Trematodes (Flukes) Trematodes (Flukes) and Cestodesand CestodesJose A. Serpa, M.D.Jose A. Serpa, M.D.

Assistant ProfessorAssistant Professor

Baylor College of MedicineBaylor College of Medicine

ReferencesReferencesThe Travel and Tropical Medicine Manual by Elaine Jong and The Travel and Tropical Medicine Manual by Elaine Jong and Christopher Sandford. Fourth Edition, 2008Christopher Sandford. Fourth Edition, 2008

Principles and Practices of Infectious Diseases. Mandel, Bennett Principles and Practices of Infectious Diseases. Mandel, Bennett and Dolin. Sixth Edition, 2005and Dolin. Sixth Edition, 2005

DPDx. Laboratory Identification of Parasites of Public Health DPDx. Laboratory Identification of Parasites of Public Health Concern (CDC). Second Edition, 2006.Concern (CDC). Second Edition, 2006.

Special thanks to Dr. A.C. White Jr. for allowing me to use some of Special thanks to Dr. A.C. White Jr. for allowing me to use some of his slideshis slides

AgendaAgenda

1.1. Trematodes (flukes): definition and Trematodes (flukes): definition and classificationclassification

2.2. Schistosomes, liver flukes and lung flukesSchistosomes, liver flukes and lung flukes

3.3. Cestodes: Intestinal tapewormsCestodes: Intestinal tapeworms

4.4. Cestodes: Tissue (cyst) stage (cysticercosis Cestodes: Tissue (cyst) stage (cysticercosis and ecchinococcosis)and ecchinococcosis)

Cayetano Heredia National Hospital and Institute of Tropical Medicine Alexander von Humboldt,

Lima , Peru

1. Trematodes1. Trematodes

TrematodesTrematodesThe flukes, or trematodes, are The flukes, or trematodes, are leaf-shaped parasites with a blind leaf-shaped parasites with a blind bifurcate intestinal tractbifurcate intestinal tract

Size varies from 1 mm to more Size varies from 1 mm to more than 10cmthan 10cm

Most are hermaphroditic, except Most are hermaphroditic, except schistosomesschistosomes

ClassificationClassification

1.1. Blood flukes (Schistosomes)Blood flukes (Schistosomes)

2.2. Hepatobiliary (Clonorchis sinensis, Opistorchis Hepatobiliary (Clonorchis sinensis, Opistorchis spp. and Fasciola hepatica)spp. and Fasciola hepatica)

3.3. Lung flukes (Paragonimus)Lung flukes (Paragonimus)

4.4. Intestinal flukes (Metagonymus, Heterophyes, Intestinal flukes (Metagonymus, Heterophyes, Fasciolopsis)Fasciolopsis)

Eggs of trematodesEggs of trematodes

From DPDx, website for laboratory diagnosis of parasitic diseases of the Division of Parasitic Diseases, National Centers for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, [http://www.dpd.cdc.gov/DPDx/].

2. A. Schistosomiasis2. A. Schistosomiasis

SchistosomiasisSchistosomiasis

Trematode infection caused by “blood flukes” Trematode infection caused by “blood flukes” which live in venules of the gastrointestinal and which live in venules of the gastrointestinal and genitourinary tractgenitourinary tract

There are approximately 200 million persons There are approximately 200 million persons infected in the world (120 million are infected in the world (120 million are symptomatic and 100 000 die each year)symptomatic and 100 000 die each year)

It affects 74 countries (80% of cases occur in It affects 74 countries (80% of cases occur in Sub-Saharan Africa)Sub-Saharan Africa)

Human Schistosomes and their Human Schistosomes and their geographic distribution geographic distribution

S. mansoni: S. mansoni: AfricaAfrica, , Brazil, Middle East, Brazil, Middle East, CaribeanCaribean

S. haematobium: S. haematobium: AfricaAfrica, , Middle EastMiddle East

S. japonicum: China, S. japonicum: China, Phillipines, SE AsiaPhillipines, SE Asia

S. mekongi: Laos, S. mekongi: Laos, CambodiaCambodia

S. intercalatum: Central S. intercalatum: Central Africa (less common)Africa (less common)

Life cycleLife cycleCercariae penetrate human skin during Cercariae penetrate human skin during contact or immersion in fresh water contact or immersion in fresh water inhabited by infected snailsinhabited by infected snails

Cercariae transform into Cercariae transform into schistosomulae , go into bloodstream and schistosomulae , go into bloodstream and then migrate to liver and lung where they then migrate to liver and lung where they mature (4-6 weeks)mature (4-6 weeks)

Adult male and female pair and migrate to Adult male and female pair and migrate to the Sup Mes vein (S. japonicum and S. the Sup Mes vein (S. japonicum and S. mekongi), Inf Mesenteric vein (S. mekongi), Inf Mesenteric vein (S. mansoni) or venous plexus sorrounding mansoni) or venous plexus sorrounding the bladder (S. hematobium)the bladder (S. hematobium)

Eggs are excreted in feces or urine and Eggs are excreted in feces or urine and deposited in fresh water. They hatch, deposited in fresh water. They hatch, miracidia emerge and infect snails of miracidia emerge and infect snails of certain species. Cercariae emerge from certain species. Cercariae emerge from infected snailsinfected snails

Clinical syndromesClinical syndromes

AsymptomaticAsymptomatic

Schistosome (cercarial) dermatitisSchistosome (cercarial) dermatitis

Acute SchistosomiasisAcute Schistosomiasis

Chronic SchistomiasisChronic Schistomiasis

Schistosome dermatitisSchistosome dermatitis

It is due to skin It is due to skin penetration of cercaria penetration of cercaria

Pruritic maculopapular Pruritic maculopapular rashrash

It can last from hours It can last from hours (first time exposed) to (first time exposed) to days (previously days (previously sensitized)sensitized)

Acute Schistosomiasis (Katayama Acute Schistosomiasis (Katayama fever)fever)

Occurs at the time of initial parasite egg-laying Occurs at the time of initial parasite egg-laying (hypersensitivity to egg- associated Ags) about 2-8 (hypersensitivity to egg- associated Ags) about 2-8 weeks after infectionweeks after infection

Consists of fever, rash/urticaria, cough, abdominal pain, Consists of fever, rash/urticaria, cough, abdominal pain, diarrhea, hepatosplenomegaly and eosinophiliadiarrhea, hepatosplenomegaly and eosinophilia

Usually in persons from non-endemic areasUsually in persons from non-endemic areas

More common with S. mansoni and S. haematobiumMore common with S. mansoni and S. haematobium

Chronic SchistosomiasisChronic Schistosomiasis

Intermittent dysentery and bowel Intermittent dysentery and bowel obstructionobstruction

Hepatosplenic diseaseHepatosplenic disease

Urinary tract diseaseUrinary tract disease

Less common: Lung or CNS diseaseLess common: Lung or CNS disease

Hepatosplenic Hepatosplenic schistosomiasisschistosomiasis

Occurs in S. mansoni , S. japonicum Occurs in S. mansoni , S. japonicum and S. mekongiand S. mekongi

Pathogenesis: granulomas around Pathogenesis: granulomas around embolized eggs that become trapped embolized eggs that become trapped in small portal veins (liver)in small portal veins (liver)

Initial stage: hepatomegalyInitial stage: hepatomegaly

Later stages: Periportal fibrosis Later stages: Periportal fibrosis blocks portal blood flow which leads to blocks portal blood flow which leads to portal hypertension (splenic portal hypertension (splenic congestion, ascites and esophageal congestion, ascites and esophageal bleed)bleed)

HBV or HCV coinfection worsens HBV or HCV coinfection worsens prognosisprognosis

Urinary tract diseaseUrinary tract diseaseOccurs in S. haematobium infectionsPassage of eggs through the bladder wall cause hematuria and dysuria (inflammation and ulcerations)Granulomatous lesions with subsequent fibrosis of the bladder wall cause urinary reflux and obstruction (hydroureter, hydronephrosis, chronic bacteriuria, renal failure and squamous carcinoma of bladder)

Lung and CNS schistosomiasisLung and CNS schistosomiasis

Eosinophilic pneumonitis results when eggs reaching the Eosinophilic pneumonitis results when eggs reaching the general circulation are trapped in the alveolar capillariesgeneral circulation are trapped in the alveolar capillaries

Aberrant migration of adult worms or embolization of Aberrant migration of adult worms or embolization of eggs to the spinal cord or brain can cause transverse eggs to the spinal cord or brain can cause transverse myelitis (S. mansoni or S. haematobium) or seizures (S. myelitis (S. mansoni or S. haematobium) or seizures (S. japonicum) respectivelyjaponicum) respectively

Keep in mind…Keep in mind…

Acute infection of humans with avian species of Schistosomes can Acute infection of humans with avian species of Schistosomes can result in an allergic skin reaction called swimmer’s itch (can not result in an allergic skin reaction called swimmer’s itch (can not mature in the human host and die in the skin). NO need of mature in the human host and die in the skin). NO need of antiparasitic therapyantiparasitic therapy

Pathogenic adult Schistosoma can persist in the human host for Pathogenic adult Schistosoma can persist in the human host for decades so infections can present in non endemic areas among decades so infections can present in non endemic areas among immigrants from endemic regionsimmigrants from endemic regions

An interesting associationAn interesting association

Prolonged and recurrent Salmonella bacteremia and/or Prolonged and recurrent Salmonella bacteremia and/or bacteriuria has been reported in patients chronically bacteriuria has been reported in patients chronically infected with schistosomiasisinfected with schistosomiasis

DiagnosisDiagnosis

Persons with a history of freshwater exposure in Persons with a history of freshwater exposure in endemic areas (even if eosinophilia is absent)endemic areas (even if eosinophilia is absent)

Identification of eggs in stool or urine samples Identification of eggs in stool or urine samples

Identification of eggs in tissues (e.g. rectal or Identification of eggs in tissues (e.g. rectal or bladder mucosa)bladder mucosa)

Serologic tests (CDC): FAST-ELISA (99% Serologic tests (CDC): FAST-ELISA (99% sensitive) and immunoblot (species-specific) sensitive) and immunoblot (species-specific)

Imaging studies (US, CT, MRI) as clinically Imaging studies (US, CT, MRI) as clinically indicated indicated

Schistosoma eggsSchistosoma eggs

Schistosoma eggs in tissuesSchistosoma eggs in tissues

TreatmentTreatment

Praziquantel is the drug of choicePraziquantel is the drug of choice

Dosing: 40mg/kg in 2 divided doses on a single Dosing: 40mg/kg in 2 divided doses on a single day (S. mansoni and S. haematobium) or day (S. mansoni and S. haematobium) or 60mg/kg in 3 divided doses 4-6h apart on a 60mg/kg in 3 divided doses 4-6h apart on a single day (S. Japonicum)single day (S. Japonicum)

Artemisinins (e.g. artemether) has Artemisinins (e.g. artemether) has antischistosomal as well as antimalarial activityantischistosomal as well as antimalarial activity

Steroids can be used along with praziquantel for Steroids can be used along with praziquantel for Katayama fever or CNS diseaseKatayama fever or CNS disease

Prevention and control of Prevention and control of SchistosomiasisSchistosomiasis

Avoid contact with fresh water in endemic areasAvoid contact with fresh water in endemic areas

Annual mass drug administration of praziquantel Annual mass drug administration of praziquantel

Environmental measures to control the snails Environmental measures to control the snails and promote sanitary disposal of human and promote sanitary disposal of human excrement (cost beyond the reach of poor excrement (cost beyond the reach of poor countries)countries)

2. B. Liver flukes2. B. Liver flukes

Liver flukesLiver flukes

They include: They include:

1.1.Clonorchis sinensisClonorchis sinensis

2.2.Opisthorchis sp. Opisthorchis sp.

3.3.Fasciola hepaticaFasciola hepatica

Clonorchis and OpisthorchisClonorchis and Opisthorchis

Largely found in the Far East, Largely found in the Far East, Southeast Asia and RussiaSoutheast Asia and Russia

The hermaphroditic adult The hermaphroditic adult worms measure 5 to 25mm x worms measure 5 to 25mm x 2 to 5mm and inhabit the 2 to 5mm and inhabit the intrahepatic biliary ductsintrahepatic biliary ducts

Humans become infected by Humans become infected by eating raw or inadequately eating raw or inadequately cooked fishcooked fish

Life cycleLife cycle

Clinical syndromesClinical syndromes

Asymptomatic eosinophiliaAsymptomatic eosinophilia

RUQ abdominal pain with jaundiceRUQ abdominal pain with jaundice

Acute biliary obstructionAcute biliary obstruction

Acute pancreatitisAcute pancreatitis

Recurrent pyogenic cholangitisRecurrent pyogenic cholangitis

CholangiocarcinomaCholangiocarcinoma

Diagnosis and Treatment Diagnosis and Treatment Based on identification of Based on identification of eggs in the stool or adult eggs in the stool or adult worms during surgery or worms during surgery or ERCPERCP

Imaging studies (US, CT Imaging studies (US, CT or MRI) can demonstrate or MRI) can demonstrate biliary dilationbiliary dilation

Praziquantel is the drug Praziquantel is the drug of choice (75mg/kg in 3 of choice (75mg/kg in 3 divided doses 4-6h divided doses 4-6h apart). apart).

Surgery or ERCP for Surgery or ERCP for acute biliary obstructionacute biliary obstruction

Fasciola hepaticaFasciola hepaticaLarge liver fluke (adult worm Large liver fluke (adult worm measures 3.0 x 1.5 cm) that measures 3.0 x 1.5 cm) that lives in the bile ducts of its lives in the bile ducts of its mammalian hosts (humans, mammalian hosts (humans, sheep and cattle)sheep and cattle)

Reported in 61 countries from Reported in 61 countries from Europe, North Africa, Asia and Europe, North Africa, Asia and South America (Bolivia and South America (Bolivia and Peru) Peru)

More than 3 million cases in More than 3 million cases in the world the world

TransmissionTransmissionParasite eggs passed in stools Parasite eggs passed in stools hatch into miracidia which hatch into miracidia which infects fresh water snails. infects fresh water snails. Cercaria emerge from snails and Cercaria emerge from snails and attach to aquatic plants (encyst attach to aquatic plants (encyst as metacercaria) as metacercaria)

Humans ingest contaminated Humans ingest contaminated aquatic plants (e.g. water cress)aquatic plants (e.g. water cress)

Metacercaria excyst, penetrate Metacercaria excyst, penetrate the intestinal wall, enter the the intestinal wall, enter the peritoneum, and then pass peritoneum, and then pass through the liver capsule to the through the liver capsule to the biliary tract biliary tract

Clinical syndromesClinical syndromes

1.1. Acute phaseAcute phase Associated with parasite migration (duodenum – Associated with parasite migration (duodenum –

peritoneal cavity – liver) and burrowing through the liverperitoneal cavity – liver) and burrowing through the liver Causes fever, abdominal pain, hepatomegaly and Causes fever, abdominal pain, hepatomegaly and

eosinophiliaeosinophilia

2. Chronic phase2. Chronic phase Due to biliary involvementDue to biliary involvement Intermittent “biliary colic”, cholangitisIntermittent “biliary colic”, cholangitis

Diagnosis and managementDiagnosis and management

Serology for acute phaseSerology for acute phase

Demonstration of eggs in stools, bile or Demonstration of eggs in stools, bile or duodenal aspiratesduodenal aspirates

Imaging studies (US, CT) show linear Imaging studies (US, CT) show linear hepatic tractshepatic tracts

Treatment is with triclabendazole Treatment is with triclabendazole (10mg/kg once or twice). Also bithionol, (10mg/kg once or twice). Also bithionol, nitazoxanide.nitazoxanide.

2. C. Lung flukes2. C. Lung flukes

Lung flukesLung flukesMost important species: Most important species:

Paragonimus westermani, P. Paragonimus westermani, P. heterotremus, P. skrjabini, P. heterotremus, P. skrjabini, P. miyazakii (Asia),miyazakii (Asia), P. africanus, P P. africanus, P uterobilateralis (Africa), P. uterobilateralis (Africa), P. mexicana, P ecuadoriensis (South mexicana, P ecuadoriensis (South and Central America)and Central America)

Cases reported from Asia, Africa Cases reported from Asia, Africa and Central and South Americaand Central and South America

Life cycleLife cycle

Adult worms lay eggs that are Adult worms lay eggs that are coughed up in the sputum or coughed up in the sputum or swallow and passed in the swallow and passed in the stoolsstools

Eggs hatch in freshwater and Eggs hatch in freshwater and develop into miracidia that develop into miracidia that infects snails (cercaria)infects snails (cercaria)

Cercaria infects freshwater Cercaria infects freshwater crustaceans (metacercaria)crustaceans (metacercaria)

Humans are infected when Humans are infected when eating raw or inadequately eating raw or inadequately cooked crabs or crayfishcooked crabs or crayfish

Metacercaria excyst in the Metacercaria excyst in the duodenum duodenum peritoneum peritoneum diaphragm diaphragm pleura pleura lung lung

Clinical manifestationsClinical manifestations

Pulmonary paragonimiasisPulmonary paragonimiasis

Extrapulmonary paragonimiasisExtrapulmonary paragonimiasis

Pulmonary paragonimiasisPulmonary paragonimiasis

Resembles pulmonary tuberculosisResembles pulmonary tuberculosis

Initial stages: cough productive of brownish Initial stages: cough productive of brownish sputum with intermittent hemoptysissputum with intermittent hemoptysis

Chronic stages: profuse expectoration, dyspnea, Chronic stages: profuse expectoration, dyspnea, hemoptysis, pleural effusions and pneumothoraxhemoptysis, pleural effusions and pneumothorax

CRX: infiltrates, cavities, cysts, nodules, pleural CRX: infiltrates, cavities, cysts, nodules, pleural effusions effusions

Extrapulmonary paragonimiasisExtrapulmonary paragonimiasis

Ectopic migration of eggs from the bowelEctopic migration of eggs from the bowel

Most common: CNS, skin, liver, peritoneumMost common: CNS, skin, liver, peritoneum

CNS: brain lesions (seizures, headaches, visual CNS: brain lesions (seizures, headaches, visual disturbances), meningitisdisturbances), meningitis

Skin: Migratory lesions (resemble cutaneous Skin: Migratory lesions (resemble cutaneous larva migrans)larva migrans)

Diagnosis and treatmentDiagnosis and treatment

Identification of eggs in stools or sputumIdentification of eggs in stools or sputum

Gram or AFB stain in sputum may destroy eggsGram or AFB stain in sputum may destroy eggs

Serology: Immunoblot from CDC (Sen: 96%, Sp: Serology: Immunoblot from CDC (Sen: 96%, Sp: 100%)100%)

Drug of choice is praziquantel (75mg/kg/day Drug of choice is praziquantel (75mg/kg/day divided in 3 doses for 2 days)divided in 3 doses for 2 days)

Adult flukesAdult flukes

3. A. 3. A. CestodesCestodesIntestinal tapewormsIntestinal tapeworms

Tapeworms (adult stage)Tapeworms (adult stage)

Tapeworms are segmented flat worms that have a head or Tapeworms are segmented flat worms that have a head or scolexscolex (which attaches to the intestine) and rhomboid-shaped segments (which attaches to the intestine) and rhomboid-shaped segments termed termed proglottidsproglottids

The tapeworms elongates from each scolex by forming proglottids The tapeworms elongates from each scolex by forming proglottids (which contain male and female reproductive organs). Adult (which contain male and female reproductive organs). Adult tapeworms may reach lengths of 4.5 – 10mtapeworms may reach lengths of 4.5 – 10m

Clinically important tapewormsClinically important tapeworms

Tapeworm Common name Transmission

Taenia solium Pork tapeworm Ingesting meat (pork) containing larvae

Taenia saginata Beef tapeworm Ingesting meat (beef) containing larvae

Dyphilobotrium sp. Fish tapeworm Ingesting fish containing larvae

Hymenolepis sp. Dwarf tapeworm Accidental ingestion of fecal material (containing eggs)

Dipyllidium caninum Dog tapeworm Accidental ingestion of dog fleas

Life cycle: generalitiesLife cycle: generalities

The proglottids (containing eggs) shed periodically in the fecesThe proglottids (containing eggs) shed periodically in the feces

Eggs are ingested by an intermediate host - cow, pig, fish. Then the Eggs are ingested by an intermediate host - cow, pig, fish. Then the eggs hatch and larvae emerge, penetrate the gut and migrate to the eggs hatch and larvae emerge, penetrate the gut and migrate to the tissues (especially the muscle) tissues (especially the muscle)

The lifecycle is completed when humans ingest encysted larvae-The lifecycle is completed when humans ingest encysted larvae-containing meatcontaining meat

EpidemiologyEpidemiology

– T. soliumT. solium is prevalent worldwide (60 million) but rare in US except in is prevalent worldwide (60 million) but rare in US except in immigrants from endemic areas of Latin America and Asiaimmigrants from endemic areas of Latin America and Asia

– T. saginataT. saginata is found worldwide (60 million), especially in Africa and Latin is found worldwide (60 million), especially in Africa and Latin America. In the US, it is seen among people who eat raw or America. In the US, it is seen among people who eat raw or undercooked beef (e.g. steak tartare)undercooked beef (e.g. steak tartare)

– D. latumD. latum is prevalent worldwide (10 million) particularly among people is prevalent worldwide (10 million) particularly among people who ingest raw, pickled, or marinated fish. who ingest raw, pickled, or marinated fish. D. latum D. latum in the US has been in the US has been associated with sushi and sashimi made of raw pacific salmon and associated with sushi and sashimi made of raw pacific salmon and some Scandinavian pickled fish dishes (carp, herring, smelt)some Scandinavian pickled fish dishes (carp, herring, smelt)

– H. nana H. nana and and H. diminutaH. diminuta(dwarf, 2cm long) is prevalent worldwide (30 (dwarf, 2cm long) is prevalent worldwide (30 million) especially in children. Because of person to person spread, million) especially in children. Because of person to person spread, nurseries and day-care facilities are sites of transmissionnurseries and day-care facilities are sites of transmission

Life cycle of DyphillobotriumLife cycle of Dyphillobotrium

Life cycle of HymenolepisLife cycle of Hymenolepis

Life cycle of DipylidiumLife cycle of Dipylidium

Clinical manifestationsClinical manifestations

Most infections are asymptomatic or with Most infections are asymptomatic or with minor abdominal symptoms. minor abdominal symptoms.

Patients may complain of passing wormsPatients may complain of passing worms

D. latumD. latum can compete for absorption of can compete for absorption of vitamin B12 causing B12 deficiency.vitamin B12 causing B12 deficiency.

Diagnosis and treatmentDiagnosis and treatment

Eggs can be identified in the stools, but Eggs can be identified in the stools, but this may require repeated examinationsthis may require repeated examinations

The eggs of The eggs of T. saginataT. saginata and and T. soliumT. solium indistinguishableindistinguishable

Gravid proglottids or the scolex can be Gravid proglottids or the scolex can be examined to tell the species apartexamined to tell the species apart

Treatment is praziquantelTreatment is praziquantel

Tapeworm eggsTapeworm eggs

TapewormsTapeworms

3. B.3. B. CestodesCestodesTissue cysts (larval stage)Tissue cysts (larval stage)

CysticercosisCysticercosis

It is a tissue infection (e.g. subcutaneous tissues, brain, eye, muscle, heart, It is a tissue infection (e.g. subcutaneous tissues, brain, eye, muscle, heart, etc) caused by the larval stage of etc) caused by the larval stage of Taenia solium. Taenia solium.

Neurocysticercosis = cysticercosis of the nervous systemNeurocysticercosis = cysticercosis of the nervous system

Cysticercosis is prevalent in Latin America, Sub-Saharan Africa, India, Cysticercosis is prevalent in Latin America, Sub-Saharan Africa, India, China and Southeast AsiaChina and Southeast Asia

– Serosurveys in endemic areas: up to 10% infection rates. Studies from Serosurveys in endemic areas: up to 10% infection rates. Studies from India, Mexico, Peru, and Ecuador documented that up to half of patients with India, Mexico, Peru, and Ecuador documented that up to half of patients with adult onset seizures had evidence of neurocysticercosis by imaging studiesadult onset seizures had evidence of neurocysticercosis by imaging studies

– In the US, NCC is primarily a disease of immigrants (Hispanics from Central In the US, NCC is primarily a disease of immigrants (Hispanics from Central America). Local transmission has been documented in the setting of America). Local transmission has been documented in the setting of household tapeworm carriershousehold tapeworm carriers

Life cycle of Life cycle of Taenia soliumTaenia solium

PathophysiologyPathophysiology

There is typically an incubation period of several years before onset of There is typically an incubation period of several years before onset of clinical symptomsclinical symptoms

This quiescent phase results from the parasite’s ability to evade the host This quiescent phase results from the parasite’s ability to evade the host immune system. However as the cysticerci age, they lose this ability which immune system. However as the cysticerci age, they lose this ability which leads to an intense inflammatory reaction (causing seizures) leads to an intense inflammatory reaction (causing seizures)

Over a few months, the inflamed lesion either resolves radiographically or Over a few months, the inflamed lesion either resolves radiographically or is replaced by a small calcification is replaced by a small calcification

Cysticerci in the cerebral ventricles often cause obstructive hydrocephalus Cysticerci in the cerebral ventricles often cause obstructive hydrocephalus as a result of mechanical obstructionas a result of mechanical obstruction

Types of neurocysticercosisTypes of neurocysticercosis

Neurocysticercosis can cause a wide spectrum of clinical forms Neurocysticercosis can cause a wide spectrum of clinical forms depending on the number of parasites, their location, and the depending on the number of parasites, their location, and the degree of host inflammationdegree of host inflammation

It can be broadly divided into:It can be broadly divided into:

1.1. Parenchymal: solitary lesion, multiple lesions Parenchymal: solitary lesion, multiple lesions

2.2. Extra-parenchymal disease:Extra-parenchymal disease:a.a. Intraventricular cystsIntraventricular cysts

b.b. Subarachnoid cystsSubarachnoid cysts

c.c. Spinal cord cystsSpinal cord cysts

Parenchymal NCCParenchymal NCC

A solitary degenerating A solitary degenerating parenchymal lesion is perhaps parenchymal lesion is perhaps the most common presentation the most common presentation of neurocysticercosis of neurocysticercosis worldwideworldwide

Seizures are the main clinical Seizures are the main clinical manifestation of this type of manifestation of this type of NCC NCC

Other symptoms: headaches, Other symptoms: headaches, neurologic focal deficitsneurologic focal deficits

Extra-parenchymal NCCExtra-parenchymal NCCIntraventricularIntraventricular

Intraventricular cysts typically Intraventricular cysts typically present with increased present with increased intracranial pressure from intracranial pressure from obstructive hydrocephalusobstructive hydrocephalus

Headache, nausea, Headache, nausea, papilledema and altered papilledema and altered mental status can also be mental status can also be presentpresent

Extra-parenchymal NCCExtra-parenchymal NCCSubarachnoidSubarachnoid

Subarachnoid NCC causes a wide Subarachnoid NCC causes a wide range of symptoms. Cysts in the range of symptoms. Cysts in the fissures (especially the Sylvian fissure) fissures (especially the Sylvian fissure) can enlarge to several cm and cause can enlarge to several cm and cause mass effect mass effect

Basal subarachnoid cysticercosis Basal subarachnoid cysticercosis carries the worst prognosis since carries the worst prognosis since numerous cysticerci may fill the basilar numerous cysticerci may fill the basilar cisterns leading to arachnoiditis. This cisterns leading to arachnoiditis. This can present as meningitis, stroke or can present as meningitis, stroke or communicating hydrocephaluscommunicating hydrocephalus

Most of these patients frequently have Most of these patients frequently have concomitant ventricular and/or concomitant ventricular and/or parenchymal diseaseparenchymal disease

Calcifications: inactive lesions?Calcifications: inactive lesions?

DiagnosisDiagnosis

Imaging studies: MRI and CTImaging studies: MRI and CT

Serology: Enzyme-linked immunoelectrodifusion transfer blot (EITB) Serology: Enzyme-linked immunoelectrodifusion transfer blot (EITB) More accurate in serum than in CSF. The assay has a nearly 100% More accurate in serum than in CSF. The assay has a nearly 100% specificity and 98% sensitivity for those with multiple cysticerci. specificity and 98% sensitivity for those with multiple cysticerci. (sensitivity is only 70% in patients with a single parenchymal cyst)(sensitivity is only 70% in patients with a single parenchymal cyst)

Screening for taeniasis in patients or household contacts(?)Screening for taeniasis in patients or household contacts(?)

Diagnostic criteriaDiagnostic criteria

Absolute criteria: Histopathology, Parasites seen in eye, MRI with cyst and Absolute criteria: Histopathology, Parasites seen in eye, MRI with cyst and scolexscolexMajor criteria: CT/MRI consistent with NCC, +EITB, resolution (spontaneous Major criteria: CT/MRI consistent with NCC, +EITB, resolution (spontaneous or with ABZ/PZQ), single enhancing lesion <20 mm w/o Symptoms or signs or with ABZ/PZQ), single enhancing lesion <20 mm w/o Symptoms or signs of other diseaseof other diseaseMinor criteria: CT compatible, clinical manifestations c/w NCC, cysticercosis Minor criteria: CT compatible, clinical manifestations c/w NCC, cysticercosis outside CNS (e.g. muscle calcifications) outside CNS (e.g. muscle calcifications) Epidemiologic criteria: Household contact of tapeworm carrier, residence or Epidemiologic criteria: Household contact of tapeworm carrier, residence or prolonged travel to endemic areaprolonged travel to endemic area

1.1. Definitive diagnosis: one absolute criterion or two major plus one minor and one Definitive diagnosis: one absolute criterion or two major plus one minor and one epidemiologic criterionepidemiologic criterion

2.2. Probable diagnosis: one major plus two minor criteria, one major plus one minor plus Probable diagnosis: one major plus two minor criteria, one major plus one minor plus one epidemiologic criteria, or three minor plus one epidemiologic criteriaone epidemiologic criteria, or three minor plus one epidemiologic criteria

TreatmentTreatment

Symptomatic therapy must be the initial goal of management in Symptomatic therapy must be the initial goal of management in neurocysticercosis. (anti-epileptic medications, surgical CSF neurocysticercosis. (anti-epileptic medications, surgical CSF diversion procedures, and corticosteroids respectively)diversion procedures, and corticosteroids respectively)

Antiparasitic medications also play an important although still Antiparasitic medications also play an important although still controversial role in the treatment of NCCcontroversial role in the treatment of NCC

Surgery (VP shunts, open craniotomy and especially endoscopic Surgery (VP shunts, open craniotomy and especially endoscopic removal of cysts) also play a role in selected cases removal of cysts) also play a role in selected cases

Treatment consensusTreatment consensus

Viable or degenerating parenchymal cysts: AED, steroids, Viable or degenerating parenchymal cysts: AED, steroids, antiparasiticsantiparasitics

Intraventricular cysts: endoscopic removal of cysts or VPS followed Intraventricular cysts: endoscopic removal of cysts or VPS followed by antiparasitics and steroidsby antiparasitics and steroids

Subarachnoid: Steroids, antiparasitics (repeated courses?) +/- VPSSubarachnoid: Steroids, antiparasitics (repeated courses?) +/- VPS

Calcifications: AED (current rec’s against use of antiparasitics)Calcifications: AED (current rec’s against use of antiparasitics)

Hydatid cystHydatid cyst

It is an infection of liver and lung due to the encysted larva of the It is an infection of liver and lung due to the encysted larva of the cestode Echinococcus spp.cestode Echinococcus spp.

Two main species:Two main species:

1.1. E. granulosus:E. granulosus: Cystic hydatid disease. Endemic in sheep raising Cystic hydatid disease. Endemic in sheep raising areas of the world (e.g South America, Middle East). There are areas of the world (e.g South America, Middle East). There are small foci in the US (California, Utah and Alaska)small foci in the US (California, Utah and Alaska)

2.2. E. multilocularis:E. multilocularis: Alveolar hydatid disease. Endemic in Alaska, Alveolar hydatid disease. Endemic in Alaska, Central Europe and Northern Japan Central Europe and Northern Japan

Dogs and wild canines are the definitive hosts (adult worms in Dogs and wild canines are the definitive hosts (adult worms in intestines). Sheep and catle (intestines). Sheep and catle (E. granulosisE. granulosis) or rodents () or rodents (E. E. multilocularismultilocularis) are the intermediate hosts (hydatic disease) ) are the intermediate hosts (hydatic disease)

Life cycleLife cycle

Clinical manifestations and Clinical manifestations and diagnosisdiagnosis

Hydatid cyst disease (Hydatid cyst disease (E. granulosusE. granulosus) presents with a slowly ) presents with a slowly expanding mass lesion usually in the liver (60%) or lungs (25%). expanding mass lesion usually in the liver (60%) or lungs (25%).

The most serious complications result from cyst rupture, which can The most serious complications result from cyst rupture, which can cause anaphylaxis or numerous daughter lesions.cause anaphylaxis or numerous daughter lesions.

Alveolar hydatid disease (Alveolar hydatid disease (E. multilocularisE. multilocularis) presents with an ) presents with an expanding infiltrative process (90% in the liver). expanding infiltrative process (90% in the liver).

Diagnosis: Imaging studies (US, CT), serology (ELISA at CDC) is Diagnosis: Imaging studies (US, CT), serology (ELISA at CDC) is 83% sensitive 83% sensitive

TreatmentTreatment

In experienced centers, In experienced centers, E. granulosusE. granulosus cysts are now mainly treated cysts are now mainly treated by PAIR procedure (percutaneous aspiration, injection of scolidical by PAIR procedure (percutaneous aspiration, injection of scolidical agents, and reaspirations). agents, and reaspirations).

PAIR should be undertaken while on albendazole therapy (spilled PAIR should be undertaken while on albendazole therapy (spilled cyst fluid can spread infection to other areas such as the peritoneal cyst fluid can spread infection to other areas such as the peritoneal cavity) cavity)

Chemotherapy alone may be attempted with albendazole for small Chemotherapy alone may be attempted with albendazole for small or inoperable lesionsor inoperable lesions

Surgical removal is the treatment of choice for complicated cysts Surgical removal is the treatment of choice for complicated cysts (e.g. communication with the biliary tract) and for (e.g. communication with the biliary tract) and for E. multilocularis. E. multilocularis. Consider pre- and post-operative albendazoleConsider pre- and post-operative albendazole