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Intestinal Schistosomiasis And Its Possible Prevention And Control
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f.
Pyuria, white blood cells in the urine. It is a sign of infection of
the urinary tract. Pyuriaoccurs in inflammation of the bladder, kidney,
or urethra, and tuberculosis of the kidney. Pyuria may be caused by an
infection from viruses. Miliary pyuria causes blood, pus, and tissue
cells, as well as bacteria, in the urine.
g. Miracidium, the larval
stages of aquatic invertebrates (e.g. Flukes) that lead sedentary,or
attached, lives in the adult stage are typically motile and
free-swimming. Such larvae are found in sponges, sessile mollusks, and
many rotifers and worms. These larvae serve to increase the distribution
of the adults
h. Fistula, an abnormal passage from an internal organ
to the body surface or betweentwo internal organs. Fistulas may occur
in many sites from the mouth to the anus and may be made for treatment
follow the course of a disease
1.3 Life cycle
Schistosoma eggs are
excreted from the human host into a fresh water environment through
urine or feces. Once an egg comes in contact with fresh water, it
hatches and releases a miracidium, a free-living and ciliated form,
which remains infective for 6–12 hours. The miracidium swims by ciliary
movement toward the snail intermediate host and penetrates its soft
tissue. The Schistosoma species are transmitted by different fresh water
snails that serve as their intermediate hosts: Biomphalaria, Bulinus,
and Oncomelania for S. mansoni, S. haematobium, and S. japonicum,
respectively.
The miracidium that penetrated the snail loses its
cilia and develops into a mother sporocyst, which multiplies asexually
to produce daughter sporocysts. These migrate to and develop in the
hepatic and gonadal tissue of the snail. Within 2–4 weeks, these
daughter sporocysts metamorphose into cercariae.Under the stimulation of
light, hundreds of free-swimming, fork-tailed cercariae leave the snail
intermediate host. They swim through the water until they come into
contact with human skin or the skin of other mammalian hosts, in the
case of S. japonicum. S. japonicum can infect more than 40 mammals that
can serve as reservoir hosts.8 The cercariae penetrate the skin by
mechanical activity and via proteolytic enzymes. Upon skin penetration,
the cercariae lose their tail and become schistosomules which pass
through the epidermis and dermis before exiting via the blood or
lymphatic vessels.
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ABSRACT - [ Total Page(s): 1 ]Schistosomiasis is a neglected tropical disease that ranks second only to malaria in terms of human suffering in the tropics and subtropics. Five species are known to infect man and there are currently over 240 million people infected worldwide. The cornerstone of control to date has been mass drug administration with 40 mg/kg of praziquantel but there are problems with this approach. Human and bovine vaccines are in various stages of development. Integrated control, targeting the life cycle, is ... Continue reading---
