This article appeared in the 2001 edition of
Conservation and the Environment in Namibia.
Antivenom project
ZEBRA SNAKE
Mike Griffin
The bite of the zebra snake, Naja nigricincta nigricincta, has always been
a problem in Namibia. This snake is very common in the country, and
appears to be attracted to and do well in populated areas, both urban
and rural. It is quick to bite, and unlike that of most cobras, its venom is
highly cytotoxic.
However, the polyvalent antivenom that is available, is ineffective in the
treatment of a zebra snake bite. The current recommended medical
treatment is radical excision around the site of the bite, of which severe
disfigurement and amputation is a common outcome. If venom finds its
way into the bloodstream, even more problems, including systemic ones,
arise. The overall treatment can be expensive, often extending for over a
year, especially if initial treatment was too conservative.
The only positive aspect is possibly that the zebra snake’s venom is slow
acting, giving the victim plenty of time to seek medical help and allowing
the medical fraternity time to debate the best course of action. Although
fatalities are rare, zebra snake bites are a serious national public health
hazard.
After a number of well-publicised cases in the mid-1980s, a local NGO
offered to sponsor the production of a species-specific serum. However,
when the South African Institute of Medical Research (SAIMR) quoted
a price of R10 000 for the trial run, the NGO lost interest. The South
African Defence Force was also interested in the development of an
effective counter-measure, as troops were regularly bitten by these
snakes. Finally, in 1992, the German Ambassador to Namibia made a
grant available, now administered by the Namibia Nature Foundation,
enabling the project to go ahead as originally planned with the SAIMR.
Raw venom would be supplied from Namibia, the SAIMR would produce
the serum and conduct initial laboratory tests, and this initial batch would
then be tested under local clinical conditions by local medical practitioner,
Dr Christo Buys. At this time, the Ministry of Environment and Tourism
(MET) became committed to co-ordinating the project, specifically in
terms of collecting and housing the snakes and extracting the venom.
Realising that a system needed to be developed to maintain and work
with a large number of highly dangerous snakes, MET officials designed
a system of individual cages with internal nest boxes that could be
closed from the outside and had double sliding glass fronts on which
sprayed venom could be gathered. This innovative idea was designed
to replace the traditional method of hand-milking snakes, which stresses
the snakes and is dangerous for the handler. Most important, the system
allowed all daily maintenance as well as venom collection to be safely
accomplished by non-professional staff.
Individual snakes were chased out of their nest boxes once a week,
and enticed to spray venom on the glass plate in front of their cage.
This might well be the only documented case in history when staff were
actually encouraged to tease captive snakes. The inside plate was then
slid out and the venom removed. As the second (outside) glass plate was
still in place, the snake was securely contained.
The snakes were kept in solitary isolation and allowed to spend all of
their time in the nest box. The rationale was that they would not rapidly
become habituated to human presence as usually happens with captive
spitting cobras, causing them to loose their desire to spray, which is
entirely a defensive action.
Once the protocol is refined, and the antivenom has proven to be
effective, the function of housing snakes and collecting venom can be
turned over to the local medical and/or private sector. Investigating and
developing future alternative out-sourcing arrangements is a part of
the project. It is unlikely that Namibia will ever develop the capacity to
produce the antivenom locally. Nevertheless, it is highly desirable that
the venom-collection process remains a Namibian initiative.
Within one year the MET had collected the requisite amount of zebra
snake venom. By this time, however, the venom institute of the SAIMR
had evolved from a socially responsible government institution to a
strictly commercial operation. The project is now on hold, until future
options can be evaluated.
2018
NOVEMBER
17