| Clinical
Features |
Trachoma is a chronic follicular
conjunctivitis that leads to scarring in the conjunctiva and
cornea. Repeat active infections occur in children < 10 years
of age. Subsequently, conjunctival scarring (cicatricial disease)
and inversion of the eyelashes so they irritate the cornea
(trichiasis) develops as a result of earlier infections. Trichiasis
predisposes to corneal ulceration and corneal opacities resulting
in decreased vision and blindness. |
| Etiologic
Agent |
Chlamydia trachomatis, serovars
A, B, Ba, and C. First description of disease in 16th-century
BC in the Ebers Papyrus. Infectious potential demonstrated
by experimental transmission of agent from a case-patient
to an orangutan in 1907. |
| Incidence |
WHO estimates that approximately
6 million cases of blindness due to trachoma and 11 million
cases of trichiasis occur yearly. Prevalence of active disease
in children varies from 10-40% in some African countries to
3-10% in several Asian countries. The overall incidence is
unknown. |
| Sequelae |
Repeat infections result in a chronic
follicular conjunctivitis that leads to scarring in the conjunctiva
and cornea. Ultimately, corneal opacification and blindness
occurs. |
| Transmission |
Primary: person-to-person transmission
by ocular and respiratory secretions. Secondary: insect vectors
such as house flies. |
| Risk
Groups |
Active infection occurs in children
< 10 years, reinfection during childhood is common. Endemic
disease is found in rural areas with limited economic means
and poor sanitation and water supplies. |
| Surveillance |
No national or international surveillance
exists. Blindness due to trachoma has been eliminated from
the United States. The last cases were found among American
Indian populations and in Appalachia. |
| Trends |
Major declines in some countries
associated with multifaceted control program. |
| Challenges |
WHO has initiated a global campaign
for the elimination of blindness due to trachoma, GET2020,
that recommends a strategy including antibiotics, improved
personal and community hygiene and sanitation, and surgery
to correct trichiasis. Campaign challenges include: establishing
surveillance for endemic trachoma, determining when mass treatment
with antibiotics is necessary (i.e., retreatment), determining
the effectiveness of improved hygiene and sanitation at preventing
a resurgence of endemic disease, monitoring for adverse effects
of mass treatment with antibiotics, and improving surgical
outcomes. Additional challenges include: improving diagnosis
of active disease, monitoring the emergence of antibiotic
resistant C. trachomatis, and improving our understanding
of the transmission and reservoirs of C. trachomatis. |
| Opportunities |
To develop laboratory methods to
monitor antibiotic resistance in C. trachomatis, assist
with the global campaign by supplying technical expertise,
and design studies to improve our understanding of C. trachomatis
transmission and reservoirs. |
|
December 2003
|
