This is the first study to provide an assessment of the economic effects of CE in humans and livestock in Peru. Studies that estimate the economic burden of CE can be very important as they identify specific areas that may need to be addressed by policy makers responsible for the design and implementation of CE control programs. The economic impact of CE has been assessed in South American countries where CE is endemic 
. A recent study in Argentina, Brazil, Chile and Uruguay demonstrated total adjusted human and animal losses of US $ 108,276,378-$ 146,580,935 for all four countries combined 
. However, it is difficult to make direct comparisons with other countries due to demographic and epidemiological differences. In addition, there is no standard approach recognized when estimating economic costs for CE in human and animal populations. For example, treatment costs for non-surgical CE patients were not estimated and included in the present study. Per capita GNI was also used in this study to account for human productivity losses rather than taking into account income losses for those who work outside the home versus those who are not officially employed. In addition, losses due to decreased fecundity were not included due to the lack of information on the true impact of CE on reproduction. In addition, livestock were not separated by age since CE prevalence data is not available for different age groups of domestic livestock. Finally, farmer investment was also not taken into consideration. In the present study, total estimated losses due to CE were U.S. $ 6,357,027 (95% CI: 4,422,699–8,788,182) of which two-thirds comprised human economic losses and the other third were animal production losses. This is a very conservative estimate based to a large extent on official sources of information which very likely underestimate the true extent of the problem. Nevertheless these estimates illustrate the negative economic impact of CE in Peru.
In Peru, surgery remains the treatment of choice for CE. Surgical treatment of CE is a costlier alternative than the less invasive puncture-aspiration-injection-reaspiration (PAIR) technique or benzimidazole use. In Argentina, a country where CE is endemic, the average cost of conventional surgery for CE of the liver was $5,936 in comparison to the cost of PAIR at $1,988 and $1,350 for albendazole treatment 
. PAIR is not available in Peru and use of benzimidazoles is reserved for prophylactic use prior to surgery 
. Use of less costlier procedures in Peru such as PAIR and sole chemotherapeutic treatment could result in lower overall treatment costs. Our estimate of the cost of surgical treatment for CE is based on the cost incurred in a public hospital located in Lima city. Costs may vary in other areas of Peru, especially in endemic areas. Therefore, our estimates may not reflect the true cost of surgical treatment in the country. In addition, this estimate does not take into account an important number of patients who receive treatment at private clinics where the cost of surgical treatment can be 4 or more times higher than in public hospitals. In one study in an endemic area of Peru, 8% of patients received treatment in private clinics compared to 44% in public hospitals and 47% in hospitals of the national health care system 
. Our estimates of treatment costs for CE underestimates the true cost of human CE as we did not include the cost of benzimidazoles given the absence of data on sole benzimidazole use against CE in Peru.
An important limitation of this study is the absence of current data on the incidence or prevalence of CE in humans and animals. Available sources of data have not been updated for the last 20–30 years. Although the Peruvian Ministry of Health has regularly collected information on outpatient consultations due to CE since 2000, it is not known how many of these cases were confirmed and the type of treatment received. Data on CE condemned livestock viscera at the national level is collected by the Peruvian Ministry of Agriculture from inspections performed in abattoirs. However, a substantial number of livestock are home slaughtered, particularly in areas endemic for CE. In addition, younger animals, which are less likely to be infected, tend to be slaughtered in abattoirs. Therefore, these official sources of information may greatly underestimate the real prevalence of infection. For example, based on official publications, the incidence of human CE in the endemic Department of Junin was 24 cases per 100,000 during 2002 
. However, epidemiological studies conducted in Junin have demonstrated that the surgical incidence can reach 127 cases per 100,000 
. Similarly, official records showed that in the coastal city of Chincha the incidence of human infection was 10 cases per 100,000 during 2005 
, but an epidemiological investigation revealed a surgical incidence of 32 cases per 100,000 population 
. For livestock, official sources indicated a prevalence of sheep CE of 10% for 2002 in the Department of Junin 
. However, epidemiological studies in abattoirs in this same area showed that as many as 77% of sheep were infected 
We estimated that 1,139 (95% CI: 861–1,489) DALYs are lost annually in Peru due to surgical cases of CE, which is comparable to CE-associated DALYs lost for Argentina, Brazil, Chile and Uruguay combined 
. DALYS lost due to CE were also found to be similar to other conditions such as malaria, amoebiasis, and leishmaniasis 
. These infectious diseases are better monitored than CE and thus their DALYs estimates are likely to better capture the true impact of those diseases on the country. In the case of CE, the absence of updated information on the frequency of human CE hampers the calculation of this socio-economic indicator. However, the number of DALYs estimated to be lost in this study is very conservative since only surgical cases of CE were evaluated.
The findings of the present economic evaluation, although conservative, highlight the monetary losses caused by CE in the Peru. Control programs could potentially prevent many of these losses in a cost-effective manner. For example, a control program implemented in the highly endemic region of La Rioja, Spain based on a combination of owned dog deworming, stray dog control, and safe ruminant carcass disposal resulted in a positive cost/benefit ratio after 8 years. This ratio increased to 1.96 by the conclusion of the 14-year program 
. Control programs have been previously implemented in Peru. For example, a pilot control program was conducted in Peru during the 1970′s which was later abandoned due largely to political instability. However, the program succeeded in reducing the number of infected dogs from 36% in 1975 to 1.6% in 1980 and the number of infected sheep from 65% in 1976 to 37% in 1980 
. There is urgent need to implement better surveillance systems to monitor the incidence/prevalence of echinococcosis in humans and animals in Peru so that they may be used as part of new control efforts for CE. In summary, CE is an important but neglected zoonotic disease in Peru which significantly affects the economy of the country.