ABSTRACT

TABLE 3 Composition of the human parasite fauna by taxonomic group and zoonotic status

Taxonomic group Zoonotic status

1 2 3 4 1-4

Protozoa 23 30 20 10 83 Trematoda 29 93 5 3 130 Cestoda 12 36 2 4 54 Nematoda 52 40 8 14 114 Acanthocephala 3 4 0 0 7 Arthropoda 20 20 3 6 49 Any 139 223 36 38 437

The breakdown according to ‘status’ and ‘zoonotic status’ (Table 4) illustrates the large proportion of our parasites that are both purely zoonotic, and scarce or rare. Of the 437, no fewer than 362 (83%) are zoonotic (Zoo stat=l or 2) and of these

only 45 are classified as ‘common’, even in restricted areas (i.e. with an abundance status of at least 3). By contrast, all but six of the 75 anthroponotic or shared forms (Zoo stat=3 or 4) (17% of the total), are common at least in restricted areas. Of these 75 forms that apparently can be maintained indefinitely in humans, 38 are shared with other maintenance hosts (Zoo stat=3), leaving just 37 forms (8% of the total), which appear to depend on man alone (Zoo stat=4). The unique status of Toxoplasma gondii, being both abundant worldwide and purely zoonotic (manman transmission is restricted to a single generation), is highlighted by Table 4.