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What is trachoma?

Greek word trakhus =rough, which refers to the pebbled appearance of the infected conjunctiva. Trachoma is a chronic infectious disease infecting the conjunctiva and cornea. 

In another word, it is chronic keratoconjunctivitis. The major causative agent is Chlamydia trachomatis, but other pathogenic microbes may often contribute to it. 

Organism originally believed to be a virus but later it is found as an obligate intracellular bacteria and classified as Chlamydia. Trachoma is a common disease among preschool-aged children, with prevalence rates that can be as high as about 60–90%.

 

Signs and symptoms

  • Follicular hypertrophy
  • Eye irritation & itching
  • Eye pain
  • Light sensitivity (photophobia)
  • Eye discharge containing pus or mucus
  • Red appearance of the sclera
  • Papillary hyperplasia
  • Pannus formation 
  • Cicatrisation in later stages (caused by C. trachomatis serotypes A, B, or C).
  • Visual impairment or blindness 

 

Mode of transmission

Trachoma can be transmitted eye-to-eye by droplets, hands, contaminated clothing, and eye-seeking flies. Sources are ocular discharges of infected persons and fomites.

It may also be transmitted by respiratory droplets or via fecal contamination.

Communicability: 

Trachoma is a disease of low infectivity. It is infective as long as active lesions are present in your conjunctiva, but not after complete cicatrization.

 

Risk factors

The disease is common in areas where the living conditions are crowded, sanitation is poor, the personal hygiene of the people is also poor, inadequate access to water, and lack of education. All these risk factors promote disease occurrence and disease transmission.

The pattern of disease

According to Macallan classification, there are four major stages of the disease. It progresses through stages I-IV. Maximum infectivity is in the early cases and  Stage IV is noninfectious. 

The inflammatory lesion may undergo spontaneous resolution or may progress to conjunctival scarring and fibrosis that can cause inward deviation of eyelashes also known as trichiasis or of the lid margin i.e. entropion. 

Those eyelashes can cause abrasion of the cornea that finally leads to corneal ulceration, followed by scarring and visual loss. 

 

Classification of trachoma

The classification based upon public health point of view is classified into 2 types; they are

 

Blinding trachoma

A community with blinding trachoma can be identified by the presence of lesions such as entropion, trichiasis, and corneal ulcers. Blinding trachoma requires urgent control measures in comparison to the non-blinding type.

 

Non-blinding trachoma

it often becomes blinding trachoma when other ocular pathogens interact synergistically and enhance the risk of damage to eyesight.

 

Causative agents

  • The classical endemic trachoma is caused by C. trachomatis of serotypes A, B, or C.
  • The sexually transmitted C. trachomatis of serotypes D, E, F, G, H,l, J, or K may also cause an eye disease that is difficult to differentiate from endemic trachoma.
  • Inclusion conjunctivitis is a milder case of your eye. These strains of organism rarely produce permanent visual loss, but they cause respiratory infections like pneumonia in infants and genital tract infections in sexually active adults.
  • Other organisms like Morax-Axenfeld diplobacillus (most innocuous), the Koch-Weeks bacillus (most widespread), the gonococcus (most dangerous), etc. often contribute to the disease process. 

Complications 

There are various complications are present after a repeated or secondary attack in your eyes, including:

  • Inner eyelid scarring 
  • Eyelid deformities like entropion( inward-folding eyelid ) or trichiasis (ingrown eyelashes), which can lead to scratch in your cornea.
  • Corneal scarring or cloudiness
  • Partial or complete vision loss

 

Lab diagnosis of Trachoma

Direct Cytopathologic Examination

The characteristic feature is inclusion bodies i.e. Halberstaedter Prowazek /HP bodies, which may be demonstrated in an area like conjunctival scrapings.

It can be seen after staining with Giemsa, Castaneda, or Machiavelli’s methods. As they possess a glycogen matrix they may be stained with iodine solution.

 

Culture characteristics 

The culture can be done in the following way, they are:

In embryonated Eggs

chlamydia may be grown in the yolk sac of 6-8 days old eggs. The material is treated with streptomycin or polymyxin B and eggs are incubated at 35°C in a humid environment

 

Cell Culture

Tissue culture is done by using stationary phase cells (i.e. non replicating cells). This is considered to be a method of choice for isolation. 

The bacterial growth in HeLa-229, McCoy BHK-21, Buffalo green monkey kidney cells, etc. are similar to the narrow range of cells when they infect in vivo.

 

Diagnosis of trachoma

Your doctor or consultant can diagnose trachoma by the method of physical examination or by collecting a sample of bacteria from your eyes to a laboratory for testing. But in general lab tests aren’t always available in areas where trachoma is the most common.

 

Treatment and control measures of trachoma

Epidemiological survey

This is done to identify and delimit communities with blinding trachoma, assess the magnitude of the problem, to identify local conditions and other causes of blindness.

 

Chemotherapy 

The main activity in trachoma control is chemotherapeutic intervention. The objective of chemotherapy is to reduce the severity, lower the incidence, and in the long run decrease the prevalence of trachoma.

The antibiotic of choice is 1 % ophthalmic ointment or oily suspension of tetracyclines. Erythromycin and rifampicin have also been used.  Mass treatment (or blanket treatment) may be given to the entire community.

 

Vaccines that are efficacious and safe are still not available but however, to the ultimate control of trachoma, are good standards of hygiene that accompany improvement in standards of living.

 

Surgical correction

Individuals with lid deformities (i.e. trichiasis, entropion, etc) should be actively sought out and necessary surgical procedures can be performed and followed up. It has an immediate intervention to prevent blindness. 

trachoma

Surveillance 

Since trachoma is a familial disease, the entire family group should be under surveillance. Yearly clinical surveillance has to be performed in an endemic area.

 

Health education

The population needs to be educated to carry out long-term antibiotic treatment by themself. The mothers of young children should be the target for the education of health. Measures of personal and community hygiene should also be included in programs of health education. This would require a permanent change in the behavior patterns and also environmental factors. Also, the improvement of living conditions and quality of life of the people is an important factor.

Program Evaluation

The control program must be evaluated at frequent intervals. The effect of the intervention can be evaluated by the changes in the age-specific rates of active trachoma and also in the prevention of trichiasis and entropion. 

Proper hygiene

  • Face washing and hand-washing. 
  • Fly control: in your home or home boundaries reducing numbers fly which can help to eliminate a source of transmission of trachoma. 
  • Proper waste management 
  • Improved access to and uses of water

According to WHO, the elimination programs in endemic countries are being implemented and using the SAFE strategy. This consists of:

 

  • Surgery to treat the blinding stage (trachomatous trichiasis);
  • Antibiotics to clear the infection, particularly mass drug administration of the antibiotic such as azithromycin, which is contributed by the manufacturer to elimination programs, by the International Trachoma Initiative;
  • Facial cleanliness; and
  • Environmental improvement, specifically improving access to water and sanitation.

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