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

ments to maintain dipping infrastructure,
provide effective animal health extension service
and import drugs and acaricides has been
undermined.
The consequences of the control of ECF by
currently available methods are therefore grim;
extension staff generally do not have transport,
most public dips are poorly managed and nonfunctional,
the few operational ones are often
dilute in acaricides concentration, drugs are not
readily available to government veterinarians,
and if they are available in local markets, they
are too expensive for most smallholder farmers,
Other considerations which have rendered
acaricide application a less reliable method
include shortages of water for public dips, the
developn'c,.t of resistance to acaricide by tick
populationi, uncontrolled cattle movements,
civil unrest, contamination of the environment
or food with toxic residues of acaricides and the
existence of alternative hosts for ticks (mainly
wild ungulates) in proximity to cattle (Young et
al, 1988; Dolan, 1989).
Even when drugs for chemotherapy are
readily available, their successful application
requires diagnosis of the disease at its early
stage )f development. This specialisation is
bcyond the capacity of many rimallholder
farmers because of the poor state of the animal
health service infrastructure. This factor,
coupled with the high cost of drugs, impli s that
only a small proportion of animals which become
infecwd with the disease receive treatment.
There is evidence that production losses due
to tick infestation per se are too small to justify
intensive acaricide application on economic
grounds in zebu and Sanga cattle (Norval et al,
1988; Pegram et al, 1989). Furthermore, the
existence of endemic stability in some areas
implies that control can be selective, strategic
and focused only on susceptible target cattle
populations (Perry et al, 1990).
New methods of ECF control
The limitations associated with the current
methods of ECF control and the opportunities for
reducing reliance on intensive acaricide use in
the region have prompted the search for new,
safer, cheaper and more sustainable control
strategies through immunisation.
At present, the only practical method of
immunisation is by the infection and treatment
method (Radley, 1981). This involves the
inoculation of cattle with a previously characterised
and potentially lethal dose of sporozoites
of T parva and simultaneous treatment with
antibiotics. This confers life- long immunity to
the animal.
The method has been shown to be technically
efficacious in field trials carried out in different
countries of the region (e.g. Robs on et al, 1977;
Morzaria et al, 1985; Musisi et al 1989; Mutugi
et al, 1989).
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Immunisation through the infection and
treatment method has been estimated to cost
US$ 1.50-US$ 20.00 (Radley, 1981; Kiltz, 1985;
Mukhebi et al, 1990), US$ 0.01-US$ 0.90 being
the cost ofproducing one dose ofthe vaccine and
the balance being the cost of delivering the
-vaccine to the animal in the field. The output will
vary amongcountries depending on their policies
regarding the production or procurement,
delivery and pricing of the vaccine. Some
countries conduct pilot immunisation programmes
to provide data for the planning and
implementation of widespread application of the
infection and treatment method.
Assessing the economics of the
infection and treatment method
There are few studies on the economic analysis
of the infection and treatment method. Mukhebi
et al (1989) showed that inmUnisation of beef
cattle under farm conditions was extremely
profitable. It yielded a marginal rate of return of
up to 562%and it allowed a reduction in acaricide
use from a frequency oftwice a week to once every
three weeks and even to the mere u+e of prolonged
release acaricide-impregnatod ear tags.
Perry et al (1990) used : cost-effective
analysis to assess alternative tick and tick-borne
disease control strategies in communal lands of
Zimbabwe. The alternative control strategies,
some of which the Department of Veterinary
Services had started implenenting, e.g.
strategic dipping, would make less intensive use
of expensive acaricides and rely more on
controlled immunisation and the phased
development of natural immunity to tick-borne
diseases. The investigation revealed that
alternative strategies were more cost effective
than the previous intensive acaricide use
practice and would reduce (save) the cost of tick
and tick-borne disease control by up to 68% from
the estimated amount of US$ 9 million annually.
Mukhebi et al (1992) assessed, ex-ante, the
economics of immunisation by the infection and
treatment method in the eastern, central and
southern African region affected by ECF. The
analysis showed high potential economic
rcturns, with a benefit-cost ratio in the range of
9 to 17 under various assumptions.
However, the costs of the method and the
economics of its application will obviously vary
in time and space in each country depending on
the cattle type and prevailing level of disease
risk, the effect of immunisation on livestock
productivity as well as the existing structure of
costs and prices.
Limitations of the infection and
treatment method
The infection and treatment method ofimmunisation,
however, has some technical limitations.
It does not eliminate the need for acaricide