Protozoa and Worms

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Protozoa and Worms

Leishmaniasis

• Three major forms: (1) cutaneous (Fig. 70.1); (2) mucocutaneous (Fig. 70.2); and (3) visceral (e.g. liver, spleen).

Fig. 70.1 Variable presentations of cutaneous leishmaniasis. Ulcerated plaques with rolled border (A) and central crusting (A, B). Plaque with translucent borders containing telangiectasias and central scarring (C). Cutaneous leishmaniasis is sometimes mistaken for a basal cell carcinoma in adults. A, C, Courtesy, Julie V. Schaffer, MD.

Fig. 70.2 Mucocutaneous leishmaniasis. Ulceration and induration of the nasal vestibule extending onto the cutaneous lip due to Leishmania braziliensis. Courtesy, Kalman Watsky, MD.

• Caused by more than 15 different species of Leishmania (Table 70.1).

Table 70.1

Four major species of Leishmania that cause cutaneous disease.

^* Can also cause mucosal leishmaniasis or visceral leishmaniasis in immunocompromised individuals.

• Vector = sandfly (Phlebotomus and Lutzomyia spp.) (Fig. 70.3).

Fig. 70.3 Life cycle of Leishmania species. Promastigotes develop within the gut of the sandfly and then migrate to the proboscis.

• Disease seen worldwide but endemic in areas of Asia, Africa, Latin America, and the Mediterranean basin (Fig. 70.4).

Fig. 70.4 Distribution of cutaneous leishmaniasis. Adapted with permission from Davidson RN, Leishmaniasis. In Cohen J, Powderly WG (Eds.), Infectious Diseases. Edinburgh, UK: Mosby, 2004.

• Cutaneous disease affects skin only and is commonly a papule that expands and ulcerates (Fig. 70.5); pattern may be sporotrichoid (Fig. 70.6); lesion(s) may heal spontaneously (Fig. 70.7).

Fig. 70.5 Ulcerated nodule with rolled border. Courtesy, Omar P. Sangüeza, MD.

Fig. 70.6 Sporotrichoid form of cutaneous leishmaniasis. With permission from Tyring S, Lupi O, Hengge U (Eds.), Tropical Dermatology. Oxford: Churchill Livingstone, 2005.

Fig. 70.7 Scars secondary to previous cutaneous leishmaniasis. Circular scars at previous sites of cutaneous leishmaniasis are often the only sign of a prior infection. Courtesy, Omar P. Sangüeza, MD.

• Mucocutaneous form, often due to Leishmania brasiliensis, involves mucosal (e.g. nose, lips, oropharynx) sites as well as the skin.

• Visceral leishmaniasis (kala-azar) affects the bone marrow, spleen, and liver and is commonly due to Leishmania donovani; symptoms include fever, cough, lymphadenopathy, and hepatosplenomegaly; post-kala-azar dermal leishmaniasis may follow treatment.

• Rx: for an isolated lesion, conservative therapy (e.g. observation, heat, cryotherapy) or topical paromycin can be used; for more extensive disease, IV or IM pentavalent antimony (sodium stibogluconate, meglumine antimonate), oral miltefosine.

• For assistance in diagnosis and treatment, helpful sources of information include the Centers for Disease Control and World Health Organization.

Amebiasis

• Protozoan infection (Entamoeba histolytica) that most commonly causes colitis; fecal–oral spread.

• Occasionally presents in the skin with necrotic ulcers that can resemble pyoderma gangrenosum or verrucous plaques that resemble squamous cell carcinoma or condyloma acuminatum.

• Skin involvement generally secondary to extension of rectal amebiasis to perianal or perigenital skin or extension of a liver abscess to skin of abdominal wall.

• Rx: for Entamoeba histolytica

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