According to a new report, Kate Middleton is pregnant with her and Prince William 's third child just four months after welcoming their daughter. Kate Middleton with Princess Charlotte in May.(Photo Credit: Getty Images).ccording to a new report, Kate Middleton is pregnant with her and Prince William 's third child just four months after welcoming their daughter. Kate Middleton with Princess Charlotte in May. (Photo Credit: Getty Images).
For other uses, see etiology. Etiology (/iËtiËÉlÉdÊi/ ; alternatively aetiology) is the study of causation, or origination. The word is derived from the Greek Î±á¼°ÏÎ¹Î¿Î»Î¿Î³Î¯Î±, aitiologia, giving a reason for (Î±á¼°ÏÎ¯Î±, aitia, cause; and -Î»Î¿Î³Î¯Î±, -logia).
If the disease is not treated, however, it may progress to the stage where it causes subjective symptoms and abnormal physical findings. Therefore, the distinction be-tween asymptomatic and symptomatic disease is one of degree, depending primarily on the extent of the disease. The term etiology means cause. A disease of unknown etiology is one for which the cause is not yet known. Unfortunately, many diseases fall into this category. If the cause of a disease is known, the agent responsible is called the etiologic agent. The term pathogenesis refers to the manner by which a disease develops, and a pathogen is any microorganism, such as a bacterium or virus, that can cause disease. Classifications of Disease Diseases tend to fall into several large categories, although the diseases in a specific