Affect is a psychological term for an observable expression of emotion. A person's affect is the expression of emotion or feelings displayed to others through facial expressions, hand gestures, voice tone, and other emotional signs such as laughter or tears. Individual affect fluctuates according to emotional state.
There are over 3,000 different species of cockroaches-some are considered pests while others are beneficial in their natural environment. The three main types of cockroaches commonly found in homes in South Africa include the German cockroach, Oriental cockroach and American cockroach.
Disease-producing organisms such as bacteria, protozoans, and viruses have been found on cockroach bodies. Different forms of gastroenteritis (food poisoning, dysentery, diarrhea, and other illnesses) appear to be the principal diseases transmitted by German cockroaches.