Sample surveys, involving 178 Nicaraguan ranches, revealed 170 bovine
deaths from vampire-transmitted paralytic rabies from 1970 to 1974.
After control was initiated (1974), no cattle died in treated herds,
though 67 head in untreated neighboring herds did succumb. Extrapo-
lation of survey data suggested that rabies deaths among the 2,600,000
cattle in the country (1974 estimate) averaged 1,820 head annually
prior to implementation of the control program. Losses in beef and
milk production, prior to control, were estimated from cattle owner
observations to be 44 kg of beef or 261.096 1 of milk per animal per
year. The survey data on production losses, when extrapolated to a
national level, equaled an estimated annual economic loss of $2.4
million (U.S.). The effects of control were estimated to continue at
an annually decreasing rate for 10 years for an accumulated benefit
of 6.8 times the benefits of the first year following implementation.
Total accumulated benefits are estimated to be $16.4 million. The
cost for the 4-year program, wherein 148,142 cattle and 2,696 vampire
bats were treated, was $6,500 to the cattle owners and $482,400 to the
Nicaraguan Ministry of Agriculture. Net economic gain from vampire
bat control in Nicaragua was estimated at $15.9 million. The first-
year average net benefit per herd was $2,220 to ranchers with more
than 100 head, $500 to cattle owners with 11-100 head, and $42 to the
owners of 10 or less cattle, based on benefits per head owned of
$7.30 for the first year after the control program was implemented.

Social well-being was slightly improved by the control of vampire
bats. Fear of being bitten was decreased in some people as a result
of control efforts, but fear increased in others due to divulgence of
information on the consequences of vampire bites. Cases of vampire
attacks on humans decreased from 48 treated and 17 untreated cases in
1973, prior to control, to 33 treated and no untreated cases in 4.5
years following implementation of the control program.

Analyses of available secondary data and survey results indicate that
correct application of the control technology produces no harmful
effects on nontarget species, particularly wildlife and other species
of bats. Wildlife habitat is not destroyed and the biological equi-
librium between populations of vampires and their natural hosts is
improved.

A final report on the evaluation of the socio-economic impact of vam-
pire bat control programs, based on technology developed by the Denver
Wildlife Research Center, is scheduled for release in mid-1979.

Vampire bat control workshop

In February, Dr. Enrique Sanchez of the Nicaraguan Ministry of Agri-
culture Vampire Bat Control Program and Dr. G. Clay Mitchell of the
DWRC, conducted a vampire bat control workshop and training seminar in
Asuncion, Paraguay. Forty veterinarians from the Paraguayan Ministry
of Agriculture attended the course.
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