Echinococcosis - A Detailed Overview PDF

Echinococcosis  Learning Objectives  Understand epidemiological disease distribution both worldwide as well as in areas of high endemicity in Egypt.  Recognize hydatid, infections as zoonotic disease where man is an accidental intermediate host.  Understand pathophysiological mechanisms of cy...

Echinococcosis  Learning Objectives  Understand epidemiological disease distribution both worldwide as well as in areas of high endemicity in Egypt.  Recognize hydatid, infections as zoonotic disease where man is an accidental intermediate host.  Understand pathophysiological mechanisms of cyst development in the human body.  Recognize hydatid disease as a cause of single or multiple cysts of the liver, spleen, and lungs.  Differentiate hydatid disease from other causes of cystic diseases of the liver, spleen, or lungs.  Utilize laboratory and radiological investigations to reach a final diagnosis.  Design an appropriate management strategy according to the site and stage of disease.  Understand the role of medical treatment in managing hydatid disease.  Key features Zoonotic parasitic disease principally transmitted between dogs and domestic livestock, particularly sheep Human cystic echinococcosis occurs in parts of the world where sheep are raised and dogs are used to herd livestock. The liver is the most common site of the echinococcal or hydatid cyst followed by lungs; cysts occur less frequently in the spleen, kidneys, heart, bone, and central nervous system. New sensitive and specific diagnostic methods and effective therapeutic approaches against cystic hydatid disease (CHD) have been developed in the last 10 years. Treatment options include surgery, chemotherapy with anthelminthic agents, or puncture- aspiration-injection-re- aspiration (PAIR), the latter being restricted to the treatment of liver cysts. Despite some progress in the control of echinococcosis, this zoonosis continues to be a major public health problem in several countries and in several others it constitutes an emerging and re-emerging disease. Echinococcus Life Cycle o 1. The adult Echinococcus granulosus worm resides in the small intestine of the definitive hosts (dogs, other canines). o 2. Proglottids release eggs, which are passed in the feces. o 3. After ingestion by an intermediate host (usually, sheep, goats, swine, cattle, horses, camels, or humans), the egg hatches in the small intestine and releases an oncosphere, which penetrates the intestinal wall and migrates through the circulatory system into various organs, especially the liver and lungs. o 4. In these organs, the oncosphere develops into a cyst, which enlarges gradually; protoscolices and daughter cysts form within the cyst. The definitive host becomes infected by ingesting the cyst-containing organs of the infected intermediate host. o 5. After ingestion, protoscolices evaginate and attach to the intestinal mucosa. o 6. They develop into adult stages in 32 to 80 days Echinococcus worm INTRODUCTION Cystic echinococcosis is the infection of humans and mammals by the larval stage of the zoonotic cestode Echinococcus granulosus. It is also known as cystic hydatid disease (CHD). EPIDEMIOLOGY Echinococcal infection is widely prevalent in regions of the world where dogs are used to care for large flocks of sheep. In endemic regions, the practice of feeding raw infected viscera of slaughtered livestock to dogs facilitates transmission of E. granulosus. NATURAL HISTORY, PATHOGENESIS AND PATHOLOGY o The adult tapeworm of E. granulosus parasitizes a wide variety of canids (e.g. domestic dogs, foxes, wolves, and dingoes), which serve as final, definitive hosts. o These adult worms are small, They typically localize in the lower duodenum and jejunum of the definitive host. o Embryophores (eggs) containing infective embryos are expelled in large numbers in the feces of the final host. o Intermediate hosts are usually farm animals (e.g. sheep, cattle, swine or horses), that acquire infection by ingestion of infectious eggs in the pasture. o The embryo or oncosphere is released by the action of gastric and intestinal enzymes, penetrates the intestinal wall and is transported by the blood stream to the liver or other organs. o Once the oncosphere reaches its final location, it develops into an echinococcal cyst (metacestode). oThe echinococcal cyst is a fluid-filled, spherical, unilocular cyst that con- sists of an inner germinal layer of cells supported by an acellular, laminated membrane of variable thickness. oEach cyst is surrounded by a host-produced layer of granulomatous adventitial reaction. oSmall vesicles called brood capsules bud internally from the germinal layer and produce multiple protoscolices by asexual division. oIn humans, who are accidental hosts, the slowly growing hydatid cysts can attain a volume of several liters and contain many thousands of protoscolices. oWith time, internal septations and daughter cysts can form, disrupting the unilocular pattern typical of the young echinococcal cysts. Hydatid cyst CLINICAL FEATURES Signs and symptoms of hydatid disease depend on the organ involved and the size of the cyst. The onset of symptoms varies from months to several years and results from pressure exerted by the growing cyst. Cysts grow at varying rates. Cysts occur more frequently in the liver (52–77%;, followed by the lungs (9–44%;) and other locations (13– 19%). Most infections have a single cyst.  LIVER CYSTS Liver cysts occur more frequently in the right lobe Most individuals with hepatic hydatid cysts are asymptomatic. Physical examination may reveal abdominal distention and a palpable mass in the upper right quadrant of the abdomen, with or without hepatomegaly. When the cyst has reached large dimensions, complications usually occur.  Cysts sometimes become infected with bacteria and can clinically resemble a liver abscess.  Acute signs and symptoms follow rupture of a cyst, which can occur spontaneously, secondary to a traumatic event or during surgery. 1. Rupture may occur into a bile duct, resulting in obstructive jaundice and colic-like pain followed by bacterial overgrowth. 2. Rupture into the peritoneal cavity usually leads to secondary formation of numerous peritoneal cysts from released protoscolices and, on rare occasions, to peritonitis. 3. Rupture and leakage of cyst fluid may also lead to an erythematous rash or to anaphylaxis. Liver hydatid cyst U/S hepatic hydatid cyst CT: hepatic hydatid cyst LUNG CYSTS Non-complicated lung cysts rarely produce symptoms and are usually found incidentally after a routine chest radiograph. In patients who are symptomatic, chest pain with fever, cough, dyspnea and hemoptysis are often the presenting symptoms; the illness can be confused with pulmonary tuberculosis. Complete or partial rupture of a cyst often leads to expectoration of hydatid fluid and/or membranes, followed by bacterial overgrowth and a lung abscess. Physical examination may reveal dullness with absence of breath sounds. Rupture into the lung may cause pneumothorax and empyema, allergic reactions (e.g. pruritus, urticaria) and, rarely, anaphylactic shock. Rupture into the pleural space with secondary formation of hydatid occurs rarely. Plain X ray: Lung hydatid cyst CT: Thoracic hydatid cyst  OTHER SITES Hydatid cysts have been reported in almost any organ. The spleen is the next most common abdominal organ affected, accounting for 3–5% of all abdominal cysts. Heart or intracerebral cysts each have been reported in 1–1.5% of patients.  The first symptom of cerebral cysts may be raised intracranial pressure or focal epilepsy  kidney cysts may be manifested by loin pain or hematuria  Bone cysts are often asymptomatic until pathologic fractures occur, and because of the resemblance, they are often misdiagnosed as tuberculous lesions.  Cysts in the heart are especially dangerous because they may rupture and cause systemic dissemination of the protoscolices, anaphylaxis, or cardiac tamponade. CT: Intracranial hydatid cyst PATIENT EVALUATION, DIAGNOSIS, AND DIFFERENTIAL DIAGNOSIS o The presence of an enlarged liver and/or palpable mass in the right upper quadrant of the abdomen, or a cannon ball-appearing lesion on chest radiographs suggests the clinical diagnosis of hydatid disease. o A patient coming from an endemic area who gives a history of expectoration of a salty- tasting fluid with hemoptysis has a high probability of having a pulmonary hydatid cyst. o Hepatic hydatid cysts can be confused with any space-occupying lesion, including congenital liver cysts, choledochal cysts, amebic or bacterial liver abscess, and primary and secondary hepatic tumors. o Symptoms caused by lung cysts may be similar to those of pulmonary tuberculosis. o Congenital cysts, bronchogenic cysts, and lung abscesses may also be confused with pulmonary hydatid cysts. o Abdominal ultrasonography and computed tomography (CT) are the methods of choice for detecting abdominal cysts. o In 1995, the World Health Organization-informal Working Group on Echinococcosis (WHO- IWGE) developed a standardized classification that could be applied in all settings to allow for a natural grouping of the cysts into three relevant groups: active cystic echinococcosis (CE) 1 and 2, transitional (CE3) and inactive (CE4 and 5). o The WHO-IWGE classification differs from the previous Gharbi’s classification introduced in 1981 by adding a “cystic lesion” (CL) stage (undifferentiated). o CE3 transitional cysts are differentiated into CE3a (with detached endocyst) and CE3b (predominantly solid with daughter vesicles). CE1 and CE3a are early stages and CE4 and CE5 late stages. o A posteroanterior chest radiograph is the method of choice for diagnosis of lung cysts. o A wide variety of serologic assays have been developed with varying sensitivities and specificities. However, a considerable number of patients, particularly those with lung cysts, may not develop a detectable immune response. o Parasitologic examination of expectorated or aspirated fluid may reveal protoscolices and/ or hooklets. TREATMENT “WATCH AND WAIT”  Ultrasound surveys have revealed the presence of cysts which have consolidated and calcified and have become inactive.  If such lesions do not compromise organ functions or cause symptoms then a “Watch and wait” approach may be taken leaving the cysts untreated.  Careful ultrasound monitoring should be done in these situations. CHEMOTHERAPY Benzimidazole therapy can cure, or partially improve, two-thirds of cysts. Benzimidazoles are also indicated in patients with multiple cysts in one or more organs or with peritoneal hydatidosis.  Perioperative use of benzimidazoles can reduce the risk of secondary echinococcosis following surgery. Albendazole should also be used in prophylaxis before and after puncture-aspiration-injection-re- aspiration (PAIR). Both albendazole (10–15 mg/kg/day) and mebendazole (40–50 mg/ kg/day) have demonstrated efficacy against cystic echinococcosis.  However, the results for albendazole have been superior An intermittent treatment schedule with cycles of 28 days with 14-day periods of rest has been recommended in the past, but evidence suggests that continuous treatment with no monthly interruptions may be equally effective. Administration of albendazole with fat-rich meals facilitates absorption and bioavailability. Adverse reactions (neutropenia, liver toxicity, alopecia and others), reversible upon cessation of treatment, have been noted in a few patients. Examination for adverse reactions (aminotransferases and blood-count) should be performed regularly: every 2 weeks during the first 3 months and then monthly for 1 year. Contraindications to chemotherapy include pregnancy, chronic hepatic diseases and bone marrow depression.  The combination of praziquantel and albendazole has been used successfully in the treatment of hydatid disease. Nitazoxanide does not appear to be effective. PERCUTANEOUS ASPIRATION OF HEPATIC CYSTS UNDER ULTRASONOGRAPHIC GUIDANCE (PAIR) PAIR is a technique for the treatment of cysts in the liver and other abdominal locations. PAIR consists of: (i) percutaneous puncture using sonographic guidance; (ii) aspiration of substantial amounts of the liquid contents; (iii) injection of a protoscolicidal agent (e.g. 95% ethanol or hypertonic saline) for at least 15 minutes; and (iv) re-aspiration. PAIR is usually indicated for patients who cannot undergo surgery, for those who refuse surgery or for cases of relapse after surgery, or failure to respond to benzimidazoles.  PAIR is contraindicated for inaccessible or superficially located liver cysts, for CE2 and CE3b cysts, for inactive or calcified cystic lesions (CE4, CE5) and for lung cysts.  The presence of biliary fistulae is also a contraindication for protoscolicide use. Recent application of PAIR in conjunction with albendazole has been used with good results and offers an alternative to surgery. Some studies have shown that PAIR has a lower rate of complications, shorter (or no) hospitalization and lower costs than does surgical removal, and is the method of choice for the treatment of hepatic cysts in centers having experience with this technique. PAIR should be performed with monitoring so that potential complications of anaphylaxis, asthma or laryngeal edema can be adequately treated. Combined use of albendazole (10 mg/kg/day for 8 weeks) and PAIR has been shown to be more effective than either treatment alone.  SURGERY Surgery remains the treatment of choice in :  Cysts are large (>10 cm diameter),  Secondarily infected  Or located in certain organs (i.e. brain, heart). The main objective of surgery is total removal of the cyst while avoiding the adverse consequences of spilling its contents. Pericystectomy, is the usual procedure, but simple drainage, capitonage, mar- supialization and resection of the involved organ may be used depending on the location and condition of the cyst(s). Preoperative albendazole or mebendazole is indicated to prevent secondary recurrences following leakage or rupture of cyst and spillage of its contents. Monitoring Results of Treatment It has been observed that in echinococcosis, it is easier to prove treatment failure than treatment success; however, noninvasive methods for monitoring cyst size, consistency,and integrity have substantially improved our ability to assess viability of hydatid cysts. Objective response to treatment, whether surgery or chemotherapy or both, is best assessed by repeated evaluation of cyst(s) size and consistency at 3-month intervals with ultrasound imaging or at longer intervals with CT or MRI. Since the time of appearance of recurrence is extremely variable, monitoring should be continued for 3 or more years. Changes in titers of serologic tests have not by themselves been able to define the outcome of chemotherapy or PAIR, presumably because of continued antigenic stimulation from parasitic tissue. In contrast, following successful radical surgery, antibody titers decline and sometimes disappear; titers rise again if secondary hydatid cysts develop. PREVENTION Periodic mass treatment of dogs with praziquantel, prohibition of giving raw infected viscera to dogs and adequate inspection of abattoirs, as well as educational measures to change human practices that facilitate hydatid disease transmission, have been effective in control- ling echinococcosis. Alveolar echinococcosis (AE) It is caused by E. multilocularis,whose final and intermediate hosts are foxes and their rodent prey, respectively. Human infection caused by this species is one of the most lethal parasitic infections and is characterized by a tumor-like, infiltrative growth. LARVAL CESTODE INFECTIONS  ILO’s  Understand epidemiological disease distribution both worldwide as well as in areas of high endemicity in Egypt.  Recognize hydatid, cysticercosis, sparganosis and coenuriosos infections as zoonotic disease where man is an accidental intermediate host.  Understand pathophysiological mechanisms of cyst development in the human body.  Recognize hydatid disease as a cause of single or multiple cysts of the liver, spleen, and lungs.  Differentiate hydatid disease from other causes of cystic diseases of the liver, spleen, or lungs.  Utilize laboratory and radiological investigations to reach a final diagnosis.  Design an appropriate management strategy according to the site and stage of disease.  Understand the role of medical treatment in managing hydatid and other tissue cystodes disease.  Understand appropriate preventive measures for tissue cystodes based on an understanding of their life cycle.  CYSTICERCOSIS DEFINITION INFECTION OF HUMAN TISSUES WITH LARVAE OF THE PORK TAPEWORM TAENIA SOLIUM HUMAN CYSTICERCOSIS IT IS ACQUIRED THROUGH ORAL- FECAL ROUTE WHEN HUMANS INGEST TAPEWORM EGGS, THEY DEVELOP CYSTICERCI WITHIN THEIR TISSUES IN THE SAME WAY PIGS DO CYSTICERCOSIS IS THEREFORE CONTRACTED FROM INGESTING MATERIAL CONTAMINATED BY HUMAN FECES CONTAINING TAPEWORM EGGS AND NOT FROM EATING INFECTED PORK CONTAINING CYSTICERCI. HUMANS ARE INCIDENTAL INTERMEDIATE HOST AND REPRESENT A DEAD END FOR THE PARASITE. HUMANS HARBORING AN INTESTINAL TAPEWORM CAN INFECT THEMSELVES WITH CYSTCERCOSIS (ANUS-HAND-MOUTH) CLINICAL MANIFESTATIONS THE CLINICAL FEATURES OF CYTICERCOSIS ARE VARIABLE, DEPENDING ON THE INFLAMMATORY RESPONSE AROUND CYSTICERCI AND THEIR NUMBERS, SIZE AND THE LOCATION. NEUROCYSTICERCOSIS EPILEPSY: MOST COMMON CAUSE OF ADULT ONSET EPILEPSY WORLDWIDE FOCAL SEIZURES WITH SECONDARY GENERALIZATION ARE MOST COMMON SINGLE OR MULTIPLE CYSETICERCI AR E USUALLY PR ESENT WITHIN THE BR AIN PAR ENCHYMA AND MAY BE SUR ROUNDED BY FOCAL ENCEPH ALITIS AND EDEMA R AISED ICP DEMENTIA OR PSYCHIATR IC ILLNESS HYDROCEPHALUS CHRONIC MENINGITIS BASAL AR ACHONDITIS CR ANI AL NERVE PALSIES VASCULITIS AND CER EBR AL INFAR ACTS DUE TO DEATH OF CYSTICERCI SPINAL CYSTICERCOSIS OPHTH ALMIC CYSTICERCOSIS MOST COMMON IN R ETINA OR SUBR ETINA MAY FLOAT IN VITR EOUS OR AQUEOUS HUMORS CHOR IDOR ETINITIS R ETINAL DETACHMENT VASCULITIS MUSCULAR AND SUBCUTANEOUS CYSTICERCOSIS PALPA BLE OR PEA-LIK E NODULES ASYMMTOMATIC, ALTHOUGH TR ANSIENT LOCAL PAIN AND TENDER NESS MAY OCCUR MASSI VE MUSCULAR PSEUDOHYPERTROPHY DIAGNOSIS BIOPSY FOR SUBCUTANEOUS LESIONS R ADIOLOGY : PLAIN X R AY OF THE THIGH OR OTHER MUSCLES, PLAIN X R AY OF SKULL -----INTR ACR ANIAL CACIFICATIONS CT MR I SEROLOGY ENZYME LINK ED IMMUNOELECTROTR ANSFER E BLOT DD TB NEOPLASM HYDATID CYST TOXOPLASMOSIS TR EATMENT PR A ZIQUANTEL (50-75MG/KG/ DAY PO FOE 2 W EEKS) OR ALBENDA ZOLE 15MG/ KG/PO FOR 8-15 DAYS R ECENTLY SHORT COURSE OF THR EE DOSES OF 75-100 MG/KG OF PR A ZIQUANTEL IN THE SAME DAY H AS BEEN R EPORTED BET W EEN THE 2R D AND FIF TH DAY OF THEW R APY, PATIENTS H AVE EXACER EBATION OF NEUROLOGIC SYMP TOMS DUE TO LOCAL DEATH OF LARVAE --------TR EATED BY CORTICOSTEROIDS TO CONTROL EDEMA SYMPTOMATIC NEUROCYSTICERCOSIS ANTICONVULSANT DRUGS FOR SEI ZUR ES OR AL CORTICOSTEROIDS FOR R AISED ICP AND AR ACHONIDITIS INSERTION OF VENTR ICULO -PERSISTENT SHUNT FOR HYDROCEPH ALUS OPHTH ALMIC CYSTICERCOSIS LOCAL AND SYSTEMIC CORTICOSTEROIDS CESTOIDAR DRUGS? CRYOTHERAPY?? PHOTOCOAGULATION? EXCISION OF A LIVING CYSTICERCI BEFORE THE ONSET OF SIGNIFICANT INTRAOCULAR INFLAMMATION HAS A GOOD PROGNOSIS MUSCULAR AND SUBCUTANEOUS CYSTICERCOSIS ASYMPTOMATIC LESIONS DO NOT REQUIRE TREATMENT EXCISION OR TREATED WITH CESTOIDAL DRUGS FOR LESIONS CAUSING PRESSURE  SPARGANOSIS IT IS CAUSED BY INFECTION WITH SPARGANA, WHICH AR E SECOND STAGE LARVAE (PLEROCERCOIDS) OF DIPHYLLOBOTHR ID TAPEWOR MS OF THE GENUS SPIROMETR A IT IS PR ESENT IN SOUTHEAST ASIA THE ADULT PAR ASITE DOES NOT DEVELOP IN HUMANS. MODE OF INGECTION: INGESTING THE PROCERCOID IN THE FIRST INTER MEDI ATE HOST (CYCLOPS) WHEN DR INK ING CONTAMINATED WATER INGESTING THE PLEROCERCOID IN SECOND INTER MEDI ATE HOSTS SUCH AS FROGS FROM POULTICES PR EPAR ED FROM FROGS INFECTED WITH PLEROCERCOIDS THAT AR E APPLIED DIR ECTLY TO ULCERS, SOR ES AND INFLAMED EYES CLINICAL MANIFESTATIONS CNS: BR AIN A BSCESSES, INTR ADUR AL SPINAL COR D INFECTION, SEI ZUR ES, HEADACHE, HEMIPAR ESIS, PAR ASTHESI AS, MEMORY LOSS AND CONFUSION SUBCUTANEOUS TISSUES ENCAPSULATED INFLAMMATORY NODULES IN WHICH MAY DEVELOP INTO A BSCESSES EYE: CONJUNCTIVITIS, PER IOR BITAL EDEMA DI AGNOSIS EXTR ACTION OF INTACT PAR ASITE ELISA ASSAY TREATMENT SURGICAL EXCISION PR A ZIQUANTEL MIGHT BE ADVISABLE  COENUR I ASIS IT IS A ZOONOTIC DISEASE OF HUMANS CAUSED BY INFECTION WITH THE LARVAL STAGE ( COENURUS) OF TAENI A MULTICEPS. ADULT TAPE WOR M AR E FOUND IN THE SMALL INTESTINE OF CANIDS USUALLY DOGS. GR AVID PROGLOTTIDS AR E PASSED IN FECES AND DISINTIGR ATE TO FR EE EGGS. EGGS WHEN INGESTED BY HUMANS , THE EGGS DEVELOP INTO COENUR I HUMAN COENUR IASIS IS R AR E BUT IT HAS BEEN R EPORTED IN USA, ENGLAND, FR ANCE AND BR A ZIL CLINICAL MANIFESTATIONS NEUR AL COENUR I ASIS: SPACE OCCUPYING LESIONS IN CER EBRUM, VENTR ICLES, POSTER IOR HOR N, BR AIN STEM, SPINAL COR D AND AMONG THE CR ANIAL NERVES SUBCUTANEOUS COENUR I : IN INTERCOSTAL R EGIONS AND ANTER IOR ABDOMINAL WALL. THESE CYSRS AR E CONFUSED WITH LIPOMA, GANGLION AND NEUROFIBROMA OCULAR COENUR I: IN VITR EOUS, ANTER IOR CH AMBER AND CONJUNCTI VA. DI AGNOSIS X- R AY CT SUBCUTANEOUS CYSTS MAY BE PALPATED OCULAR LESION BY OPHTH ALMOSCOPE TR EATMENT SURGICAL EXCISION IS THE USUAL TR EATMENT PR A ZIQUANTEL CAN CAUSE SER IOUS TOXIC ENDOPHTH ALMITIS AND LOSS OF VISION THE BEST TR EATMENT IS R EMOVAL THROUGH CLOSED VITR ECTOMY