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Trachoma is a chronic progressive infection of the
conjunctiva and cornea that may cause partial or total blindness. Visit:
Chlamydial
Infection
;
Chlamydial Conjunctivitis (Inclusion
Conjunctivitis).
;
Chlamydial Infection of the Genital Tract
;
Psittacosis (Ornithosis,Parrot Fever)
;
Lymphogranuloma Venereum
.
Infection with
Chlamydia trachomatis, subgroups A , B , Ba , and C is the leading
cause of preventable blindness in the world.
Visit :http://www.chlamydiae.com
:
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;
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The blinding complications are associated with progressive conjunctival scarring.
The disease is
worldwide, associated with poverty, and most prevalent in dry or sandy
regions.
Only humans
are naturally infected. Poor personal hygiene and inadequate public
sanitation are common factors.
Mode of
infection:
Spread mostly
by direct contact, trachoma is also transmitted by fomites,
contaminated water, cosmetics, and probably flies.
Subclinical
infections are an important reservoir.
Clinical
presentation:
In endemic
areas infection is acquired early in childhood, becomes chronic, and
eventually progresses to blindness.
An abrupt
onset of palpebral and conjunctiva inflammation leads to lacrimation,
purulent conjunctivitis, and photophobias.
As chronic
inflammation progresses over months and years there is scarring of the
upper tarsal plate and corneal keratitis, with formation of a vascular
pannus .
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Scarring, trichiasis and entropian eventually interfere with
normal ocular function. Secondary bacterial infections and corneal
ulceration are common.
Image Link: Chlamydia trachomatis - Life Cycle:
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Morphological features:
In a study of
specimens taken from patients with active trachoma the histology
showed inflammatory infiltrate organized as lymphoid follicles in the
underlying stroma. The impression cytology showed cytoplasmic
elementary bodies.
In specimens taken from patients with scarring
trachoma light microscopic studies showed subepithelial fibrous
membrane formation, squamous metaplasia and loss of goblet cells,
pseudogland formation in conjunctiva, degeneration of orbicularis
oculi muscle fibres, subepithelial vascular dilatation, localized
perivascular amyloidosis and subepithelial lymphocytic infiltration.
Accessory lachrymal glands and the ducts of glands showed subepithelial infiltration and scarring.
Note:
In trachoma
the cornea is eventually invaded by blood vessels and fibroblasts to
form the trachomatous pannus . Necrosis eventually occurs, specially in the
lymphoid follicles, causing extensive conjunctival scarring.
Resorption of lymphoid follicles at the limbus results in indentations
called Herbert's pits. On microscopic examination the desquamated
conjunctival epithelium exhibits glycogen-rich intracytoplasmic
inclusion bodies and large macrophages containing nuclear fragments (Leber
cells).
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Diagnosis of
Trachoma:
Diagnosis of
trachoma is based on the clinical findings and the demonstration of
organisms in smears or cultures.
Scrapings of
the superficial conjunctiva stained with Giemsa or by direct immunofluorescence
may reveal diagnostic intracytoplasmic inclusions.
Treatment:
Trachoma
responds to topical and systemic tetracycline, but endemic trachoma is
difficult to treat because of repeated exposure. All members of a
family or social group should be treated to prevent retransmission.
Vaccines have
been ineffective, and those administered systemically tend to
exacerbate the disease.
Improved
hygiene and public sanitation are the most effective control measures.
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