Supplemental visual material
(worldwide distribution maps)
Trichinella spiralis (T-1) (green) is the most common member
of the genus. The world
distribution as depicted is almost certainly an under-representation.
The isolate has
a low tolerance to freezing, but has a high reproductive potential in
swine, laboratory rats, and laboratory mice. It is the primary cause of
domestic animal trichinosis although it also occurs in sylvatic hosts.
Trichinella nativa (T-2) (yellow) is a Holarctic species with a
very high resistance to freezing. It is common in carnivores and has a
low infectivity for swine and rats. Trichinella nelsoni
(T-7) (red) is found in subsaharan Africa. It has no
tolerance to freezing, a relatively high tolerance to heat, primarily
infects Hyaenidae and Felidae, and has a low infectivity for swine and
rats. Trichinella murrelli (T-5) (green) is found in
North America. Its range probably extends down into Mexico. It has a low
tolerance to freezing, primarily
infects carnivores, and has a very low reproduction in swine and rats.
A Trichinella isolate, termed T-6 (red), is similar to
T. nativa. It, too, has a relatively high tolerance to
freezing and primarily infects carnivores. It is also capable
of interbreeding with T. nativa. Nonetheless, several molecular
differences exist between the two. Trichinella britovi
(T-3) (green) occurs in Eurasia and has been introduced into Africa. It
is common in sylvatic
carnivores, and occasionally infects domestic animals. It has a low
infectivity for rats, moderate infectivity for swine, and a moderately
good tolerance to freezing. Isolates capable of interbreeding with
T. britovi include T-9 (purple) in Japan and T-8
(yellow) from carnivores in Southern Africa. Some molecular differences
exist between these two genotypes and T. britovi. T-9 from Japan is
actually more similar to T. murrelli than to T. britovi.
Three non-encapsulating Trichinella species exist. Trichinella
pseudospiralis (T-4) (red dots) infects over a dozen species of
mammals, as well as raptors, some passeriform birds, and chickens. It has
moderate infectivity for swine,
rats, and mice. Several genetically distinct populations
are known to occur. Trichinella papuae
(T-10) (yellow) was originally isolated from a wild pig and has larvae
somewhat larger than
T. pseudospiralis. Though capable of infecting laboratory mice, it
is unable to infect chickens but can infect some reptiles. Trichinella
zimbabwensis (green) is the third known non-encapsulated species. It
known to naturally infect reptiles in Africa, but experimentally it
can also infect some mammals.
Originals. Data obtained from the following sources:
- Dick TA and Pozio E. 2001. Trichinella spp. and
Trichinellosis. In, Parasitic Diseases of Wild Mammals, Samuel WM et
al. eds. 2nd ed. Iowa State University Press, Ames, Iowa. pp. 380-396.
- Murrell KD et al. 2000. Vet Parasitol 93: 293-307
- Pozio E. 1998. Parasitol Today 14: 35-38.
- Pozio E. and La Rosa G. 2000. J Parasitol 86: 134-139.
- Pozio E. and Murrell KD. 2006. Adv. Parasitol. 63: 367-439.
- Pozio E et al. 2001. Int J Parasitol 29: 1825-1839.
- Pozio E et al. 1992. J Parasitol 78: 647-653.
- Pozio E et al. 1992. J Parasitol 78: 654-659.
- Pozio E et al. 1989. Parasitol Today 5: 169-170.
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