Trachoma

Trachoma is a debilitating eye disease caused by the  bacterium and is one of the leading causes of blindness worldwide. If left untreated, this bacterial illness primarily affects the conjunctiva, leading to recurrent cycles of inflammation, roughening, and scarring of the inner surface of the eyelids, as well as erosion of the corneal surface. These ocular complications often result in permanent blindness. The World Health Organization (WHO) has classified 20 illnesses and disease groupings as neglected tropical diseases, including trachoma, which is considered the most frequent infection that causes visual impairment in underprivileged countries.  As living standards have improved, trachoma has declined significantly in most North American and European countries. Sharp reductions in the worldwide burden of the disease have been attributed to intentional management measures implemented over the past few decades. However, despite prolonged and intensive interventions, the prevalence of trachoma persists in certain cultures. Trachoma manifests in 2 distinct stages, each presenting unique symptoms and complications.  These symptoms include persistent keratoconjunctivitis characterized by inflammation of the conjunctiva, known as active trachoma. This inflammation results from recurrent infections with conjunctival strains of the bacterium .  The progression to the second stage of the illness is marked by periods of intense conjunctival inflammation, leading to eyelid scarring. Trichiasis is a disorder in which the eyelashes rotate inward and come in touch with the eyeball due to scarring. In addition, a condition called entropion can occur concurrently with trichiasis, where a portion or all of the eyelid edge curls inward. Inverted eyelashes that scratch the cornea increase the risk of corneal opacity and visual problems, leading to blindness in severe chronic conditions. Any of these pathological processes or clinical manifestations induced by indicate the presence of trachoma (see  Eye Disorders and Trachoma-Associated Symptoms). In addition, it is essential to understand how trachoma is transmitted to implement preventative measures. Trachoma mainly spreads through direct and indirect contact with secretions from the noses and eyes of infected individuals. Additionally, transmission can occur through direct contact, hand-eye contact, contact with contaminated objects (fomites), and eye-seeking flies. Several factors contribute to the spread of trachoma, including crowded living conditions, poor hygiene practices, and limited access to medical care. Additionally, socioeconomic status, climate, and cultural customs play significant roles in the transmission of the disease. These factors, often referred to as the "3 F's" in studies, contribute to its dissemination among populations: Face-to-face contact: Close contact facilitates the rapid transmission of the highly infectious trachoma disease. This often happens through actions such as kissing, embracing, or sharing intimate objects such as towels and washcloths with an affected individual. During such interactions, the exchange of infected nasal and ocular secretions between individuals can easily spread the bacteria from one person to another. Flies: Flies, particularly species such as , have a significant role in the transmission of trachoma. These flies are attracted to the secretions from people's noses and eyes and act as mechanical vectors by carrying the bacteria on their bodies. Subsequently, they transfer the infection from one person to another. This mode of transmission is especially common in unsanitary environments where flies are plentiful. Fomites: Fomites, such as contaminated inanimate objects or surfaces, also contribute to the spread of the bacteria. Infected individuals can transfer the bacterium to items such as linens, towels, or everyday utensils. Those who subsequently come into contact with these contaminated fomites and then touch their face or eyes are at risk of contracting the bacteria.