Trachoma Flashcards
What are the main preventable/treatable causes of blindness?
Cataract – treatable not preventable
Trachoma
Onchocerciasis
Vitamin A deficiency
Refractive errors
other causes of blindness:
- diabetes
- glaucoma
- corneal opacities
- ARMD
WHO 2015 considered trachoma
Endemic in 42 countries
> 200 million people at risk
1.9 million visually impaired
0.5 million irreversibly blind
What is trachoma caused by?
Commonest infectious cause of blindness.
Caused by bacteria chlamydia trachomatis
Causes chronic/recurrent conjunctivitis – conjunctiva lining of eye, inflammation of this
Scarring – trichiasis (eyelashes deviate and rub on eyeball, damaging and painful) – corneal opacity
What are the chylamdia trachomatis serovars?
A to C prefer to infect conjunctiva.
D to L3 prefer to infect genital tract.
Otherwsie similar, 99% homology between ocular and genital strains
What is follicular and intense trachoma?
Follicular trachoma (TF) - Ct infection often present – can see follicles, aggregates of lymphocytes
Intense trachoma (TI) - Ct infection typically present at high bacterial load
What is active trachoma?
What is trachomatous scarring?
TF and or TI referred to as active trachoma
Active trachoma is commonly used among small children
Ct infection is typically associated with active trachoma
Trachomatous scarring TS – Ct infection not usually found, scarring of conjunctiva.
As scar forms and contracts, eyelashes turn inwards, causing trachomatous trichiasis – eyelashes rub on cornea, painful and causes you to become blind due to damage to cornea
What is trichiasis?
Becomes commoner in adults from their 40s
Is commoner among women – may be due to being exposed to more children
Leads to blindness through corneal trauma
Treatment would be epilation or surgery to turn eyelashes.
End stage is corneal opacity, eye is blind
Eyelashes have traumatised cornea and there has been secondary infection.
What methods can be used to diagnosis infection?
ELISA
eye swab on microscope to detect
PCR using DNA from swab - do molecular detection
What are the 5 F’s of trachoma transmission?
Flies - take protein meals to lay eggs
Fomites - inanimate articles other than food and water, contaminated by infectious discharge from patient and capable of transmitting infectious agent to the healthy person
Fingers
Within the Family
Between close Friends
Path to trachoma
Spread of disease
Active trachoma
Scarring
Trichasis
Corneal opacity
Blindness
Treatment of trachoma
Before 1990 tetracycline hydrochloride eye ointment used twice daily for 6 weeks
- but ointment melts and is difficult to give to child
trials done with azithromycin, found that
- azithromycin had sustained reduction in TF and infection
- reduction followed by rapid re-emergence in villages with tetracycline eye oiintment
What did Pfizer agree on to help eliminate trachoma?
1988 Pfizer agreed to donate azithromycin for control and elimination of trachoma, and WHO passed resolution calling for global elimination of blinding trachoma as a health problem by 2020
What is the SAFE strategy recommended by WHO to treat trachoma?
Surgery for advanced disease – reposition turned in eyelashes so they don’t scrape against cornea
Antibiotics to clear C.trachomatis infection, treats infection and decrease transmission in endemic regions
Facial cleanliness – helps to reduce transmission
Enviornmental improvement to reduce transmission - access to water and basic sanitation , prevent flies breeding
What is the surgery for trichiasis?
Bilamellar tarsal rotation procedure is effective, but 19 - 23% recurrence after 2 years in clinical trials – posterior lamellar tarsal rotation better PLTR – stitch differs
Higher recurrence (up to 41%) under operational conditions in Tanzania and The Gambia
What is epilation used for?
Often practised in trachoma-endemic communities, using homemade forceps
Relieves symptoms, but lashes grow back
May be an alternative to surgery in those with few lashes touching the eye
