What are the other Names for this Condition? (Also known as/Synonyms)

• Dermatitis Linearis
• Nairobi Fly Rash
• Rove Beetle Dermatitis

What is Paederus Dermatitis? (Definition/Background Information)

• Paederus Dermatitis is a form of irritant contact dermatitis that develops on contact with certain narrow-bodied insects belonging to the genus paederus. It results in the formation of fluid-filled blisters that may ulcerate and scar at the area of contact
• These insects, known as rove beetles, cause a characteristic skin irritation on direct skin contact due to release of certain toxic chemicals. The condition develops within 2 days following contact with the insect
• Paederus Dermatitis is treated by washing the affected area with mild soap and water, followed by application of topical steroids and antibiotic creams, as necessary. The prognosis is good with early treatment, although permanent scarring may be noted in some individuals

Who gets Paederus Dermatitis? (Age and Sex Distribution)

• Paederus Dermatitis may be observed in individuals of any group
• Both males and females are affected
• Worldwide, there is no racial or ethnic preference observed. The condition is mostly observed in certain parts of Africa and Europe

However, reports of Paederus Dermatitis have been recorded in Asia (India, Malaysia, Sri Lanka, etc.), Australia, South America (Brazil, Argentina, etc.).

What are the Risk Factors for Paederus Dermatitis? (Predisposing Factors)

The risk factors for Paederus Dermatitis include:

• Contact with the rove beetles - rubbing or crushing the insect against the skin can result in Paederus Dermatitis. The beetle is almost ubiquitous in the tropical and sub-tropical regions of the world
• The rove beetles are attracted to fluorescent lights. Thus, living quarters, hospital wards, dormitories, and army barracks that have such lighting systems have reported infestations

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Paederus Dermatitis? (Etiology)

Paederus Dermatitis is caused from exposure to the toxin released in the hemolymph of female rove beetles. The toxic chemical (known as paederin) corrodes the skin and causes the characteristic skin rashes.

What are the Signs and Symptoms of Paederus Dermatitis?

The signs and symptoms of Paederus Dermatitis that may appear within 24-48 hours following exposure to the insect may include:

• Presence of linear red rashes on skin at the site of insect contact
• This develops to form pus and fluid-filled blisters
• Pain, discomfort, and burning sensation
• At the flexural folds, both surfaces on contact may present the rashes
• If the eye is affected, it can result in periocular dermatitis and keratoconjunctivitis

Extensive skin blistering along-with systemic symptoms, such as fever, vomiting, joint pain, and nerve pain, may be seen with severe cases of Paederus Dermatitis.

How is Paederus Dermatitis Diagnosed?

A diagnosis of Paederus Dermatitis may involve the following exams and procedures:

• Physical examination of the individual and medical history evaluation (a history of contact with the rove beetle is essential to establish the condition)
• Blood tests, analysis of pus, culture of the fluid being drained (for causative pathogen), as needed
• Dermoscopy: Dermoscopy is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
• Skin biopsy (if necessary): A skin tissue biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. A biopsy is seldom needed

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Paederus Dermatitis?

The possible complications due to Paederus Dermatitis include:

• Emotional stress due to cosmetic issues
• Superimposed bacterial and fungal skin infections; cases of bacterial infection by Pseudomonas sp. is reported
• Sometimes, a vast stretch of skin may be involved showing skin shedding and ulceration
• Increased skin pigmentation may be noted after the condition resolves
• Permanent scarring
• Treatment complications

How is Paederus Dermatitis Treated?

The treatment measures available for Paederus Dermatitis include:

• Washing the affected skin area with large amounts of water and mild soap
• Use of cold compress
• Application of topical steroids
• Application of antiseptic creams such as tincture iodine
• Use of moisturizing and soothing creams such as calamine lotion
• Topical anesthetics may help relieve the symptoms of pain and discomfort
• Treating secondary infections via antifungal or antibiotic creams, if required
• Oral medications, if prescribed

Regular follow up visits with the healthcare provider is recommended.

How can Paederus Dermatitis be Prevented?

Paederus Dermatitis may be prevented by considering the following steps:

• Immediately washing the skin area with mild soap and water, which came into contact with the rove beetles
• If the rove beetles are found on the body, gently remove them without directly touching or crushing the insects. The insects may be transferred (walked) onto a piece of paper or blown off
• Using fly meshes on doors, windows, and ventilator openings, where possible
• Using nets while sleeping
• Since the insects are attracted to lights, turning them off while sleeping is helpful in reducing the risk for the condition

What is the Prognosis of Paederus Dermatitis? (Outcomes/Resolutions)

• The prognosis of Paederus Dermatitis is generally good with adequate treatment, although it may take a few weeks for the condition to resolve
• However, post-inflammatory scarring or increased skin pigmentation may be noted

Additional and Relevant Useful Information for Paederus Dermatitis:

• Paederus Dermatitis is not caused by the blister beetle, another beetle that causes blister beetle dermatitis through the secretion of a chemical called cantharidin

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/skin-disorders/