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ABSTRACTS
Numerous other species of wild carnivora must be regarded as potential carriers of
rabies. The species most commonly concerned with rabies transmission is Cynictis
penicillata (Yellow mongoose).
This animal has been responsible for the death of some human beings and cattle, be was
causing some 80 known outbreaks of rabies. That the disease is more prevalent in this
animal is not to be ascribed to any greater susceptibility to the virus of rabies, nor does
the animal become any more ferocious when rabid than other species of carnivora. The
reason is rather to be found in the fact that it is very abundant, living in small colonies
near to one another, thus increasing the chances of contact for transmission much more
than in the other animals, which are comparatively less abundant, and with a more soli-
tary mode of living. As the yellow mongoose seems to play the major role and the
infection discovered in other animals, until proved otherwise, may well be regarded as
accidental, the campaign must be directed mainly against the former. With this species
should be included the suricate and ground squirrel on account of their close association,
commensal habits and on account of the damage to crops done by the last.
The restraint of any kind on wild animals was out of question and total eradication
of any one or all of the species concerned in the dissemination of rabies could not be
contemplated. It was suggested that if at the time of an outbreak all infected animals
as well as all susceptible ones, which might come in contact with them are destroyed,
the disease must die out at that point as the virus cannot exist outside living animals.
Should the area immediately become reoccupied by uninfected animals this would be of
no consequence. The hope was expressed that by treating each successive outbreak of
rabies in this fashion, the incidence of rabies would gradually be reduced.
In regard to the epizootology of the disease it has been observed that rabies may
smoulder in the lesser carnivora in a comparatively small area for periods up to eleven
years, without being discovered. There are many instances where the disease has
appeared recurrently after periods of up to eight years. Areas where a sporadic ont¬
break has occurred, should be regarded as suspect until it can be proved otherwise
Owing to the long period of incubation in rabies, in some cases a period of six months
or more, the possibility of spreading the disease by movement of domestic animals is
very real and may explain why the disease may at times take unexpected long jumps.
However, apart from a few cases where animals were removed during the incubation
period of the disease, it has been found that the disease spreads relatively slowly to
adjoining areas by means of wild carriers.
From the extensive observations made it has been concluded that drought or scarcity
of vegetation to some extent at least may influence the number of outbreaks of rabies
recorded. This would not necessarily mean that epizootics occur during such periods
The larger number of outbreaks recorded during such periods is probably due to the
fact that meercats traverse larger areas searching for food, and when they become rabies
they are easily seen, or the scanty vegetation allows such animals to wander further
afield than when the grass is high and tall. It appears that the epizootology of rabies
in South Africa is very closely associated with the habits, mode of life, migration, fo
distribution, burrows and colony formation of the various wild carnivora. As a p
liminary to attempting control measures, a careful study of these factors which influence
the epizootics has been made and a brief description of each of the species of animals
concerned with the dissemination of rabies has been given. It was obvious, that
accurate knowledge of the internal structure of the colonies and burrows was required
in order to devise the best methods for the destruction of vectors, e.g. fumigation, e
and to determine the causes of failure to kill these animals in the warrens.
A preliminary investigation was conducted near Wesselsbron, where an outbreak
of rabies had occurred. It consisted chiefly of studying the formation of the colonies
and the structure of the burrows of the Cynictis, Geosciurus, and Suricata. A consi-
derable number of colonies, both small and large were dug up, during the course of
these and subsequent experiments, and they were described and sketched to scale.
To devise the most effective and yet economical method of destruction of these
vectors four methods, viz. gassing the burrows with poisonous gases such as Hydrogen
cyanide, Carbon monoxide, Sulphurous gases and Carbon bisulphide (a heavy gas) ;
trapping; destruction of the burrows and their inhabitants by means of explosives ;
and poisoning with bait. Of the various methods tried to destroy meercats, gassing