Trichoma

• In an eye infection caused by infection with the non-genital strain of bacterium Chlamydia trachomatis.
• predominantly affects young children
• is a contagious infection of the eye 
• Mode of transmission

• predominantly spread by infected ocular and nasal secretions passed between young children.
• children may be reinfected several times a month.
• The bacteria are transmitted through the following routes:
  • Direct eye-to-eye spread (e.g. while playing or sharing a bed)
  • Conveyance on fingers
  • Indirect spread via fomites (e.g. shared towels, pillow cases, face cloths)
  • Coughing/sneezing
  • Eye-seeking flies

Incubation period

• The incubation period of C. trachomatis is 5 to 10 days.
  •  However most episodes of infection are reinfections and usually occur in children with already established clinical disease.

Infectious period

• The infectious period is 2 to 3 months. It may be shorter with repeated infections and decrease with age.

Clinical presentation and outcome

• Cases of active trachoma are often asymptomatic or may present with discharging or red eyes.
• Multiple infections cause conjunctival scarring (trachomatous scarring) 🡪
  • leading to eyelid contraction and in-turned margin (entropion) 🡪 
  • Scars contract over time, distorting the eyelid margin and pulling eyelashes inward (trachomatous trichiasis).
    • The resulting in-turned eyelashes rub on the eyeball, causing painful corneal scarring and corneal opacity. 
    • If not treated with surgery to the eyelid to correct in-turned eyelashes, corneal scarring can end in blindness in later adult life. This can occur 20–40 years after the initial trachoma infections. 

• It is estimated that some 150 to 200 episodes of reinfection may be necessary to lead to blindness
• Trachoma is the leading infectious cause of blindness, with blinding trachoma the result of a complex interaction between the actual infection and immune response.
• almost exclusively in remote Aboriginal communities in the NT, South Australia and Western Australia.
• Endemic classification
  • if >5% of children aged 5–9 years have active trachoma
  • >0.2% of adults or 0.1% of the whole population has trichiasis.
• Prevention
  • community-wide screening occurs in communities that are identified as at risk. 

Differentials

• Conjunctivitis
  • Infectious
    • Viral
    • Bacterial (e.g., staphylococcus and Chlamydia species)
  • Noninfectious
    • Allergic
    • Dry eye
    • Toxic or chemical reaction
    • Contact lens use
    • Occult conjunctival neoplasm
    • Foreign body
    • Factitious
    • Idiopathic
• Keratitis
  • Infectious
    • Bacterial
    • Viral
    • Fungal
    • Acanthamoeba
  • Noninfectious
    • Recurrent epithelial erosion
    • Foreign body
• Uveitis
• Episcleritis/scleritis
• Acute glaucoma
• Eyelid abnormalities
• Entropion
  • Lagophthalmos with globe exposure
  • Trichiasis
  • Molluscum contagiosum
• Orbital disorders
  • Preseptal and orbital cellulitis
  • Idiopathic orbital inflammation (pseudotumor)

Examination

• The ‘3Ts’ of trichiasis examination:
  • Think to do it
  • use a Thumb to lift the lid so the lashes lift away from the eye
  • and use a Torch to provide enough light to see the dark lashes.

WHO simplified grading system for trachoma

	Grade		Signs
Infectious	TF	Trachomatous inflammation- Follicular	Presence of 5 or more follicles of >0.5mm in diameter on the upper tarsal conjunctiva
	TI	Trachomatous inflammation – Intense	Presence of pronounced inflammatory thickening of the upper tarsal conjunctiva obscuring more than half of the normal deep tarsal vessels
Non-infectious	TS	Trachomatous conjunctival Scarring	Presence of easily visible scars on the upper tarsal conjunctiva
	TT	Trachomatous Trichiasis	Presence of at least one in-grown eyelash touching the eyeball, or evidence of recent removal of in-turned lashes
	CO	Corneal Opacity	Presence of corneal opacity blurring part of the pupil margin

Diagnosis & Laboratory tests 

• The diagnosis of active trachoma is based on clinical examination. 
• Contacts of case need to be identified.
• to confirm trachoma infection are currently not recommended except perhaps to exclude other viral or bacterial infection

Screening 

• ATSI children aged 5–9 years who are residents of the community based on school enrolments, child health nurse records and other sources. 
• It is important to remember that treatment of cases of active trachoma found during screening programs should not be managed separately from the treatment of households and communities
• Reducing the prevalence of trachoma in a community is dependent on completing all treatment in as short a timeframe as possible

Treatment

• If a diagnosis of trachoma is made clinically the case and all contacts should be treated.
• The target is for 100% of active cases to receive treatment, and for 85% of contacts to receive treatment.
• Treatmnt is determined by the prevalence of active trachoma cases within the community at time of screening, and may involve treating all household contacts or mass treatment of the whole community.
• There may be a requirement for repeat treatments on an annual basis depending on the disease prevalence in the community

Rx: 

Azithromycin in a single dose is recommended for the treatment of both cases & their contacts >3kg 

(Azithromycin 20mg/kg (maximum dose of 1000mg) orally as a single dose. 

Single dose azithromycin is contraindicated only in the case of a known allergyi, and weight less than 3 kg

There are no other contraindications for administration of single dose azithromycin

• Should a spontaneous case be detected outside of community-wide screening, the index case and their household require treatment
• There is strong evidence to support community-wide treatment/ mass drug administration in reducing the prevalence of trachoma

Screening and treatment schedule of contacts according to prevalence

Trachoma prevalence in screened children aged 5-9 years	Treatment	Treatment frequency	Screening frequency
≥20%	Single-dose azithromycin to people >3kg living in houses with children <15 years of age	0, 6, 12, 18 & 24 months	Screen at 36 months after the initial screen (12 months after the 5th treatment)*
≥5 to < 20% and there is no obvious clustering of cases	Single-dose azithromycin to people >3kg living in houses with children <15 years of age	0, 12 & 24 months	Screen at 36 months after the initial screen (12 months after the 3rd treatment)*
≥5 to < 20% and cases are obviously clustered within several households and health staff can easily identify all household contacts of cases	Single-dose azithromycin to people >3kg living in houses with an active trachoma case	Once at 0 months. Further treatment determined by prevalence at next screen	Screen at 1 year to determine prevalence

Age	Azithromycin Syrup	Azithromycin Tablets
Under 5 years	1 bottle for every 2 children requiring treatment.
5-10 years	1 bottle for every child requiring treatment.
10 – 12 years	1.5 bottles for every child requiring treatment.
Over 12 years		1000mg = 2 x 500mg tablets for each person requiring treatment.

Prevention: SAFE strategy.

• S – Surgery for trichiasis: Surgical procedures to reduce impact of trichiasis
• A – Antibiotics: Antibiotic (azithromycin) treatment of individual active trachoma cases and to reduce the community reservoir of infection
• F – Facial cleanliness: Promote clean faces to reduce spread of infection
• E – Environmental health – improve water access, good sanitation, waste and fly control, and reduce overcrowding