**2.2.1.6 Treatment of CE**

Surgery is still the treatment that has the potential to remove *E. granulosus* cysts and lead to complete cure (WHO, 1996). Up to 90% of the patients can be treated surgically if a cyst does not have a risky localisation or if the disease is not too far advanced. However, surgery may be impractical in patients with multiple cysts localised in several organs and if surgical facilities are inadequate. Chemotherapy and PAIR offer an attractive option for treatment, especially in inoperable patients and for cases with a high surgical risk.

#### 2.2.1.6.1 Surgery

Surgery is indicated for large liver cysts with multiple daughter cysts; single liver cysts, situated superficially that may rupture spontaneously or as a result of trauma; cysts that are infected; cysts communicating with biliary tree and/or exerting pressure on adjacent vital organs; cysts in the lung, brain and kidney, bones and other organs.

Surgery of CE is contraindicated as defined for surgical procedures in general, i.e. patients refusing surgery, patients at the extremes of age, pregnant women, and patients with concomitant severe diseases (i.e. cardiac, renal or hepatic diseases, diabetes and hypertension). Also, surgery is contraindicated in patients with multiple cysts or cysts difficult to access, dead cysts either partly or totally calcified, and in patients with very small cysts.

The protoscolicides appareantly effective are: 70-95% ethanol, 15-20% hypertonic saline solution, and 0.5% cetrimide solution. These substances should be left in the cyst cavity for at least 15 minutes to obtain an optimal efficacy.

The risks of surgical intervention include secondary echinococcosis owing to spillage of viable parasite material during the intervention. Recurrence can be due to incomplete cyst removal or to previously undetected cysts. Anaphylactic reactions represent a further risk on rare occasions. Postoperative fatality is about 2% or less, but may be higher in the second or further operations or if medical facilities are inadequate.

2.2.1.6.2 Puncture, aspiration, injection, re-aspiration (PAIR)

This technique includes the following steps (WHO, 2001):


PAIR should be accompanied by a chemotherapeutic coverage to minimise risks of secondary echinococcosis and should be reserved for use by skilled and well experienced physicians with a surgical and intensive care back-up team well prepared to deal

available. Secondary tests for antibody detection are used to increase specificity and these are: arc 5, identification of IgG subclasses, and immunoblotting which demonstrates the reactivity of serum antibodies with subunits of *E. granulosus* antigens (Craig, 1997; Di Felice, 1986; Ioppolo, 1996; Leggatt & McManus, 1994; Leggatt, 1992; Ligthowlers & Gottstein, 1995; Profumo, 1994; Sheperd & McManus, 1987; Siracusano & Vuitton, 1997; Wen & Craig, 1994). Generally, these tests are less sensitive, but more specific than primary test systems. Putative hydatid cyst fluid samples obtained by puncture or after surgical intervention can be tested for the presence or absence of *Echinococcus* antigen through binding of enzyme-labelled anti-*Echinococcus* (hydatid cyst fluid) antibodies in an ELISA with a monoclonal antibody against antigen 5 (Ag5) that may be useful in confirmation of the *Echinococcus* nature of the fluid

Surgery is still the treatment that has the potential to remove *E. granulosus* cysts and lead to complete cure (WHO, 1996). Up to 90% of the patients can be treated surgically if a cyst does not have a risky localisation or if the disease is not too far advanced. However, surgery may be impractical in patients with multiple cysts localised in several organs and if surgical facilities are inadequate. Chemotherapy and PAIR offer an attractive option for treatment,

Surgery is indicated for large liver cysts with multiple daughter cysts; single liver cysts, situated superficially that may rupture spontaneously or as a result of trauma; cysts that are infected; cysts communicating with biliary tree and/or exerting pressure on adjacent vital

Surgery of CE is contraindicated as defined for surgical procedures in general, i.e. patients refusing surgery, patients at the extremes of age, pregnant women, and patients with concomitant severe diseases (i.e. cardiac, renal or hepatic diseases, diabetes and hypertension). Also, surgery is contraindicated in patients with multiple cysts or cysts difficult to access, dead

The protoscolicides appareantly effective are: 70-95% ethanol, 15-20% hypertonic saline solution, and 0.5% cetrimide solution. These substances should be left in the cyst cavity for

The risks of surgical intervention include secondary echinococcosis owing to spillage of viable parasite material during the intervention. Recurrence can be due to incomplete cyst removal or to previously undetected cysts. Anaphylactic reactions represent a further risk on rare occasions. Postoperative fatality is about 2% or less, but may be higher in the second

PAIR should be accompanied by a chemotherapeutic coverage to minimise risks of secondary echinococcosis and should be reserved for use by skilled and well experienced physicians with a surgical and intensive care back-up team well prepared to deal

especially in inoperable patients and for cases with a high surgical risk.

organs; cysts in the lung, brain and kidney, bones and other organs.

cysts either partly or totally calcified, and in patients with very small cysts.

at least 15 minutes to obtain an optimal efficacy.

or further operations or if medical facilities are inadequate. 2.2.1.6.2 Puncture, aspiration, injection, re-aspiration (PAIR) This technique includes the following steps (WHO, 2001): percutaneus puncture of cysts under ultrasonic guidance

 injection of protoscolicidal substance (preferably 95% ethanol) re-aspiration of the fluid cyst content after 15 min to 20 min.

aspiration of a substantial amount of cyst fluid

(Paul & Stefaniak, 1997). **2.2.1.6 Treatment of CE** 

2.2.1.6.1 Surgery

immediately with complications. Aspirates of liver cysts must be analysed immediately for traces of bilirubin and protoscoleces or hooks. PAIR should only be performed under chemotherapeutic coverage, except in early pregnant patients (Filice & Brunetti, 1997). The PAIR sequence is (WHO, 2001):

There are some critical points to take into account when proceeding with the PAIR protocol:


Indications for PAIR: we use this technique for patients with:


Contraindications for PAIR:


Echinococcosis/Hydatidosis 311

should be checked at 2-week intervals during the first 3 months because in rare instances severe and not always reversible leukopaenia has been observed in early phases of chemotherapy. Serum drug concentrations (ABZ-sulfoxide or MBZ parent compound) should be monitored after 2 and 4 weeks of chemotherapy, respectively, in order to identify levels too high (possibly toxic) or too low (ineffective). For MBZ, it has been recommended to determine serum or plasma levels 4 h after the morning dose. Oral drug doses can be adapted to individual patients in order to achieve adequate serum levels, but such attempts are not always effective. Unfortunately, only few laboratories have the capability to measure ABZ-sulfoxide or MBZ serum drug levels (see also section on AE). Follow-up examinations, including imaging if needed, should be carried out at intervals of about 3 to 6 months for 1 to 3 years after termination of chemotherapy because of the relatively high rate of relapses.

A new vaccine against echinococcosis would be highly desirable in order to provide longterm prevention of the disease and to complement control programs. Vaccines against ovine hydatidosis have demonstrated its efficacy when targeting the larval stage of the parasite (Lightowlers, 2001). However, if used in the field we would need to vaccinate all the animals in a herd to achieve good results and this would be very costly to control programs. Otherwise, a vaccine protecting dogs against the adult worm would have to be given to only a few animals to protect the environment, because dogs are less numerous than other animals in the herd. Also, domestic dogs are the key in the transmission to livestock and humans. Therefore, some authors have proposed a recombinant oral vaccine given to the small number of dogs keeping the herd would decrease the number of *E. granulosus* adult worms and, consequently, the number of infective eggs. This measure would help reduce the contamination risk factors for humans and livestock, would be cost-effective for the owners of the dogs, and could help increase the overall efficacy of control programs in

Some candidates have been used to induce immune response with vaccination. One of those is Eg-95 encoding gene that is expressed in the oncosphere, protoscoleces, and immature and mature adult worms of *E. granulosus*. EG95 vaccine antigen is a secreted glycosylphosphatydilinositol (GPI)-anchored protein containing a fibronectin type III domain, which is ubiquitous in modular proteins involved in cell adhesion. EG95 protein represents one of the targets of immunity induced by the vaccine because there is a high degree of sequence gene conservation between different isolates (Zhang, 2003). A mixture of different EG95 isoforms increases the ability of *E. granulosus* to invade different hosts and could possibly maximize vaccine efficacy (Haag, 2009). Other candidates for vaccine are the homologous sequences of two of the S3Pvac peptides, GK1 and KETc1, identified and further characterized in *Taenia crassiceps* WFU, *Taenia solium*, *Taenia saginata*, *E. granulosus* and *E. multilocularis*. Comparisons of the nucleotide and amino acid sequences coding for KETc1 and GK1 revealed significant homologies in these species and the results of a study indicate that GK1 and KETc1 may be considered candidates to be included in the formulation of a multivalent and multistage vaccine against these cestodiases because of

Alveolar echinococcosis (AE) is an infection caused by the metacestode stage of *E. multilocularis*, which is characterised by a tumour-like, infiltrative and destructive growth

their enhancing effects on other available vaccine candidates (Rassy, 2010).

2.2.1.6.4 Vaccines

endemic countries (Petavy, 2008).

**2.2.2 Alveolar echinococcosis (AE)** 


#### 2.2.1.6.3 Chemotherapy

The documentation of the experience about chemotherapy with benzimidazoles in CE is now extensive. Third part of the patients treated with benzimidazoles is achieving the cure with a complete and definitive disappearing of the cysts, and higher proportion (30-50%) has obtained a considerable reduction of the cyst size and also relieve of their symptoms. However, 20-40% of the cases don't respond as expected. Smaller and isolated cysts (less than 7mm.), surrounded by a minimal adventitial membrane respond better than complicated with multiple separations or with son cysts, or surrounded by a thick or calcified adventitial membrane which are refractory to the treatment. There are two main drugs for chemotherapy: albendazole (10-15 mg/kg/day twice per day; 3- to more than 6 monthly courses with free intervals of 14 days) for treating patients with single or multiple cysts (Gemmell & Roberts, 1995), and mebendazole (40-50 mg/kg/day; everyday in three doses per day during 3-6 months). Albendazole continuous courses have shown equal or improved efficacy for 3 to 6 months or longer without an increase of adverse effects (Franchi et al., 1999). When comparing both drugs, albendazole and mebendazole, some researchers concluded that albendazole was better regarding complete cure rates and relieve of the symptoms (Franchi et al., 1999). Albendazole has a better pharmacokinetic profile than mebendazole facilitating higher intestinal absorption and penetration into the cysts. There are described some adverse reactions (neutropenia, hepatic toxicity, alopecia, and others) in a few number of patients which are reversible when treatment is interrupted. Doses, duration, and follow-up of treatment must be taken individually for each patient. However, it seems that minimum duration has to be for three months. It is difficult to predict the longterm prognosis for every patient; therefore it's necessary to do a long-term follow-up, with US or other imaging methods to be able to evaluate the result of the treatment.

Chemotherapy is also useful as a surgical complement and albendazole has been used as a pre-surgical treatment to facilitate the surgical manipulation of the cysts inactivating the protoscoleces previously, modifying the integrity of the cyst membranes and reducing the consistency of the cysts. Treatment with benzimidazoles is recommended to prevent the relapse of the disease, which is the secondary echinococcosis when the content of the cysts is spread after its spontaneous or accidental rupture. When it occur the best option is to treat with three cycles of albendazole or the continuous administration of mebendazole during 1- 3 months.

Praziquantel at doses of 40 mg/kg is a potent protoscolicide and could be used as a preventive drug after the cyst content spillage when the rupture of the cyst or as a protoscolicide when PAIR is applied.

Other drugs as nitazoxamide (at doses of 500mg/12h for 3-24 months) has been evaluated in the effectiveness in disseminated cystic echinococcosis (DCE) that failed to respond to surgical and antiparasitic therapy. Three patients improved: one with muscle involvement (clinico-radiological response), one with lung involvement (radiological response), and another with soft tissue and bony involvement (clinico-radiological response of soft tissue cysts) (Pérez-Molina et al., 2011).

Benzimidazoles are contraindicated in pregnancy because they are teratogenic.

Monitoring of the patients is needed and medical and laboratory examinations for adverse reactions are necessary initially every 2 weeks then monthly (WHO, 1996). Leukocyte counts

The documentation of the experience about chemotherapy with benzimidazoles in CE is now extensive. Third part of the patients treated with benzimidazoles is achieving the cure with a complete and definitive disappearing of the cysts, and higher proportion (30-50%) has obtained a considerable reduction of the cyst size and also relieve of their symptoms. However, 20-40% of the cases don't respond as expected. Smaller and isolated cysts (less than 7mm.), surrounded by a minimal adventitial membrane respond better than complicated with multiple separations or with son cysts, or surrounded by a thick or calcified adventitial membrane which are refractory to the treatment. There are two main drugs for chemotherapy: albendazole (10-15 mg/kg/day twice per day; 3- to more than 6 monthly courses with free intervals of 14 days) for treating patients with single or multiple cysts (Gemmell & Roberts, 1995), and mebendazole (40-50 mg/kg/day; everyday in three doses per day during 3-6 months). Albendazole continuous courses have shown equal or improved efficacy for 3 to 6 months or longer without an increase of adverse effects (Franchi et al., 1999). When comparing both drugs, albendazole and mebendazole, some researchers concluded that albendazole was better regarding complete cure rates and relieve of the symptoms (Franchi et al., 1999). Albendazole has a better pharmacokinetic profile than mebendazole facilitating higher intestinal absorption and penetration into the cysts. There are described some adverse reactions (neutropenia, hepatic toxicity, alopecia, and others) in a few number of patients which are reversible when treatment is interrupted. Doses, duration, and follow-up of treatment must be taken individually for each patient. However, it seems that minimum duration has to be for three months. It is difficult to predict the longterm prognosis for every patient; therefore it's necessary to do a long-term follow-up, with

Cysts communicating with the biliary tree

2.2.1.6.3 Chemotherapy

3 months.

protoscolicide when PAIR is applied.

cysts) (Pérez-Molina et al., 2011).

Cysts open into the abdominal cavity, bronchi and urinary tract.

US or other imaging methods to be able to evaluate the result of the treatment.

Chemotherapy is also useful as a surgical complement and albendazole has been used as a pre-surgical treatment to facilitate the surgical manipulation of the cysts inactivating the protoscoleces previously, modifying the integrity of the cyst membranes and reducing the consistency of the cysts. Treatment with benzimidazoles is recommended to prevent the relapse of the disease, which is the secondary echinococcosis when the content of the cysts is spread after its spontaneous or accidental rupture. When it occur the best option is to treat with three cycles of albendazole or the continuous administration of mebendazole during 1-

Praziquantel at doses of 40 mg/kg is a potent protoscolicide and could be used as a preventive drug after the cyst content spillage when the rupture of the cyst or as a

Other drugs as nitazoxamide (at doses of 500mg/12h for 3-24 months) has been evaluated in the effectiveness in disseminated cystic echinococcosis (DCE) that failed to respond to surgical and antiparasitic therapy. Three patients improved: one with muscle involvement (clinico-radiological response), one with lung involvement (radiological response), and another with soft tissue and bony involvement (clinico-radiological response of soft tissue

Monitoring of the patients is needed and medical and laboratory examinations for adverse reactions are necessary initially every 2 weeks then monthly (WHO, 1996). Leukocyte counts

Benzimidazoles are contraindicated in pregnancy because they are teratogenic.

should be checked at 2-week intervals during the first 3 months because in rare instances severe and not always reversible leukopaenia has been observed in early phases of chemotherapy. Serum drug concentrations (ABZ-sulfoxide or MBZ parent compound) should be monitored after 2 and 4 weeks of chemotherapy, respectively, in order to identify levels too high (possibly toxic) or too low (ineffective). For MBZ, it has been recommended to determine serum or plasma levels 4 h after the morning dose. Oral drug doses can be adapted to individual patients in order to achieve adequate serum levels, but such attempts are not always effective. Unfortunately, only few laboratories have the capability to measure ABZ-sulfoxide or MBZ serum drug levels (see also section on AE). Follow-up examinations, including imaging if needed, should be carried out at intervals of about 3 to 6 months for 1 to 3 years after termination of chemotherapy because of the relatively high rate of relapses.

#### 2.2.1.6.4 Vaccines

A new vaccine against echinococcosis would be highly desirable in order to provide longterm prevention of the disease and to complement control programs. Vaccines against ovine hydatidosis have demonstrated its efficacy when targeting the larval stage of the parasite (Lightowlers, 2001). However, if used in the field we would need to vaccinate all the animals in a herd to achieve good results and this would be very costly to control programs. Otherwise, a vaccine protecting dogs against the adult worm would have to be given to only a few animals to protect the environment, because dogs are less numerous than other animals in the herd. Also, domestic dogs are the key in the transmission to livestock and humans. Therefore, some authors have proposed a recombinant oral vaccine given to the small number of dogs keeping the herd would decrease the number of *E. granulosus* adult worms and, consequently, the number of infective eggs. This measure would help reduce the contamination risk factors for humans and livestock, would be cost-effective for the owners of the dogs, and could help increase the overall efficacy of control programs in endemic countries (Petavy, 2008).

Some candidates have been used to induce immune response with vaccination. One of those is Eg-95 encoding gene that is expressed in the oncosphere, protoscoleces, and immature and mature adult worms of *E. granulosus*. EG95 vaccine antigen is a secreted glycosylphosphatydilinositol (GPI)-anchored protein containing a fibronectin type III domain, which is ubiquitous in modular proteins involved in cell adhesion. EG95 protein represents one of the targets of immunity induced by the vaccine because there is a high degree of sequence gene conservation between different isolates (Zhang, 2003). A mixture of different EG95 isoforms increases the ability of *E. granulosus* to invade different hosts and could possibly maximize vaccine efficacy (Haag, 2009). Other candidates for vaccine are the homologous sequences of two of the S3Pvac peptides, GK1 and KETc1, identified and further characterized in *Taenia crassiceps* WFU, *Taenia solium*, *Taenia saginata*, *E. granulosus* and *E. multilocularis*. Comparisons of the nucleotide and amino acid sequences coding for KETc1 and GK1 revealed significant homologies in these species and the results of a study indicate that GK1 and KETc1 may be considered candidates to be included in the formulation of a multivalent and multistage vaccine against these cestodiases because of their enhancing effects on other available vaccine candidates (Rassy, 2010).

#### **2.2.2 Alveolar echinococcosis (AE)**

Alveolar echinococcosis (AE) is an infection caused by the metacestode stage of *E. multilocularis*, which is characterised by a tumour-like, infiltrative and destructive growth

Echinococcosis/Hydatidosis 313

a. For classification, the plane projecting between the bed of the gallbladder and the

*Source*: European Network for Concerted Surveillance of AE: PNM system for the

*Source*: European Network for Concerted Surveillance of Alveolar Echinococcosis: PNM

Hepatic lesions are characterised in US and CT by heterogenous hypodense masses, often associated with necrotic cavities. The lesion contours are irregular and there is lack of a welldefined wall. Calcifications are often found and exhibit a typical pattern in regard to shape and distribution: clusters of microcalcifications or irregular plaque-like calcified foci are located in the central or peripheral parts of the lesions. Discrepancies between US and CT patterns can be found. Hyperechoic haemangioma-like nodules could represent early forms of AE lesions. Quite frequently an extension of the lesions beyond the liver is found toward diaphragm, lungs, pericardium, retroperitoneum, hepatoduodenal ligament and

Magnetic resonance imaging is used to observe compression or obstruction of inferior vena cava, the hepatic veins or the portal branches. Pathognomonic aspects are represented by

The routine laboratory tests do not yield specific findings. The blood sedimentation rate is elevated in most of the cases. The numbers of leucocytes and platelets may be depressed in patients with splenomegaly. Lymphopaenia is frequent in advanced cases, and eosinophilia is usually absent. Cholestasis with or without jaundice is observed in patients with intrahepatic bile duct compression or obstruction. Cholangitis and/or liver abscesses, which usually result from bile duct obstruction, are associated with typical alterations of the laboratory parameters. Hypergammaglobulinaemia is present in most of the patients and reflects the specific and polyclonal antibody response. In about one-half of the patients, the

system for the classification of human cases of alveolar echinococcosis.

Diagnosis of AE is based on similar findings and criteria as in CE.

presence of specific anti-*E. multilocularis* – IgE can be demonstrated.

MX: Not completely evaluated

inferior vena cava divides the liver in two lobes b. Vessels means inferior vena cava, portal vein and arteries

c. Chest X-ray and cerebral CT negative

classification of human cases of AE.

M0: No metastasis(c) M1: Metastasis

**2.2.2.3 Diagnosis of AE** 

multicystic honeycomb-like images. **2.2.2.4 Laboratory findings of AE** 

pancreas.

with the potential to induce serious disease with a high fatality rate. Metacestodes develop primarily almost exclusively in the liver varying from small foci of a few millimetres in size to large areas of infiltration (15-20 cm.). From the liver, the metacestode tends to spread to both the adjacent and distant organs by infiltration or metastasis formation (Eckert, 1998). Cases of AE are characterized by an initial asymptomatic incubation period of 5-15 years duration and a subsequent chronic course. Fatality rate in untreated or inadequately treated persons is high.

High burden of AE is known to be common in certain rural communities in China whilst it is generally rare and sporadic elsewhere. Recently, a study was carried out to estimate the global incidence of this disease by country (Torgerson, 2010). They undertook a detailed review of published literature and data from other sources suggesting that there are approximately 18,235 (CI 11,900–28,200) new cases of AE per annum globally with 16,629 (91%) occurring in China and 1,606 outside China. Most of these cases are in regions where there is little treatment available and therefore will be fatal cases. They were able to calculate that AE results in a median of 666,434 DALYs per annum (CI 331,000-1.3 million).
