A Blinding Burden of Epic Proportions
Trachoma is the leading cause of infectious blindness worldwide. The disease is a bacterial infection of the eye that is caused by chlamydia trachomatis, and though it causes irreversible blindness, trachoma can be treated if diagnosed early. Trachoma is spread through direct contact with infected individuals and through contact with flies.
The World Health Organization (WHO) estimates that trachoma affects about 21.4 million people worldwide, of which 2.2 million are visually impaired and 1.2 million are blind. Other estimates have suggested the rate might be much higher, with up to 5 million people at risk of going blind and over 80 million people infected. The burden is indeed massive.
Trachoma is hyper-endemic in many the world’s poorest and most remote areas and often affects the most vulnerable members of communities – women and children. Repeated infection can lead to blindness. In hyper-endemic areas the disease is most common in pre-school children and the prevalence rates can be as high as 60-90%. Due to the transmission cycle of the disease, and the fact that women are most often the caregivers of young children, adult women are at much greater risk of developing the blinding complications of trachoma.
Did you know?
Trachoma was once endemic in Europe and the United States. European immigrants to America had their eyelids flipped and examined upon arrival at Ellis Island in New York. Nine of 10 immigrants diagnosed with active trachoma were returned to their home countries. Trachoma disappeared in Europe, even before antibiotics, because of improved living standards.
Though it is estimated that only about 1% of people with trachoma develop trichiasis (when repeated infections cause the eyelashes to turn inwards, scratch the cornea and lead to blindness), a person's risk of trichiasis increases in relation to the number, duration and intensity of trachoma infections he or she has had over the course of a lifetime. The WHO estimates the economic cost of trachoma, in terms of productivity loss, is $2.9 billion annually.
Transmission cycle and symptoms:
Infection spreads through direct contact with eye, nose or throat secretions of infected individuals and through flies. Infection is often passed from child to child and from child to mother. Often beginning in childhood and progressing slowly, trachoma can become chronic with the more painful symptoms emerging only later in adulthood.
Trachoma transmission is common in communities with water shortages that prevent people from washing their hands and faces regularly, and where there are also crowded living conditions and numerous flies. Signs of early trachoma include itching and irritation and slight discharge from the eye. As the disease progresses, symptoms include light sensitivity and blurred vision. Though single episodes of infection usually do not cause permanent damage, repeated infections can lead to scarring of the upper eyelid. The scarring causes the eyelid to turns inwards (trichiasis) and the eyelashes scratch the cornea, which can lead to blindness.
Diagnosis and treatment:
In resource-poor settings, the standard method of diagnosing trachoma is a grading system that was developed by the WHO. The grading system is based on clinical examinations and can be done in the field by trained technicians. Due to the fact that trachoma is a bacterial infection, the strategy for treatment, prevention and control is multi-faceted and combines both individual and community-oriented measures.
The strategy is summarized with the acronym SAFE: Surgery to reverse trichiasis and preserve sight; Antibiotics to rid the body of active infection; Facial cleanliness to prevent person-to-person transmission; and Environmental improvements to improve both hygiene and sanitation, and prevent flies from breeding in human feces.
The WHO established an alliance to eliminate blinding trachoma by 2020 (GET2020) and partners are working together to implement the SAFE strategy in endemic countries. The antibiotics for trachoma, azithromycin (Zithromax®) and tetracycline (for infants), need to be distributed on an annual basis for a minimum of three years. Pfizer has been generously donating Zithromax since 1998. If the goal of eliminating blinding trachoma by 2020 is to be a reality, each component of the SAFE strategy needs to be incorporated into control programs.