Indian Journal of Dermatology
: 2013  |  Volume : 58  |  Issue : 5  |  Page : 337--341

Epidemiological study of insect bite reactions from Central India

Sumit Kar, Atul Dongre, Ajay Krishnan, Swati Godse, Neha Singh 
 Department of Dermatology, Venereology and Leprosy, MGIMS, Sevagram, Maharashtra, India

Correspondence Address:
Sumit Kar
Department of Dermatology, Venereology and Leprosy, MGIMS, Sevagram - 442 102, Maharashtra


Introduction: The physical effects of the arthropod bites on human skin receive less attention, especially in the rural areas where the per capita income is less. Ours is a rural-based hospital, the vicinity having more of plants, trees, and forests; we undertook the study to find out the relation of insect bite dermatitis in a rural area. Materials and Methods: The study was carried out in the Dermatology outpatient department of our institute on 100 subjects of insect bite dermatitis who were questioned retrospectively about the sequence of events besides their environmental and living conditions. They were examined thoroughly and the relevant clinical findings were noted, also taking into account the prior treatment taken by them, if any. Results and Conclusions: It was found that insect bite dermatitis has no age or gender preponderance, and the protective factors for the same are use of full sleeve clothes and keeping the doors and windows closed at night. On the contrary, the risk factors are residence in areas of heavy insect infestation, use of perfumes and colognes, warm weather in spring and summer and the lack of protective measures. However, there was no direct association of atopy with increased risk of developing insect bite dermatitis.

How to cite this article:
Kar S, Dongre A, Krishnan A, Godse S, Singh N. Epidemiological study of insect bite reactions from Central India.Indian J Dermatol 2013;58:337-341

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Kar S, Dongre A, Krishnan A, Godse S, Singh N. Epidemiological study of insect bite reactions from Central India. Indian J Dermatol [serial online] 2013 [cited 2023 Feb 5 ];58:337-341
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Whether we are hiking in the mountains or playing in our backyard, we run the risk of exposure to the offended arthropods. The number of skin disorders caused by arthropods varies from trivial bites and stings to severe systemic reactions and even death. [1],[2] Arthropods produce an injury to the skin by a variety of mechanisms; one or more of which may be involved in an individual case. [3] Moisture, warmth, carbon dioxide, estrogens and lactic acid in sweat are among various factors that have been found to attract mosquitoes. [4] The important species that molest man belong to 4 families: Apidae, Bombidae (bees), Vespidae (wasps), Formicidae (ants). Population studies suggest that approximately 1/3 rd of the individuals suffering from systemic reactions have a personal history of atopic disease. [5],[6] Large local reactions are swellings exceeding a diameter of 10 cm and lasting longer than 24 hrs, with an occasional blister. [7] Certain occupations may carry an increased risk of reactions to arthropods. [8] Forestry workers, for example, may be exposed to the urticating hair of caterpillars of certain species of Lepidoptera, and dock workers handling food stuffs may be attacked by mites infesting the cargo. [9] Also, pregnant women appear more attractive to mosquitoes than the non-pregnant. [10]

 Materials and Methods

The study was conducted on 18,523 routine patients visiting Dermatology outpatient department of our institute, which included 100 patients of insect bite dermatitis and spanned over a period of 11 months from January 2010 to November 2010. All patients visiting the Dermatology outpatient department of our institute were assessed for insect bite dermatitis and were subsequently asked a pre- modulated questionnaire. Patients with diabetes mellitus, hypertension, and pregnant women were excluded from the study. The results were tabulated and assessed using EPI INFO 6 software.


Individuals vary widely in their response to the bite of a particular insect, but for the most bites of different species, there is a high degree of similarity. Accordingly, it is difficult to determine the responsible species on the basis of the appearance of the lesion. There are, however, important clues that a particular eruption is probably caused by an insect. The frequency of chief complains of itching, burning, and pain as per the questionnaire used in our study stratified by gender was 84.4%, 13.3%, 2.2% in males and the corresponding figures for female patients were 81.8%, 7.3%, 10.9%, respectively.

The distribution of duration of complaints stratified by different complaints was 8.4% and 91.67% keeping itching as the chief complaint in cases with duration more than 1 month and duration less than 1 month, respectively. The corresponding figures for chief complains of burning and pain were 0%, 10% and 0%, 7%, respectively. The gender-wise distribution for insect bite dermatitis was 45% in males and 55% in females (not statistically significant). Itching was the main chief symptom that was complained by majority of our patients and the most common sites were the exposed areas of skin like forearms, arms and legs [Table 1].{Table 1}

Use of blankets at night was reported in 49% of patients in our study. Most of the patients in our study (86%) slept in the bed rather than over the floor (14%). Majority of patients in our study had electricity facilities at home, and lights or fans were on in the night in 95% cases.

The use of an insect repellent was reported only in 35% cases as against 65% patients who did not use any insect repellent. The surrounding of the homes of the patients were plants in 56% cases and trees and cow dung in 37% and 5% of cases, respectively. Two of our study cases did not reveal the surroundings of their home. Keeping of domestic animals at home was reported in 32% of our study cases (cat 8%, dog 11%, cow 9% and bull 4%).

Among all the patients reporting to the OPD for insect bite dermatitis, 33% cases knew the cause being an insect bite and 32% cases had seen the insect. Mosquito nets were used by 12% cases in our study. The suspected time of an insect bite stratified by gender was at night in 20% male patients and in 21% female patients. 13%of male patients reported insect bite while in sleep and the corresponding figure for female patients was 15%. Morning time, day time, and evening time cases were 2%, 0%, 9% in case of males and in females the reported figures were 6%, 1% and 12%, respectively.

History of atopy (personal and family) was reported in 2% and 10% cases respectively while 88% cases had no relation to atopy. When asked about the history of an insect bite in family members in the past 24 hours; 10% cases reported a positive history.

The windows were closed in 79% cases as against open ones in 21% of the cases. The housing conditions of 89% of our study cases were pukka while kuchha in the rest 11% of the cases.

There has been no marked variation in symmetry of distribution of itching as unilateral itching was reported in 43% cases as against 40% cases who had bilateral itching complaints. Majority of the patients had discrete configuration of the lesions (58%) [Figure 1] and [Table 2].{Table 2}{Figure 1}

Majority of patients in our study had erythema, papule, or papulo-vesicle over the site of insect bite, followed by others who had the diagnostic insect bite mark over the skin [Figure 2]. Vesicles, bullae, plaques were less so reported in our patients [Table 3].{Table 3}{Figure 2}

Tenderness of Lesion

Tenderness of the lesions was reported in 22% of our cases as against 78% of those who had no tenderness. Hence, the chief manifestation of insect bite dermatitis is an itching rather than pain.

Treatment History

Amongst our study cases those visiting the skin OPD, 18% cases had already taken some or other form of prior treatment.


Of the 30 or so orders of insects, only a few have significance for dermatologists like Anoplura (lice), Diptera (flies, mosquitoes), Cleoptera (beetles), Hemiptera (bedbugs, kissing bugs), Siphonaptera (fleas), Hymenoptera (ants, bees, wasps), and Lepidoptera (butterflies and moths). Insects can be distinguished from other arthropods by the presence of 3 body segments, a pair of antennae, and 6 legs. Insect bite dermatitis needs to be differentiated from other dermatological conditions like atopic dermatitis, contact dermatitis, impetigo, mycosis fungoides, scabies etc. There have been reports of patients developing a generalized reaction to an insect bite as with the bites of sand fly, chigger bite, ticks, kissing bugs, etc., but none such case was reported in our study. [11] The initial dermatitis caused by an insect bite may rarely become an inciting factor for other grave condition as was observed in one of the pediatric patients referred to our OPD who developed purpura fulminans over the site of previous insect bite [Figure 3]. Another case wherein insect bite as an initial lesion provoked Kaposi's sarcoma with oral lesions has been on the records. [12] Anaphylaxis may be a dreaded complication of insect bite dermatitis; however, unusual presentations have been on the records, wherein wasp stings are known to be associated with Type 1 renal tubular acidosis. [13] Multiple organ dysfunction syndrome (MODS) following single wasp sting has been reported in a 12-year-old child who died after a single wasp sting. [14] On the other hand, patients with trivial manifestations of insect bite may not visit a health care provider and may seek the help of Poison Control Cells over a tele-conference as in the United States. [15] However, such a concept is yet not prevalent in a rural set-up like ours where we conducted our study and people choose to follow home remedies or simply ignore a trivial insect bite.{Figure 3}

Arthropod-related skin diseases have been reported in frequent travelers up to the extent of 31% of all skin diagnosis and insect bite including super infected bites, abscesses, and allergic reactions account for 38% of the cases. However, such a co-relation was not a part of our study.

Majority of the patients in our study had discrete configuration of lesions. Bedbug bites, for example, are usually multiple, painless and linear in configuration. A row of 3 beg bug bites is sometimes referred to as breakfast, lunch, dinner sign. [16]

Another uncommon yet interesting aspect that arises out of diagnosing insect bite dermatitis is the similarity it may pose with other dermatological conditions. One such case, which has been notified, is caterpillar dermatitis which was misdiagnosed as guttate psoriasis in a 7-year-old female child who presented with papule and erythema, which increased in size from rice grain to bean size with scaling over the surface, the lesions gradually being spread to involve the trunk and the limbs.

Also, vice versa holds true wherein other dermatological conditions can be misdiagnosed as insect bite dermatitis. A case, which is noteworthy in this regard, comes from Japan in a 56-year-old lady who had skin candidiasis but was wrongly diagnosed as to have poisonous moth dermatitis. [17]

Kalisperumal et al., in a study conducted in JIPMER, Pondicherry in 2003, have reported that the proportion of pediatric patients visiting Skin OPD for insect bite dermatoses was 5.27% of the total number of cases. The corresponding figures for our study were 10.21%, thus making it evident the increased propensity of insect bite dermatitis in a rural area like ours as compared to that in South India. [18]

An itch can be cutaneous (pruritoceptive, e.g.: Dermatitis), neuropathic (e.g.: Multiple sclerosis), neurogenic (e.g.: Cholestasis), mixed (e.g.: Uremia) or psychogenic. Although an itch of cutaneous origin shares a common neural pathway with pain, the afferent C fibers subserving this type of pain are a functionally distinct subset since they respond to histamine, acetylcholine and pruritogens but are insensitive to mechanical stimuli. Histamine is the main mediator of itch in insect bite reactions and in most forms of urticaria. In these circumstances, the itch responds well to H 1 anti-histamines. Certain species cause lesions over specific sites, which aid in diagnosis as in the case of sand flea (Tunga penetrans), the causative agent of Tugiasis where the lesions occur exclusively over the feet. Also, response to bites is somewhat dependant on the body site, those on the lower legs tending to be more severe and more persistent.

Although insect bite reactions are mostly transient, papules and nodules occasionally persist for long periods, sometimes as a result of unrestrained scratching. The morphology of the lesions varies with the order of the causative insect, which is usually typical in any particular case and may rarely pose difficulty in diagnosis. For example, in case of Hymenoptera stings, burning and pain are the usual chief complaints followed by the development of an intense local erythematous reaction with swelling and urticaria. Many species of beetles contain chemicals that cause blistering of human skin as in the case of Spanish fly (Lytta vesicatoria) that contains the chemical cantharidin, which causes vesiculation of skin. Graif et al. in their study on school children found that there is an increased incidence (36.9%) of allergic reactions to insect stings in children with any of the atopic diseases as compared to their counterparts (24.8%). [19] However, such an association was not found in our study as only 2% cases had a positive history of atopy.

We would like to conclude our study with certain facts and figures; for example, insect bite dermatitis has no age or gender preponderance. Most cases of insect bite occur at night when patients are asleep. There is no lymph node involvement in insect bite dermatitis. The usual sites of insect bite are the exposed areas of the skin, more so in the case of flying insects like mosquitoes and flies, and the lesions tend to be unilateral in majority of the cases. On the contrary, trunk may be involved in case of bedbugs or blister beetle bites, which may be unilateral or bilateral. The morphology of lesions involved in insect bite dermatitis is usually discrete rather than being linear or grouped. Insect bite dermatitis was found to be more common in people residing in the vicinity of forests owing to the increased risk of exposure to the insects. Also, keeping of the pets at home proved to be a predisposing factor for insect bite dermatitis. Yet another set of risk factors include residence in area of heavy insect infestation, warm weather, spring and use of perfumes and colognes.

The use of insect repellents, keeping the doors and windows closed at night, using full sleeve clothes and blankets while sleeping were all found to be preventing factors for insect bites.


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