Parasitic worms, also known as helminths, are a leading cause of global morbidity and mortality, particularly in low-income and resource constrained regions. More than 1 billion people in developing areas of sub-Saharan Africa, Asia, and the Americas are infected with one or more helminth species.1 The helminths causing human disease include the nematodes (roundworms) and the platyhelminths (flatworms). The platyhelminths are further subdivided into the cestodes (tapeworms) and the trematodes (schistosomes and other flukes).
Individuals with helminthic infections of the lung often seek medical advice due to cough, chest pain, or shortness of breath. They may have unexplained laboratory abnormalities (eosinophilia) or imaging abnormalities (nodule or a mass). In non-endemic areas, they pose a diagnostic challenge given their overlap with other clinical syndromes. A thorough history that includes travel to or long-term residency in endemic areas as well as environmental or dietary exposure are key to the diagnosis. Helminthic infections of the lung may be categorized by their principal clinical presentation (Fig. 136-1). Once the diagnosis is suspected, clinicians must pursue appropriate diagnostic testing to direct therapeutic intervention (Table 136-1). Herein we outline a diagnostic approach to suspected pulmonary disease caused by helminths, followed by review of the most common helminths affecting the respiratory system.
Approach to the diagnosis of suspected pulmonary helminthic diseases.
TABLE 136-1Treatments for Helminthic Pulmonary Diseases ||Download (.pdf) TABLE 136-1 Treatments for Helminthic Pulmonary Diseases
|Parasite ||Therapies ||Comments |
|Ascaris lumbricoides ||Preferred: albendazole 400 mg orally as a single dose Alternate: mebendazole 500 mg orally as a single dose or 100 mg twice daily for three days ||Antihelminthic treatment is only effective against adult worms in the intestinal phase. |
|Ancylostoma duodenale Necator americanus ||Preferred: albendazole 400 mg orally as a single dose Alternate: mebendazole 500 mg orally as a single dose or 100 mg twice daily for three days ||Antihelminthic treatment is only effective against adult worms in the intestinal phase. |
|Strongyloides stercoralis ||A single dose of ivermectin (200 µg/kg orally) for patients with uncomplicated infection. Oral or parenteral formulations of ivermectin alone or in combination with albendazole have been used for patients with hyperinfection syndrome or disseminated disease. ||Ivermectin is only effective against the intestinal stages of the parasite. |
|Wuchereria bancrofti Brugia malayi ||Diethylcarbamazine (6 mg/kg divided in three daily doses for 21 days) ||Corticosteroids have been used as adjunctive therapy, but clinical trials are lacking to define dose and duration. |
Visceral larva migrans: albendazole 400 mg orally twice daily for 5 days
Ocular larva migrans: albendazole 400 mg orally twice daily for 14 days
|Corticosteroids are recommended for ocular disease or severe visceral disease. |
|Echinococcus granulosus ||The mainstay of treatment for pulmonary hydatid cyst is surgery. Albendazole 400 mg orally twice daily for 3 to 6 months is ...|