[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 11 The Trematodes
279
Developed
miracidium
Small lateral spine
(difficult to see)
A
Size range: 50-85 m by 38-60 m
B
FIGURE 11-10 A, Schistosoma japonicum egg. B, Schistosoma japonicum egg. (B from Mahon CR, Lehman DC,
Manuselis G: Textbook of diagnostic microbiology, ed 4, St Louis, 2011, Saunders.)
Large
terminal spine
Developed
miracidium
B
A Size range: 110-170 m by 38-70 m
FIGURE 11-11 A, Schistosoma haematobium egg. B, Schistosoma haematobium egg. (B from Mahon CR, Lehman DC,
Manuselis G: Textbook of diagnostic microbiology, ed 4, St Louis, 2011, Saunders.)
Epidemiology
There are a number of reservoir hosts capable
of carrying Schistosoma spp. These include
monkeys, cattle and other livestock, rodents, and
domesticated animals such as dogs and cats. The
specific geographic distribution of each of the
three Schistosoma spp. vary by species.
It is believed that S. mansoni originated in the
Old World because it is prevalent primarily in
parts of Africa. Transport of the organism to the
New World most likely occurred via the slave
trade. Known endemic areas include Puerto Rico,
the West Indies, and portions of Central and
South America.
The geographic distribution of S. japonicum
is limited to the Far East. Areas known to harbor
the parasite include parts of China, Indonesia,
and the Philippines. There is evidence to suggest
that although portions of Japan were once known
endemic areas, it may no longer be considered
as such.
S. haematobium has been known to occur primarily
in the Old World. Almost all of Africa and
portions of the Middle East, including Iran, Iraq,
and Saudi Arabia are considered endemic regions.