Abstract

Objective:

To review the published literature on parasitic infections of external eye.

Methods:

Published articles and case reports on parasitic infections of external eye were reviewed and relevant information was collected.

Results:

Parasitic infections of the eye are rare. However, being more commonly seen in developing nations, they require active measures for screening, diagnosis, and therapy. Parasites of importance causing external ocular disease are protozoan parasites, such as Leishmania; metazoans, such as nematodes (roundworms), cestodes (tapeworms), and trematodes (flatworms); or ectoparasites, such as Phthirus pubis and Demodex.

The dermoscope allows physicians to examine the macroscopic and microscopic primary morphology of skin lesions, identify subtle clinical clues, confirm naked-eye clinical diagnoses, and monitor treatment progress while posing little threat to the young patient. This review summarizes important dermoscopic structures seen in infectious and inflammatory skin conditions and hair disorders in children. Scabies, pediculosis, phthiriasis, molluscum contagiosum, tinea nigra, and verrucae are well characterized dermoscopically by delta-shaped structures, ovoid-shaped nits, the crab louse, red corona, brown strands or spicules, and multiple densely packed papilla with a central black dot surrounded by a whitish halo, respectively. These dermoscopic structures will be discussed, focusing on the dermoscopic morphologies and dermoscopic sensitivity for diagnosis and its utility in monitoring treatment progress. Dermoscopy has also been shown to significantly improve the clinician's diagnostic and monitoring accuracy of inflammatory skin lesions such as psoriasis, which is characterized dermoscopically by uniformly distributed dotted blood vessels, and lichen planus, which is characterized by whitish lines on a purple to reddish background. Dermoscopy of the hair and scalp (trichoscopy) facilitates the differential diagnosis of hair diseases in children, including alopecia areata, trichotillomania, and tinea capitis. It can also assist in the diagnosis of multiple genetic hair shaft disorders, such as monilethrix, trichorrhexis invaginata, trichorrhexis nodosa, pili torti, and pili annulati.

A 70-year-old woman came to ophthalmology outpatient department with complaints of repeated episodes of itching, redness and watering in both eyes of 3 months duration. She was treated with antibiotics elsewhere but had no improvement. Slit lamp examination showed lice and nits anchored to the eyelashes. Light microscopic examination of the matted eye lashes and crusts further helped in identification of the ectoparasites as Phthirus pubis (Pubic louse or Crab louse) with typical morphology.

We describe a case of chronic conjunctivitis related to phthiriasis palpebrarum. A 36 year-old female presented with gradual pruritus and painless ocular hyperaemia over the previous 3 months. On examination, nasal pterygium, conjunctival hyperaemia, oedema, and mild hypertrophy of the palpebral margin were observed. A slit-lamp examination revealed numerous creamy oval structures approximately 1 mm in diameter localised in the middle area of the lashes, and bloody crusts and a semi-transparent deposit were present in the superior palpebral margin. Based on the observation of numerous nits at the base of the eyelashes and the ectoparasite in the palpebral margin, a diagnosis of phthiriasis palpebrarum was made. The patient was referred to an infectologist for evaluation of other sexually transmitted diseases and examination of other body areas. She was successfully treated with oral ivermectin, shampoo for ciliary hygiene and artificial tears. Other recommendations to avoid re-infestation were made, such as changing, washing and sterilising clothes, towels and sheets daily. This report emphasizes the importance of the correct diagnosis and management of this disease, considered as sexually transmitted.

The diagnosis of human phtiriasis (often referred to as the "crab" or the "pubic louse") can be more difficult than other types of pediculosis (Pediculus corporis and Pediculus capitis) because this insect has a smaller body of 1.2 x 0.8 mm, may be lighter in color, not as mobile and therefore harder to see to the naked eye. Can dermoscopy aid to perform a better analysis of the skin? The clinical experience developed in two patients gives an affirmative answer, moreover adding useful information of insect and its eggs already known to entomologists but never used in dermatological diagnosis. The identification in vivo can distinguish Phthirus pubis from other skin signs while the conical shape of the operculum and the wide fixing sleeve of egg to hair, tells what species of louse is infesting, even if the insect is unavailable or nits are elsewhere from the pubic area. Entodermoscopy, provided that dermatologists have some knowledge of entomology, therefore promises advantages over standard microscopic examination.

This case has been filed as a 21-year old male patient who was diagnosed with P. pubis present in his tibial hair. The agent was not found in body parts of the patient other than both lower extremities. The infestation is thought to stem from using second-hand furniture which had been bought the day before the case developed; as other possible ways of infection such as transmission through the rest of the residents of the house were ruled out in our medical investigation. It is understood that second-hand furniture pieces such as mattresses, quilts, carpets, and sofas might be a source of infection of P. pubis including tibial hair areas. The conclusion is that, in infested people or those who are exposed to such a risk, this possibility should be taken into account.

Transmission of the crab louse Phthirus pubis generally occurs by close body contact. Diagnosis is usually clinical and screening for other sexually transmitted infections (STIs) is indicated. While most evidence is extrapolated from studies of head lice treatments, topical pediculicides are recommended and treatment of sexual contacts is indicated.

Dermatoscopy, also known as dermoscopy, epiluminescence microscopy, or surface microscopy, is a noninvasive technique allowing rapid and magnified (× 10) in vivo observation of the skin with the visualization of morphologic features often imperceptible to the naked eye. Videodermatoscopy (VD) represents the evolution of dermatoscopy and is performed with a video camera equipped with lenses providing higher magnification (× 10 to × 1000). Over the past few years, both dermatoscopy and VD have been demonstrated to be useful in a wide variety of cutaneous disorders, including ectoparasitic infestations, cutaneous/mucosal infections, hair and nail abnormalities, psoriasis, and other dermatologic as well as cosmetologic conditions. Depending on the skin disorder, both dermatoscopy and VD may be useful for differential diagnosis, prognostic evaluation, and monitoring response to treatment. Nowadays, it represents an important and relatively simple aid in daily clinical practice.