ABSTRACTS
259
of the burrows with calcium cyanide dust followed up by trapping, has proved to be the
most effective. The gassing consisted of blowing finely powdered calcium cyanide dust
(cyanogas) with a hand-pump into the burrows. When this dust comes into contact
with air it gives off hydrogen cyanide, leaving a residue of inert calcium hydroxide and
impurities contained in the powder.
Imperfect working of a gassing pump; using poor quality, old or spent cyanide
powder (good fresh powder should have a very fine pulverulent texture and have a bluish
slate colour); gassing when the humidity, looseness and gas-absorbing properties of the
soil are too high ; bad circulation of gas in the intricate tunnel maze of a colony, due to
the presence of obstructions and long cul-de-sacs; closing any openings before gas has
emerged from them and finally, failure to fumigate for a long enough period, i.e. until
powder is seen emerging from all openings before these are closed,were found to be the
likely causes which might lead to failure or ineffective work.
Although rabies occurs over a large part of the Union yet it is restricted to more or
less well-defined centres and localities where it seams to smoulder for long periods and
thence spread slowly. Where outbreaks occur a preliminary inspection is carried out
to establish the probable extent of the infection and therefore the area to be treated.
This is based on the occurrence of colonies, whether there is a break in their continuity
or not, the topographical features, etc. As soon as this is completed, a programme is
drawn up and the whole area is divided into sections, which are to be treated in sequence.
Operations are then started and carried on according to the method. The area is traversed
in strips to locate the colonies, and gas them. This is followed by systematic inspection
and trapping, until no meercats are left. To ensure success attention should be paid to
locate all the colonies ; to comb the veld systematically to ensure that all the meercats
have been chased into the burrows prior to gassing; to fumigate thoroughly—bearing
in mind the pitfalls mentioned above ; to close all disused holes and colonies ; to revisit
systematically all colonies and set traps where required and to continue trapping as long
as any holes are being re-opened while operations last in that area.
If it is possible to eradicate or greatly to reduce the meercats, it follows that the
disease will find it more and more difficult to persist and spread. Thus, by systematically
destroying the carriers in the infected centres, by starting in the sparsely infected areas
and gradually closing in on the heavily infected central areas, the incidence of the
disease will, it is hoped, be greatly reduced and in time even eradicated. This is the
scheme as envisaged and now being carried out in the Union.
For continuous and large-scale extermination of meercats the operations can be
carried out to advantage by units or groups of eight people under the supervision of a
trained officer. The supervisor should be selected for his energy and reliability, as the
whole scheme depends on the thoroughness with which the work is executed.
All the equipment necessary for such a unit comprises two gassing pumps, a supply
of cyanide dust, a few spades, and about two hundred three-inch gin traps. Such a
unit must, of course, be self-contained and mobile, i.e. provided with its own camping
outfit and transport, so as to be on the spot the whole time and not to waste time going
to and from their homes. Naturally in all undertakings of this nature the cost involved
should not be out of proportion to results obtained. From the summary of the work
performed on the five infected farms, and the expenditure in eradicating the meercats,
it is estimated that such a party can clean an area of 1,000 morgen in four days, at an
approximate cost of a little over £9.
For small-scale operations (e.g. for the farmer, who wishes to clean up his farm),
the only equipment necessary would be one pump at £2-15s.; say two dozen traps at
1s. 6d. each, and a small amount of cyanogas. If the eradication is undertaken on a
cooperative basis (several neighbouring farmers pooling together their equipment and
labour) the cost can be brought down, well within the reach of every one.
Although the proposed campaign against the carriers of rabies constitutes the main
attack on the disease, yet other measures of more general nature such as prevention of
fresh importation of rabies, prevention of its spread by domestic and other animals
especially dogs and cats and above all nation-wide propaganda to enlighten the public ;
report all suspicious cases; help destroy and keep down meercats; and to collaborate
with the State in all its measures to eradicate rabies, should not be overlooked. [R. L. K.]