Hydatid Disease PDF

HYDATID DISEASES Objectives By the end of the lecture you will be able to answer: 1.What is the causative agents of hydatid diseases? 2.What are the clinical features of this disease? 3. What investigations done? 4. What are treatment options? HYDATID DISEASE (ECHINOCOCCOSIS) Zoonotic d...

HYDATID DISEASES Objectives By the end of the lecture you will be able to answer: 1.What is the causative agents of hydatid diseases? 2.What are the clinical features of this disease? 3. What investigations done? 4. What are treatment options? HYDATID DISEASE (ECHINOCOCCOSIS) Zoonotic disease Humans contract disease from the dog Common in sheep-grazing areas of the world SPECIES Echinococcus granulosus Echinococcus multilocularis Echinococcus oligarthrus ECHINOCOCCUS GRANULOSUS Tapeworm Hermaphrodite Resides in canine’s ileum Has a head and three segments Terminal segment contains eggs Head has hooks / suckers The three proglottids (the first is immature, the second is mature & the third is the gravid segment), it is one of the smallest tapeworms (3-6 mm in length).  Hydatidosis is an endemic parasitic disease in countries where sheep are prolific. This is particularly the case in Mediterranean countries including North Africa, Spain and Portugal. The parasite, Echinococcus granulosus, is a cestode that grows in the small intestine of its definitive host, usually a dog.  The host puts off eggs of the parasite within stool and when an intermediate host (sheep or human) ingests vegetables contaminated with definitive host feces, larvae of the parasite exit the eggs in the duodenum. The larvae(oncosphere) pass through the intestinal wall and carried by blood- stream to liver, lung, brain or another organ where they form cysts. The liver is the most common site of infection, 70% of hydatid cysts develop in the liver, 20% develops in the lungs, 10% develop in other sites e.g. brain. The embryos develop into large fluid-filled hydatid cysts. If we examined the cyst we will identify 3 layers: 1. an outer fibrous layer formed by the host, 2. Laminated layer formed by the parasite (non-nucleated layer) and 3. Inner nucleated germinal layer which generates many protoscoleces within "brood capsules."  From the inner lining of the cyst wall ,protoscoleces( i.e. scoleces with invaginated tissue layers) bud and protrude into the fluid filling the cyst Without treatment, cysts grow and eventually form fistulas into adjacent organs or rupture into the peritoneal cavity. Older cysts have an increased risk of daughter cyst formation, which is an important factor for recurrence of disease after surgery. The life cycle is completed when the entrails (e.g., liver containing hydatid cysts) of slaughtered sheep are eaten by dogs. Pathogenesis: E. granulosus usually forms one large fluid-filled cyst (unilocular) that contains thousands of individual scoleces as well as many daughter cysts within the large cyst. Free brooad capsules & free protoscoleces lying at the bottom of the large cyst are called "hydatid sand" => diagnostically important.  - The cyst acts as a space-occupying lesion, putting pressure on adjacent tissue.The cyst fluid contains parasite antigens, which can sensitize the host. Later, if the cyst ruptures spontaneously or during trauma or surgical removal, life- threatening anaphylaxis can occur. - Rupture of a cyst can also spread protoscoleces widely. CLINICAL FEATURES:The clinical presentation depends on: the mechanical effect of the cyst, allergic reaction to cyst components & complications due to rupture of the cyst. Asymptomatic Symptomatic due to swelling causing pressure effects Abdominal pain Dyspepsia Vomiting Mechanical effect of the cyst : - Cyst may press on adjacent organs: Liver => painful enlargement (common presentation). Bile ducts or on major blood vessels. Lungs => Cysts in the lungs can erode into a bronchus causing cough, breathlessness, hemoptysis and it may cause lung collapse if it compresses a main bronchus. Brain => cerebral cysts can cause headache and focal neurologic signs. Allergic reaction to cyst components : - Hydatid fluid may escape to the circulation and it can cause fatal anaphylactic shock, if Hydatid fluid is in small amount it only cause’s urticaria. CLINICAL FEATURES...cont Complications Anaphylaxis / dissemination due to rupture into: ▪ Peritoneum ▪ Pleura ▪ Pericardium ▪ Bronchioles ▪ Obstructive jaundice Bacterial infection leading to abscess Diagnosis: is based on microscopic examination demonstrating the presence of brood capsules containing multiple protoscoleces or Histopathology (detection of the three layers). Aspiration for diagnostic purposes should not be done when the cyst is inside the body. Casoni skin test (Asten test): inject 0.1 ml sterile Hydatid fluid intradermally, immediate reaction in 20 minutes means positive result. Unreliable test because it may remain positive long after the cyst has been removed.  X-rays Ultrasonography CT scan / MRI Serological tests ULTRASONOGRAPHY Cyst: well-circumscribed; difficult to distinguish from simple cyst Multivesicular cyst (‘cartwheel sign’): presence of daughter cysts ‘Split-wall sign’: fall in pressure of the cyst resulting in separation of endo- and ectocyst Simple cyst Multivesicular Cyst -’Cartwheel sign’ ’Split-wall sign’ SEROLOGY –DETECTION OF ANTIBODIES TO GERMINAL MEMBRANE Immunoelectrophoretic (IE) test Complement fixation test (CFT) Indirect haemagglunitation test (IHT) ELISA HYDATID DISEASE -TREATMENT Surgical approaches vary from complete resection (e.g. total pericystectomy or hepatectomy) to minimal invasive procedures (e.g. percutaneous aspiration of cysts). More recently, reports have been published on laparoscopic surgery for hepatic hydatid cysts. The choice of therapy depends on several factors: general condition of the patient, number and localization of the cysts, the surgeon’s experience and the presence of special services such as intensive care unite. Conservative Surgery PAIR Medical CONSERVATIVE MANAGEMENT OLD, UNFIT PATIENT WITH SMALL, ASYMPTOMATIC CALCIFIED CYSTS SURGERY THE PRIMARY TREATMENT FOR HYDATID DISEASE IS SURGERY A protoscolicidal agent, e.g., hypertonic saline, should be injected into the cyst to kill the organisms and prevent accidental dissemination. Other agents include : Cetrimide , H2O2 , Ethanol , Silver nitrate , Formaline ( may cause biliary damage => not recommended ). PAIR Puncture Aspiration, Injection & Re-aspiration MEDICAL TREATMENT Albendazole Mebendazole MEDICAL TREATMENT Preoperatively to decrease complications due to spillage Poor surgical candidates Widely disseminated; not amenable to surgery Disseminated Hydatid Cysts in Abdomen