aistand south~ern afrkca - (PDF, 101 mb) - USAID

aspect. needs urgent attention. Valutible
information will be shortly available in
Zimbabwe (J. Barrett, Natural Resources
Institute, Chatham Maritime, 1992, personal
communication).
In the case of trypanotolerant cattle, the lack
of historical records meant that the costs of
importation and multiplication could not be
accounted for in Zaire or Togo. Hence, results
were limited to the economics of the ongoing
production systems. In addition, further
research is also required on the reasons why
farmers often prefer zebus to the smaller
trypanotolerant breeds when disease risk is not
too high.
Profitability of trypanosomiasis
control
The results provide estimates of returns to
ckapital invested in cattle production systems
using trypanotolerant cattle and/or trypanocidal
drugs. On the basis of the site averages, both
methods were economically and financially
profitable: social rates of return ranged from 15
to 53% and private rates from 10 to 29%. Output
was low but the profits were attractive as all the
systems required few inputs. However, due to the
growing drug resistance of trypanosomes, future
application of this method is severely limited,
The results also show that the disease is only one
of the constraints (albeit an important one) that
cattle producers face in regions with low to
medium trypanosomiasis risk. To improve tl-e
production systems, information is required (n
other biological constraints such as feed ard
diseases and on the operational socio-economic
context and the management of the herd. This
approach would put trypanosomiasis control in
a global perspective. However, a comparison of
trypnnosomiasia control methods can be drawn
in broad terms on the basis of our results and of
those of previous studies (Itty, 1991).
is less risky and more flexible as costs and
benefits flow in parallel and operations can be
stopped with lesser losses. An interruption could
be envisaged if expected benefits were not
realised or the switch to improved methods was
desired. As lower initial investment and less
foreign currency was required in the second ret
of methods it was more likely to be implemented
by the local population with minimal external
input (e.g. trypanocides are administered by
cattle owners or by animal health assistants;
community-based tsetse control can be
implemented by traps as in Nguruman, Kenya
(ODA/KETRI, 1991)).
It would then appear that the various
techniques have specific contributions to make
and that in practice a combination of control
methods, determined by the prevailing
conditions, might prove technically more
appropriate and more profitable than the use of
a single method. For instance, therapeutic drug
treatments are suitable for very low risk
situations with low catth; density and
prophylactic treatments for cases under slightly
higher risk (Itty et al, 1988). In view of drug
resistance this method will be increasingly used
for strategic purposes and in conjunction with
other control techniques. Trypanotolerant cattle
tend to be suited for situations with low to
medium trypanosome prevalence as this
presents few risks (no collapse of control
operations). An assessment of the cost of
importing trypanotolerant stock should be
carefully conducted; indications suggest that
this is not necessarily profitable (Itty, 1991).
However, the role of trypanotolerant stock as a
control method might be modified with
decreasing trypanosomiasis risk due to human
population pressure on land and better tsetse
control techniques Their uptake will depend on
their comparative productivity once disease risk
is reduced and on farmiers' preference.
As the level of risk increases tsetse control
In the examination of the economics of
trypanosomiasis control, phasing is particularly
crucial because of the methodological clemcnt of
discounting used in cost-benefit analysis.
tends tn become the solution of choice but vector
control can be undertaken in conjunction with
drugs or tolerant livestock. Traps and screens
4
seem the most profitable and promising solution,
One can broadly distinguish trypanosomiasis
control methods according to the type of
investment: those requiring heavy initial capital
investment (aerial and ground spraying, the
sterile insect technique and importation of
trypanotolerant livestock) and those requiring
more recurrent costs (traps and screens,
deltamethrin treatment of cattle, trypanocidal
drugs and trypanotolerant cattle when locally
available). Basically, the second set of methods
although other techniques could be of
importance under specific conditions. Tsetse
control is likely to be more profitable than drugs
and trypanotolerant cattle, but is conditional on
clearedlandbecomingavailableforcattle, ahigh
carrying capacity, medium human and cattle
population densitiej prior to the intervention (for
cattle between 50% and 75% of the potential
density (Jahnke, 1974)), and cattle having
traditionally been kept by farmers who will use
4 The underlying rationale for discounting is that a monetary unit received today is more valuable that the same su 1 in the
future (time is money). This difference in value reflects the opportunity cost of capital which is the foregone value o -apital
invested in its best alternative. Thus US$ I available today could be invested at the going interest rate of, say, 7%, so bt... in
one year from now it would be worth (1 + 0.07) = US$ 1.07. By reversing this process, the value of a sum in year n can also be
expressed in present-value terms. The merit of the discounting procedure is that it allows payments and receipts occurring at
different times to be converted to a common standard in terms of their present value (Dillon and tlardaker, 1984; Itty and
Bidaux, 1991).
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