Human Hepatic Alveolar Echinococcosis Of Liver ;How Rare Is Rare ? Case Series With Review Of Literature

Echinococcosis also known as Hydatidosis or Hydatid Disease is a major human and veterinary concern. It is endemic in many parts of the world and is caused by infestation with the larval/meta-cestode stage of organisms belonging to genus Echinococcus. It is among the most dangerous zoonoses known. Transmission of AE to humans is by consumption of parasite eggs excreted with faeces of definitive hosts, foxes and dogs.Liver is the most common organ involved but the disease can also disseminate to other organs like lung, long bones and brain. Although AE is geographically confined to the northern hemisphere, but globalization and urbanization resulting in major population shifts has made it necessary for all global health care providers to have knowledge about this disease. This disease is now increasingly being reported from previously unaffected areas. Associated morbidity, treatment related costs and DALY’s ( Disease Adjusted Life Years) are high. The incidence of Cystic Echinococcosis (CE) caused by Echinococcus Granulosus (EG) is very high in our part of the world. We present our experience of four cases of AE over a short period of time. The treatment options offered and the short term follow up is discussed. ------------------------------------------------------------------------------------------------------------------------------------Date of Submission: 14-11-2018 Date of acceptance: 29-11-2018 ------------------------------------------------------------------------------------------------------------------------------------I. Introduction Echinococcosis is an endemic zoonosis. It is a major human and veterinary health concern. It is caused by infestation with the larval stage of organisms belonging to genus Echinococcus.Four species of the genus Echinococcus are known to be pathogenic to humans. E. Granulosus causing Cystic Hydatid Disease, E. Multilocularis causing Alveolar Hydatid Disease, E. Vogeli and E. Oligarthus cause a disease with a Polycystic pattern which affects various organs ( 1,2 ) Alveolar Echinococcosis( AE ) is amongst the most dangerous zoonoses known and has been referred to as„Neglected Malignant Parasitic Disease‟.It stands one among the 17 neglected tropical diseases prioritized by the WHO. Transmission of AE to humans is by consumption of parasite eggs excreted withfaeces of definitive hosts. The result of infestation by EM is a disease with a long latentperiod, finally culminating into a chronic debilitating disease with a fatal outcome if not treated timely and aggressively (3) . Liver is the most common organ involved. The disease can disseminate to other organs like lungs and long bones ( 4,5 ) . Unlike Cystic Echinococcosis which is present globally throughout all continents, AE is geographically confined to the northern hemisphere, but within that range it has a very wide distribution ( 6 ) . Globalization and urbanization resulting in major population shifts has made it mandatory for allhealth care providers to have knowledge and understanding about this disease. The disease is now increasingly being reported from previously unaffected areas. Associated morbidity, treatment related costs and DALY‟s are quite high. Human Hepatic Alveolar Echinococcosis Of Liver ;How Rare Is Rare ?.. DOI: 10.9790/0853-1711102939 www.iosrjournals.org 30 | Page II. Cases : CASE 1 :Fig 1,2 A 50 year old femalewas referred to our clinic with complaints of pain upper abdomen and post prandial fullness. AFP, CEA and CA19-9 levels were normal. ELISA for hydatid was positive. USG showed aheterogenous lesion in left lobe of liver. CT correlation revealed a hypo-dense lesion in left lobe of liver with extension into segment 5 of right lobe. The lesion had few foci of calcifications also.Left lobe IHBR were dialated and left branch of portal vein was not visualized. The patient underwent lefthepatectomy with excision of segment 5 lesions and CBD exploration + Ttube drainage ( for a dialated CBD ). Intra-operatively a hard mass of 10x12cm was found replacing the whole left lobe. Post-operative course was uneventful. Final histo-pathology report confirmed the diagnosis of AE. The patient was put on Albendazole + Praziquentel, has completed 16 months of follow up and is currently symptom free with no recurrence. CASE 2 : Fig 3,4 A 21 year old female was referred to our hospital with complaints of a dull ache in upper abdomen since last few weeks. Abdominal examination revealed hepatomegaly. Pre-operative investigations werenormal. USG revealed a 15x15 cm thick walled cystic lesion in right lobe of liver. CT correlation showed a 22x16x15 cm mass in right lobe of liver. Multiple calcific foci were seen within the lesion. She underwent a right hepatectomy. Intra-operatively whole of right lobe was replaced by the cystic lesion. There was compensatory hypertrophy of left lobe of the liver. The cyst was adherent to IVC and perihilar area. Post operatively the patient had persistent biliary leakage from the drain site for which she underwent catheter placement under radiological guidance. The bile leak persisted beyond 4 weeks and she subsequently underwent ERCP +papillotomy and placement of a plastic biliary stent. She was put on combination chemotherapy of Albendazole and Praziquantel. She is now 13 months post surgery, is under regular follow up, has gained weight and is symptom free. CASE 3 : Fig 5,6 A 75 year old female was referred to our clinic with complaints of pain upper abdomen since past few months. Physical examination was normal. Pre-operative LFT, KFT, hemogram and Tumor markers ( CEA,AFP AND CA19-9 )were within normal limits. CECT abdomen revealed two large heterogenous lesions, one in segments 4 and 5 and another lesion in segments 7 and 8. These lesions had irregular calcific foci with complex solid areas interspersed with areas of cystic degeneration. The reporting radiologist gave an impression of Intra hepatic cholangio-carcinoma vs a mesenchymal hepatic tumor. In view of a discordant diagnosis, a preoperative biopsy was done which was suggestive of AE. The patient was put on combination chemotherapy of Albendazole and Praziquantel. She is under our regular follow up. The lesion has remained stable for the past 8 months. CASE 4 : A 37 year old female, a known case of primary hypo-thyroidism was referred to our clinic with chief complaints of pain upper abdomen, and decreased appetite. Her past history was significant for pulmonary tuberculosis for which she had received full course of anti tubercular therapy. Physcial examination was normal. Tumor markers were not elevated. ELISA for hydatid was positive. USG showed a heterogenous lesion in segments 6 and 7. CT correlation revealed a heterogenous lesion with alternating cystic and solid areas. The lesion had no foci of calcifications. She underwent open excision of the lesion and the final histopathology report revealed it to be a AE lesion. She is currently on two drug chemotherapy of Albendazole and Praziquental. She has completed 10 months of follow and is symptom free with no recurrence. III. Discussion : 3.1 :NATURAL HABITAT, LIFE CYCLE AND GEOGRAPHIC DISTRIBUTION Echinococcus Multilocularis( EM ) is mainly confined to northern hemisphere. The belt stretches from Tundra zone in the north and extends southwards upto 40-45 degrees of latitude ( 7 ) . It has been reported from central Europe (Switzerland, Eastern France, West Austria, South Germany)and adjoining parts of Russia and Balkan states (Siberia, Azerbaijan, Turkey). The disease has also been reported from Central Asia (Northern Iran, Afghanistan, Northern IndiaKashmir valley). North-west Canada, Alaska and North Japan has also reported many cases. China is emerging as a new endemic focus with a large numbers of reported human cases. In many areas in China > 5% of human population has been reported to be infected with AE ( 8,9 ) . Such areas not only Human Hepatic Alveolar Echinococcosis Of Liver ;How Rare Is Rare ?.. DOI: 10.9790/0853-1711102939 www.iosrjournals.org 31 | Page have a high infestation rate in humans, but the dog population is also highly infected by the adult worm ( 10 ) . Presence of EM in the dog population may represent a quiescent stage of an increased transmission to humans. It has been warned that a major epidemic of EM may just be around the corner. With wide variability in the quality of the data collected, and with no standardization of data collection, it is not surprising for the incidence of AE to be under-reported across all endemic countries. All Echinococci species require two hosts for completion of their life cycle. Carnivores are the definitive hosts they harbor the mature adult tapeworm and the reproduction is sexual in them. Meta-cestodes develop in liver and other organs of intermediate hosts and are then consumed by definite hosts for completion of life cycle. Humans are accidental, dead end intermediate hosts and do not complete the life cycle of EM. Contrary to EG, EM is predominantly seen with a wild life cycle. For EM,carnivores like wolf, fox, coyotes and red foxesare the definitive hosts. Rodents like vole, lemming and muskrat serve as intermediate hosts. Dogs and cats can also become infected as definitive hosts, but their infection rates are low ( 11 ) .Increasing fox populations in Europe are correlated with the greater numbers of cases of AE ( 12 ) . Eggs excreted by definitive hosts are consumed by intermediate hosts. A second larval stage begin and a meta-cestode containing proto-scoleces develops in the gut of the host. 
 The metacestode 
 is a fluid filled vesicle-like organism with an outer a-cellular laminar membrane and an inner cellular germinal layer. The inner germinal layermay give rise to brood capsules by asexual budding (also called daughter cysts). Proto-scoleces arise from the inner walls of the brood capsules. There may be thousands of proto-scoleces within an aggregation of EMvesicles. Each single proto-scolex h