Treatment of uncomplicated cystic echinococcosis (CE) is complex and consists of medical treatment, surgery and piercing, aspiration, injection and reinspiration (PAIR), depending on the characteristics of the cyst. In some cases (CE4 and CE5), a conservative watch-and-wait approach is preferred because it can regress spontaneously with calcification without chemotherapeutic intervention. Medical treatment plays a role in reducing the size of cysts, stopping their development and reducing the infection and is the only treatment option in inoperable cases. The combination of medical therapy with surgery (preoperative and postoperative application) or PAIR can prevent recurrences.
Treatment of Cystic Echinococcosis
There are several treatment approaches for echinococcosis, including watch-and-wait strategy, chemotherapy, interventional radiology, and surgery. The indications for one or more treatment options are complex and depend on cyst characteristics, availability of medical and surgical equipment, and patient cooperation. Therefore, it is preferable to refer patients to reference treatment centers for echinococcosis to obtain appropriate treatment. However, the treatment methods for echinococcosis are as follows:
The choice of therapeutic modality depends on cyst stage, size, location and comorbidities. Medical therapy using parasitostatic drugs such as benzimidazoles (mebendazole and albendazole) is mainly recommended for inoperable patients with widespread disease. Drug treatment should be applied continuously for at least 3 months. However, the cost of long-term treatment is high, with numerous teratogenic side effects. Also, chemotherapy can be used as a complementary therapy to surgery or to prevent metastasis and secondary cystic areas. However, it is not recommended for the treatment of inactive or calcified cysts. The monitoring and waiting strategy is a therapeutic option for uncomplicated cysts with more than one involvement. Requires regular long-term monitoring of liver function tests and leukocyte counts.
Percutaneous treatment method is defined as an option for the management of cysts in the liver and other abdominal areas. This procedure is divided into two techniques and they are as follows:
• PAIR technique, resulting in destruction of the germinal membrane following the use of a scolicidal agent,
• Best known of modified catheterization techniques aimed at evacuating the entire endocyst. This approach is a mini-invasive procedure compared to surgery, but cysts containing juvenile vesicles are not the best indication for percutaneous treatment due to the high risk of spreading to the peritoneal cavity and bile duct.
Surgery should be evaluated carefully. Decision making is based on the characteristics of the hydatid cyst, such as the cyst type, number, size, location, and the presence or absence of associated complications, and these features are as follows:
Large cysts containing multiple juvenile vesicles,
Symptomatic and complicated cysts,
• Superficially located cysts that can rupture spontaneously or after a benign trauma,
Infected cysts in close contact with veins or adjacent vital organs,
It may also be an option for patients who are not eligible for percutaneous treatment. The surgical approach aims at parasite inactivation, evacuation of the endocyst by preventing contamination, removal of the germinal layer and residual cavity management. With respect to hepatic involvement of the abdominal areas typically, there are two surgical approaches, consisting of conservative surgery and a radical procedure using open or laparoscopic surgery. Conservative procedures include removal of parasitic cyst contents such as juvenile vesicles and germinative membrane while keeping the pericyst. The remaining space is carefully investigated to look for any evidence of cystic bile duct communication. It is then managed according to different techniques such as capitonage, omentoplasty or external drainage.
Surgeons should cover the surgical area with a scoicidal agent to prevent shedding of parasites and contamination of the peritoneal cavity. Conservative surgery is simple and safe with a relatively shorter operative time, but has high morbidity and recurrence rates. Radical surgery is the first viable treatment option for complete removal of the entire parasitic lesion. Complete resection is required whenever possible because radical surgical procedures are superior to conservative surgical methods and can cure the patient definitively. In this surgical goal, the entire cyst, together with the parasite content and pericystic tissue, is to be removed. However, his radical procedures are as follows:
Complete cystic removal through open or closed pericystectomy
During pericystectomy, a proper dividing plane between the inner layer and the outer cystic layer may limit liver parenchyma damage. Liver resection is more difficult, takes longer operation time, and has a higher risk of blood loss, but lower rates of cystic recurrence. Radical surgery is preferred due to lower morbidity, mortality and recurrence rates compared to conservative treatment. Laparoscopic treatment of abdominal (hepatic or extrahepatic) hydatid cysts is among the management approaches. It is a mini invasive surgery that can be performed safely after patient selection in special cases. Laparoscopy has several advantages and these are as follows:
Better visualization of the peritoneal cavity and internal organs,
Fast postoperative discharge,
Limited postoperative morbidity,
Good aesthetic results,
There is a lower incidence of hydatid disease in non-hepatic regions. Management and appropriate therapeutic approach mainly depend on the cystic area and the organ involved. Generally, once the removal of the cysts is complete, the prognosis is good with a low recurrence rate.
Follow-up of Hydatid Disease
For patients treated for hydatid disease, a long-term follow-up should be planned because relapses may occur in some cases. Patient monitoring is mainly based on short-range imaging techniques (USA, CT and MRI). Serological tools and specific serum antibodies dosage support imaging techniques and may reflect method viability. In addition, monitoring of the parasitostatic plasma level is necessary to adjust the therapeutic range and avoid long-term side effects of treatment.
Today, planning for echinococcosis control is based on the interruption of the parasitic life cycle. The disease can be prevented by improving hygiene in the slaughter of livestock, public education campaigns, periodic pest detoxification of dogs and adequate disposal of infected offal. Vaccination of dogs with recombinant proteins provides encouraging prospects for prevention and control.
Future vaccination may prevent the spread of echinococcosis in endemic areas. Zhao et al. It identified six dominant T-cell epitopes and five dominant B-cell epitopes in the EgA31 protein construct and six dominant T-cell epitopes and three dominant B-cell epitopes in EgG1Y162 that could represent the initiation of multiple epitope vaccines against Echinococcus granulosus. Miles et al. reported that there are 9 new proteins and 14 peptides to be tested separately as potential cystic echinococcosis vaccine candidates. Pilot field trial of EG95 vaccine against sheep cystic echinococcosis conducted by Larrieu et al. In this trial, a decrease in the incidence of EC in Argentina and good surveillance and control of the epidemiological chain of the parasite was observed.
The development of recombinant double vaccines expressing the EG95 Echinococcus granulosus antigen is a new direction in the future. Goat pox (GPV) disease and cystic hydatidosis can be prevented with live attenuated GPV AV41 vaccine; GPV is an ideal vector for expressing the EG95 antigen. The same group of researchers developed another recombinant, bivalent vaccine using morbillivirus (SRMV) expressing the EG95 antigen, which prevents both morbillivirus infection and Echinococcus granulosus infection. Given the limited treatment in CE, new clinical trials are needed to find potential drugs and new strategies to limit the transmission of infection.
Author: Ozlem Guvenc Agaoglu