 

In other words, you have to sterilize them. Then, when

they can no longer breed up to the carrying capacity of the habitat

you are trying to depopulate, you have a chance to remove all the

dogs or cats and not have them be replaced by more dogs and cats.

 

Ultimately, if the food source remains, you will end up

with another predator who fills the same niche, eating mice, rats,

the occasional bird, and food waste. If the new predator also preys

upon dogs and cats, or at least upon puppies and kittens (as do

jackals, leopards, coyotes, foxes, lynx, fisher, great horned

owls, eagles, redtailed hawks, probably osprey, etc.), dogs or

cats will not be able to reclaim the habitat even if some do

eventually cross your vaccinated & sterilized ring.

 

In disease control, what you get is another disease arriving

to take advantage of the vulnerable host animals, typically mutating

to try to get around the defenses created by vaccination or killing

the hosts. This is why there are so many different strains of

influenza, for example. The most successful strains tend to be

those that do not quickly or easily kill their hosts. The deadliest

forms, like H5N1, tend to burn themselves out relatively rapidly,

if human commerce does not keep moving them into new habitat.

 

 

 

--

Merritt Clifton

Editor, ANIMAL PEOPLE

P.O. Box 960

Clinton, WA 98236

 

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