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BEDBUGS evoke responses out of all proportion to their size. Not just
a red mark and an itch, but intense loathing, embarrassment and shame. Yet
there are compelling reasons to believe that most of the world’s population
lives with bedbugs. And there are good reasons why we should treat them
with respect. Apart from the suffering caused by their bites, some researchers
think that bedbugs could be responsible for transmitting disease.

Contrary to popular belief, adult bedbugs are visible to the naked eye
– they are between 4 and 5 millimetres long. They live in cracks and crevices
in furniture or walls near where people sleep. Bed frames and mattress seams
are popular with the bugs because they allow them easy access to food in
the form of human blood.

Telltale signs of infestation include brown or black spots of excrement
about the size of a large pinhead, near cracks and crevices, such as on
bed heads. The bugs may also leave behind clusters of pearly or white oval
eggs and cast-off skins.

No one knows the true extent of the problem. Statistics about how the
bugs are distributed tend to reflect those areas where researchers have
worked. Certainly the bugs are widespread, and the intensity of some infestations
is alarming. An inspection of a flat in Islington, north London, early last
year revealed hundreds of thousands of the insects. This is the sort of
infestation more usually associated with tropical countries. Research done
between 1984 and 1986 in Natal, South Africa, showed that 43 per cent of
dwellings had bedbugs, with between 4000 and 5000 in each of several huts.
In the Gambia last year, 37.5 per cent of children’s beds were infested.
Workers in Hyderabad, southern India, found the bugs in two out of three
houses they examined, while in 1988, babies’ cots in one orphanage in Dhaka,
Bangladesh, harboured hundreds of bedbugs each. But as the case in Islington
shows, the problem is not confined to developing countries.

Hard facts about infestations are hard to come by. Information is usually
based on the number of treatments carried out. In Britain, many companies
dealing in pest control are unwilling to release statistics about which
areas they have treated. The main source of information is the environmental
health departments of local councils, but reporting is erratic and inspections
irregular. Information about infestations is collected in different ways,
and is often discontinuous because computerised databases were introduced
at different times in different areas. It may also include data about other
household pests such as cockroaches, ants or even mice, masking the problem
of bedbugs.

Figures for England and Wales are available only for 1985/6 (although
more recent data are being compiled). The Institute of Environmental Health
Officers found that local authorities carried out 7771 treatments for bedbugs
in that year. Just over a quarter of these were in the North West – Merseyside,
Cheshire, Greater Manchester, Lancashire and Cumbria – and 17 per cent were
in Greater London. The Midlands and Northern Region – Cleveland, Durham
and Northumbria – each accounted for one-tenth of the total, while the South
West – Devon, Cornwall, Dorset – had the fewest treatments (0.3 per cent).

In Scotland the Royal Health Institute’s figures show that over half
of the 41 treatments in 1987 were carried out in Edinburgh and Glasgow.
This concentration of bedbugs in urban areas is also found in Northern Ireland,
where in 1988 there were 186 treatments in Belfast compared with 7 in Londonderry
and 2 in County Down.

Most environmental health departments are short of officers to carry
out inspections. Usually a council becomes aware of an infestation only
if someone complains – but people are often ashamed to admit that their
homes are infested and they turn to the environmental health department
only as a last resort when their own attempts to kill the bugs with household
insecticides have failed. Many cases go undetected for years, until either
the bites become unbearable or a relative or neighbour reports the problem.
Superficially, Britain appears to be treating fewer cases of bedbugs than
in the past. According to a questionnaire sent out to local authorities
in England, Scotland and Wales in 1970, bedbugs are ranked as occurring
rarely or not at all and counted as less frequent than cockroaches and fleas.
In 1989 the London Borough of Islington carried out 50 treatments, compared
with 78 the previous year and 105 in 1987. Cambridge has had five suspected
and one confirmed infestation in the past three years, whereas in the 1960s
it reported between two and three cases a week. This reduction is probably
the result of better control measures and the demolition of rundown residential
areas.

But not all areas are experiencing a decline. Nowadays, economically
deprived areas in cities seem to be the focus of most infestations. In one
city in the West Midlands, the environmental health department deals with
about 50 infestations a year, and officials say that the number is increasing.
Last year, Manchester City Council carried out 298 treatments, compared
with 277 in 1988. Most heavy infestations (of walls, furniture, or more
than one room) occur among elderly people who had been embarrassed to ask
for assistance, and people who have brought the bugs from abroad in their
luggage, especially from tropical countries. Overcrowded urban areas provide
ideal conditions for the bugs to breed and these areas are also less likely
to have the resources to deal with the problem.

Environmental health officers are convinced that many of the lighter
infestations (of bed frame and mattress) go undetected or ignored. Young
people in particular are unlikely to recognise either the symptoms of an
infestation, or the bugs themselves. In one housing estate in the West Midlands,
officers called in to deal with a cluster of three infestations found another
18 cases in the 96 houses they checked.

No one really knows how far bugs migrate along buildings such as terraced
houses. Infestations are often restricted to one house on either side of
the one that was originally infested. The way that the bugs migrate may
depend on the construction of the buildings. Bugs can also be carried on
outer clothing, but this is unlikely except in heavily infested houses.
Nevertheless, some environmental health officers are concerned that second-hand
clothes might account for the spread of bugs. Officers investigating a cluster
of infestations in Belfast found that the bugs had spread by means of infested
clothing.

The main route for migrating bedbugs is through second-hand furniture
– especially beds, as their name suggests. Officers investigating a complaint
from one woman in Coventry found that the households of her five adult children
were also infested. It turned out that they had each in turn housed her
double bed. During the Second World War, bedbugs spread when people took
bundles of infested bedding into air raid shelters. Nowadays, bedbugs can
travel for thousands of kilometres in suitcases that have been left for
some time near infested beds. Not surprisingly, this route is becoming increasingly
common and it also causes infestations in hostels and hotels – so beginning
a vicious circle.

The bugs hunt for blood at random, responding to cues such as heat,
carbon dioxide and – possibly – smell, once they are close enough. They
pierce the skin with two needle-like tubes and suck blood by means of pumps
in the head. At the same time they inject saliva containing an anticoagulant
and anaesthetic. Bedbugs take their time over a meal: it may last between
3 and 12 minutes, depending on their age and when they last fed. Their bites
are not immediately painful and do not always wake the sleeper.

People react in a wide variety of ways to being bitten. Those who have
never been bitten before usually develop inflammations similar to mosquito
bites, but larger and with a whitish, raised centre. Symptoms may not start
until 24 hours after the bite and the itch can be intense. Scratching can
cause further infection. Long-term sufferers become desensitised and the
bite appears as a small red spot which may not even itch. One striking case
of desensitisation occurred about five years ago in Oldham, near Manchester,
where an engineer repairing a Wireless for the Blind found hundreds of bedbugs
inside it. When environmental health officers visited its owner they found
a heavily infested house and an occupant who was completely unaware that
he had such a problem.

Besides itching, the bites can cause more serious problems. In 1962
researchers working in Hyderabad, India, began to think that blood loss
caused by repeated bites could contribute to iron deficiency in children.
They found that 100 feeding bedbugs take in 0.73 milligrams of elemental
iron. Babies have 75 milligrams of iron for every kilogram of body weight
– two-thirds of it in the blood in haemoglobin. Chris Bates of the Dunn
Nutrition Laboratory in Cambridge estimates that 500 bites a night would
be enough to cause mild anaemia in babies a few months old. This number
of bites is not particularly high – people living in the heavily infested
premises in north London and Natal would have suffered more bites than this.

Robert Usinger, of the University of California at Berkeley, showed
dramatically how bedbugs affect the blood by letting them feed on him from
1958 until 1964. His haemoglobin level decreased by about one-fifth during
that time and remained low even when he took iron supplements. It was several
months after the end of the experiment before his iron level returned to
anything like normal.

Bites and disease

Female bedbugs suck more blood than males – 0.0185 millilitres per meal
compared with 0.015 millilitres per meal, on average. An adult human has
4.5 litres of blood, enough to give a quarter of a million bugs a decent
meal! But it is difficult to isolate exactly how bites affect the levels
of iron in the human body. People who suffer from bedbugs are likely to
be suffering from other parasites and possibly from malnutrition, especially
in developing countries.

For a long time researchers have suspected bedbugs of transmitting all
sorts of diseases, from leprosy to smallpox and yellow fever. All other
insects that feed on humans transmit human infections, and bedbugs have
similar habits and a close association with humans. Nevertheless, the evidence
is inconclusive. Although scientists have proved that in the laboratory
bedbugs transmit Trypanosoma cruzi, the parasite responsible for Chagas’
disease, in nature bugs belonging to a different insect family, the Reduviidae,
are responsible for transmitting the disease. In 1977, William Wills and
his colleagues in Senegal found that some bedbugs contained the surface
antigen of the hepatitis B virus, which suggested that the bugs might be
a vector for this disease. Peter Jupp and his colleagues at the National
Institute for Virology in South Africa found that some bugs excreted this
antigen for as long as six weeks after feeding on blood that contained it.
But the virus itself did not multiply within the insect, nor did females
transmit it to their offspring. In 1983 they concluded that bedbugs might
transmit hepatitis B to humans by contamination from bedbug faeces or by
a human crushing bugs that contain the surface antigen for hepatitis B virus.
But so far there is no evidence that this happens in nature.

Jupp and his colleague Susan Lyons also looked at whether bugs could
transmit HIV, the virus that causes AIDS, which is similar in some respects
to the hepatitis B virus. They fed bedbugs on blood containing HIV. Although
the virus survived in the bugs for several hours, four attempts to transfer
the virus to uncontaminated blood, by interrupting the bugs as they fed
and allowing them to resume feeding on a sample of the uncontaminated blood,
all failed. Much more research is needed before we can say whether bedbugs
are involved in the transfer of HIV. Despite the suspicions and a few pieces
of circumstantial evidence, no one has yet proved that bedbugs in their
natural state transmit diseases to humans, either through bites or from
infected faeces.

Remedies for bedbugs have been around for centuries. In medieval times
people slept with a pig in the room, believing that the bugs would be more
attracted to the pig. A more appropriate remedy in overcrowded cities was
pouncing on the bugs with a bar of soap – they would stick to it.

In Britain in the 1930s, local authorities used hydrogen cyanide as
a fumigant. After 24 hours they tested for residual gas, unfortunately using
a chemical that is now known to be one of the most poisonous and carcinogenic
substances, p-diamino diphenyl acetate. Not surprisingly, this caused sickness
among fumigators and probably resulted in some deaths – certainly it killed
many cats. Officials recommended painters’ blow lamps and fumigation with
naphtha as alternative methods for getting rid of the bugs.

From the 1940s to the early 1960s, DDT began to replace previous control
measures, but the bugs eventually grew resistant to it. In Africa, householders
began to object because spraying with DDT made things worse – probably because
it killed the bugs’ natural enemies. These include earwigs, reduviid bugs
and ants, including Pharaoh ants, another household pest.

Modern methods of controlling bedbugs vary according to where the infestations
are. Developing countries usually control bedbugs as an offshoot of control
programmes against mosquitoes – mosquito nets impregnated with the insecticide
permethrin also kill bedbugs when they walk on them. Researchers found that
people in Papua New Guinea were prepared to walk for miles to have nets
treated because of their effect on the bugs, rather than on the mosquitoes.

In Britain, environmental health officers can investigate a suspected
infestation and order the owner or occupier of the infested home to ‘cleanse
the verminous premises’. Local authorities will also pay for the treatment
or destruction of heavily infested furniture. The most recent legislation
relating to bedbugs are the Rag Flock and Other Filling Materials Regulations
of 1981, which state that ‘all filling materials to which the Act applies
shall be free from vermin’, where ‘vermin’ means ‘the eggs, larvae and pupae
of insects and parasites’.

End of an infestation

Environmental health officers control bedbugs as they control cockroaches,
which have similar habits. First, they dismantle any items that they suspect
are infested, to see how bad the infestation is. They treat a light infestation
by spraying the whole room with an insecticide such as bendiocarb or a synthetic
pyrethroid. These insecticides leave long-lasting deposits that kill the
bugs when they walk over the treated area. The insecticides interfere with
the bugs’ nervous systems and work for up to three months. Treatment programmes
in Europe and the US are based on similar methods.

Dealing with a heavy infestation can mean drastic action, such as demolishing
a small part of the building to expose all the places where the bugs are
hiding. The walls and furniture are then sprayed as for a light infestation.
Sometimes a spray is used that produces unusually small droplets, which
penetrate crevices further than conventional sprays. Holes might be filled
with insecticide dusts in areas that are away from people. Smoke generators
do not work well as the insecticide settles only on horizontal surfaces.

One ingenious way of tackling the problem of infestations is to turn
the bugs’ own chemicals against them. The bugs produce a scent that attracts
them to each other so they congregate in groups. This attractant could form
the basis of a powerful control chemical, and chemists in the pest control
industry are still trying to find out more about it.

In Britain, under a new law passed in 1986, manufacturers now have to
provide evidence that their product is effective against a particular species
of insect, as well as information on how it affects other organisms. But
the greatest demand is still for chemicals that will kill insects such as
cockroaches, fleas and ants. The danger is that manufacturers will produce
insecticides with the most common pests on the label. These insecticides
cannot be sold as treatments for bedbugs unless the bugs are included in
the list of ‘target’ insects. This could leave local authorities in Britain
with fewer means of controlling bedbugs.

Bedbugs are more than just a minor irritation. They afflict millions
of people all over the world and could be a health hazard in both tropical
and temperate countries. And until we know more about their role in the
spread of disease, we must find out what is the scale of the infestation.
If not, untold numbers of people will go on suffering their presence.

* * *

The fascinating life story of a bedbug

TWO-THIRDS of the 89 species in the bug family Cimicidae are parasites
of bats. The three species of bugs that bite people probably adapted to
feed on cave dwellers who took up residence alongside the bats. They are
found all over the world except at the poles, and rarely in deserts. All
three species infest human habitations and feed on the blood of humans,
bats and, occasionally, domesticated animals.

In summer, the bedbug completes its life cycle in about six weeks, feeding
every three or four days, so populations increase rapidly. In winter its
metabolism is slower, and below a temperature of about 7 Degree C eggs will
not hatch. But adult bugs can survive without feeding for up to a year at
this temperature.

Bedbugs have bizarre mating habits. The female does not have a passage
for copulation, and the male inseminates the female by piercing the underside
of her abdomen, between the fifth and sixth segments. The sperm pass into
the female’s body fluids, possibly travelling up an oxygen gradient, until
a few hours later they reach storage organs connected to each ovary. The
female needs a meal of blood before the eggs can mature. Once the eggs are
mature, some of the sperm migrate to the ovaries and fertilise the eggs.

Females lay about 300 eggs in their lifetime. The eggs hatch into straw-coloured
nymphs about a millimetre long which moult five times before reaching the
adult stage. The nymphs need blood meals at each stage and feed as adults
do, by inserting a pair of needle-like tubes into their victim.

Fiona King works for the Medical Entomology Centre at the University
of Cambridge.

Further Reading: Insects and Hygiene by J. R. Busvine, Chapman and Hall,
1980; The Ecology of Ectoparasitic Insects by A. G. Marshall, Academic Press,
1981