Although over 28 disease pathogens have been found in bed bugs, transmission of these pathogens to humans has never been documented and is considered highly unlikely. For this reason, they are not considered a serious disease threat. Their medical significance is mainly limited to the itching and inflammation associated with their bite. Not everyone reacts to bed bites in the same fashion; some people have reactions that are delayed for several days or more while others do not react at all. Reactions to bites can also vary significantly between individuals from a mild itchy welt to a more severe rash like symptom. The most common reactions appear as a raised reddened welt similar to a mosquito bite. Bites tend to be very itchy and often appear in rows of 3-4 welts or more.