**Abstract**

Hepatic hydatid disease has been reported from ancient times. It is a zoonotic infection caused by nine recognized species of tapeworms of the genus *Echinococcus*. Some of them are known to cause human echinococcosis, and there is reasonable doubt regarding the others. Diagnosis is supported by epidemiological history, clinical presentation, radiological imaging, and serological tests. Various pathological forms may become life-threatening, and in those cases, the treatment is extremely complex. The main objective of the treatment is to completely cure the illness in order to avoid further complications and recurrences. Hepatic surgery, using different techniques, achieves best results with acceptable morbidity and mortality rates. In the South of Chile, the geographical location in which we work, this illness is endemic with high incidence and prevalence. The hepatobiliopancreatic units of the regional surgical centers of Temuco have plenty of experience treating liver hydatid disease. In this chapter we shall focus especially on epidemiology, etiopathogenesis, diagnosis, and surgical treatment of hepatic hydatidosis.

**Keywords:** hepatic hydatidosis, epidemiology, etiopathogeny, diagnosis, surgical treatment

#### **1. Introduction**

Human echinococcosis, also called hydatidosis, is a zoonosis which has been known from ancient times. There are mentions about hydatid disease both in humans and animals in documents as old as the Ebers Papyrus and the Babylonian Talmud [1, 2]. Around the mid-nineteenth century, a significant breakthrough happened when the etiology and the life cycles of different *Echinococcus* species were defined, although there are still many related questions pending to resolve [3]. Hydatid disease is caused by nine recognized species of tapeworm of the genus *Echinococcus* (*E.*). Seven of them cause different forms of human echinococcosis, and the remaining two are being studied for a possible human affectation. Some of the life cycles of these tapeworms have domestic animals as hosts, e.g., dogs as definitive hosts and sheep as intermediate hosts. Humans are accidental intermediate hosts. Other species of these parasites have wild life cycles, infecting almost exclusively wild animals and rarely humans. Additionally, more complex cycles

with interaction of wild and domestic animals have been described as well. There are reported variants of these cycles depending on geographical location [4].

Cystic echinococcosis, the most common form of hydatidosis, is an endemic zoonosis caused by the larval stage (metacestodes) of the tapeworm *E. granulosus*. In relation to the geographical distribution, the disease is present in many countries around the world [5]. The diagnosis is supported by epidemiological history, anamnestic data, clinical presentation, radiological imaging, and serological tests. Surgical treatment employs different techniques, aiming for the best outcome for the patient. Partial cystectomy, pericystectomy, and hepatic resection are performed by either open or laparoscopic surgical access, with or without neoadjuvant or adjuvant medical therapy. There are also different procedures for the evacuation of the parasite, using percutaneous or endoscopic access. In selected cases, antiparasitic drug therapy is employed as the only treatment for this illness [6]. The prognosis for these patients will depend on the selection of the most adequate therapy according to several factors mainly related to the physical status of the patient and the larval stage of the parasite and its location [7]. Complicated cases must be treated in reference centers by well-trained and experienced hepatobiliary surgeons. This zoonosis has not yet been completely eradicated, and if affected countries do not apply epidemiological control policies, a great amount of resources will have to be allocated to the treatment of this illness. Cystic echinococcosis of the liver is endemic, especially in the South of Chile [8]. For this reason, the main theme of this chapter will be centered in topics concerning this form of hydatidosis.
