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Information ⬇

Editors

HeliSiikamäki
SakariJokiranta
AnuKantele

Introduction to Extra-Intestinal Helminthiasis

  • Doctors worldwide may encounter extra-intestinal (tissue) helminthiasis when working in endemic regions or when treating visitors returning from endemic regions, immigrants or patients who have resided in tropical countries.

Distribution

  • Trichinellosis Trichinellosis is a tissue nematode infection encountered in regions where pork is consumed. Lymphatic filariasis Filariases is widespread in tropical and subtropical regions. Onchocerciasis or ”river blindness” Filariases is prevalent in tropical Africa, Central and South America as well as Yemen. Loiasis Filariases is endemic in the rain forests of West and Central Africa.
  • Schistosomiasis Schistosomiasis (Bilharziasis) is the most important infection caused by trematode worms (blood flukes). It occurs predominantly in Africa, and also in the Middle East, Central and South America as well as in East and Southeast Asia. Liver flukes Liver Flukes occur in China, in Southeast Asia and globally in sheep farming areas.
  • Of tapeworm infections, echinococcosis Liver Flukes is encountered around the world in areas where cattle, camels or sheep are farmed. Cysticercosis Cysticercosis is endemic in areas where large amounts of pork are consumed, and in these areas it is the main cause of epilepsy.

Transmission

  • Human infection occurs either by mouth (the most common route), larval penetration of the skin (schistosomiasis) or through an insect bite (loiasis, onchocerciasis, lymphatic filariasis).
  • Tissue-invasive helminths cannot be transmitted from person to person. Cysticercosis, however, forms an exception as it may be transmitted by a person carrying the Taenia solium worm in his/her intestines.

Significance worldwide

  • The various forms of extra-intestinal helminthiasis are very prevalent diseases worldwide. About 240 million people are affected by schistosomiasis and it causes over 200 000 deaths annually in tropical Africa. About 120 million people are affected by filariasis.

Diagnosis

  • Tissue-invasive helminths typically cause eosinophilia and increased IgE concentrations.
  • Various methods are available for the diagnosis of a helminthic infection.
    • Detection of worm eggs or worms in the faeces (schistosomiasis, liver flukes, sometimes cysticercosis)
    • Schistosome eggs can be detected in the faeces, urine or a tissue biopsy specimen.
    • In lymphatic filariasis and in loiasis microfilariae can be found in a blood sample and in onchocerciasis in a skin biopsy specimen.
    • Antibody assays (echinococcosis, Fasciola hepatica, filariasis, cysticercosis, schistosomiasis, trichinellosis)
    • Imaging studies: A CT or MRI scan of the head may reveal cysticercosis, and an echinococcal hydatid cyst is usually seen in a CT or MRI scan, or ultrasound examination of the liver.

Prevention

  • Improvement of general hygiene, avoidance of possible vectors, meat inspection and avoidance of water contact in endemic regions.

Extra-intestinal helminthiasis

Disease and causative organismMode of transmissionSymptomsSuggestive findingsDiagnosisTreatment
Echinococcosis Echinococcosis (Echinococcus granulosus, Echinococcus multilocularis)Animal faeces-intestineUsually no symptoms, cyst-induced pressureCyst discovered as an incidental finding during imaging studies (usually in the liver), eosinophilia (not always)Imaging studies, echinococcus antibody assay (a negative antibody test does not exclude the disease)Monitoring/pharmacotherapy (albendazole1) )/ PAIR method (puncture, aspiration, injection, re-aspiration) /surgery
Cysticercosis Cysticercosis (Taenia solium)Faeces-intestineEpilepsy, other CNS symptomsEosinophilia (not always)Imaging studies, cysticercus antibody assay (a negative antibody test does not exclude the disease), biopsy if indicatedMonitoring/pharmacotherapy (albendazole1) ) + glucocorticoid)
Loiasis (Loa loa) FilariasesFly-skinUsually no symptoms. Pruritus, urticaria, transient local swelling of subcutaneous tissues, observation of the worm as it crosses the conjunctivaEosinophiliaDetection of microfilariae from a blood sample collected at midday; antibody assayPharmacotherapy
Lymphatic filariasis Filariases (Wurchereria sp. and Brugia sp.)Mosquito-skinRecurring febrile lymphangitis and lymphadenitis, usually affecting the limbs. Obstructed lymph channels and chronic oedema (elephantiasis)EosinophiliaDetection of microfilariae from a blood sample collected at midnight; antibody assayPharmacotherapy
Onchocerciasis Filariases (Onchocerca volvulus)Gnat-skinPruritus, non-tender subcutaneous nodules, chronic lymph node enlargements, ocular symptomsEosinophiliaDetection of microfilariae from subcutaneous tissue or an adult worm in a subcutaneous nodule. Detection of antibodies (significant result, if positive).Pharmacotherapy
Liver fluke diseases Liver Flukes(Fasciola hepatica, Clonorchis sinensis, Opistorchis sp.)Water plants/fish-intestineHepatomegaly, biliary symptomsEosinophiliaDetection of eggs in the faeces or bile, flukes in bile ducts. Antibody assay in Fasciola hepatica.Pharmacotherapy (Fasciola hepatica: triclabendazole1) ), other liver flukes: praziquantel1) )
Schistosomiasis Schistosomiasis (Bilharziasis) (Schistosoma sp.)Water-skinIn acute schistosomiasis fever, urticaria, asthmatic symptoms, hepatosplenomegaly, enlarged lymph nodes. In chronic schistosomiasis haematuria or intestinal symptoms.Eosinophilia, haematuriaIn acute schistosomiasis antibody assay. In chronic schistosomiasis detection of eggs in the faeces or urine, antibody assay, urinary bladder or colon biopsy.In acute schistosomiasis glucocorticoid, specific therapy praziquantel1) )
Trichinellosis Trichinellosis (Trichinella sp.)Raw meat-intestineFever, myalgiaEosinophiliaAntibody assayNo good specific therapy available, mebendazole, albendazole1) ). In acute phase NSAIDs, glucocorticoid.
1) In some countries only under special licence

Related Keywords ⬆

ATC Code:

P02CA01

P02CA03

P02BX04

Primary/Secondary Keywords