Estimates of current numbers of human helminth (worm) 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
And to respond to the rest of your comment, you wouldn't exactly be aware that you have a parasite problem.