Cockroaches are among the most common pests infesting homes and apartments. They are especially troublesome where food is prepared and sanitation is lacking. Cockroaches are repulsive and embarrassing to most people simply by their presence. They may contaminate food, kitchen utensils, and other household items, and they leave an unpleasant odor. Because cockroaches move freely from filth to food, they can transfer pathogenic microbes that cause food poisoning and other illnesses. Many people are also allergic to cockroach excrement and their shed skins. Cockroach-produced allergens may cause congestion, sneezing and watery eyes, as well as life-threatening bronchial inflammation (asthma) characterized by recurrent cough, wheezing, and difficulty breathing. Asthma triggered by cockroaches is especially common among children living in densely populated housing conditions where infestations are often severe.