Paederus dermatitis is an acute irritant dermatitis resulting from contact with pederin, a hemolymph released when paederus beetles are crushed against the skin. It is characterized by the sudden onset of erythematous, vesiculobullous lesions on the exposed areas and associated with burning, stinging, and itching. The various synonyms include “dermatitis linearis,” “rove beetle dermatitis,” “Staphylinidae dermatitis, “whiplash dermatitis,” and “spider lick dermatitis.” The distribution is worldwide but is mostly reported from hot tropical climate areas. Outbreaks of beetle dermatitis from various regions of India are reported particularly during the rainy months. Sporadic cases are seen in any season. A total of 120 girls residing in residential girl’s hostels attended the D.V.L department during November and December with similar complaints. Data of 3 years from November 2016 to December 2019 were analyzed for epidemiological and clinical features. In statistical analysis, continuous variables such as age and duration are described as range or mean + or – standard deviations. Discrete variables are shown as percentage.
This is a 3-year retrospective study from November 2016 to December 2019 done at D.V.L. Department, Government General Hospital. A total of 120 girls with a history of skin rash of sudden onset and clinical evidence of acute (erythema, edema, vesiculations, and erosion) or subacute (mild erythema and scaling) dermatitis were included in the study. The patients included in this study were all females as they were brought from girls’ residential hostel by their hostel wardens and caretakers. The presence of agricultural areas (paddy fields, corn, and sugar cane) around the area of hostel was noted. Type of hostel buildings, protected with screens, pattern of lighting in the corridors and rooms were enquired and noted as they were risk factors for causing paederus dermatitis.
Paederus dermatitis was diagnosed based on the history and clinical features.
The clinical details of all the patients were recorded using a standard pro forma which included age, sex, duration, history of other members or roommates being affected, and past history of similar episodes. The caretakers admitted that hostels were surrounded with agricultural fields and paddy harvesting had just begun during this time. They denied any known chemical exposures. The description given by the students and caretakers as small (<2 cm) reddish-brown insect with wings is suggestive of rove beetles.
The cutaneous examination was focused on morphology of the skin lesions, pattern, number, site, and extent of involvement. Systemic features such as constitutional symptoms – fever, malaise, and lymphadenopathy were also noted. Based on the severity, they were treated with antihistamines, antibiotics, and topical corticosteroids on the affected area. Patients were followed up for 2 weeks, and all lesions healed without sequelae in 7–10 days. They were advised to close windows, keep protective screens, and stay inside the rooms during the night.
In our study of 120 cases, all were girls residing in girls’ hostels located in outskirts of Nizamabad near paddy fields. The age ranged from 10 to 16 years with a mean age of 14.2 years. The majority (83.3%) of patients presented to the hospital during November and December (harvesting months), and isolated cases (16.6%) were reported randomly throughout the year.
All of them had history of sudden onset of skin rashes overnight or early morning of the next day and contact with beetles. The description given by the patients, small (<2 cm) reddish-brown insect with wings was suggestive of rove beetles, although they were not able to procure them.
Most of the patients presented within 48–72 h onset of lesion. The mean duration of symptoms was 4 days. The common complaints were burning sensation and itching. Facial involvement was significant and observed in 99 (82.5%) cases. In addition to the face, other sites affected were the neck in 82 (68.3%), forearms in 41 (34.16%), and upper trunk in 30 (25%) patients. Diffuse facial involvement was noted in 64 (64.6%) and localized facial involvement in 35 (35.4%).
In the majority of the cases, diffuse erythema, fine scaling, and patchy exfoliation were the predominant features [Figures 1-4] and minimal crusting also noted in few cases [Figure 5]. Erythema, edema, scaling, and crusting mimicking subacute eczema [Figure 6] were observed in few cases.
Paederus dermatitis is an irritant contact dermatitis which occurs when beetles of Paederus genus are crushed on the skin and releasing the hemolymph pederin. The genus Paederus belongs to the family Staphylinidae (rove beetles) and order Coleoptera (beetles).
They are small, elongated 5–10 mm long with dark orange bodies and blackheads, tips of the abdomen, and front wings.
Paederus dermatitis is more common in tropical and subtropical regions worldwide. Sporadic cases are seen in any season when the insect is active, but large outbreaks are reported particularly during the rainy months. Outbreaks of Paederus dermatitis have also been reported in various countries including India. The most important Indian species are Paederus fuscipes, Paederus irritans, Paederus sabacus and Paederus himalayicus.
Major clustering of cases has been reported between March to May and August to October. This type of seasonal variation has been attributed to the breeding patterns of the insects and the relation of the insect population to rainfall.
Other documented risk factors for paederus dermatitis are living in forested areas, using artificial, especially fluorescent light, sleeping with the windows open, and not using bed nets. At night, bright light sources attract the flying beetles from their habitats to human localities, these findings were established in a study conducted in Malaysia.
The classical paederus dermatitis is characterized by sudden onset of burning or stinging sensation with the appearance of vesicles and pustules on erythematous and edematous base with subsequent crusting and desquamation. The other morphological patterns described are dermatitis linearis, localized pustular dermatitis, kissing lesions, and erythematous patches with pustules and erosions. An atypical variant characterized by diffuse erythematous and desquamative lesions predominantly occurring in the upper body and face also described in the literature. The various possible causes for this atypical variant mentioned in the literature are contact with a different species of Paederus, recurrent contact during a short period, existing atopic dermatitis or atopic diathesis, and immunologic reaction resulting in the eczematous pattern. Extensive skin involvement can be sometimes associated with systemic symptoms.
Commonly the exposed parts of the body such as the face, neck, and arms are affected. Periocular lesions frequently occur secondary to transfer of pederin by the fingers or direct contact with periorbital skin. The common ocular presentation is unilateral periorbital dermatitis with or without keratoconjunctivitis, known as “Nairobi eyes.” Edema, conjunctivitis, and excess lacrimation are common symptoms.
Paederus dermatitis may affect either sex or age. In our study, all the cases were girls as they were brought from girls’ residential hostels. Age of the patients in this study group ranged from 10 to 16 years with a mean age of 14.2 years.
In our study, the majority of the cases were presented from mid-November to the end of December. Rice harvesting season in this area indicates a distinct seasonal trend in (83.3%) of cases. Very few isolated cases (16.6%) are reported randomly throughout the year.
Outbreaks of paederus dermatitis during November and December in the past 3 years coincide with the harvesting season which could be explained by variations in habitat specificity. In contrast to the previous studies, we observed a rise in incidence during the early winter season (November and December). Various investigators from different parts of India have reported different patterns of incidence: March to July in Orissa, April in South India, the postmonsoon season in Rajasthan, and July in Punjab indicating that the pattern may vary in different geographical and climatic zones of the country.
Several authors have opined that proximity to paddy fields where the insects may be found in large numbers could be an important factor in outbreaks of the disease. Similar observations were reported by Handi et al., Padhi et al., and Gnanaraj et al. where the maximum number of cases occurred in November and December constituting up to 92% of all cases. In a study by Coondoo and Nandy, two spikes were noted during April and November. In Padhi et al.’s study, maximum cases were noted from March to July. The risk factors based on history were that hostel was surrounded by agricultural fields and paddy harvesting was done during November and December. The doors of the rooms and windows were not screened to prevent the entry of insects. Fluorescent lamps used for lighting in the hostel rooms and corridors attract beetles.
In our study, the face and neck was predominantly affected in 82 (68.3%) cases, followed by forearms in 41 (34.16%) cases which were similar to Gopal et al.’s study, where head and neck were the most commonly affected site (38.60%), followed by the upper extremity (24.40%). In various studies from Sierra Leone (Qadir), Sri Lanka, and India exposed body parts such as the head, neck, and upper extremities were most commonly affected. A similar observation was made in a study on 77 cases of beetle dermatitis in Punjab by Handa et al. and in a study by Padhi et al., Gnanaraj et al., and Kalla et al. Lesions were mainly detected on the face, front of the neck, and upper back. Contact with insects was reported during the nighttime while walking through corridors. Washrooms were located away from the rooms, and walking through corridors or open areas during nighttime was the main cause of paederus dermatitis in our study.
In our study, the most common clinical presentation is diffuse erythema, scaling and minimal crusting, and persistent exfoliation (desquamative lesions) involving the face and upper back mimicking subacute eczema which was described as atypical variant in Todd et al.’s study and other studies.
Preventive measures include reducing the insect population in the surroundings. Furthermore, advised to keep doors and windows screened and closed at night to minimize exposure. In case of exposure, gentle removal of the insect from the skin, wash the pederin-contaminated area with plenty of water, and avoid touching their eyes.
Species identification of the paederus beetles was not done. Furthermore, a histopathologic examination was not done.
An atypical variant of paederus dermatitis was observed in the majority of the cases with diffuse erythematous and desquamative lesions predominantly involving the face and neck. Awareness about varied clinical features will help in early diagnosis and to undertake preventive measures.
Declaration of consent
The authors certify that they have obtained all appropriate consent forms, duly signed by the parent(s) of the patient. In the form the parent(s) has/have given his/her/their consent for the images and other clinical information of their child to be reported in the journal. The parents understand that the names and initials of their child will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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