Bedbugs - A problem of the past, a bigger problem for the future, who can help?
airmid healthgroup ltd report by Geraldine Hughes
The impact of the rapidly increasing global prevalence of bedbugs cannot be underestimated. Once close to eradication in the late 1940’s, bedbugs have made a staggering resurgence particularly in the United States over the past 10 years but also in western European countries including Ireland and the UK where infestation report rates are increasing and distribution areas are expanding. Although the basis and point source for this resurgence is unclear, large bedbug infestations have been attributed to increased worldwide travel, altered insecticide management, and increased resistance to widely used broad spectrum insecticides. High resistance has been reported to many of the more limited insecticides still available to combat them.
Two species of bedbugs targets humans as their preferred host of: the common bedbug (Cimex lectularius), which has worldwide distribution, and the tropical bedbug (Cimex hemipterus), which is found primarily in tropical regions. Traditionally regarded as a pest control problem exclusive to areas of low socioeconomic status, bedbug infestations have been reported in the finest hotels and housing facilities in the US and Europe.
Bedbugs are hematophagous i.e. they feed primarily on human blood. Their mouth parts are specially evolved to pierce human skin and withdraw blood quickly and discretely. Anticoagulants and anaesthetic compounds are injected with salvia during biting effectively numbing the bite area while maximizing blood flow from the host. Feeding can last up to ten minutes for an adult before a fully engorged state has been reached.
Adult bed bugs fast running wingless insects, 4-5mm long when fully grown and rust brown in colour. They are dorsoventrally flattened and extremely thin, facilitating their ability to hide in the narrowest of cracks close to the sleeping host. The undersides of mattresses, within furniture structures, under floorboards, behind skirting, and in carpets in various cracks are popular locations for bedbugs to be found.
Heavy infestations have a distinctive sweet smell; blood spots would be evident on the bedding surfaces and increased biting experienced by the occupants of the house.
Physical Description and Life Cycle
Bedbugs undergo incomplete metamorphosis during their life cycle.
- Mated adult females will lay up to 5 eggs per day for the duration of their life. Eggs are a translucent colour approx 1 mm in length and will stick strongly to the surface upon which they are laid.
- Hatching of 1st Instar nymphs occurs 10 days later. After feeding, the 1st instar nymph will shed its skin and emerge slightly larger in size as a 2nd Instar nymph.
- This cycle will occur a further 4 times before the adult stage is reached. Each nymphal stage requires at least one blood meal to progress to the next stage of development.
Figure 1: Bedbug Life Cycle
Bedbugs thrive in conditions where there is a constant blood supply and are most active at night. Attracted by warmth, moisture and the exhalation of CO2 by the host, bedbugs quickly and secretly bite repeatedly, feeding primarily on exposed surfaces of skin such as the face, neck, arms, and hands.
When regular blood meals are not available, a state of metabolic dormancy is adapted allowing the bedbugs to survive for many months until a blood supply has returned. Larvae can survive inside dwellings for several months without a blood meal, but they do not progress into the next life cycle stage until feed. Similarly mated females will not produce eggs during times of starvation.
Remarkably, bedbugs have adapted to survive for up to 18 months without feeding and up to 2 years in colder environments.
Public Health Importance
Unlike other blood-feeding arthropods (mosquitoes, tsetse flies and sand flies), to date there is no evidence to prove that bedbugs are disease vectors or play any role in the transmission of diseases between humans.
They are a huge biting nuisance and while some people will not experience any discomfort, others will display significant allergic reactions due to the injection of saliva and anti coagulant by the bedbug in to the host during biting.
The main clinical presentation of bedbugs is a skin rash. Bite distribution frequently follows a line or curve on exposed areas of skin. Lesion may develop numbers range from several to many, depending on habitat-infestation intensity. InPiduals that are allergic to C. lectularius bites often experience itching and erythematous. Secondary bacterial infections may follow as a result of constant scratching, irritation and breaking of the skin. Bedbug infestations also result in anxiety, insomnia or worsening of an existing mental health condition.
The massive increase in international travel in recent years has most certainly facilitated the movement of bedbugs. Many people are unaware of the threat of bedbugs and therefore do not take the necessary steps to avoid transmission, Prevention of infestation is definitely better than cure. People are commonly responsible introducing bed bugs from an infested area into their homes via luggage or clothes. It is important to check for bedbugs when staying in hotels or hostels. Always look under the sheets and inspect mattress. Tell-tale signs of an infestation include blood spots or bedbug encasements on the bedding or mattress. Time should be taken to inspect all areas of the home if a bedbug infestation is suspected and the necessary steps should be followed to eliminate it as soon as possible.
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