liver worm disease



Overview

Definition

Hepatic encystment disease, also known as hepatic echinococcosis, is a zoonotic liver parasitic disease caused by the larvae of Echinococcus granulosus (Echinococcus granulosus) parasitizing the human liver.

Classification

It is currently recognized that there are four types of echinococcus tapeworm larvae that can cause this disease, and there are two main types of common liver worm disease in China, fine-grained echinococcus tapeworm infection leading to cysticercosis; and multi-housed echinococcus tapeworm infection leading to vesicular worm disease.

Morbidity

According to the 2010 National Health and Family Planning Commission’s “Action Plan for Prevention and Control of Follicular Disease (2010-2015)”, the average prevalence of Follicular Disease in the western part of the country is 1.08%, and in some areas of the Tibetan Plateau, the prevalence can be as high as 6%.

Questions you may be concerned about

What is the difference between hepatic encapsulosis and liver cysts

The difference between hepatic encapsulosis and hepatic cysts lies in the different causes, symptoms, and treatments.

1. Different causes: Hepatic cysticercosis is infected when a person swallows food contaminated by worm eggs; the cause of liver cysts is still unclear, and most of them are caused by congenital developmental abnormalities. However, it is worth mentioning that hepatic cysts can be caused by hepatic cysticercosis, which manifests as cyst-like lesions.

2. Symptoms are different: Hepatic cysticercosis generally has no symptoms in the incubation period, but may also appear weakness, insomnia, emaciation, epigastric fullness, lack of appetite, nausea, vomiting, biliary colic, cholecystitis, respiratory difficulties, splenomegaly, abdominal fluid, lower limb edema and other symptoms; liver cysts generally have no obvious symptoms, the cysts of a larger size may appear abdominal distension, abdominal pain and other symptoms.

3. Different treatment methods: single hepatic cysts can be given to the hepatic cyst de-roofing and windowing; hepatic cysts should be completely removed during surgery to eliminate parasites, eliminate the residual cavity, and should also be taken orally after the operation to expel worms.

Regardless of hepatic cysts or hepatic cysts, patients should consult the doctor in time, complete the relevant examinations, make a clear diagnosis, and then take the corresponding treatment plan.

Causes

Causes

The causative agent of cysticercosis is the eggs of Echinococcus granulosus, while the causative agent of blastocysticercosis is the eggs of Echinococcus multilocularis.

Humans are the intermediate hosts of both tapeworms.

Dogs are the main final hosts of Echinococcus granulosus, while foxes and wolves are the main hosts of Echinococcus multilocularis.

Pathogenesis

Cysticercosis

Adult Echinococcus granulosus tapeworms parasitize the small intestine of canine carnivores (dogs, foxes, wolves and other final hosts), producing eggs that are excreted in the feces and contaminate pastures, water sources and the environment.

Eggs can be accidentally ingested by a variety of herbivores (cattle, sheep, etc.) and intermediate hosts such as humans, with sheep being the most common. Hatched larvae can parasitize visceral tissues and cause encapsulation.

There is no direct human-to-human transmission.

Vesicular echinococcosis

The route of infection for liver vesicular echinococcosis is essentially the same as for cystic echinococcosis, although foxes and wolves are the main terminal hosts and rodents (mice, voles, etc.) and humans are its intermediate hosts.

The primary lesion of vesicular echinococcosis is in the liver in almost 100% of cases, with a predominance of the right hemiliver. Most patients present with epigastric distension, epigastric mass, obstructive jaundice, and only in the middle to late stages of the disease, so its prognosis is poor.

Similar to tumor, it can directly invade adjacent tissues, and can also spread to distant places through lymph and bloodstream, so it is called “worm cancer”.

Symptoms

Cysticercosis is mainly mechanical damage to the human body, the severity of echinococcus larvae by the size, number, parasitism time, often 5 to 20 years after infection before symptoms.

Vesicular form of encapsulation is more serious than cystic form of encapsulation, and has a higher mortality rate.

Main Symptoms

Localized compression symptoms

Liver involvement, the liver area may have slight pain, pressure, and swelling sensation, hepatomegaly, and abdominal pain.

Compression of portal vein, ascites.

Compression of bile ducts, leading to obstructive jaundice, cholecystitis.

Body surface mass

If the site of parasitism is superficial, body surface mass will be formed.

Allergic reaction

Massive overflow of cystic fluid leads to allergic reactions, manifesting as angioneurotic edema, urticaria, asthma, and even anaphylactic shock, which is life-threatening.

Toxicity symptoms

Loss of appetite, weight loss, emaciation, anemia, affecting development, cachexia.

Complications

Acute cholangitis

Rupture of the echinococcus capsule invades the bile duct, causing acute inflammation, manifested as biliary colic, chills, high fever, jaundice.

Acute peritonitis

Rupture of the echinococcal larval sac into the abdominal cavity, resulting in acute diffuse peritonitis, manifested by generalized abdominal pressure, rebound pain, and abdominal muscle tension.

Invasion of lungs

Irritation of the respiratory tract may result in shortness of breath and chest pain.

If it breaks into the bronchial tubes, small fragments of germinal sacs, cysts, and keratocysts can be coughed up.

Invasion of the cranium

Invasion of the cranium can present with headache, vomiting, and seizures.

Fractures

Echinococcus granulosus destroys bone and is prone to fractures of the pelvis, concha, and long bones, and bone shattering.

Other complications

The damage to the liver is even more severe in vesicular coccidiosis. Vesicular coccidia grow in a diffuse infiltrating pattern and can involve the entire liver, causing liver failure and hepatic encephalopathy.

Vesicular coccidia can also induce cirrhosis with portal hypertension and complicate fatal upper gastrointestinal hemorrhage.

Consultation

Department of Medicine

Gastroenterology

With manifestations such as discomfort in the liver area, hepatomegaly, ascites, jaundice, etc., especially with epidemiologic history, it is recommended to seek prompt medical treatment, which may include Infectious Diseases and Hepatology.

General Surgery

Once the diagnosis of hepatic encysted disease is confirmed, those who need surgical treatment can go to General Surgery or Hepatobiliary Surgery.

Preparation for medical treatment

Preparation for medical consultation: registration, preparation of documents, common questions

Tips for medical treatment

Try to keep a record of symptoms and duration.

Bring information about previous visits and medications so that the doctor can adjust the treatment plan.

Preparation Checklist

Symptom list

Pay particular attention to the time of onset of symptoms, special manifestations, etc.

Have pain or discomfort in the liver area?

Any yellowing or paleness of the skin or eyes?

Any increase in weight, abdominal circumference?

Any body surface lumps?

Any skin swelling, rash, wheezing?

Any loss of appetite, weight loss?

Any chest pain, difficulty breathing, coughing up foreign objects?

Any headaches, vomiting, seizures?

How long have the above symptoms lasted?

List of medical history

Is there a history of encopresis? Has there been any treatment?

Has there been contact with wild foxes, dogs?

Are domestic dogs, cattle, or sheep kept?

Are engaged in shearing, milking, processing of fur?

Checklist

Test results from the last six months, which can be brought to the doctor’s office

Laboratory tests: blood test, liver and kidney function, coagulation function, immunology test.

Imaging tests: abdominal ultrasound, abdominal CT.

Diagnosis

Hepatic encysted disease has an insidious onset and nonspecific clinical manifestations. Diagnosis is mainly based on imaging tests. Immunological examination is helpful for the diagnosis of asymptomatic patients or patients with atypical imaging manifestations, as well as for differential diagnosis.

Diagnosis is based on

medical history

The following conditions may be present:

History of contact with wild foxes and dogs.

Dogs, cattle, and sheep kept in the home.

Farmers and ranchers in the western region.

Work is processing furs, shearing sheep, milking cows and sheep.

History of travel and contact in infected areas.

History of trauma and fracture.

Clinical manifestations

Symptoms

Pain in the liver region, jaundice, ascites.

Allergic reactions such as angioneurotic edema, urticaria, asthma, and even anaphylaxis.

Loss of appetite, weight loss, emaciation, anemia, cachexia.

Headache, vomiting, seizures and other manifestations of cranial invasion.

Physical signs

Abdominal mass may be present; yellowing of skin sclera.

The abdominal wall is firm to palpation and elastic to pressure.

There is tremor in the abdomen on percussion; mobile turbid sounds are positive with >1000 ml of ascites.

Immunologic examination

Commonly used tests are enzyme-linked immunosorbent assay (ELISA), indirect hemagglutination assay (IHA), dot-immuno-colloidal gold filtration assay (DIGFA) and so on.

Serologic tests for liver cysticercosis focus on the lipoprotein antigen b and antigen 5 of the cystic fluid of the worms.

The main test for hepatic blastocystic inclusion disease is the heat-resistant antigen Em2.

Imaging

Abdominal ultrasound

Ultrasound is preferred for the diagnosis of hepatic encapsulosis and is convenient, noninvasive, and economical.

Abdominal CT

Compared with ultrasound, abdominal CT has a clearer observation, clarifies the location of the lesion, understands the relationship between the lesion and the blood vessels and bile ducts, and helps to select and design the surgical method and assess the surgical risk.

Magnetic Resonance Imaging (MRI)

MRI plays a similar role to CT. The advantage of MRI over CT is that there is no radiation.

Cholangiography

Intraoperative cholangiography in hepatic cysticercosis serves to accurately suture bile duct leaks in the cyst and helps in complex liver resections and liver transplantation.

PET-CT

To assess the metabolic activity of hepatic cysticercosis lesions, the presence or absence of metastases, the feasibility of radical surgery, and postoperative recurrence.

It is the “gold standard” for the termination of antipelvic drug therapy for both types of hepatic blastomycosis.

Differential diagnosis

Hepatic cysticercosis needs to be differentiated from congenital hepatic cysts, bacterial liver abscess, gallbladder effusion, right-sided pyelonephrosis, congenital cystic dilatation of the common bile duct, and hepatic blastema.

Hepatic vesicular cysticercosis needs to be differentiated from hepatocellular carcinoma, hepatic hemangioma, bacterial liver abscess, congenital hepatic cyst, and hepatic cysticercosis.

Congenital liver cysts

Congenital liver cysts have no epidemiologic history, thin and smooth cyst wall, no calcification, homogeneous cyst fluid, no typical imaging features of cysticercosis, and mostly negative immunologic diagnosis.

Bacterial liver abscess

Bacterial liver abscess has no epidemiological history, the systemic toxic symptoms are more serious, the imaging examination suggests that the cystic wall of the lesion and the internal septum can be seen as striated or punctate blood flow signal or enhancement, and it can also be identified with the help of the immunological test for worms.

Hepatocellular carcinoma

Hepatocellular carcinoma develops rapidly and has a relatively short course. The periphery of typical liver cancer foci is mostly “rich blood supply area”, while the periphery of liver blastema foci is mostly “poor blood supply area”. Hepatic blastomycosis lesions are relatively slow-growing and have a long duration of disease. It can be effectively differentiated with the help of alpha-fetoprotein and immunologic tests for liver worm disease.

Treatment

Aim of treatment: to completely remove and kill the worms, and to cure liver worm disease.

Treatment principle: radical hepatic resection of the lesion is the mainstay, supplemented by long-term drug treatment.

Surgical treatment

Both types of liver cysticercosis are mainly treated by surgery, early diagnosis and early surgery is the key to successful treatment.

Hepatic cysticercosis

Precautions for cysticercosis surgery

Preoperative perfect imaging examination, qualitative, localization, quantitative, and the relationship with the surrounding important blood vessels and bile ducts, fully assess the difficulty and risk of surgery, and choose the best surgical method.

Hydrocortisone should be used routinely during surgery to prevent allergic reaction caused by spillage of cystic fluid; protect the surrounding organs to prevent contamination by spillage of the cystic fluid of worms and abdominal implantation.

Postoperatively: repeat ultrasound and follow up the surgical results.

Commonly used surgical methods for cysticercosis

Complete excystectomy and partial hepatectomy are preferred.

Subtotal resection of the external capsule, modified internal capsule removal, percutaneous fine needle aspiration to drain the cystic fluid, laparoscopic hepatic cysticercosis removal, and liver transplantation are also available.

Surgical indications for cysticercosis

Single cyst, multiple cysts or collapsed internal cysts with an average diameter of ≥5cm.

Encysted sacs with an average diameter of <5 cm but located in the first and second hepatic hilar, resulting in serious complications (obstructive jaundice, portal hypertension, and not-plus syndrome).

Serious complications occurred.

High drug side effects, inability to adhere to the medication, more than six months of medication but the lesions continue to increase in size.

Contraindications to surgery for cysticercosis

Important organs such as heart, lung, liver and kidney are dysfunctional and cannot tolerate surgery.

The average diameter of the cysts is less than 5cm, and there is no complication and inactivity.

Hepatic follicular schistosomiasis

The infiltrative growth pattern of hepatic blastomycosis dictates that hepatic resection is the preferred radical procedure, with resection greater than 1 cm of normal hepatic tissue from the margins of the lesion to ensure structural integrity and functional compensation of the remaining liver.

Other surgical options include palliative surgery, local ablative therapy, liver transplantation, and isolated liver resection.

Pharmacologic treatment

Anti-cysticercosis drugs mainly include albendazole and mebendazole.

Domestic and foreign experts recommend that albendazole is preferred for both types of cysticercosis.

The dosage and precautions of drugs for the two types of encapsulated diseases are similar.

The drug course is divided into three kinds:

Therapeutic medication: long-term medication is recommended, albendazole 10-15mg/(kg-d), divided into two times after breakfast and dinner.

Preoperative prophylactic medication: a course of 3 to 7 days, used as above.

Postoperative prophylactic medication: radical resection surgery (including complete removal of the external capsule and hepatic lobectomy) does not need to take antipacking drugs after surgery. The solid and calcified cysts of internal capsule removal surgery do not need to take oral antipacking drugs; while the monocystic, polycystic and internal capsule collapse types need to take drugs.

Interventional therapy

Interventional external drainage is currently the mainstay of treatment for patients with advanced hepatic blastocystic cysticercosis who cannot undergo radical resection, which reduces serious complications, prolongs the patient’s life, and buys time for liver transplantation.

Liver transplantation

Liver transplantation has been recognized as a treatment for end-stage liver disease. However, due to the high cost of liver transplantation, the difficulty in sourcing donor livers, and the concomitant possibility of recurrence, it is considered the last option in treatment.

Prognosis

Cure

Hepatic cysticercosis

The prognosis is good and most can be cured by surgery or medication.

Cured

Clinical symptoms and signs: disappearance.

Imaging: disappearance, solidification and calcification of the cysts.

Effective

Clinical symptoms and signs: remission, or significant reduction of major symptoms.

Imaging examination: no significant enlargement of the encapsulated worms, shrinkage >2cm or reduction of lesions >2, signs of separation of the internal capsule. Echo enhancement in the cystic contents and increased spot enhancement.

Ineffective

Clinical signs and symptoms: no relief or aggravation.

Imaging: increased diameter of the encapsulated worms.

Hepatic follicular schistosomiasis

Poor prognosis, early and intermediate stages can mostly be cured by radical resection.

Cured

Disappearance of lesions, complete calcification.

Effective

Clinical symptoms and signs improve.

Ultrasonography has one of the following manifestations: lesion shrinkage, no enlargement, echo enhancement.

Ineffective

No relief of clinical symptoms and signs, ultrasonography: no change in the lesion, progressive enlargement.

Daily

Daily management

Ensure the safety of drinking water, prevent quoting contaminated water sources.

Avoid contaminating food with worm eggs, heating and sterilizing can kill the eggs.

Do personal protection and pay attention to personal hygiene.

Try not to contact wild foxes and wild dogs.

Disease monitoring

The recurrence rate of encapsulated worm disease is high, whether it is surgical treatment, or drug treatment, need to be closely monitored.

Patients taking albendazole for long-term treatment of liver cysticercosis need to have regular review of blood, urine, liver and kidney function, ultrasound or CT to assess the efficacy of the medication.

Follow-up review

In order to determine whether cure has been achieved and to prevent recurrence, follow-up imaging is performed long term after treatment, >3 years for liver cysticercosis and >10 years for blastocysticercosis.

Patients who have undergone radical resection for hepatic cysticercosis are followed up with ultrasound or CT every 3-6 months for >2 years.

In patients with hepatic cysticercosis who have undergone endocyst removal, cystic solid and calcified types are followed up regularly every year; whereas monocystic, polycystic, and endocystic collapsed types require oral antipacking medication for 3-12 months, with reassessment to decide on the interval between reviews.

Prevention

Eradication of feral rats is the main method of eradicating the source of infection.

Control feral dogs and deworm domestic dogs regularly.

Avoid contact with wild foxes.

Hygienic diet, wash hands before meals, separate plates for hot and cold food, do not accidentally eat uncooked food.

Pay attention to food hygiene, especially when traveling and living in the wild and infected areas, do not eat raw food and drink contaminated water.

Dispose of animal offal correctly, especially in infected areas, such as by deep burial or incineration.

For people in the endemic areas of western bursal disease, they should raise awareness of disease prevention, conduct regular check-ups, and improve immunological tests, X-rays and ultrasound examinations, so as to detect and eradicate the disease at an early stage.