Feature articles

04 August 2020

PESTWATCH: Delusional parasitosis and cable bugs

TECHNICAL | PPC100 August 2020

In this PestWatch, BPCA Technical Officer Natalie Bungay takes a look at pests that aren’t real. What is delusional parasitosis and how do we deal with it?

– includes reference to self-harm

PestWatch Delusional parasitosis and cabel bug for pest professionals


  • Delusional parasitosis is a mental health condition in which people believe they or their homes are infested with insects or parasites
  • Recognising the symptoms is vital so that pest professionals can proceed sensitively
  • Do not attempt to supply a medical diagnosis
  • A monitoring service may help alleviate sufferers’ symptoms
  • Always recommend a GP visit where appropriate.

Delusional parasitosis (DP) or, in more medical terms, delusions of parasitosis (DoP), is a rare mental health condition which manifests in the person’s firm belief that he or she has pruritus (an itch) due to an infestation with insects, usually on the skin rather than just in the environment.

Sufferers rarely exhibit obvious cognitive impairment or other signs of ongoing mental health conditions.

It is possible that pest professionals may come across this condition at some point in their careers.

We must make sure that the conclusions of DoP are not quickly judged. If you do come across it, ensure that you are sensitive to the sufferer. Record the necessary information and perhaps even recommend GP assistance if appropriate.

Recognising the signs

The only sign of DoP in some people may be their conviction that they have a parasite inside them. They may also believe that their furniture, home or surroundings are also infested with this parasite.

Another common symptom reported is a crawling feeling on their skin. The medical term for this is ‘formication’.
Some people may also have symptoms like:

  • Feelings of itchiness or burning
  • Feeling of numbness
  • Complaining that they have a crawling or prickling feeling under the skin
  • Scratching and picking at the skin
  • Skin lesions or ulcers caused by scratching
  • Using chemicals to scrub the skin
  • Self-mutilation, in serious cases
  • Using dangerous home remedies, like harmful pesticides, on themselves.

Don’t get caught out

DoP is not to be confused with a general paranoia of insects which is far more common and often caused by long-term actual biting insect infestations. For example, when a person has experienced a bed bug infestation they may suffer for some time afterwards with an ‘itch reaction’ or concern that the bugs are still present.

Similarly, many people experience itchiness and a sudden urge to scratch when talking about certain insects, for example, fleas!

There may be some of us who have experienced a situation where the sufferer of DoP presents you with clothing lint, pieces of skin, or other debris contained in plastic wrap, on adhesive tape, or in matchboxes.

They then typically state that these contain the parasites. However, after inspection, these collections bear no evidence of insects or parasites. This is a common sign that you may be faced with a sufferer of DoP.

In practice

I remember a case resembling this, but only once during 18 years in pest management.

A pest management division I worked within would happily receive insect specimens to identify via the post and, on one particular occasion, the package was on the large size.

It contained over a dozen ‘samples’ of the ‘insect’ that a gentleman was concerned about. He reported they were crawling over him; after washing he found them in the bath, in his bed and described where he’d find them on his body.

The sample package (I was careful to wear gloves when handling it!), contained numerous plastic bags, sticky tape, matchboxes and anything else that could be sourced for containment of the ‘insect’ samples.

Of course, after much microscope work, there was nothing but lint, food debris, hair and dead skin samples present: no insects were evident.

We then had to communicate these results to the gentleman, which was incredibly challenging.

Delusional parasitosis can be a symptom of other underlying mental health issues or can be brought on by grief, stress and anxiety

Dealing with Delusional parasitosis

When you first receive a call for ‘biting insects’ from a sufferer of DoP, you may instantly be aware of it: their descriptions are mostly ‘on their body’ rather than on the bed, carpet etc and ‘in the environment around them’.

They may also say that the insects are burrowing into their skin and they can see them but, when having sought medical advice, the GP has found nothing and the sufferer seems agitated at the fact the GP has concluded this.

Usually, they will have tried lots of different DIY chemical treatments to their environment and body, with no apparent success.

When faced with a potential case of DoP, it is of the utmost importance to show empathy and understanding to the sufferer.

What are cable bugs?

Not to be confused with delusional parasitosis, the cable bug is a recent phenomenon and occurs most commonly in offices.

People often end up with insect-like bite marks on exposed skin but an investigation of buildings presumed infested shows no evidence of any insect activity.

What is actually happening is high levels of static electricity, often generated by people wearing synthetic soled shoes walking on shallow piled polypropylene carpets, the kind often used in offices.
People become electrostatically charged and attract uncharged particles of nylon carpets and fibre-glass insulation material which come into contact with their skin.

These sharp microscopic fibres cause an allergic reaction on the skin surface causing the characteristic round reddened mark associated with biting insects.

Know your limits

It is important to remember that we are not medical professionals.

If the customer mentions physical concerns about mites or insects, you should simply state that this must be looked at by a GP to assess it and, unfortunately, you are not qualified to discuss or comment on such issues.

However, you may want to offer an inspection and monitoring service to confirm the presence or exclusion of biting insects in their home. While doing this, you should explain the monitoring process to help the customer understand what you propose to do.

In some circumstances, practices such as this can help the sufferer to ‘see’ that there are no insects in their home, possibly helping to alleviate their symptoms.

However, DoP sufferers may not take this on board as evidence, such is their conviction that they have an infestation.

If, after inspection and monitoring, you reach the conclusion that there are no insects, and the customer is still adamant they're being bitten, then urge them to visit their GP. Unfortunately, you can do no more than that.

Crucially, you must not agree with the sufferer just to placate them; you will only make the situation worse.
It is possible that the sufferer will get angry and upset at the fact that you, as a pest professional, cannot solve their problem but you cannot legally carry out insecticide treatments if there are no insects present.

Should I discuss DoP with the potential sufferer?

This is where it gets tricky.

Mental health is a sensitive subject and potential sufferers of DoP may feel that you are ‘accusing’ them of being ‘crazy and irrational’ if you suggest that this is the cause of their distress.

It is inadvisable to use words such as ‘imaginary’, ‘delusional’ or ‘hypochondria’. Use of these words can often make those suffering with DoP angry and defensive.

Our advice is to avoid bringing the subject up, not only for the aforementioned reasons but also, in reality, we are not qualified to make a diagnosis of DoP.

It must be up to a GP to refer a patient to psychological professionals if they feel this is necessary. Signposting is an important part of every profession and there’s no harm in admitting this isn’t your specialist area.

In the most sensitive way possible, you should recommend that if the customer feels they are in physical distress, they should seek help from a GP. If they have already done this, gently recommend that a second opinion from another doctor might yield more information.

In extreme cases, if you feel the customer is at risk from themselves or in danger because of their mental state (DoP can often trigger suicidal thoughts) you may consider contacting social care in the local authority for the region you are working within. They will be able to visit the sufferer if they feel it necessary.


Never do a precautionary insecticide treatment without identifying a pest species - even if you think it’ll put your client’s mind at ease. Chances are it won’t work and you’ll cause more distress in the future. Plus, it’s illegal.

We’ve been asked before if you can spray water to help calm a client. Telling a client you’re spreading a pesticide when you’re not is incredibly unprofessional, unhelpful and again - potentially illegal.

Further reading

Delusional parasitosis MSD manuals

Source: PPC100

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