Illustration of Flea Allergy Dermatitis and Cat Flea Entomology Through Description of an Outbreak Among the Hostel Inmates in Mizoram

Background: Flea allergy dermatitis (FAD) manifests due to bites or contact with cat flea or dog flea, their faeces or debris. FAD due to cat flea results in extremely pruritic skin lesions. Cat fleas can also act as a vector for multifarious infectious pathogens. The reports on FAD in humans are very scarce, and there are no such reports from India. Aims and Objectives: To illustrate an outbreak of flea allergic dermatitis (FAD) among hostel inmates in Mizoram, and to describe the entomology of the cat flea, the characteristic patterns and clinical presentation of FAD, as well as the appropriate control and preventive measures. Methodology: The investigators visited the hostel premises to obtain detailed history, examine all the hostel inmates, to perform environmental assessment, and to collect samples from the stray cats and the surfaces. This on-site visit and assessment were preceded by the clinical visit of two cases of cat flea allergy dermatitis who conveyed the fact that many inmates in their hostel had a similar problem which was of recent onset. Necessary treatment measures and flea elimination strategy were also explained to the inmates and the hostel authorities. Results: Twenty-two (out of 39) inmates developed FAD. Pruritus was a predominant symptom. Skin lesions were predominantly erythematous papules, nodules, and wheals. The lower limbs, especially areas below knee were affected predominantly. Lesions persisted for about a week. The surfaces (hostel floors and door mats) were washed with sodium hypochlorite solution. The bed linen and clothes of the hostel inmates were thoroughly washed in hot water. These measures led to the resolution of the outbreak. The microscopic examination revealed adult cat flea, eggs, larvae, and faecal dirt. Conclusion: In this article, we have described various aspects of cat flea entomology, flea allergy dermatitis, its control and preventive measures through the illustration of an outbreak among hostel inmates in Mizoram. There are no published scientific data from India describing this entity. Moreover, cat fleas can act as a vector for transmitting various dreadful pathogens, which further emphasises the importance of identifying this dermatosis aptly.