How common are parasites in the world?

Estimates of current numbers of human helminth infections

Source: Journal of Parasitology 85:379-403 Dr. D.W.T. Crompton (Crompton, D.W.T. [1999] How much human helminthiasis is there in the world?)

The species shown in red are considered to be the "commonest helminths or
those judged to have [the] most general public health significance."


Helminth species Numbers
(millions) Distribution
Ancylostoma duodenale and Necator americanus 1,298.00 Worldwide; developing countries
Ascaris lumbricoides 1,472.00 Worldwide; developing countries
Brugia malayi and Brugia timori 13.00 E. Indonesia islands; Philippines; S.E. Asia; Southern China; India.
Clonorchis sinensis 7.01 China; Korea; Taiwan; Vietnam
Diphyllobothrium latum 9.00 Worldwide where certain raw fish is eaten.
Dracnunculus medinensis 0.08 Sub-Sahara Africa; Yemen
Echinococcus granulosus and Echinococcus multilocularis 2.70 Worldwide
Echinostoma spp. 0.15 Philippines; Thailand
Fasciola hepatica and Fasciola gigantica 2.40 China; Egypt; Europe; Iran; South America
Fasciolopsis buski 0.21 Bangladesh; Cambodia; China; India; Indonesia; Laos; Thailand; Vietnam.
Heterophyes heterophyes (and related species) 0.24 Egypt; Iran; Korea
Hymenolepis nana 75.00 Americas; Australia; developing countries
Loa loa 13.00 West and central Sub-Saharan Africa
Metagonimus yokogawai (and related species) 0.66 Korea; S.E. Asia.
Onchocerca volvulus 17.66 Central and South America; Sub-Saharan Africa; Yemen
Opisthorchis viverrini and Opisthorchis felineus 10.33 Kazakhastan; Laos; Thailand; Ukraine
Paragonimus westermani (and related species) 20.68 China; Laos; Korea; Ecuador; Peru
Schistosoma haematobium 113.88 Africa; E. Mediterranean region
Schistosoma intercalatum 1.73 Sub-Saharan Africa
Schistosoma japonicum 1.55 China; Western Pacific region
Schistosoma mansoni 83.31 Africa; Caribbean; E. Mediterranean region
Schistosoma mekongi 0.91 Cambodia; Laos
Strongyloides stercoralis 70.00 Worldwide (warmer countries)
Taenia saginata 77.00 Worldwide (related to beef consumption)
Taenia solium 10.00 Worldwide (related to raising pigs for pork)
Trichuris trichiura 1,049.00 Worldwide; developing countries
Wuchereria bancrofti 107.00 Asia; Central and South America; Sub-Saharan Africa; West Pacific countries

"It is estimated that pinworms infect more than 400,000,000 people throughout the world (10% of humans), and in many areas of the world (e.g., North America and Europe) it is the most common nematode parasite of humans.On a world-wide basis, however, Ascaris lumbricoides ranks #1 infecting more than 1,000,000,000 people (25% of humans).

"Ascaris Lumbricoides has a world-wide distribution and is most prevalent in tropical areas. 25% of the world population harbors the parasite. "

Ascaris lumbricoides is one of the largest and most common parasites found in humans.The adult females of this species can measure up to 18 inches long (males are generally shorter), and it is estimated that 25% of the world's population is infected with this nematode.The adult worms live in the small intestine and eggs are passed in the feces.A single female can produce up to 200,000 eggs each day!About two weeks after passage in the feces the eggs contain an infective larval or juvenile stage, and humans are infected when they ingest such infective eggs."

Fasciola hepatica is found in parts of the United States (view distribution), as well as in Great Britian, Ireland, Europe, the Middle East, the Far East, Africa, and Australia.

more info at: http://www.dreddyclinic.com/integrated_med/parasites.htm