The likelihood of bed bugs increases if the affected individual has been traveling, or if they have acquired used beds or furnishings before symptoms started to appear. Bed bugs also are suspect if you wake up with itchy welts you did not have when you went to sleep. It’s important to recognize, however, that not all bite-like reactions are due to bed bugs. Confirmation requires finding and identifying the bed bugs, shed skins, fecal spots, etc., which often requires the help of a professional. (Other possible sources of irritation that may be mistaken for bed bugs are discussed in University of Kentucky entomology fact sheet ENT-58, Invisible Itches: Insect and Non-Insect Causes). 
Jump up ^ Anderson, J. F.; Ferrandino, F. J.; McKnight, S.; Nolen, J.; Miller, J. (2009). "A carbon dioxide, heat and chemical lure trap for the bed bug, Cimex lectularius" (PDF). Medical and Veterinary Entomology. 23 (2): 99–105. doi:10.1111/j.1365-2915.2008.00790.x. PMID 19499616. Archived (PDF) from the original on 16 August 2017. Retrieved 27 May 2010.
Infestations with bedbugs date back to ancient Egypt.1 The incidence of bedbugs in developed countries decreased in the 1940s because of the availability of more effective pesticides (especially DDT) and improved economic and social conditions.2 In the past decade, however, a significant resurgence of bedbug populations has occurred. This is attributed to a combination of factors, including increased pesticide resistance, more frequent travel, lack of public awareness, and inadequate pest control programs.3 In a 2010 survey, 95 percent of more than 500 U.S. pest management companies reported encountering a bedbug infestation during the preceding year, compared with only 25 percent of companies during 2000.4 Bedbugs spread actively by migrating from one infested room to another, often through ventilation ducts. They also spread passively, carried in the seams of travelers’ luggage, bedding, or furniture.5 Bedbugs do not travel directly on human hosts.6
Hello! Almost overnight I have had a series of small bumps appear on my chest. These bumps look like pimples and they don’t itch at all. I had bed bugs well over a year ago and once they were treated I never saw anything except these bumps recently. My sister thinks I’m just being paranoid because we’ve both checked the bed and saw no signs. And because my chest is always covered, but my arms and legs that are are exposed never have places. I realize that I’m probably being paranoid, but I just wanted an outside opinion.
It was stated in 2012 that no truly effective insecticides were available.[6] Insecticides that have historically been found effective include pyrethroids, dichlorvos, and malathion.[4] Resistance to pesticides has increased significantly over time, and harm to health from their use is of concern.[3] The carbamate insecticide propoxur is highly toxic to bed bugs, but it has potential toxicity to children exposed to it, and the US Environmental Protection Agency has been reluctant to approve it for indoor use.[33] Boric acid, occasionally applied as a safe indoor insecticide, is not effective against bed bugs[34] because they do not groom.[35]

The size of bed bug bites varies with a number of different factors. Bed bugs inject an anti-coagulant along with their saliva when they pierce the skin to take a blood meal. This anti-coagulant is mostly responsible for how a person reacts to the bite and determines the size of the bug’s bite. Since people will have various sensitivities to the bed bug’s bite, the size of the bite will vary, as well. Another factor that influences the size of a bed bug reaction is the number of times a person is bitten. Bite reactions of people bitten many times are also variable, and their response may be either more or less intense as the number of bites increases.