**3. Conclusion**

Human echinococcosis is a zoonotic larval cestode disease usually caused by *Echinococcus granulosus* or *E. multilocularis*. Infection is chronic taking years for symptoms to develop. The medical impact of the late stages of human cystic or alveolar echinococcosis may be significant though morbidity and mortality are usually grossly under-reported in endemic areas. Because of diagnosis and treatment are difficult and reservoirs of infection are maintained in domestic livestock, dogs or wildlife, the disease is difficult to assess in terms of public health and requires long-term control interventions. Globally, 3.6 million disability-adjusted life-years (DALYs) could be lost due to echinoccocosis, and this disease is included in an important group of neglected non vector-borne zoonotic infections that are currently not sufficiently prioritised (WHO/DFID-AHP, 2006).

Liver transplantation should only be considered in patients with very severe hilar extension, leading to uncontrolled biliary infections, symptomatic secondary biliary cirrhosis with ascites or severe variceal bleeding owing to portal hypertension (Bresson-Hadni, 1997). It

Forms of human polycystic echinococcosis (PE) are caused by *E. vogeli* and *E. oligarthrus*,

Metacestode of *E. vogeli* is characterized by its polycystic form filled with liquid with a tendency to form conglomerates with multiples small spaces inside. The most affected organ in the intermediate host is the liver. Metacestode of *E. oligarthrus* is similar to *E. vogeli* but the division in secondary spaces is less frequent and the laminar membrane is significantly

Wild and domestic dogs as definitive hosts and paca (*Cuniculus paca*) as intermediate host participate in the life-cycle of *E. vogeli*. Polycystic echinococcosis due to *E. vogeli* has been communicated in the majority of the countries belonging to the neotropical region of America; including Panama, Colombia, Argentina, Ecuador, Brasil, Bolivia and

*E. oligarthrus* is the unique *Echinococcus* specie that uses felids as definitive hosts. Infections naturally acquired have been demonstrated affecting pumas, jaguars, and other wild felids.

Clinical and radiological presentation is very similar to infection with multiple cysts of *E. granulosus*, and differential diagnosis depends on isolation of protoscoleces and morphological hook characteristics (D'Alessandro, 1997). Immunodiagnosis using a purified antigen of *E. vogeli* allowed discrimination between cases of PE and CE, but differentiation between PE and AE was not always possible (Gottstein, 1995). Albendazole with doses of 10 mg/kg/day has been used for chemotherapy in six cases with success of treatment in four

Only three human cases have been reported to date, two orbital in Venezuela and Surinam and one cardiac in Brazil with 2 cysts (1.5 cm diameter) (D'Alessandro, 1997). The diagnosis

Human echinococcosis is a zoonotic larval cestode disease usually caused by *Echinococcus granulosus* or *E. multilocularis*. Infection is chronic taking years for symptoms to develop. The medical impact of the late stages of human cystic or alveolar echinococcosis may be significant though morbidity and mortality are usually grossly under-reported in endemic areas. Because of diagnosis and treatment are difficult and reservoirs of infection are maintained in domestic livestock, dogs or wildlife, the disease is difficult to assess in terms of public health and requires long-term control interventions. Globally, 3.6 million disability-adjusted life-years (DALYs) could be lost due to echinoccocosis, and this disease is included in an important group of neglected non vector-borne zoonotic infections that are currently not sufficiently prioritised (WHO/DFID-AHP, 2006).

requires long-term and continuous postoperative chemotherapy.

which are confined in their distribution to Latin American countries.

**2.2.3 Polycystic echinococcosis (PE)** 

**2.2.3.1 Polycystic echinococcosis due to** *E. vogeli* 

and improvement in two (D'Alessandro, 1997).

was based on morphology of protoscolex hooks.

**2.2.3.2 Polycystic echinococcosis due to** *E. oligarthrus* 

thinner.

Venezuela.

**3. Conclusion** 

Echinococcosis is therefore a neglected disease which is under-reported and requires urgent attention in common with a number of other zoonoses in order to reduce morbidity and to help alleviate poverty in poor pastoral areas of the sub-tropics and temperate zones. It's also difficult to formulate interventions and to apply cost-effective control programmes in this disease.

Human behaviour is crucial in facilitating transmission of this infection between domestic animal hosts as a result of traditional pastoral and husbandry practices (Mcpherson, 2005; Craig, 2007). Dogs are also susceptible to infection with *E. multilocularis* and *E. vogeli* (whose intermediate hosts are principally rodents) and therefore dogs may constitute a greater zoonotic reservoir of infection compared to natural wild canid hosts. Peri-domestic transmission may occur and could for example sustain a level of transmission of *E. multilocularis* in highly endemic communities (Li, 2005), but is probably not responsible for long-term maintenance of these Echinococcus species adapted to small mammals. Therefore, echinococcosis is a disease where humans may acquire infection from wild or domestic animal hosts but the parasite cannot be directly transmitted between humans (Wolfe, 2007), and due to all of these concepts treatment of human echinococcosis cases will have no effect on pathogen transmission. We will need to apply interventions to reduce human exposure or break transmission cycles in order to control the disease. This places echinococcosis in a 'difficult-to-deal-with' category; firstly, unlike the other neglected parasitic diseases humans can not act as a definitive host, and secondly, echinococcosis in livestock (or dogs) is not perceived as an animal health problem.

Clinical symptoms and subsequent diagnosis occur in adults (20-60 years) but infections in children may also become symptomatic (Soriano Arandes et al., 2010), and imaging techniques are the basis for diagnosis preferably accompanied by a specific serological test (Craig et al., 2003). Surgical removal of cysts/cystic masses, cyst drainage or organ resection, are the main form of treatment, often supported by high dose albendazole cover; the latter also has a benefit in medically-only treated cases (WHO, 2001).

The key factors of echinococcosis as a neglected disease are best described in a recent paper (Craig et al., 2007):


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