Bedbugs

Cimex hemipterus is the tropical bedbug.

Not considered to be disease vectors.

Bedbugs are insects that infest human dwellings and take blood meals from humans that result in skin reactions.

Bedbugs undergo five nymphal stages that require a blood meal to transition to the adult form.

Among the human pathogens detected in bedbugs are hepatitis B virus, hepatitis C virus,, Trypanosoma cruzi, HIV, and methicillin-resistant Staphylococcus aureus: but there is no evidence to confirm that bed bugs are capable of acting as vectors of these diseases to other humans.

Bedbugs thrive in warm and dark environments.

They harbor in dark recesses such as bedclothes, mattresses, springs, bedframes, cracks, crevices, and wallpaper.

These arthropods do not possess wings, and their movement typically occurs via direct physical contact with surfaces.

They cannot fly or jump, but can move fast about 3-4 ft./min.

Bedbugs are flat, approximately 5 mm ovoid and wingless insects visible to the eye.

Bedbugs are nocturnal and attracted to a host’s body temperature and exhalation of carbon dioxide.

Recent resurgence of this insect in developed countries.

Bedbug global resurgence started in the late 1990’ due to increased urbanization, international travel, and insecticide resistance.

Resurgence is due to multiple factors including resistance to insecticides, ineffective pest control related practices, lack of knowledge about preventing infestations, and increase domestic and international travel.

Increased bug infections since 1980 in the U.S.

Found in temperate and tropical regions of the world.

Wingless, obligate ectoparasites that feed on the blood of bats, birds and mammals.

Adult bugs are oval shaped, flat and about 5 mm long and easily seen.

Reddish brown in color as adults while immature bugs are much smaller and may be a light yellow.

Bites may be present in clusters or occurring in a straight line or zigzag pattern in a row of at least 3 to 5 bites.

 The most common skin lesions are pruritic, macular papular, and erythematous.

Of the skin lesions include wheals, vesicles and less frequently bullar and nodules.

A central  punctum may be seen in some cases.

Bedbugs attack exposed areas of the skin and are attracted to humans because of high body temperature and carbon dioxide production.

Bed bug bites are painless and attributed to their needle-like stylets that penetrate the skin.

Bed bug bites occur on any exposed part of the body that are not covered by sheets and blankets, such as arms, legs, feet, face, and neck.

Skin lesions are noticed immediately after a person arises but sometimes develop over the following days.

Patients often exhibit characteristic lined and curved bite patterns on exposed areas of the body.These patterns are from either a single bed bug probing to find a productive capillary bed or many bed bugs feeding along a zone of exposed skin.

Patients may develop macules or papules, usually within 48 hours, appearing as 2- to 5-mm pruritic, erythematous papules or wheals with a central hemorrhagic punctum.

Skin lesions tend to be intensely itchy.

Skin reactions ma mimic urticaria producing edema in the upper dermis, as well as a perivascular inflammatory infiltration with lymphocytes, eosinophils, and mast cells.

Occasionally, more-severe bullous lesions can develop.

Spread by principally 2 mechanisms: active transmission and passive transmission.

Active transmission occurs by bed bugs crawling across to other areas.

Passive transmission, involves transfer of bed bugs via such fomites as clothes, bags, linens, and furniture.

Evidence also suggests that bed bugs are capable of dispersing by small air currents and by static electricity.

Cause erythematous or urticarial lesions.

Pyrethroids most widely used to control bed bugs.

Linear or cluster formation of lesions is typical.

Some individuals do not experience a reaction from the bed bug bite itself, and have a small punctum with no surrounding reaction.

The severity of cutaneous reactions varies between individuals.

Parasitic insects of the cimicid family that feed exclusively on blood.

Between blood meals, bedbugs hide in dark places: cracks, crevices, walls, luggage, bed clothes, mattresses, bed springs, bed frames, baseboards, wallpaper, electrical switch plates, and electrical cable conduits.

Bed bugs emerge from hiding places primarily during the night to feed on sleeping humans.

Sites of infestations include: hotels, private homes, apartments, public transport vehicles, trains, cruise ships, airplanes, theaters, hospitals, and military buildings.

Cimex lectularius, the common bed bug, is the prefers to feed on human blood.

Phylum: Arthropoda

Class: Insecta

Order: Hemiptera

Superfamily: Cimicoidea

Family: Cimicidae

The preferred habitat of Cimex lectularius is warm houses and especially near or inside beds and bedding or other sleep areas.

Bed bugs are mainly active at night, but are not exclusively nocturnal.

They usually feed on their hosts without being noticed.

Adverse health effects include skin rashes, psychological effects, and allergic symptoms.

An infestation of bed bugs can result in anxiety, depression, disruption in sleep, ostracism, financial burdens, or loss of work.

Bedbug infestations is associated with sleep disturbance, psychological distress, anxiety, depression, and post traumatic stress disorder, resulting in severe impact on mental and emotional health.

Psychological manifestations include: nightmares, phobias, hypervigilance, insomnia, anxiety, avoidance behaviors, delusions, and personal dysfunction, with people worrying that they may be bitten at night.

Patients with an infested home may feel shame in social isolation and rarely may cause serious psychiatric consequences.

Suicide if the infestation is severe has been described.

Patients often awake because of itching, and scratching may  exacerbate the itch sensation and further disturbed sleep.

Unaffected individuals may have concerns that they have a bed bug infestation.

Incorrect diagnosis of skin lesions may cause unaffected individuals to take measures to eradicate nonexistent bedbugs, resulting in distress.

Do not transmit any pathogens as disease vectors.

Because of their ability to survive up to 5 months without feeding, leaving infested rooms vacant is not an effective solution in resolving a bed bug infestation.

Bed bugs feed at nite on humans.

Certain signs and symptoms suggest the presence of bed bugs; finding the adult insects confirms the diagnosis.

Diagnosis of a bedbug infestation is based on history, examination of the skin, and of the environment.

Reports of recent travel in dwellings with high rates of occupant turnover, such as hotels, motels, hostels, and shelters, and the report of a new lesion on awakening because bedbugs are nocturnal, and similar symptoms and cohabitants suggests the infestation.

Diagnosis requires inspection of rest areas including beds, sofas and their surroundings.

The presence of exoskeletons or bedbug dark fecal spots on the mattress and bedding is a clear sign of infestation.

Typical skin findings include multiple pruritic, erythematous papules on exposed areas of the head, neck, and extremities.

The skin papules may have a hemorrhagic punctum and may be arranged in linear groups, giving rise to characteristic “breakfast, lunch, and dinner” sign.

Some bites may cause localized bullous reactions, and widespread papular urticaria as a result of an immune response to salivary proteins released during feeding.

Bed bugs emit a musty, sweet odor produced by specialized glands, and some describe a characteristic odor as a berry scent.

Trained sniffer dogs can detect bedbugs with a main detection rate of 44%.

Inspection of sleeping quarters, furniture, or defects and floors and walls at night may be beneficial as bedbugs are nocturnal.

Bedbug monitors, mechanical traps that can be placed near suspected infestation sites can lure bedbugs with heat or carbon dioxide for diagnostic purposes.

Eradication is linked to early detection.

Non-chemical control methods are essential.

Vacuum cleaners can rapidly reduce bedbug population and remove some eggs.

Vacuum cleaners need to have disposable bags which can immediately be removed and sealed in plastic after use.

Steaming mattresses and other furniture covered in unremovable textiles at 60°C, will kill all stages of bedbugs in less than one minute.

Bedbug traps are commercially available, but are not effective for eradication.

Differential diagnosis for other arthropod bites that result in pruritic papules: bat bugs or swallow bugs, scabies, fleas, Cheyletiella mites, and other mite species, and dermatitis

A bed bug adult or nymph recovered from a patient, and if laboratory identification is desired, the specimen can be stored dried or placed into a liquid transport medium to prevent desiccation of and damage to of the specimen.

In the early 1940s, they were mostly eradicated in the developed world, but have increased in prevalence since 1995.

Prevalence increase is likely due to pesticide resistance, governmental bans on effective pesticides, and international travel.

In New York City recent data suggests the prevalence of 12% in some neighborhoods.

Pest control companies indicate that at least 80% of hotels have had to deal with bedbugs, and 40% managed  an the infestation in the past month.

Diagnosis of an infestation involves both finding bed bugs and the occurrence of compatible symptoms.

Skin symptoms of frequently self-limiting and usually resolved within 1-2 weeks.

Diagnosis must be confirmed by physical detection of the insects.

The linear feeding pattern can be a reasonable indicator, this feeding pattern does not occur in all cases.

Bed bug detection can be accomplished by: visual inspection, isolation with physical traps baited with chemical attractants, or through the action of bed bug–detection dogs.

Other signs of bed bugs include: molted cast skins of bed bugs, or feces or blood on bedding, mattresses, or wallpaper.

Skin biopsies yield nonspecific results and are unnecessary.

Treatment involves the elimination of the insect, including its eggs.

Skin reactions to most bedbug bites resolve after one week without treatment.

Symptom control can be achieved with mid potency topical cortical steroids.

Antihistamines and gabapentinoids can be used for symptoms.

Associated bacterial infection should be treated with topical or systemic antibiotics depending on severity.

Bites should be washed with soap or anti-septic solutions.

Topical glucocorticoids and antihistamine medications may help for highly pruritic lesions.

Bed bug bites may lead to a range of skin manifestations from no visible effects to prominent blisters.

Eradication requires an integrated strategy, combining temperature extreme measures applied to infested items or entire rooms, laundering, vacuuming, and insecticides.

Insecticide resistance is increasing with resistant gene variants.

Insecticide treatments with pesticides such as DDT and pyrethroids are administered by professionals.

Bed bugs can be infected with at least 28 human pathogens, but are not are capable of transmitting any of these to humans.

Adult bed bugs are light reddish-brown, flattened, oval-shaped, and have no hind wings.

The front wings are vestigial,

They have segmented abdomens with microscopic hairs that give them a banded appearance.

Adults bedbugs grow to 4–5 mm long and 1.5–3 mm wide.

Newly hatched nymphs are translucent.

Newly hatched bed bugs are lighter in color, and become browner as they moult and reach maturity.

A bed bug nymph of any age having consumed a blood meal has a bright red, translucent abdomen..

The color fades to brown over the next several hours, and to opaque black within two days as the insect digests its meal.

Their movements are ant-like.

When crushed they emit a disagreeable odor.

They use pheromones and kairomones to communicate about nesting locations, feeding, and reproduction.

They can survive a wide range of temperatures.

Below 61.0 °F adults enter semihibernation and can survive longer.

They can survive for at least five days at 14 °F, but die after 15 minutes of exposure -26 °F.

They show high desiccation tolerance, surviving low humidity and a 35–40 °C range even with loss of one-third of body weight; earlier life stages are more susceptible to drying out than later ones.

The lifecycle comprises six stages: egg, four nymphal stages, and adult.

The thermal death point for C. lectularius is 45 °C (113 °F).

All stages of life are killed by 7 minutes of exposure to 46 °C (115 °F).

Obligatory bloodsucking insects, that feed on humans only when other prey are unavailable.

They obtain additional moisture from water vapor in the surrounding air.

They are attracted to their hosts primarily by carbon dioxide, secondarily by warmth

That prefer exposed skin, preferably the face, neck, and arms of a sleeping person.

Bedbug’s mouth parts saw through the skin, and inject saliva with anticoagulants and painkillers.

Responses to such bites varies from extreme allergic reaction to no reaction at all in about 20% of cases.

The bite usually produces a swelling with no red spot.

If many bugs feed on a small area, reddish spots may appear after the swelling subsides.

Although under certain cool conditions adult bed bugs can live for over a year without feeding.

Under warm conditions they try to feed at five- to ten-day intervals.

Adult bedbugs live up to 4-5 months.

On average, starved bedbugs at room temperature will die after 70 days.

Adults can generally survive for about five months without food.

Younger bed bugs cannot survive nearly as long.

DNA from human blood meals can be recovered from bed bugs for up to 90 days.

A bed bug pierces the skin of its host with a rostrum, or beak.

The rostrum is composed of the maxillae and mandibles, modified into elongated shapes.

The entire maxillary and mandibular bundle penetrates the skin.

The insect cuts a path through tissue for the maxillary bundle to reach an appropriately sized blood vessel, that fills the insect with blood in three to five minutes.

The bug then withdraws from the feeding position and folds the entire unit back under the head, and returns to its hiding place.

A bed bug becomes completely engorged with blood, between five and ten minutes.

A bed bug may spend less than 20 minutes in physical contact with its host

A bed bug does not try to feed again until it has either completed a moult or, if an adult, has thoroughly digested the meal.

Sexual attraction in bed bugs is based primarily on size, and males mount any freshly fed partner regardless of sex.

Bed bugs have five immature nymph life stages and a final sexually mature adult stage.

Bed bugs must molt six times before becoming fertile adults, and must consume at least one blood meal to complete each molt.

Each of the immature stages lasts about a week, depending on temperature and the availability of food, and the complete lifecycle can be completed in as little as two months.

Fertilized females with adequate nutrition lay three to four eggs each day continually, possibly generating as many as 500 eggs.

A single pregnant bed bug, can be responsible for an infestation over a matter of weeks, rapidly producing generations of offspring.

C. lectularius feeds every five to seven days.

C. lectularius aggregates under all life stages and mating conditions.

Males excrete an aggregation pheromone that attracts females and arrests other males.

Can exist singly, but tend to congregate once established.

Strictly parasitic, it spend only a tiny fraction of their lifecycles physically attached to hosts.

Following feeding, it relocates to near beds or couches in clusters of adults, juveniles, and eggs.

The insect returns occurs by following chemical trails.

Harbor sites vary greatly and include: luggage, inside of vehicles, within furniture, amongst bedside clutter, electrical sockets and computers.

Bedbugs may also nest near bats, birds, rodents, cats and dogs, though humans are the preferred host of C. lectularius.

Bedbugs can also be detected characteristic smell of rotting raspberries.

Eradication requires a combination of nonpesticide approaches and the occasional use of pesticides.

Mechanical approaches, such as vacuuming insects and heat-treating or wrapping mattresses, are effective, while a combination of heat and drying treatments is most effective.

An hour at a temperature of 113 °F or over, or two hours at less than 1 °F kills them.

A domestic clothes drier or steam kills bedbugs.

They can go without eating for 100 to 300 days, depending on temperature.

Pesticides that have historically been found effective include pyrethroids, dichlorvos, and malathion.

Resistance to pesticides has increased significantly over time, and harm to health from their use is of concern.

Natural enemies of bedbugs include the masked hunter insect, cockroaches, ants, spiders, mites, and centipedes.

Biological pest control is not considered practical for eliminating bed bugs from human dwellings.

Increase prevalence in the developed world may be by increased international travel, resistance to insecticides, and the use of new pest-control methods that do not affect bed bugs.

Household cockroach populations that have declined from the use of insecticides, and they are the major bed bug predator have also led to bed bugs resurgence

Bans on DDT and other potent pesticides have also increased bed bug population.

C. lectularius is the species best adapted to human environments, being is found in temperate climates throughout the world.

The increase in bed bug populations in the early 20th century attributed to the advent of electric heating, which allowed bed bugs to thrive year-round instead of only in warm weather.

The decline of bedbug populations in the 20th century is often credited to potent pesticides that had not previously been available.

Bedbug infestations resurged since the 1980s: for contributing factors may be complacency, increased resistance, bans on pesticides, and increased international travel.

Following bed bug bites good hygiene should be maintained to prevent secondary infection and scratching the bites is avoided.

Asymptomatic bed bug bites do not require treatment, and management of patients with significant pruritus includes a topical corticosteroid, systemic antihistamine, or both.

Secondary infections require management with appropriate antibiotics.