Many factors are indirectly linked to the presence of trachoma including lack of water, absence of latrines or toilets, poverty in general, flies, close proximity to cattle, and crowding. The final common pathway, though, seems to be the presence of dirty faces in children, facilitating the frequent exchange of infected ocular discharge from one childs face to another. Most transmission of trachoma occurs within the family. Diagnosis
McCallans classification
McCallan in 1908 divided the clinical course of trachoma into four stages:

WHO classification
The World Health Organization recommends a simplified grading system for trachoma. The Simplified WHO Grading System is summarized below:
Trachomatous inflammation, follicular (TF)—Five or more follicles of >0.5 mm on the upper tarsal conjunctiva
Trachomatous inflammation, intense (TI)—Papillary hypertrophy and inflammatory thickening of the upper tarsal conjunctiva obscuring more than half the deep tarsal vessels
Trachomatous scarring (TS)—Presence of scarring in tarsal conjunctiva. Trachomatous trichiasis (TT)—At least one ingrown eyelash touching the globe, or evidence of epilation (eyelash removal)
Corneal opacity (CO)—Corneal opacity blurring part of the pupil margin

Prevention
Although trachoma was eliminated from much of the developed world in the 20th century (Australia being a notable exception), this disease persists in many parts of the developing world, particularly in communities without adequate access to water and sanitation. Environmental measures
Environmental improvement: Modifications in water use, fly control, latrine use, health education, and proximity to domesticated animals have all been proposed to reduce transmission of C. trachomatis. These changes pose numerous challenges for implementation.
After the Egyptian Campaign (1798–1802) and the Napoleonic Wars (1798–1815), trachoma was rampant in the army barracks of Europe and spread to those living in towns as troops returned home. Stringent control measures were introduced, and by the early 20th century, trachoma was essentially controlled in Europe, although cases were reported until the 1950s. Today, most victims of trachoma live in underdeveloped and poverty-stricken countries in Africa, the Middle East, and Asia.In the United States, the Centers for Disease Control says, "No national or international surveillance [for trachoma] exists. Blindness due to trachoma has been eliminated from the United States. The last cases were found among Native American populations and in Appalachia, and those in the boxing, wrestling, and sawmill industries (prolonged exposure to combinations of sweat and sawdust often led to the disease). In the late 19th and early 20th centuries, trachoma was the main reason for an immigrant coming through Ellis Island to be deported. "In 1913, President Woodrow Wilson signed an act designating funds for the eradication of the disease. Immigrants who attempted to enter the U.S. through Ellis Island, New York, had to be checked for trachoma. During this time, treatment for the disease was by topical application of copper sulfate. By the late 1930s, a number of ophthalmologists reported success in treating trachoma with sulfonamide antibiotics.