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

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

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

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

• 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).

• 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.

• 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, metronidazole; other treatments include diloxanide, tinidazole.

• Balamuthia mandrillaris can infect immunocompetent (especially children) and immunocompromised patients; the typical cutaneous lesion is a slow-growing indurated plaque on the central face with eventual hematogenous spread to the central nervous system.

• Acanthamoeba spp. can cause cutaneous papulonodules and encephalitis in immunocompromised patients.

• Trypanosoma cruzi carried by reduviid (kissing) bugs.

• Endemic in areas of Central and South America.

• Systemic disease that can affect the autonomic nervous system, gastrointestinal tract, and heart.

• Primary acute phase: local erythema and edema at inoculation site ± regional lymphadenopathy; when periorbital, termed Romaña sign (Fig. 70.8).

• Chronic phase seen after years to decades: congestive heart failure, arrhythmias, including heart block, megacolon, megaesophagus.

• Vector = tsetse fly.

• Found in both West (Trypanosoma brucei gambiense) and East (Trypanosoma brucei rhodesiense) Africa.

• Skin findings: trypanosomal chancre (localized bite reaction; Fig. 70.9) and annular erythematous eruption with fever.

• Winterbottom’s sign – enlargement of nodes of posterior cervical triangle – classic finding in West African form.

• Worldwide infection secondary to Toxoplasma gondii; oocytes present in cat feces or infected meat.

• Rare skin involvement; congenital infections present with necrotic or hemorrhagic papules on the trunk (‘T’ in TORCH complex).

• Common presentations include cervical lymphadenitis or chorioretinitis.

• Tissue cysts may lead to recrudescence in immunosuppressed individuals.

• Secondary to larvae of animal (e.g. usually wild/domestic dogs/cats) hookworms (intestinal nematodes), e.g. Ancylostoma braziliense.

• Worldwide, but especially common in tropical/subtropical areas and the southwestern United States.

• Larvae in infected soil, including sand, penetrate the skin.

• Pruritic, inflamed, serpiginous tracks are produced by migrating organisms (Fig. 70.10); migration averages 1–2 cm/day.

• Most common locations are the lower extremities, especially the feet, and buttocks, due to walking and sitting at the beach.

• DDx: not to be confused with larva currens (secondary to Strongyloides; see Table 70.2).

• Disease is self-limited but treatment can include oral albendazole or ivermectin; topical thiabendazole for localized disease.

• Secondary to Onchocerca volvulus, a tissue-dwelling nematode.

• Vector = black fly (Simulium).

• Endemic in Africa, Yemen, and some areas of Central and South America; near fast-flowing rivers.

• Skin findings: subcutaneous nodules containing adult worms (onchocercomas), pruritic papular dermatitis, depigmented, lichenified skin, especially over the shins (sowda) (Fig. 70.11).

• Chronic ocular involvement leads to sclerosing keratitis, iridocyclitis, and ultimately blindness, hence the name river blindness.

• Rx: oral ivermectin.

• Tissue nematodes (Wuchereria bancrofti or Brugia malayi/B. timori) infect the lymphatic system.

• Vector = mosquito (Culex, Anopheles, Aedes spp.).

• Endemic in tropical and subtropical regions of India, the Americas, and Africa.

• Acute form: lymphangitis and orchitis.

• Chronic form: lymphedema, elephantiasis (the enlarged limb becomes indurated with skin folds and overlying verrucous changes), hydrocele, chyluria.

• Complicated by recurrent cellulitis.

• Trematode (fluke) infection secondary to three major species with specific geographic distributions (Africa – Schistosoma hematobium, Asia – S. japonicum, South America – S. mansoni); intermediate host is the freshwater snail; organisms penetrate skin.

• Variants of cutaneous disease – cercarial dermatitis (transient erythema, urticaria, or pruritic papules), Katayama fever (systemic allergic reaction with urticaria, fever, chills, sweats, headache, peripheral eosinophilia).

• Chronic fibro-occlusive disease in the liver (S. japonicum), intestine (S. mansoni), or urinary tract (S. hematobium).

• Cercariae of >20 species of animal schistosomes (e.g. Ornithobilharzia) can penetrate skin and cause swimmer’s itch.

• Worldwide; endemic to the Great Lakes.

• Erythematous papules on exposed skin (Fig. 70.12).

• Self-limited (7–10 days).

• Not to be confused with seabather’s eruption (secondary to Linuche, Edwardsiella spp.), which affects areas under the swimsuit (see Chapter 72).

• Cestodes (tapeworms; e.g. Taenia solium) that more commonly infect animals may infect humans; spread from ingestion of contaminated meat or fecal–oral spread.

• Skin findings: small, asymptomatic papulonodules.

• May have systemic involvement of the brain, eye, heart, muscles, or peritoneal cavity.

• Cestode (tapeworm Echinococcus) that usually infects dogs; spread from ingestion of contaminated dog feces.

• Human may be an intermediate host and develop liver or lung hydatid cysts.

• Rarely leads to urticaria, asthma, or anaphylaxis.

• Due to ingestion of raw or poorly cooked fresh water fish (e.g. ceviche) and eels or frogs that contain larvae of Gnathostoma spp. (nematodes).

• Transient subcutaneous swellings that may be pruritic are due to migration of the larvae.

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

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

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

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

• 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).

• 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.

• 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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