Sometimes when a customer complains of being bitten, the truth is much more complex than simply identifying the pest in question.

When you’ve been in the pest industry long enough, you will probably get called out on a job to deal with a homeowner who is being bitten, by ‘unknown insects’. However, on inspection you can find no trace of the culprit; no fleas, no bed bugs, no bird mites, nothing. Only on questioning the homeowner may you start to get a bit suspicious.

It’s possible you may have come across a case of delusionary parasitosis, a mental condition. In contrast to a phobia, where the person is frightened of the insect (being bitten or being infested), persons suffering from delusionary parasitosis actually believe they are being bitten, attacked or infested, but they’re not!

Persons suffering from delusionary parasitosis will often complain of bites, itching or crawling sensations on or under the skin. The scratching of these apparent symptoms will lead to skin irritations, visible signs which may further reinforce their belief. Typically if they notice any skin changes they will go to the doctor or dermatologist. If they bring this up when you visit, it’s a potential warning sign. If they haven’t noticed any skin changes, it is more likely they will have called you first, suspecting some ‘mite’ infestation.

Sufferers of this condition, often have an obsessional personality as a predisposing factor. Although anyone can be a sufferer, the main group affected tends to be white, middle-aged women. The most important point to understand is that this is a mental condition and needs to be handled accordingly.

What should you do?

Treat the case as any normal pest control job.

1) Speak to the customer on arrival

The discussion may well set some alarm bells ringing. A classic presentation is where the suffer will readily show you a matchbox containing the culprit or sticky tape where they believe the culprit has been caught. Often this may simply be a collection of dust, lint and other debris. Nevertheless, you should listen to their feedback, with particular attention to their believed location and time of attacks, as this can give you some focus to the inspection.

2) Carry out a thorough inspection

This needs to be a thorough inspection. You clearly need to establish whether there is or is not an infestation. Given the nature of this condition, the culprit is assumed to be small/microscopic, so if it is a real infestation it is likely to be fleas, bed bugs or bird lice, which can sometimes be missed if the inspection is not thorough.

A complicating factor of this condition is that a previous real infestation or insect bites obtained outside the house could have triggered the delusion. As such you should consider whether an issue lies outside the home, either in the yard or from a recent trip.

Should you carry out a treatment?

As with any pest control treatment, you should not carry out a treatment unless there is a pest issue – you should not carry out a treatment ‘just in case’. If the homeowner is suffering from delusional parasitosis, carrying out a treatment will only make the situation worse. It won’t solve the problem and could well leave you open to re-treatments when issue doesn’t go away. Just say you are “unable to find anything”, but don’t let your feedback develop into an argument. If they are suffering from delusional parasitosis, it’s an argument you cannot win.

If you strongly believe they may be suffering from delusional parasitosis, you could suggest that they visit their doctor to have “the bites or itching checked out”. You are not a physician so don’t be manipulated into checking out the person’s body, clothes or specimens and certainly don’t suggest to them that they have delusionary parasitosis!

You could consider leaving it open for them to call you again in a week or two if the ‘bites’ continue or reappear. A second negative inspection would then confirm your suspicions and you should politely confirm that you can simply find no cause and therefore there is nothing else you are able to do. It is important to close off the customer, as they will continually call you if they believe you are a sympathetic ear.

Illusionary parasitosis

This is quite different to delusionary parasitosis – the suffers do exhibit some genuine skin affliction but this is then incorrectly attributed to some small insect that is infesting the home or office. Such illusions are particularly common in offices, where the illusion becomes ‘contagious’.

Common environmental factors that could be causing the ‘bites’ (skin irritations) include carpet fibres, static electricity, low humidity, ventilation and indoor air pollutants. In such cases, the symptoms often occur in more than one person, although again it tends to be more common in women. Sometimes the illusion can occur when one person has been bitten outside work (for example on a weekend away) and then first noticed it at work. The ‘bites’ can then spread to others by the power of suggestion. Stress can often be a factor in these illusions.

Again, a comprehensive pest inspection needs to be carried out, but if no pests are found, no treatment should be carried out. Certainly don’t suggest the bites are ‘imaginary’, but suggest that other environmental causes could be responsible (and that this is not uncommon). To investigate alternative causes, you could recommend that the company consult an industrial hygienist.

Further reading: Government of Western Australia, Department of Health, Delusional Infestation – A management guide for Pest Management Technicians.

Techletter, Pest Control’s Role in Classic Delusions of Parasitosis.

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