**2. Epidemiological characteristics**

#### **2.1. Epidemiological significance**

Ocular infectious processes are among the clinical entities that are relevant to the epidemiol‐ ogy. The high incidence of infections in patient care institutions has resulted in high-quality infection control processes and monitoring of various entities of epidemiological relevancy. For example, viral conjunctivitis primarily represents a challenge for management and prevention. Thus, it is common for diseases such as hemorrhagic conjunctivitis and follicular conjunctivitis to be part of the epidemiological surveillance.

The difficulty of the epidemiological surveillance of ophthalmic diseases lies in the limitation of performing a specific etiologic diagnosis of infection, since in practice ophthalmic infections are treated empirically based on the clinical picture and the physician's experience. Ophthal‐ mologists and laboratory staff should not forget that care of patients with endophthalmitis is usually performed at the first level of care, where the general practice is responsible for the greatest amount of attention to this disease. Thus, control programs for conditions such as trachoma are necessary to prevent them from reemerging and being attentive and vigilant regarding emerging diseases.

Within emerging diseases, changes are observed in response to treatment but more important in the modification to the incidence and prevalence to disease. Reports of bacterial strain resistant to antibiotics and changes in the behavior expected of diseases are increasing. Therefore, new mechanisms of resistance of microorganisms, comorbidity states in individu‐ als, new mechanisms of transmission, etc., that explain what changes in the conditions have occurred are sought. One explanation is the presence of more than one causal agent of infectious disease, coinfections.

The mechanisms developed by various microorganisms when present concurrently can alter significantly the clinical presentation, diagnosis, and treatment.

Coinfections resemble clinical pictures presented by other clinical entities and have an adverse effect, as the usual outcome is the use of multi-treatment that fails, causing refractory man‐ agement and in many cases ending in loss of vision or surgical interventions. This reveals the importance of presenting cases of coinfections of the eye.

Although eye coinfections are not the subject of epidemiological surveillance, they are not as rare as previously thought and can represent 3.88 % of endophthalmitis cases, for example, and more than 50 % in some series of patients with conjunctivitis reported in the literature [6, 7].
