Cyst echinococcosis (CE) is one of the most important zoonosis in Chile, where studies
have focussed mainly in moist southern regions. The present study was conducted to
determine the prevalence of cystic echinococcosis (CE) in livestock and humans in
the semiarid Coquimbo region in north-central Chile. A review of all surgical cases
of CE in humans reported in the Elqui, Limarí and Choapa provinces in Coquimbo region
for the period comprising 1995-2006 was obtained. In addition, a retrospective study
of CE covering condemnation records from slaughterhouses of these provinces from the
same period was carried out. The surgical incidence of CE in humans ranged between
2.3 and 8.5 cases per 10(5) people, with more cases reported in provinces with a higher
percentage of rural inhabitants (Limarí and Choapa). A total of 174,034 cattle, 22,208
goats, 35,404 sheep, 25,355 swine and 9391 equines were examined during the period.
Higher prevalence of CE was detected in cattle (24%), followed by swine (14%), sheep
(11%), goats (6%), and equines (9%). More cases of CE in livestock were also found
in provinces with higher rural population. The overall trend of the prevalence of
CE for each livestock species across years was a significant downward one, except
for swine in Elqui and sheep and swine in Choapa. Cattle showed higher prevalence
of CE in liver in Elqui, in kidney in Limarí and in lungs in Choapa. Swine showed
similar prevalence by organs in all provinces. Sheep showed higher prevalence of CE
in liver in Elqui and Limarí and lower prevalence in Choapa. Goats presented higher
prevalence of CE in kidney in all provinces, and equines had higher prevalence of
CE in liver in the provinces where animals were slaughtered. Further studied are needed
to assess whether these differences are due to different strains affecting these species
or due to ecological factors. When analyzing the CE prevalence of each species within
each province, a negative correlation between prevalence of CE in goats and rainfall
in the Limarí province was found. This could be attributed to changes in management
practices and/or ecological factors. This study shows that surveillance of CE at slaughterhouses
combined with the analyses of incidence in humans can be used to detect areas with
a higher risk of infection. Improvements in record-keeping of infected animals at
slaughterhouses are proposed in order to trace back farms where infection was most
likely acquired.