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Table 1 Epidemiologic aspects, route for transmission, and methods used for the definitive diagnosis of the parasitic diseases

From: Parasitic diseases as a cause of acute abdominal pain: imaging findings




Geographic distribution

1 Hosts/vectors

2 Transmission

Final diagnosis (routinely used method)

Cystic echinococcosis(c) [3,4,5,6]

E. granulosus(a)


High prevalence in Mediterranean regions, southern and central parts of Russia, central Asia, China, Australia, South America and Africa

1 Definitive hosts (dogs and foxes)

Intermediate hosts (sheep and human)

2 Ingestion of eggs

- Imaging based (primarily ultrasound findings)

- Serologic assay

- Aspiration of cyst content during imaging guided intervention

E. multilocularis


Asia, Central Europe and the northern parts of Europe, and North America

E. oligarthrus

Very rare, 106 human cases

Central and South America

E. vogeli

Fascioliasis(c) [3, 7]

F. hepatica(a)


Worldwide, high prevalence in Europe and America

1 Intermediate hosts (Freshwater snails)

Definitive hosts (herbivorous mammals, including humans)

2 Ingestion of watercress or contaminated water containing encysted larva

- Stool examination

- Serologic assay

F. gigantica

Tropical areas of Asia and Africa

Ascariasis(c) [3, 8]

Ascaris lumbricoides


Asia, Africa, and South America

1 No intermediate host

Humans are the only definitive hosts

2 Ingestion of fecally contaminated food

Stool examination

Toxocariasis(c) [9]

T. canis(a)



1 Intermediate hosts (rabbit, lamb, fowl)

Definitive hosts (domestic dogs and cats). Humans are accidentally infected intermediate hosts

2 Ingestion of eggs from contaminated foods

Serologic assay

T. cati

Intestinal taeniasis(c) [10,11,12]

T. saginata


Sub-Saharan Africa and the Middle East, Eastern Europe, the Philippines, and Latin America

1 Intermediate hosts (pigs for T. solium, cattle for T. saginata)

Definitive hosts (Humans are the only definitive hosts)

2 Ingestion of larvae for taeniasis and ingestion of eggs for cysticercosis

Stool examination

T. solium

Worldwide; especially in Mexico, Latin America, West Africa, Russia, India, Manchuria, and Southeast Asia

T. asiatica

Taiwan, Korea, Indonesia, Nepal, Thailand and China

Amoebiasis(c) [13]

E. histolytica(b)


Worldwide. Endemic in developing parts of Central and South America, Africa, and Asia

1 Humans are the principal host and reservoir

2 Ingestion of the cyst from fecally contaminated food or water

- Stool examination

- The real-time PCR (to identify E. histolytica)

E. dispar(a)

E. moshkovskii

Malaria(c) [14, 15]

P. falciparum(b)


Tropical Africa, South America, South-eastern Asia, and Western Pacific

1 Vectors (Anopheles mosquitos)

2 Transmitted by infected female mosquitoes’ bites

Microscopic examination of blood

P. vivax

P. ovale

P. malariae

P. knowlesi

Visceral leishmaniasis(c) [16]


200,000–400,000/per year

Northeast of the Indian subcontinent, East Africa

1 Vectors (Phlebotomus sandflies)

2 Transmitted by infected Phlebotomus sandflies’ bites

- Bone marrow sampling

- Serological examination

Leishmania infantum

Mediterranean region, Latin America

Dientamoebiasis(c) [17]

Dientamoeba fragilis



1 Humans are the principal host

2 Fecal-oral (hypothetical transmission via Enterobius vermicularis eggs)

Stool examination

Anisakiasis(c) [18]

Anisakis simple

3/1,000,000 in Japan

Japan, Korea, Latin America, and Europe (Scandinavia, The Netherlands, Spain, France, Britain). Over 90% of cases are from Japan

1 Intermediate hosts (different species of crustaceans, fish, or squid)

Definitive hosts big sea mammals (whales, dolphins, or seals)

Humans are accidentally infected intermediate hosts

2 Ingestion of raw or undercooked fish containing larvae of the anisakis worm

Endoscopy, histopathological examination

  1. aMost common
  2. bMore severe clinical presentation
  3. cReferences