BedBug (Cimex lectularius)

The bedbug (or bed bug) is an insect of the family Cimicidae that lives by hematophagy - feeding on the blood of humans and other warm-blooded hosts. Its name comes from its preferred habitat: mattresses, sofas, and other furniture. Although not strictly nocturnal, bedbugs are mainly active at night.

Biology

The common bedbug (Cimex lectularius) is the species best adapted to human environments. It is found in temperate climates throughout the world and feeds on human blood. Other species include Cimex hemipterus, found in tropical regions, which also infests poultry and bats, and Leptocimex boueti, found in the tropics of West Africa and South America, which infests bats and humans. Cimex pilosellus and Cimex pipistrella primarily infest bats, while Haematosiphon inodora, a species of North America, primarily infests poultry.

Adult bedbugs are reddish-brown, flattened, oval, and wingless, with microscopic hairs that give them a banded appearance. A common misconception is that they are not visible to the naked eye. Adults grow to 4–5 mm (1/8th – 3/16th of an inch) in length and do not move quickly enough to escape the notice of an attentive observer. Newly hatched nymphs are translucent, lighter in color and become browner as they moult and reach maturity. In size, they are often compared to lentils or apple seeds.

Feeding habits

Bedbugs are generally active just before dawn, with a peak feeding period about an hour before sunrise. However, they may attempt to feed at other times, given the opportunity, and have been observed to feed at any time of the day. They climb the walls to the ceiling and jump down on feeling a heat wave. Attracted by warmth and the presence of carbon dioxide, the bug pierces the skin of its host with two hollow tubes. With one tube it injects its saliva, which contains anticoagulants and anesthetics, while with the other it withdraws the blood of its host. After feeding for about five minutes, the bug returns to its hiding place. The bites cannot usually be felt until some minutes or hours later, as a dermatological reaction to the injected agents, and the first indication of a bite usually comes from the desire to scratch the bite site. Because of their dislike for sunlight, bedbugs come out at night.

Although bedbugs can live for a year or as much as eighteen months without feeding, they typically seek blood every five to ten days. Bedbugs that go dormant for lack of food often live longer than a year, well-fed specimens typically live six to nine months. Low infestations may be difficult to detect, and it is not unusual for the victim not to even realize they have bedbugs early on. Patterns of bites in a row or a cluster are typical as they may be disturbed while feeding. Bites may be found in a variety of places on the body.

Bites

In most observed cases, bites consist of a raised red bump or flat welt, and are often accompanied by intense itching. The red bump or welts are the result of an allergic reaction to the anesthetic contained in the bedbug's saliva, which is inserted into the blood of its victim. Bedbug bites may appear indistinguishable from mosquito bites, though they tend to last for longer periods. Bites may not become immediately visible, and can take up to nine days to appear. Bedbug bites tend to not have a red dot in the center such as is characteristic of flea bites. A trait shared with flea bites, however, is tendency towards arrangements of sequential bites. Bites are often aligned three in a row, giving rise to the colloquialism "breakfast, lunch and dinner." This may be caused by the bedbug being disturbed while eating, and relocating half an inch or so farther along the skin before resuming feeding. Alternatively, the arrangement of bites may be caused by the bedbug repeatedly searching for a blood vein. People react very differently to bedbugs, and individual responses vary with factors including skin type, environment, and the species of bug. In some rare cases, allergic reactions to the bites may cause nausea and illness. In a large number of cases, estimated to 50% of all people, there is no visible sign of bites whatsoever, greatly increasing the difficulty of identifying and eradicating infestations.

People commonly respond to bed bug infestations and their bites with anxiety, stress, and insomnia. Individuals may also get skin infections and scars from scratching the bedbug bite locations.

Most patients who are placed on systemic corticosteroids to treat the itching and burning often associated with bed bug bites find that the lesions are poorly responsive to this method of treatment. Antihistamines have been found to reduce itching in some cases, but they do not affect the appearance and duration of the lesions. Topical corticosteroids, such as hydrocortisone, have been reported to expediently resolve the lesions and decrease the associated itching.

Many patients also experience temporary relief of itching and inflammation with the application of hot water to the bite. The water should be quite hot (about 120 °F) because if it is not hot enough it may cause aggravation of the symptoms. The water should be hot enough to cause minor discomfort, but care must be taken not to burn the skin and this treatment should only be self-administered in order to reduce the risk of a burn. Itching and inflammation can be relieved for several hours by applying hot running water, a hot washcloth, or even using a blowdryer to heat the area of the bite, for 10 seconds to 1 minute (or longer if desired). There is disagreement as to why heat causes the symptoms to abate. Some hypotheses propose that heat overwhelms the nerve endings that signal itch, that heat neutralizes the chemical that causes the inflammation, or that heat triggers a large release of histamine causing a temporary histamine deficit in the area.

Disease transmission

Bedbugs seem to possess all of the necessary prerequisites for being capable of passing diseases from one host to another, but there have been no known cases of bed bugs passing disease from host to host. There are at least twenty-seven known pathogens (some estimates are as high as forty-one) that are capable of living inside a bed bug or on its mouthparts. Extensive testing has been done in laboratory settings that also conclude that bed bugs are unlikely to pass disease from one person to another. Therefore bedbugs are less dangerous than some more common insects such as the flea. However, transmission of Chagas disease or hepatitis B might be possible in appropriate settings.

The salivary fluid injected by bed bugs typically causes the skin to become irritated and inflamed, although individuals can differ in their sensitivity. Anaphylactoid reactions produced by the injection of serum and other nonspecific proteins are observed and there is the possibility that the saliva of the bedbugs may cause anaphylactic shock in a small percentage of people. It is also possible that sustained feeding by bedbugs may lead to anemia. It is also important to watch for and treat any secondary bacterial infection.

reff: From Wikipedia